Descriptions of the ecological criterion of the species. Type and its criteria. Flora in ecological criteria

A species is a collection of individuals that are similar in terms of the criteria of the species to such an extent that they can vivo interbreed and produce fertile offspring.

A fertile offspring is one that can reproduce itself. An example of infertile offspring is a mule (a hybrid of a donkey and a horse), it is sterile.

View criteria- these are signs by which 2 organisms are compared to determine whether they belong to the same species or to different ones.

• Morphological - internal and external structure.
• Physiological and biochemical - how organs and cells work.
• Behavioral - behavior, especially at the time of reproduction.
• Ecological - a combination of factors external environment necessary for the life of the species (temperature, humidity, food, competitors, etc.)
• Geographic - area (distribution area), i.e. the area in which the species lives.
• Genetic-reproductive - the same number and structure of chromosomes, which allows organisms to produce fertile offspring.

View criteria are relative, i.e. one cannot judge the species by one criterion. For example, there are twin species (in the malarial mosquito, in rats, etc.). They do not differ morphologically from each other, but have a different number of chromosomes and therefore do not give offspring. (That is, the morphological criterion does not work [relatively], but the genetic-reproductive one works).

1. Establish a correspondence between the trait of a honey bee and the criterion of the species to which it belongs: 1) morphological, 2) ecological. Write the numbers 1 and 2 in the correct order.
A) social life
B) the difference in the size of males and females
C) development of larvae in combs
D) the presence of hair on the body
D) feeding on nectar and pollen of flowers
E) compound eyes

Answer

2. Establish a correspondence between the trait that characterizes the agile lizard and the species criterion: 1) morphological, 2) ecological
A) the body is brown
B) eats insects
B) is inactive at low temperatures
D) respiratory organs - lungs
D) breeds on land
E) the skin does not have glands

Answer

3. Establish a correspondence between the sign of a quick lizard and the criterion of the species that it illustrates: 1) morphological, 2) ecological
A) winter torpor
B) body length 25-28cm
B) spindle-shaped body
D) differences in the color of males and females
D) living on the edges of forests, in ravines and gardens
E) feeding on insects

Answer

4. Establish a correspondence between the sign of the mole and the criterion of the species to which this sign belongs: 1) morphological, 2) ecological. Write the numbers 1 and 2 in the correct order.
A) the body is covered with short hair
b) very small eyes
C) digs a passage in the soil
D) front paws are wide - digging
D) eats insects
E) breeds in the nesting chamber

Answer

1. Establish a correspondence between the characteristic of the species Wild pig (boar) and the criterion of the species to which this characteristic belongs: 1) morphological, 2) physiological, 3) ecological. Write down the numbers 1, 2 and 3 in the correct sequence.
A) The number of piglets in a brood depends on the fatness of the female and her age.
B) Pigs are active during the day.
C) Animals lead a herd life.
D) The color of individuals is from light brown or gray to black, the piglets are striped.
D) The method of obtaining food is digging the earth.
E) Pigs prefer oak and beech forests.

Answer

2. Establish a correspondence between the characteristic of the common dolphin species (dolphin-dolphin) and the criterion of the species to which this characteristic belongs: 1) morphological, 2) physiological, 3) ecological
A) Predators, they feed on different types of fish.
B) Males are 6-10 cm larger than females.
C) Animals have mastered aquatic environment a habitat.
D) The size of the body is 160-260 centimeters.
E) Pregnancy of females lasts 10-11 months.
E) Animals lead a herd life.

Answer

3. Establish a correspondence between the characteristic of the Asian Porcupine species and the criterion of the species to which it belongs: 1) morphological, 2) physiological, 3) ecological. Write the numbers 1, 2 and 3 in the correct order.
A) Paws are equipped with long claws.
b) Animals eat plants.
C) Pregnancy of females lasts 110-115 days.
D) The longest and sparser needles grow on the lower back of animals.
E) The female secretes milk after the birth of the cubs.
E) Animals are nocturnal.

Answer

4. Establish a correspondence between the signs of the tapeworm and the criteria of the species: 1) morphological, 2) ecological, 3) physiological. Write down the numbers 1, 2, 3 in the order corresponding to the letters.
A) body size up to 3 m
B) on the head, in addition to suckers, there are hooks
C) an adult worm lives in the human small intestine
D) reproduces parthenogenetically
D) larvae develop in the body of domestic and wild pigs
E) pork tapeworms are highly prolific

Answer

5. Establish a correspondence between the characteristics of the blue whale species and the criteria for the species: 1) morphological, 2) physiological, 3) ecological. Write down the numbers 1-3 in the order corresponding to the letters.
A) Females breed every two years.
B) The female produces milk for seven months.
C) Whale lice and barnacles settle on the skin of whales.
D) Whalebone plates are pitch black.
E) The length of some individuals reaches 33 meters.
E) Sexual maturity of individuals occurs at four to five years.

Answer

6. Establish a correspondence between the characteristic of a quick lizard and the criterion of the species to which it belongs: 1) morphological, 2) ecological, 3) physiological. Write down the numbers 1-3 in the order corresponding to the letters.
A) ground type limbs
B) the presence of horny scales on the skin
B) the development of the embryo in the egg
D) laying eggs on land
D) fluctuating body temperature
E) feeding on insects

Answer

1. Establish a correspondence between examples and types of adaptation: 1) morphological, 2) ethological, 3) physiological. Write down the numbers 1, 2, 3 in the order corresponding to the letters.
A) deaf nettle resembles stinging nettle
B) a chipmunk stores food for the winter
C) the bat falls into a state of winter dormancy
D) when threatened, the opossum freezes
D) the shark has a torpedo-shaped body
E) bright coloring of the poison dart frog

Answer

2. Establish a correspondence between the characteristics of organisms and types of adaptations: 1) behavioral, 2) morphological, 3) physiological. Write down the numbers 1-3 in the order corresponding to the letters.
A) knotty stick insect
B) freezing in danger in an opossum
C) crystals of potassium oxalate on the hairs of leaves and shoots of stinging nettle
D) incubation of eggs in the mouth by tilapia
D) bright coloring of poison dart frogs
E) removal of excess water through the kidneys in the form of weakly concentrated urine by crayfish

Answer

Choose one, the most correct option. What characteristic of the species Rosyanka rotundifolia should be attributed to the physiological criterion?
1) the flowers are regular, white, collected in an inflorescence brush
2) uses insect proteins as food
3) distributed in peat bogs
4) leaves form a basal rosette

Answer

Choose one, the most correct option. Find the name of the view criterion in the specified list
1) cytological
2) hybridological
3) genetic
4) population

Answer

1. Select from the text three sentences that describe the ecological criterion of the species. Write down the numbers under which they are indicated in the table. (1) The housefly is a two-winged insect that serves as food for insectivorous birds. (2) Her oral apparatus licking type. (3) Adult flies and their larvae feed on semi-liquid food. (4) Female flies lay their eggs on rotting organic debris. (5) Larvae white, have no legs, grow rapidly and turn into red-brown pupae. (6) The adult fly develops from the pupa.

Answer

2. Read the text. Choose three sentences that describe the ecological criterion of the plant species Pemphigus vulgaris. In your answer, write down the numbers under which they are indicated. (1) Pemphigus vulgaris is mainly found in the Mediterranean region of Europe and Africa. (2) Pemphigus vulgaris grows in ditches, ponds, stagnant and slow-flowing water bodies, swamps. (3) Leaves of plants are dissected into numerous thread-like lobes, leaves and stems are provided with vesicles. (4) Pemphigus flowers from June to September. (5) Flowers are yellow, 5-10 per peduncle. (6) Pemphigus vulgaris is an insectivorous plant.

Answer

3. Read the text. Choose three sentences that describe the ecological criterion of the house mouse species. Write down the numbers under which they are indicated in the table. (1) The house mouse is a mammal of the genus Mouse. (2) Original range - North Africa, tropics and subtropics of Eurasia. (3) Settles mainly near human habitation. (4) Leads a nocturnal and twilight lifestyle. (5) A litter usually has 5 to 7 babies. (6) Under natural conditions it feeds on seeds.

Answer

4. Read the text. Choose three sentences that describe the ecological criteria for the fieldfare thrush species. Write down the numbers under which the selected statements are indicated. (1) Fieldfare thrush is a large bird. (2) Thrushes live in central Russia. (3) Fieldfare thrushes settle along forest edges, in city squares and parks. (4) They feed on the ground, looking for earthworms, slugs and insects under dry leaves and moss. (5) In winter, they feed on the fruits of mountain ash, hawthorn and other berries that ripen on the bushes. (6) Fieldfare thrushes nest in small colonies ranging from 2-3 to several dozen nests.

Answer

5. Read the text. Choose three sentences that describe the ecological criterion of the African ostrich species. Write down the numbers under which the selected statements are indicated. (1) The African ostrich is a large squid weighing up to 90 kg and growing up to 3 m. (2) Lives in open savannahs and semi-deserts, north and south of the zone equatorial forests. (3) The beak is straight, flat, with a horny "claw" on the mandible, the eyes are large - the largest among land animals, with thick eyelashes on the upper eyelid. (4) The legs are powerful, two-toed, the plumage is loose, the barbs of the feathers do not interlock with each other and do not form feather plates. (5) The usual food is plants - shoots, flowers, seeds, fruits, but on occasion it also eats small animals - insects (locusts), reptiles, rodents and the remains of the meals of predators. (6) The African ostrich can go without water for a long time, getting moisture from the plants it eats, but on occasion it likes to drink and likes to bathe.

Answer

6. Read the text. Choose three sentences that describe the ecological criterion for the species of the cabbage white butterfly. Write down the numbers under which they are indicated. (1) The cabbage white butterfly has a mealy-white color on the upper side of the wings. (2) There are dark spots on the front pair of wings. (3) In spring and summer, the butterfly lays its eggs on the leaves of cabbage or other cruciferous plants. (4) The eggs hatch into yellow caterpillars that feed on plant leaves. (5) Caterpillars become a bright blue-green color as they grow. (6) A grown caterpillar crawls onto a tree, turns into a chrysalis, which hibernates.

Answer

7. Read the text. Choose three sentences that describe the ecological criterion of the species Cornflower blue (sowing). Write down the numbers under which they are indicated. (1) Blue cornflower is a weed plant of the Compositae family, found in fields in grain crops. (2) Often the plant lives along roads, near forest belts. (3) An upright cornflower stem reaches up to 100 cm in height. (4) The flowers are bright blue. (5) Blue cornflower is a light-loving plant. (6) The flowers contain essential oils, tannins and other substances.

Answer

Choose one, the most correct option. To apply an ecological criterion to the description of an animal species means to characterize
1) variability of signs within the normal range of reaction
2) a set of external signs
3) the size of its range
4) a set of intended feed

Answer

1. Read the text. Choose three sentences that describe the morphological criterion of the rhinoceros beetle species. Write down the numbers under which they are indicated. (1) The rhinoceros beetle lives in the European part of Russia. (2) Its body is brown. (3) Sexual dimorphism is well expressed. (4) Rhinoceros beetle larvae develop in compost heaps. (5) Males have a horn on their heads. (6) Beetles can fly into the light.

Answer

2. Read the text. Choose three sentences that describe the morphological criterion of the shrub cherry species. Write down the numbers under which the selected statements are indicated. (1) Shrub cherry is a low shrub or small tree 3-6 m high. (2) Brown bark, ellipse-shaped leaves, pointed. (3) Bush cherry is one of the ancestors of common cherry varieties. (4) Grows in Russia in the European part of the country and in the south of Western Siberia. (5) The flowers are white, collected 2-3 in an umbel inflorescence. (6) Cherry blossoms in April-May, and the fruits ripen in early summer.

Answer

3. Read the text. Choose three sentences that describe the morphological criterion for the species of oak veronica. Write down the numbers under which the selected statements are indicated. (1) Veronica oak grows in forest clearings, meadows, hillsides. (2) The plant has a creeping rhizome and a stem 10-40 cm tall. (3) Leaves with serrated edges. (4) Veronica oakwood blooms from late May to August. (5) Pollinated by bees and flies. (6) The flowers are small, blue, collected in a raceme inflorescence.

Answer

4. Read the text. Choose three sentences that describe the morphological criterion of the species Field Sparrow. Write down the numbers under which they are indicated. (1) The field sparrow is distributed throughout Eurasia, excluding the Far North, northeast and southwest Asia. (2) The field sparrow is somewhat smaller than the house sparrow, but has a more slender body, brown crown and black spots on white cheeks. (3) Individuals of the species weigh approximately 20–25 g. (4) Sparrows nest along the edges of groves, in light forests, and parks. (5) The clutch usually consists of five or six eggs. (6) The eggs are white or greyish in color with numerous small dark speckles.

Answer

5. Read the text. Choose three sentences that describe the morphological criterion of the species of Scots pine. Write down the numbers under which they are indicated.(1) Scotch pine is a photophilous plant. (2) When its seed germinates, five to nine photosynthetic cotyledons appear. (3) Pine is able to develop on any soil. (4) Green pine leaves are needle-shaped and arranged in pairs on short shoots. (5) The elongated shoots are arranged in whorls that form once a year. (6) Pollen from male cones is carried by the wind and lands on female cones where fertilization takes place.

Answer

1. Read the text. Choose three sentences that describe the genetic criteria for a species. Write down the numbers under which they are indicated. (1) There are a number of criteria by which one species differs from another. (2) Each species has its own specific karyotype. (3) An important feature of a species is its habitat. (4) In individuals of the same species, chromosomes have a similar structure. (5) Human somatic cells have 46 chromosomes. (6) Most mammals are sexually dimorphic.

Answer

2. Read the text. Choose three sentences that describe the genetic criterion for the Black Rat animal species. Write down the numbers under which they are indicated. (1) It has been established that two species are hidden under the name "black rat": rats with 38 and 42 chromosomes. (2) The black rat lives in Europe, in most countries of Asia, Africa, America, Australia; its distribution is not continuous, but is associated mainly with human dwellings in port cities. (3) The ranges of such species may overlap geographically, and in the same area outwardly indistinguishable individuals of black rats may live side by side without breeding. (4) Differences in karyotype different types provide isolation during interspecific crossing, because they cause the death of gametes, zygotes, embryos or lead to the birth of infertile offspring. (5) In Europe, two races of the black rat are approximately equally distributed, of which one has a typical black-brown fur color, darker than that of the gray rat, and the other is practically blond, with a white belly, similar in color to ground squirrels. (6) Studies of the number, shape, size and structure of chromosomes make it possible to reliably distinguish twin species.

Answer

Choose two correct answers from five and write down the numbers under which they are indicated. Which of the following is not a type criteria?
1) Genetic
2) Biocenotic
3) Cellular
4) Geographic
5) Morphological

Answer

1. Read the text. Choose three sentences that describe the physiological criteria for the type of yellow ground squirrel. Write down the numbers under which the selected statements are indicated. (1) Yellow ground squirrel lives in desert uncultivated lands. (2) The ground squirrel feeds on the succulent parts of the steppe grasses, plant bulbs and seeds. (3) It also eats insects: locusts, grasshoppers, beetles and caterpillars. (4) A female gives birth to an average of seven cubs. (5) During the heat of summer and winter, it hibernates. (6) During hibernation, the body temperature of the animal drops to 1-2 ° C, the heart beats at a frequency of 5 beats per minute.

Answer

2. Read the text. Choose three sentences that describe the physiological criterion for the type of animal Terrible poison dart frog. Write down the numbers under which they are indicated. (1) One of the most venomous vertebrates on Earth, these small tree frogs found in a small area of ​​southwestern Colombia, mainly in the lower tiers of tropical rainforests. (2) They have bright, contrasting coloration, males and females are of the same size. (3) The skin glands of the dire dart frog secrete a mucus containing a strong poison, batrachotoxin. (4) The poison protects the animal both from fungi and bacteria and from natural enemies, which can be fatally poisoned when dart frog venom gets on the skin or mucous membranes. (5) Dart frogs are diurnal, in nature they feed mainly on ants, other small insects and mites. (6) Animals are very active, and fasting for 3-4 days can not only weaken a healthy, well-fed individual, but also cause her death.

Answer

3. Read the text. Choose three sentences that describe the physiological criteria for the thermophilic bacterium Thiobacillus thermophilica. Write down the numbers under which they are indicated. (1) An ecologically distinct group in nature is represented by thermophilic microorganisms living in nature at temperatures from 40 to 93 degrees. (2) Hot springs North Caucasus, rich in hydrogen sulfide, are abundant with thermophilic species of thionic bacteria, such as the thiobacterium Thiobacillus thermophilica. (3) This thermophilic bacterium is capable of division and development at temperature regime from 40 to 70-83 degrees. (4) The membranes of thermophilic bacteria have high mechanical strength. (5) Thermophilic bacteria have enzymes that can function at high temperatures, providing the necessary rate of chemical reactions in the cell. (6) Spores of thermophilic bacteria are much more heat resistant than spores of mesophilic forms, and maximum speed colony growth occurs at an optimal temperature of 55-60 degrees.

Answer

4. Read the text. Choose three sentences that describe the physiological criterion of the species Silver Poplar. Write down the numbers under which they are indicated. (1) Poplars grow very quickly, reaching their final height at the age of forty. (2) The height of poplar trees ranges from 30 to 60 meters. (3) The plant does not live long, mostly up to eighty years. (4) Poplar roots are thick, strong, in many species located superficially. (5) Kidney cells form a sticky, resinous substance. (6) The wood of the tree is soft and very light, the trunk is straight, the crown can have a variety of shapes.

Answer

Answer

2. Establish a correspondence between the characteristics and criteria of the species: 1) physiological, 2) ecological. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) herbivore
B) pregnancy within one month
B) nocturnal
D) the birth of several cubs
D) high heart rate

Answer

1. Read the text. Choose three sentences that describe the geographical criterion for the type of tuatara. Write down the numbers under which they are indicated. (1) Single modern representative order of beak-headed reptiles. (2) Outwardly similar to a lizard, up to 75 cm long, along the back and tail there is a crest of triangular scales. (3) Before the arrival of Europeans, inhabited the North and South Islands of New Zealand. (4) At the end of the 19th century, it was exterminated and survived only on nearby islands in a special reserve. (5) Listed in the Red Book International Union Conservation of Nature and Natural Resources (IUCN). (6) Successfully bred at the Sydney Zoo.

Answer

2. Read the text. Choose three sentences that describe the geographical criterion for the type of plant Siberian cedar pine. Write down the numbers under which they are indicated. (1) Siberian cedar pine, or Siberian cedar- one of the species of the genus Pine; evergreen tree, reaching 35-44 m in height and 2 m in trunk diameter. (2) Siberian pine is very common in Western Siberia throughout the forest belt from 48 to 66 degrees N, and in Eastern Siberia, due to permafrost, the northern border of the range deviates sharply to the south. (3) In Siberia, it prefers sandy and loamy soils, but can also grow on stony substrates and sphagnum bogs. (4) In Central Altai upper bound distribution of cedar lies at an altitude of 1900-2000 m above sea level. (5) Siberian cedar also grows in Mongolia and northern China. (6) Siberian cedar pine frost-resistant, shade-tolerant, demanding on heat, air and soil humidity, avoids soils with close occurrence of permafrost.

Answer

3. Read the text. Choose three sentences that describe the geographical criterion for the type of animal European grayling. Write down the numbers under which they are indicated. (1) European grayling - freshwater fish subfamilies of graylings of the salmon family, weighing up to seven kilograms. (2) The life of these fish is associated with a certain water temperature, so grayling is not found in grassy places, deep coastal bays and fiords. (3) This species of fish lives in the basins of the White and Baltic Seas, in the basin of the Arctic Ocean, from Finland to the Tyumen region. (4) Smaller graylings live in the rivers, their weight barely reaches the weight of more than 1 kg. (5) Fish, making seasonal migrations in search of food, reach the upper reaches of the Dniester, Volga and Ural rivers. (6) Grayling is also found in the large northern lakes of the European part of Russia - Onega, Ladoga and some other reservoirs, in which it chooses rocky, less often sandy shallows.

Answer

4. Read the text. Choose three sentences that describe the geographical criterion for the species of the Song Thrush. Write down the numbers under which they are indicated. (1) The song thrush is a small songbird of the thrush family found in Europe, Asia Minor and Siberia. (2) The song thrush inhabits Various types forests and equally numerous in deciduous forests, and in the taiga. (3) Adult birds feed on invertebrates, song thrushes feed their young on various insects and small worms, and in autumn they eat various berries and fruits. (4) The range of the song thrush characterizes it as a northern, cold-resistant bird, choosing forests with young spruce or juniper for nesting sites. (5) Actively inhabits the northern regions of the Scandinavian Peninsula and is numerous in the East European forest tundra, penetrating even into the tundra, actively spreading to the east. (6) Absent in Southern Europe, on the islands mediterranean sea, although there are biotopes suitable for song thrushes.

Answer

1. Read the text. Select three sentences that describe the biochemical criterion for the species Stinging nettle. Write down the numbers under which they are indicated. (1) Stinging nettle is a perennial herbaceous plant with a strong root and a long horizontal branching rhizome. (2) Nettles are protected from being eaten by herbivores by stinging hairs found on all parts of the plant. (3) Each hair is a large cell. (4) The wall of the hair contains silicon salts, which make it brittle. (5) The content of formic acid in the cell sap of the hairs does not exceed 1.34%. (6) Young nettle leaves contain many vitamins, so they are used as food.

Answer

1. Establish a correspondence between the characteristic features of the type Bittersweet nightshade and the criteria of the species to which they are referred: 1) morphological, 2) ecological, 3) biochemical. Write down the numbers 1-3 in the order corresponding to the letters.
A) Poisonous substances are formed and accumulated in the plant.
B) Ripe berries contain a lot of sugar.
C) The berries are bright red in color.
D) The flowers are lilac, have the correct shape.
D) Plants are common in vegetable gardens and river banks.
E) Plant height - 30-80 centimeters.

Answer

2. Establish a correspondence between the features and criteria of the species Stinging nettle: 1) ecological, 2) morphological, 3) biochemical. Write down the numbers 1-3 in the order corresponding to the letters.
A) a perennial plant with a strong root and a long rhizome
B) grows in forest clearings, in weedy places, along fences
C) ascorbic acid, carotene, vitamins B and K are formed in the leaves
D) nettle blooms from early summer to early autumn
D) flowers are small, unisexual, with a greenish perianth
E) potassium oxalate accumulates in leaf cells

Answer

© D.V. Pozdnyakov, 2009-2019

1. Biological species and its criteria.

All life on the planet is represented by separate species.

A species is a historically established set of individuals that have a hereditary similarity in morphological, physiological and biochemical features; able to freely interbreed with each other and produce fertile offspring; adapted to certain environmental conditions and occupying a certain area.

Each type of organism can be described by a set of characteristic features and properties, which are called features of the species. Features of a species that distinguish one species from another are called type criteria.

The most commonly used general view criteria are: morphological, physiological, genetic, biochemical, geographical and ecological.

Morphological criterion - based on the external and internal similarity of individuals of the same species.

The morphological criterion is the most convenient and is therefore widely used in species taxonomy.

However, the morphological criterion is insufficient to determine the difference sibling species with significant morphological similarity.

Twin species practically do not differ in appearance, however, individuals of such species do not interbreed.

Species-twins are quite common in nature. About 5% of all species of insects, birds, fish, etc. have twin species:

- black rats have two twin species;

- the malarial mosquito has six twin species.

The use of a morphological criterion is also difficult in cases where individuals of the same species differ sharply from each other in appearance, the so-called polymorphic species.

The simplest example of polymorphism is sexual dimorphism, when there are morphological differences between males and females of the same species.

It is difficult to use the morphological criterion in the diagnosis of domestic animal species. Breeds bred by humans can differ significantly from each other, remaining within the same species (breeds of cats, dogs, pigeons).

Thus, the morphological criterion is insufficient to determine the species belonging of individuals.

The physiological criterion characterizes the similarity of life processes in individuals of the same species, primarily the similarity of reproduction.

Between individuals of different species there is a physiological isolation, which is manifested in the fact that individuals of different species almost never interbreed with each other. This is due to differences in the structure of the reproductive apparatus, the timing and places of reproduction, in the rituals of behavior during mating, etc.

If interspecific crossing does occur, then the result is interspecific hybrids that are characterized by reduced viability or are infertile and do not produce offspring:

For example, a hybrid of a horse and a donkey is known - a mule, which is quite viable, but barren.

However, in nature there are such species that can interbreed with each other and produce fertile offspring. (for example, some species of canaries, finches, poplars, willows, etc.).

Consequently, the physiological criterion is insufficient to characterize the species.

A genetic criterion is a set of chromosomes characteristic of each species, a strictly defined number, size and shape.

Individuals of different species cannot interbreed, as they have different sets of chromosomes, differ in number, size and shape:

- for example, two closely related species of black rats differ in the number of chromosomes (one species has 38 chromosomes, and the other 48) and therefore do not interbreed.

However, this criterion is not universal:

- first, in many different species, the number of chromosomes can be the same (for example, many species of the legume family have 22 chromosomes each);

- secondly, within the same species, individuals with a different number of chromosomes can be found, which is the result of mutations (for example, in silver carp there are populations with a set of chromosomes 100, 150, 200, while their normal number is 50).

Thus, on the basis of a genetic criterion, it is also impossible to reliably determine the belonging of individuals to a particular species.

The biochemical criterion makes it possible to distinguish species according to biochemical parameters (the composition and structure of certain proteins, nucleic acids, and other substances).

It is known that the synthesis of certain macromolecular substances is characteristic only of certain species ( for example, many plant species differ in their ability to form and accumulate certain alkaloids).

However, there is a significant intraspecific variability in almost all biochemical parameters, up to the sequence of amino acids in the molecules of proteins and nucleic acids.

Therefore, the biochemical criterion is also not universal. In addition, it is not widely used, as it is very laborious.

The geographic criterion is based on what each species occupies certain territory or water area.

In other words, each species is characterized by a specific geographical area.

Many species occupy different ranges, but most species have overlapping ranges.

There are species that do not have a specific geographical range, i.e. living on vast expanses of land or ocean, the so-called cosmopolitan species :

- some inhabitants of inland waters - rivers and freshwater lakes (many species of fish, reeds);

- Cosmopolitans also include medicinal dandelion, shepherd's purse, etc.;

- cosmopolitans are found among synanthropic animals - species that live near a person or his dwelling (lice, bedbugs, cockroaches, flies, rats, mice, etc.);

- Cosmopolitans also include indoor and cultivated plants, weeds, pets that are under human care.

In addition, there are species that do not have clear distribution boundaries or have a broken geographical range.

Due to these circumstances, the geographical criterion, like others, is not absolute.

The ecological criterion is based on the fact that each species can exist only under certain conditions, fulfilling its functional role in a particular biogeocenosis.

In other words:

Each species occupies a certain ecological niche in a complex system of ecological relationships with other organisms and factors of inanimate nature.

An ecological niche is a set of all environmental factors and conditions within which a species can exist in nature.

It includes the whole complex of abiotic and biotic environmental factors necessary for the organism to live, and is determined by its morphological fitness, physiological reactions and behavior.

The classic definition of an ecological niche was given by the American ecologist J. Hutchinson (1957).

According to the concept formulated by him, an ecological niche is a part of an imaginary multidimensional space (hypervolume), individual dimensions of which correspond to the factors necessary for the normal existence of a species (Fig. 1).

two-dimensional niche three-dimensional niche

Rice. 1. Ecological niche model according to Hutchinson

(F 1, F 2, F 3 - the intensity of various factors).

For example:

- for the existence of a terrestrial plant, a certain combination of temperature and importance is sufficient (two-dimensional niche);

- for a marine animal, temperature, salinity, oxygen concentration (three-dimensional niche) are necessary.

It is important to emphasize that the ecological niche is not just the physical space occupied by a species, but also its place in the community, determined by its ecological functions and its position relative to the abiotic conditions of existence.

According to the figurative expression of Y. Odum, an “ecological niche” is the “profession” of a species, its way of life, and “habitat” is its “address”. ”

For example, a mixed forest is a habitat for hundreds of species of plants and animals, but each of them has its own and only one "profession" - an ecological niche. Elk and squirrel have the same habitat, but their ecological niches are completely different.

Consequently, the ecological niche is not a spatial, but a functional category.

At the same time, it is important to realize that the ecological niche is not something that can be seen. An ecological niche is an abstract abstract concept.

An ecological niche defined only by the physiological characteristics of organisms is called fundamental and the one within which the species actually occurs in nature - implemented.

However, the ecological criterion is also insufficient to characterize the species.

Some different species in different habitats may occupy the same ecological niches:

- antelopes in the savannas of Africa, bison in the prairies of America, kangaroos in the savannas of Australia, marten in the European and sable in the Asian taiga lead the same way of life, have a similar type of nutrition, i.e. in different biogeocenoses they perform the same functions and occupy similar ecological niches.

It often happens the other way around - the same species in different habitats is characterized by different ecological niches. Most often this is due to the availability of food and the presence of competitors:

In addition, the same species in different periods of its development can occupy different ecological niches:

- so, the tadpole eats plant food, and the adult frog is a typical carnivore, so they are characterized by different ecological niches;

- migratory birds in connection with migrations are also characterized by different ecological niches in winter and summer;

- among algae there are species that function either as autotrophs or as heterotrophs. As a result, at certain periods of their lives, they occupy certain ecological niches.

Thus, none of these criteria can be used to determine whether an individual belongs to a particular species. It is possible to characterize a species only by the totality of all or most of the criteria.

The genetic (cytogenetic) species criterion, along with others, is used to distinguish between elementary systematic groups, analysis of the state of the view. In this article, we will consider the characteristics of the criterion, as well as the difficulties that a researcher using it may encounter.

In different industries biological science type is defined differently. From an evolutionary perspective, we can say that a species is a collection of individuals that have similarities external structure and internal organization, physiological and biochemical processes capable of unlimited interbreeding, leaving fertile offspring and genetically isolated from similar groups.

A species can be represented by one or several populations and, accordingly, have a whole or dissected range (habitat area / water area)

Species nomenclature

Each type has its own name. In accordance with the rules of binary nomenclature, it consists of two words: a noun and an adjective. The noun is the generic name, and the adjective is the specific name. For example, in the name "Dandelion officinalis", the species "officinalis" is one of the representatives of plants of the genus "Dandelion".

individuals related species within the genus they have some differences in appearance, physiology, and ecological preferences. But if they are too similar, then their species affiliation is determined by the genetic criterion of the species based on the analysis of karyotypes.

Why does a species need criteria?

Carl Linnaeus, the first to give modern titles and who described many types of living organisms, considered them unchanged and non-variable. That is, all individuals correspond to a single species image, and any deviations from it are a mistake in the embodiment of the species idea.

From the first half of XIX century, Charles Darwin and his followers substantiate a completely different concept of the species. In accordance with it, the species is changeable, heterogeneous and includes transitional forms. The constancy of the species is relative, it depends on the variability of conditions environment. The elementary unit of existence of a species is a population. It is reproductively isolated and corresponds to the genetic criterion of the species.

Given the heterogeneity of individuals of the same species, it can be difficult for scientists to determine the species affiliation of organisms or distribute them between systematic groups.

Morphological and genetic criteria of a species, biochemical, physiological, geographical, ecological, behavioral (ethological) - all these are complexes of differences between species. They determine the isolation of systematic groups, their reproductive discreteness. And by them it is possible to distinguish one species from another, to establish the degree of their relationship and position in the biological system.

Characteristics of the genetic criterion of the species

The essence of this trait is that all individuals of the same species have the same karyotype.

The karyotype is a kind of chromosomal "passport" of the body, it is determined by the number of chromosomes present in mature somatic cells organism, their size and structural features:

• the ratio of the length of the arms of the chromosomes;
• the position of the centromeres in them;
• the presence of secondary constrictions and satellites.

Individuals belonging to different species will not be able to interbreed. Even if it is possible to produce offspring, as with a donkey and a horse, a tiger and a lion, then interspecific hybrids will not be prolific. This is due to the fact that the halves of the genotype are not the same and conjugation between chromosomes cannot occur, so gametes are not formed.

In the photo: a mule is a sterile hybrid of a donkey and a mare.

Object of study - karyotype

The human karyotype is represented by 46 chromosomes. In most species studied, the number of individual DNA molecules in the nucleus that form chromosomes falls within the range of 12–50. But there are exceptions. The fruit fly Drosophila has 8 chromosomes in the cell nuclei, and the small representative of the Lepidoptera family Lysandra has a diploid chromosome set of 380.

An electron micrograph of condensed chromosomes, which allows one to assess their shape and size, reflects the karyotype. Analysis of the karyotype as part of the study of the genetic criterion, as well as comparison of karyotypes with each other, helps to determine the species of organisms.

When two kinds are one

The common feature of view criteria is that they are not absolute. This means that the use of only one of them may not be sufficient for an accurate determination. Organisms that are outwardly indistinguishable from each other may be representatives of different species. Here the morphological criterion comes to the aid of the genetic criterion. Twin examples:

1. To date, two species of black rats are known, which were previously defined as one due to their external identity.
2. There are at least 15 species of malarial mosquitoes that are distinguishable only through cytogenetic analysis.
3. In North America, 17 species of crickets were found that have genetic differences, but are phenotypically related to a single species.
4. It is believed that among all species of birds there are 5% of twins, for the identification of which it is necessary to apply a genetic criterion.
5. The confusion in the taxonomy of mountain bovids was eliminated thanks to karyological analysis. Three varieties of karyotypes have been identified (2n=54 in mouflons, 56 in argali and argali, and 58 chromosomes in urials).

One of the species of black rats has 42 chromosomes, the karyotype of the other is represented by 38 DNA molecules.

When one view is like two

For species groups with large area range and number of individuals, when geographical isolation operates within them or individuals have a wide ecological valence, the presence of individuals with different karyotypes is characteristic. Such a phenomenon is another variant of exceptions in the genetic criterion of a species.

Examples of chromosomal and genomic polymorphism are common in fish:

• in rainbow trout, the number of chromosomes varies from 58 to 64;
• two karyomorphs, with 52 and 54 chromosomes, were found in the White Sea herring;
• with a diploid set of 50 chromosomes, representatives of different populations of silver carp have 100 (tetraploids), 150 (hexaploids), 200 (octaploids) chromosomes.

Polyploid forms are found in both plants (goat willow) and insects (weevils). House mice and gerbils can have a different number of chromosomes that is not a multiple of the diploid set.

Twins by karyotype

Representatives of different classes and types may have karyotypes with the same number of chromosomes. There are much more such coincidences among representatives of the same families and genera:

1. Gorillas, orangutans, and chimpanzees have a 48-chromosome karyotype. In appearance, the differences are not determined, here you need to compare the order of nucleotides.
2. There are insignificant differences in the karyotypes of the North American bison and the European bison. Both have 60 chromosomes in a diploid set. They will be assigned to the same species if the analysis is carried out only by genetic criteria.
3. Examples of genetic twins are also found among plants, especially within families. Among willows, it is even possible to obtain interspecific hybrids.

To identify subtle differences in the genetic material in such species, it is necessary to determine the sequences of genes and the order in which they are included.

The influence of mutations on the analysis of the criterion

The number of karyotype chromosomes can be changed as a result of genomic mutations - aneuploidy or euploidy.

With aneuploidy, one or more additional chromosomes appear in the karyotype, and there may also be a smaller number of chromosomes than in a full-fledged individual. The reason for this violation is the non-disjunction of chromosomes at the stage of gamete formation.

The figure shows an example of aneuploidy in humans (Down syndrome).

Zygotes with a reduced number of chromosomes, as a rule, do not proceed to cleavage. And polysomic organisms (with "extra" chromosomes) may well be viable. In the case of trisomy (2n+1) or pentasomy (2n+3), an odd number of chromosomes will indicate an anomaly. Tetrasomy (2n + 2) can lead to an actual error in determining the species by genetic criteria.

Multiplication of the karyotype - polyploidy - can also mislead the researcher when the mutant karyotype is the sum of several diploid sets of chromosomes.

Complexity of the criterion: elusive DNA

The uncoiled DNA strand diameter is 2 nm. The genetic criterion determines the karyotype in the period preceding cell division, when thin DNA molecules repeatedly spiralize (condense) and represent dense rod-shaped structures - chromosomes. Chromosome thickness is on average 700 nm.

School and university laboratories are usually equipped with microscopes with a low magnification (from 8 to 100), it is not possible to see the details of the karyotype in them. Resolution light microscope, in addition, allows you to see objects at least half the length of the shortest light wave at any, even the highest magnification. The smallest wavelength is for violet waves (400 nm). This means that the smallest object visible in a light microscope will be from 200 nm.

It turns out that the stained decondensed chromatin will look like cloudy areas, and the chromosomes will be visible without details. See clearly and compare different karyotypes allows an electron microscope with a resolution of 0.5 nm. Considering the thickness of filamentous DNA (2 nm), it will be clearly distinguishable under such a device.

Cytogenetic criterion at school

For the reasons described above, the use of slides on laboratory work according to the genetic criterion of the species is impractical. In tasks, you can use photographs of chromosomes obtained under an electron microscope. For the convenience of working in the photo, individual chromosomes are combined into homologous pairs and arranged in order. Such a scheme is called a karyogram.

Sample assignment for laboratory work

Exercise. Consider the given photographs of karyotypes, compare them and conclude that individuals belong to one or two species.

Photographs of karyotypes for comparison in laboratory work.

Working on a task. Count the total number of chromosomes in each karyotype photo. If they match, compare them in appearance. If not a karyogram is presented, find the shortest and longest among the chromosomes of medium length in both images, compare them according to the size and location of the centromeres. Make a conclusion about the difference / similarity of karyotypes.

Answers to the task:

1. If the number, size and shape of the chromosomes match, then the two individuals whose genetic material is presented for study belong to the same species.
2. If the number of chromosomes differs by a factor of two, and chromosomes of the same size and shape are found in both photographs, then most likely the individuals are representatives of the same species. These will be diploid and tetraploid karyotypes.
3. If the number of chromosomes is not the same (it differs by one or two), but in general the shape and size of the chromosomes of both karyotypes are the same, we are talking about normal and mutant forms of the same species (the phenomenon of aneuploidy).
4. At different amount chromosomes, as well as the discrepancy between the characteristics of size and shape, the criterion will attribute the presented individuals to two different species.

In the conclusion, it is required to indicate whether it is possible to determine the species affiliation of individuals based on the genetic criterion (and only it).

Answer: it is impossible, since any species criterion, including genetic, has exceptions and can give an erroneous result of the determination. Accuracy can only be guaranteed by the use of a set of type criteria.

Goals: to form the concepts of "type" and "type criteria"; showmechanisms of reproductive isolation in nature; continue the formation of skills to give a morphological description of plants, work with texts, compile tables, analyze, formulate conclusions.

Equipment: paintings on zoology: "Hare-hare”, “Hare hare”, “Brown bear”, “White bear”; distributingexact material "Hare hare and hare-hare", "Raven and crow".

During the classes

I.Organizing time

The teacher announces the topic and objectives of the lesson.

11. Updating knowledge

1. Completion of tasks (orally).

Task number 1

Name the types of plants and animals you know that live near your home or school.

Task number 2

The teacher shows the picture Brown bear and ask questions:

The name of this species of animal is Brown Bear. Which of thesetwo words refers to the generic name, what - to the specific?

Name another species of animal from the same genus. (This is a bear white).

The teacher hangs a picture illustrating a polar bear next to the picture "Brown Bear".

Compare two species of the same genus. Show similarities and differences.

Task number 3,

In the specified list of animals, count the number of individuals, species and genera.

1. Hedgehog ordinary.

2. Common fox.

3. Himalayan or white-breasted bear.

4. Djungarian hamster.

5. White hare.

6. Brown bear.

7. Hamster Syrian or golden.

8. Hare-hare.

9. Eared hedgehog.

10. The fox is ordinary.

(Answer:number of individuals - 10; species - 9; childbirth - 5 (Hedgehog, Lisi-tsa, Bear, Hamster, Hare).)

When completing the last task, a number of students have a problem: to attribute the white hare and the hare to the same species or totwo different types. Is it true or false that the hareis a white hare a hare in winter?

Report "Hare hare and hare hare".

- What conclusion can be drawn from the results of all assignments to update knowledge?

Conclusion:

1. To designate a species, a double (binary) butmenclature, according to which the genus to whichrefers to the species (noun), and then the species name (adj. dumbbell).

2. Individuals of different species differ from each other in placestania, outward signs and etc.

3. Similar species are combined into one genus.

4. Species is the main category of biological classification.

III . Learning new material

1. Teacher's story.

- What is a species and what are its criteria?

IN Questioning about species and species criteria is central to the theory of evolution and has been the subject of numerous studies.research in the field of systematics, zoology, botany and otherSciences. And this is understandable: a clear understanding of the essencespecies is necessary to elucidate the mechanisms of evolutionary process.

A strict generally accepted definition of the species has not yet been developed.nerd. In biological encyclopedic dictionary we are onwe go to the following definition of the form:

“A species is a set of populations of individuals capable of interbreedingwith the formation of fertile offspring inhabiting a certainarea, which have a number of common morphophysiological features remote from other similar groups of individuals in practiceCzech total absence hybrid forms.

Compare this definition with the one in your textbook.(textbook by A.A. Kamensky, § 4.1, p. 134).

Let us explain the concepts that occur. in the view definition:

area- area of ​​distribution of a given species or population in nature.

population(from lat. “Pop uius "- people, population) - totalthe number of individuals of the same species with a common gene pool and occupationcovering a certain territory - an area.

gene pool- the totality of genes that individuals haveof this population.

Consider the history of the development of views on the species in biology.

The concept of species was first introduced into science by an English botanist John Ray inXVII century. Foundational work on the species problemwas written by a Swedish naturalist and naturalistCarl Linnaeus in XVIII centuryin which he proposed the firstscientific definition of the species, clarified its criteria.

Teacher's comments. K. Linnaeus believed that the species is a unigreasy, really existing unit of living matter, morphologically homogeneous and unchanging . All individuals of the species, according to the scientist, have a typical morphological appearance, and variations are random deviations. , the result of an imperfect implementation of the idea of ​​the form (a kind of deformity). Scientistbelieved that species are unchanging, nature is unchanging. The idea is unchangedof nature rested on the concept of creationism, according towhich all things were created by God. Applied to biologyLinnaeus expressed this concept in his famous formulamule "There are as many species as different forms first produced the Infinite creature".

Another concept belongs Tom Baptiste Lamarck- ledto whom the French naturalist. According to his concept, the views are real Not exist, is a purely speculative concept invented forto make it easier to consider collectively large quantity individuals, because, according to Lamarck, “in nature there is noanything but individuals. Individual variability is continuous, therefore, the boundary between species can be drawn here and there - where it is more convenient.

The third concept was prepared in the first quarter XIX century. She was justified Charles Darwin and subsequent biologistmi. According to this concept, species have an independent reality. Viewheterogeneous, is a system of subordinate units. WITHAmong them, the basic elementary unit is the population. Species, by Darwin, change, they are relatively constant and areultatum of evolutionary development .

Thus, the concept of "species" has a long history of formation in biological science.

Sometimes the most experienced biologists are at a dead end, determiningwhether these individuals belong to the same species or not . Why is that happens, are there precise and strict criteria thatcould resolve all doubts?

Species criteria are traits by which one species differs.comes from another. They are also isolation mechanisms.interbreeding, independence, independently hundreds of species.

We know that one of the main features of biological matter on our planet is discreteness. It's in expressed in the fact that it is represented by separate species, notinterbreeding with each other, isolated from each other gogo.

The existence of a species is ensured by its genetic unity.(individuals of the species are able to interbreed and produce viable fertile offspring) and its genetic independence (impossiblethe possibility of interbreeding with individuals of another species, not viablestability or sterility of hybrids).

The genetic independence of the species is determined by the totalthe intensity of its characteristic features: morphological, physiological, biochemical, genetic, lifestyle features, behavior, geographical distribution, etc. This is Crete eriivid.

Let's get to know them.

2. Work in groups

Each group receives a text illustrating one of the view criteria. After 5 minutes, you need to talk about the essence of this criterion and what is the disadvantage of this criterion. As the groups perform, the class fills in the table “View criteria”.

Table No. 1

View criteria.

Criterion name	Signs of individuals by criterion	Exception
1. Morphological	The similarity of the external and internal structure of organisms.	Twin species, sexual dimorphism, polymorphism.
2. Physiological	The similarity of all life processes and the possibility of obtaining fertile offspring when crossing.	Different species have similar life processes. The presence of interspecific hybrids.
3. Environmental	Similarity in terms of feeding methods, habitats, sets of environmental factors necessary for existence.	Ecological niches of different species overlap.
4. Geographic	They occupy a certain area.	Cosmopolitans. Coincidence of ranges of different species.
5. Biochemical	The similarity in biochemical parameters is the composition and structure of proteins, nucleic acids.	There are species very close in biochemical composition.
6. Ethological	similarity in behavior. Especially in mating season(courtship rituals, marriage songs, etc.).	There are species with close behavior.
7. Cytogenetic a) Cytological	Individuals of the same species interbreed and produce fertile offspring (based on the similarity of the number of chromosomes, their shape and structure).	Chromosomal polymorphism within a species; many different species have the same number of chromosomes.
b) Genetic	Genetic isolation of species. Presence of post-population mechanisms of isolation. The most important of them are the death of male gametes (genetic incompatibility), the death of zygotes, the non-viability of hybrids, their sterility, and finally, the inability to find a sexual partner and give viable fertile offspring.	The dog and the wolf, the poplar and the willow, the canary and the finch give fertile offspring. (Presence of interspecific hybrids)
8. Historical	The community of ancestors, a single history of the emergence and development of the species.

So, the species criteria by which we distinguish one species from another, together determine the genetic isolation of the species.dov, ensuring the independence of each species and diversityin nature. In fact, in the development of these isolating species recognitionkov and is the process of formation of species. That is whythe study of species criteria is of decisive importance forunderstanding the mechanisms of the evolutionary process taking place on our planet.

3. Formulation of conclusions.

After filling in the table, conclusions are formulated:

1) Species criteria by which one species differs from anotherth, together they determine the genetic isolation of species, ensuring the independence of each species and their diversity in nature.

2) There is not a single species criterion that could berecognized as absolute and universal.

3) To methods of isolation that prevent the crossing of different species include:

A) differences in areas, habitats => impossibility of meeting;

b) different periods of reproduction;

V) differences in the structure of the genital organs;

G) non-viability or sterility of hybrids;

e) different rituals of "courtship" during the breeding season.

4) A species is genetically relatively isolated bathroom system, which proves the reality of the existence of species in nature.

Remember what was said in the text “A white hare and a harehare". What type criteria are used to describe the tsev?

Answer the question:

- What species criteria are used in the description of animals?

1). The mute swan often bends S-shaped neck , and the beak and head are held obliquely to the water. At timesdredging makes a characteristic hissing sound, according to which he receivedits name. The mute swan is common in isolated areasin the middle and southern strip of Europe and Asia from southern Sweden, Denmark andPoland in the west to Mongolia, Primorsky Krai and China in the East.Everywhere in this territory it is rare, often a pair from a pair nests on the groat a great distance, and in many areas it is completely absent.Inhabits estuaries overgrown with aquatic vegetation, lakes, sometimeseven swamps, preferring the deaf, little visited by man.

The small or tundra swan is distributed throughout the tundraAsia from the Kola Peninsula in the west to the Kolyma Delta in the East,entering the forest-tundra region and the western islands of the Arctic. For nestingselects swampy and low grassy areaslakes scattered over them, as well as river valleys aboundingoxbows and channels.

Mating games are peculiar and take place on land. At the same time, the male walks in front of the female, stretches his neck, sometimes raises his wings,making a special clapping sound with them and screaming loudly.

2). Go native martin. topcatches, back, wings and tailblue-black, rump and all underpartswhite. Tail with sharp triangularnotch at the end. dwellermountain and cultural landscapes.It nests on the walls of rocks and buildings. P erelet bird. Keeps in packsin the air or sitting on wires, more often than other swallows sits on zearth. Breeds in colonies. The nest is molded from lumps of clay in the formhemisphere with side entrance. Clutch of 4-6 white eggs in May - June. Goal os - voiced "tirrch-tirrch"

Coast swallow. The top of the head, neck, back, wings, tail and stripe across the chest are grayish-brown, the throat, chest and abdomen are white. Tail with a shallow notch.

Inhabits river valleys, where it nests on steep clay or sandy banks. Common or multiple migrant. Lives in flocks, nests in colonies. Nests are arranged in burrows along steep river banks. Clutch of 4-6 white eggs in May-July. Voice - low "chirr- chirr

Homework

According to the textbook A.A. Kamensky, § 4.1, questions after the paragraph, terms.

Individually:

1) The message "Is it true that the raven is the husband of the crow?"

2 ) Using literary sources, give specific examplesMeasures of geographical, ecological and ethological criteria.

Supplementary material for group work.

View criteria

Morphological criterion

It was the first and for a long time the only criterion used to describe species.

Morphological criterion is the most convenient and noticeable, thereforeand is now widely used in the taxonomy of plants and animals.

We can easily distinguish by the size and color of the plumage of a largespotted woodpecker from green woodpecker, lesser spotted woodpecker and yellow(black woodpecker), great tit from crested, long-tailed, blueand chickadees, meadow clover from creeping and lupine, etc.

Despite the convenience, this criterion does not always “work”. You can’t use it to distinguish between twin species, practicallymorphologically different. There are many such species among malarialmosquitoes, fruit flies, whitefish. Even birds have 5% of twin species, andThere are 17 of them in one row of North American crickets.

The use of morphological criteria alone canlead to erroneous conclusions. So, K. Linnaeus in particularexternal structure attributed the male and female mallard ducks to different species. Siberian hunters identified five variations based on the color of fox fur: gray foxes, moths, crosses, black-brown and black. In England, 70 species of butterflies, along with individuals with a light color, also have themes.nye morphs, the number of which in populations began to increase inconnection with forest pollution. Polymorphism - widespreadphenomenon. It occurs in all species. It also affects those features by which species differ. In lumberjack beetles, for example, in barbeled flowersexact, found in late spring on a bathing suit, in addition to tiIn the peak form, up to 100 color aberrations occur in populations. In the days of Linnaeus, the morphological criterion was the main one, sincewaist that there is one typical form for the species.

Now that it is established that a species can have many forms, such asthe logical concept of species is discarded and the morphological criterion is notalways satisfies scientists. However, it must be recognized that this criterionis very convenient for systematizing species, and in most determinants of animals and plants it plays a major role.

Physiological criterion

Physiological features of various types of plants and bellynyh are often a factor that ensures their genetic selfvalue. For example, in many fruit flies, the sperm of individuals of a foreign speciesYes, it causes an immunological reaction in the female genital tract, which leads to the death of spermatozoa. Hybridization of various species andsubspecies of goats often leads to a violation of the periodicity of the fetuswearing - the offspring appears in winter, which leads to his death. Crossbreedsthe study of different subspecies of roe deer, for example, Siberian and European,sometimes leads to the death of females and offspring due to large size fetus.

Biochemical criterion

Interest in this criterion has emerged in recent decades in connection withdevelopment of biochemical research. It is not widely used, since there are no specific substances characteristiconly for one species and, in addition, it is very laborious and far not universal. However, they can be used in cases wherewhen other criteria do not work. For example, for two twin speciesbutterflies from the genus Amata (A. p h e g ea and A. g ugazzii ) diagnosticand signs are two enzymes - phosphoglucomutase and esterase-5, allowing even identify hybrids of these two species. IN Lately widely used comparative study of the composition of DNK in practical taxonomy of microbes. The study of the composition of DNA allowed to revise the phylogenetic system of various groups microorganisms. The developed methods make it possible to compare the compositionDNA in bacteria preserved in the depths of the earth and now livingforms. For example, a comparison was made of the composition of DNA in a lyingabout 200 million years in the thickness of salts of the Paleozoic bacterium pseudosalt-loving monads and in living pseudomonads. The composition of their DNA turned out to be identical, and biochemical properties - similar.

Cytological criterion

The development of cytological methods has allowed scientists to investigate theRmu and the number of chromosomes in many species of animals and plants. A new direction has appeared - karyosystematics, which has introduced somecorrections and clarifications to the phylogenetic system built on the basis of morphological criteria. In some cases, the number of chromosomes servescharacteristic feature of the species. Karyological analysis allowed, for example, to streamline the taxonomy of wild mountain sheep, whichry different researchers identified from 1 to 17 species. The analysis showedthe presence of three karyotypes: 54 chromosome - in mouflons, 56rhomosomal - in argali and argali and 58-chromosome - in inhabitantsmountains of Central Asia - urials.

However, this criterion is not universal. First, atmany different species have the same number of chromosomes and their shape is similar. Secondly, individuals with different numbers of chromosomes may occur within the same species. These are the so-called chromosomal and genomicpolymorphism. For example, goat willow has a diploid - 38 and a tetraploid the new number of chromosomes is 76. In silver carp, there are populations with a setrum chromosomes 100, 150, 200, while their normal number is 50. In the rainbow trout, the number of chromosomes varies from 58 to 64, in the White Seadi meet individuals with 52 and 54 chromosomes. In Tajikistan on the siteonly 150 km long, zoologists discovered a population of mole voles with a set of chromosomes from 31 to 54. In gerbils from different habitats, the number of chromosomes is different: 40 in Algerian gerbils skian populations, 52 - in Israeli and 66 - in Egyptian. To infusion current time, intraspecific chromosomal polymorphism was found in 5% of ctotal genetically studied species of mammals.

Sometimes this criterion is incorrectly interpreted as genetic. Undoubtedly, the number and shape of chromosomes is an important feature that prevents crossbreedingof individuals of different species. However, this is rather a cytomorphologicalcriterion, since we are talking about intracellular morphology: the numberand the shape of chromosomes, and not about the set and structure of genes.

E tological criterion

For some animal species, a mechanism that preventsbaptism and leveling the differences between them are especiallybennosti their behavior, especially during the mating season. Partner recognition own species and rejection of courtship attempts by males of another speciesbased on specific stimuli - visual, soundchemical, tactile, mechanical, etc.

In the widespread genus warblers, different species are very similarlive on top of each other morphologically, in nature they cannot be distinguished either by color or by size. But they all differ very well in song and by habits. The song of the willow warbler is complex, similar to the song of the chaffinch, only without his final knee, and the song of the chiffchaff is aboutstenky monotonous whistles. Numerous twin species of ameRican fireflies of the genus P hotinus were first identified bydifferences in their light signals. Male fireflies in flight flashes of light, the frequency, duration and alternation of whichspecific to each species. well known but that a number of species of orthoptera and homopterans living within,of the same biotope and breeding synchronously, differ onlythe nature of their calling signals. Such double species with acousticreproductive isolation are found, for example, in crickets, skating fillies, cicadas and other insects. Two closely related species of Americanfrogs also interbreed because of differences in the call of males.

Differences in demonstrative behavior often play a decisive role in reproductive isolation. For example, related species of Drosophila flies fromdiffer in the specifics of the ritual of courtship (according to the nature of the vibrationwings, leg trembling, whirling, tactile contacts). Two closespecies - the herring gull and the klusha have differences in the degree of pronouncedhundreds of demonstrative poses, and seven species of lizards of the genus S se1horns s differ in the degree of raising the head when courting sexual partners.

Environmental criterion

Behavioral features are sometimes closely related to the ecological specifics of the species, for example, to the peculiarities of nest construction. Three species of our common tits nest in hollows deciduous trees, predominantly birches. The great tit in the Urals usually chooses deep a hollow in the lower part of a birch or alder trunk, formed in a re as a result of rotting of the knot and adjacent wood. This hollow is inaccessible to woodpeckers, crows, or predatory mammal. Tit moskovka populates frost cracks in the trunks of birch and alder. Hathe egg prefers to build a hollow itself, plucking cavities into rottenor old birch and alder trunks, and without this time-consuming procedure, she will not lay eggs.

Features of the lifestyle inherent in each species determineits position, its role in the biogeocenosis, that is, its ecologicalniche. Even the closest species, as a rule, occupy different econiches, that is, they differ in at least one or two ecological signs.

Thus, the econiches of all our species of woodpeckers differ in the nature of their diet. Great spotted woodpecker feeds on larch seeds in winter tsy and pines, crushing cones in their "forges". black woodpeckerzhelna extracts barbel larvae and gold beetles from under the bark and from woodfir, and the small spotted woodpecker hammers soft alder wood or extracts nase lumps from the stems of herbaceous plants.

Each of the 14 species of Darwin's finches (named afterC. Darwin, who first paid attention to them), living on the Galapagos islands, has its own specific eco-niche, which differs from others primarily in the nature of food and ways of obtaining it.

Neither the ecological nor the ethological crite discussed aboverii are not universal. Very often individuals of the same species, but oncepopulations differ in a number of lifestyle featuresand behaviour. And vice versa, different species, even very distant ones, in the systemchemically, may have similar ethological characteristicsor play the same role in the community (for example, the role of a herbivorous mammal and insects, say, such as locusts, are quite comparable).

Geographic criterion

This criterion, along with the ecological one, takes the second (after the morphological) place in most determinants. When determining many species of plants, insects, birds, mammals and othergroups of organisms whose distribution is well studiedThe distribution of the range plays a significant role. In subspecies, the ranges, as a rule, do not coincide, which ensures their reproductive isolation and, in fact,, their existence as independent subspecies. many kindsoccupy different ranges (such species are called allopatric And). But a vast number of species have overlapping or overlappingexpanding ranges (sympatric species). In addition, there are typeshaving clear boundaries of distribution, as well as braid speciesmopolitans living on vast expanses of land or ocean. INdue to these circumstances, the geographical criterion cannot be universal.

Genetic criterion

Genetic unity of the species and, accordingly, genetic isolationit from other species - the main criterion of the species, the main speciesa sign due to a complex of features of the structure and lifeactivities of organisms of this species. Genetic compatibilitybridge, similarity of morphological, physiological, cytologicaland other signs, the same behavior, living together - all thiso creates the necessary conditions for successful reproduction andspecies production. At the same time, all these traits provide geneticisolation of a species from other similar species. For example, oncelychia in the song of thrushes, warblers, warblers, finches and finches, deafand common cuckoo prevent the formation of mixed pairs,despite the similarity of their coloration and ecology (hybrids are almost never found in birds with a specific song). Even in those cases I, when, despite isolation barriers, interbreeding occurredthe formation of individuals of different species, a hybrid population, as a rule, does not arise, since a number of post-populationisolation mechanisms. The most important of them is the death of male gametes (genetical incompatibility), death of zygotes, non-viability of thereeds, their sterility, finally, the inability to find a sexualpartner and produce viable fertile offspring. We know thatEach species has its own set of specific features. Interspecific hybrid will have characteristics intermediate betweenfeatures of the two original parental forms. His song, for example will not be understood by either a chaffinch or a finch if it is a hybrid of these species, and he will not find a sexual partner. In such a hybrid,the formation of gametes, the finch chromosomes contained in its cells “do notfind the chromosomes of the finch and, not finding a homologous partner, do notconjugate. As a result, gametes with a disturbed set are formed.chromosomes, which are usually not viable. And as a resultThis hybrid will be sterile.

Raven and crow

I will say right away: Raven is not the "husband" of the crow, but an independent species.

The raven is one of the largest members of the crow family., weighs from 0.8 to 1.5 kg. The color of the plumage, beak and legs is monophonic black color.

The raven is distributed almost throughout the northern hemisphere: it occursalmost throughout Europe, Asia, excluding Southeast, in NorthAfrica and North America. Everywhere he leads a settled way of life. Inhabits forests, deserts and mountains. In treeless areas keeps atrocks, coastal cliffs of river valleys. Mating and mating games onin the south of the country are celebrated in the first half of February, in the north - inMarch. Couples are constant. Nests are usually placed on the tops of tall trees. In clutch from 3 to 7, more often 4-6, eggs are bluish-green in color. ki with dark markings.

Raven is an omnivorous bird. His main food is carrion, which he oftenfinds everything in landfills and slaughterhouses. Eating carrion, he performslike a sanitary bird. It also feeds on rodents, eggs,and chicks, fish, various invertebrates, and placesmi and grains of cereals.

The crow in general physique resembles a crow, but significantlysmaller than it: weighs from 460 to 690 g.

The described species is interesting in that, according to the color of the plumage, it breaks upinto two groups: gray and black. The hooded crow is well knownnew two-tone color: head, throat, wings, tail, beak and legs are black, the rest of the plumage is gray. Black Crow is all black, with a metallic blue and purple sheen.

Each of these groups has a local distribution. The gray crow is widespread in Europe, Western Asia, the black crow in Central and Western Europe, on the one hand, in Central, East Asia and North America, on the other.

The crow inhabits the edges and outskirts of forests, gardens, groves, thickets of river valleys, less often rocks and slopes of coastal cliffs. It is partly sedentary, partly migratory bird.

In early March, in the southern parts of the country and in April-May in the northern and eastern parts, egg laying begins. The clutch usually contains 4-5 pale green, bluish-green or partially green eggs with dark spots and speckles. The crow is an omnivorous bird. From animals, she eats various invertebrates - beetles, ants, mollusks, as well as rodents, lizards, frogs and fish. From plants, it pecks grains of cultivated cereals, seeds of spruce, field bindweed, bird buckwheat, etc. In winter, it feeds mainly on garbage.

White Hare and European Hare

The genus of hares proper, which includes the hare and hare, as well as another 28 species , quite numerous. The most famous hares in Russia are hare and hare. White hare can be found on the territory from the coast of the Arctic Ocean to the southern border of the forest zone, in Siberia - to the borders with Kazakhstannom, China and Mongolia, and on Far East- from Chukotka to And North Korea. The hare is also common in the forests of Europe, as well as in the east of Northern America. Rusak lives on the territory of European Russia from Kareliasouth of the Arkhangelsk region to the southern borders of the country, in Ukraine and in the Zakavcasier. But in Siberia, this hare lives only in the south and west of Lake Baikal.

Belyak got its name due to snow-white winter fur. Only the tips of his ears remain black all year round. Rusak, in some northern areas, also brightens greatly by winter, but it never happens to be snow-white. And in the south it does not change color at all.

The hare is more adapted to life in open landscapes, since it is larger than the white hare, and it runs better. At short distances, this hare can developspeed up to 50 km/h. The hare's paws are wide, with dense pubescence to fall less into loose forest drifts. And the hare already has paws, after all, in open places, snow, as a rule, is hard, packed, “trodden down by the wind.”

The body length of the hare is 45-75 cm, weight is 2.5-5.5 kg. The ears are shorter than those of the hare. The body length of a hare is 50-70 cm, weight is up to 5 (sometimes 7) kg.

breed hares usually two, and in the south three or even four times a year. Wu harebelyakovs in the output can be two, three five, seven hares, and the hare- usually only one or two hares. Rusaks begin to taste grass two weeks after birth, and whites even faster - a week later.

In the process of practical human activity, the concept of the form was formed. When describing animals, this concept was already used by Aristotle. However, a sufficiently long period was not endowed with scientific content and was used as a logical term. The concept under consideration acquired the status of a unit of classification in the process of developing taxonomy. John Ray ( English naturalist) developed the idea of ​​a species as a component of taxonomy. At the same time, scientists identified three the most important characteristics this unit. Thus, a species, according to Ray, is a set of organisms that are characterized by a common origin. This systematic unit combines organisms similar in morphological and physiological characteristics. In addition, it is a self-reproducing system.

Ray considered the origin to be the main indicator. So, the naturalist attributed similar plants to one species, reproducing their own kind from their seeds.

A significant expansion and also its deepening occurred thanks to the works of Linnaeus, who showed that a species is a real elementary and stable unit of wildlife, isolated from other species. This concept began to be applied as a home and plants. However, in those days, the view was considered as a consequence of creative action.

Lamarck proclaimed in his writings the position that in nature there are unchanging systematic units of plants and animals. Species are constantly transforming, changing, moving into other species. In this regard, according to Lamarck, the old systematic unit cannot be separated from the new one. Thus, the French naturalist came to the conclusion about the denial of the reality of the species, while affirming the idea of ​​development.

Darwin's teaching was based on a different proposition. This position was scientifically substantiated. In accordance with it, the developing real species is conditioned by historical development under the influence. In accordance with the Darwinian teaching, a comprehensive study of systematic units was carried out. So, the study of the morphological criterion of the species was carried out, as well as experimental, genetic research structure and ways of its formation. These activities were of decisive importance in substantiating the population aspect of a systematic unit as the main form of development and existence of the organic world as a whole.

Today it is believed that the organic environment includes a variety of life forms. At the same time, "view" is a universal phenomenon for all living nature. The considered systematic unit is formed in the course of evolutionary transformations due to natural selection. As a result, it represents a specific stage (link) in the development of living organisms and is the main form of existence on the planet of life.

One species differs from another in a set of common features - criteria. Together, these features form the reality of systematic units.

Morphological ones are based on the presence of certain hereditary traits in all individuals of the same species. Individuals within one systematic unit, in other words, have a similar external and internal structure. The morphological criterion of a species is considered quite convenient and a simple sign. Moreover, this characteristic was used by taxonomists earlier than other characters and was the main one for a certain period. However, it should be noted that the morphological criterion of the species is rather relative. This feature is necessary but not sufficient. The morphological criterion of a species does not allow one to distinguish between systematic units that have a significant similarity in structure, but do not interbreed with each other. For example, systematic twin units. So, the name includes about fifteen species, indistinguishable externally, but previously considered one species. It has been established that about 5% of all systematic units are twins. Thus, the morphological criterion of species cannot be the only sign of difference.