Convergence and divergence in biology examples. Amazing examples of convergence in nature. The evolutionary process within similar systematic groups, ...
Convergence (in biology) Convergence(from lat. Converge - I approach, converge) in biology, the convergence of signs in the process of evolution of non-closely related groups of organisms, their acquisition of a similar structure as a result of existence in similar conditions and equally directed natural selection. As a result of K., organs that perform the same function in different organisms acquire a similar structure. For example, in the swimming fossil reptiles of ichthyosaurs and in mammalian dolphins, the shape of the body and forelimbs in the process of evolution acquired a convergent resemblance to the shape of the body and fins of fish ( rice. see article Analogy in biology). Convergent similarity is never deep. Wed Divergence. A. A. Makhotin.
Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
See what "Convergence (in biology)" is in other dictionaries:
CONVERGENCE IN BIOLOGY- CONVERGENCE IN BIOLOGY. In biology, the term "convergence" is most often used in comparative anatomy, embryology and paleontology. The concept of K. was introduced by the zoologist Oskar Schmidt. It matches the concept... Big Medical Encyclopedia
CONVERGENCE (from Latin convergo I approach, converge), in biology, the emergence of similarities in structure and functions in groups of organisms relatively distant in origin in the process of evolution. The result of living in similar conditions and the same ... ... encyclopedic Dictionary
Similarities between thylacine and wolfs. Initially, the aardvark, due to a number of striking structural features, was assigned to the same family as the South American anteaters, but the superficial resemblance to them turned out to be the result of a convergent ... Wikipedia
- (from the Latin convergens, the genitive convergentis is declining, approaching), convergence, convergence, for example, the convergence of languages, the emergence of common properties in different languages due to prolonged and intense contacts, leading to ... ... Modern Encyclopedia
- (from lat. convergo I approach, I converge), in biology, the emergence of similarities in structure and functions in groups of organisms relatively distant in origin in the process of evolution. The result of living in similar conditions and in the same direction ... ... Big Encyclopedic Dictionary
English convergence; German Konvergenz. 1. In sociology, the process of gradual convergence of opposing societies and systems. 2. In biology, the emergence in the course of evolution of a similar structure and functions of unrelated organisms due to their adaptation to ... ... Encyclopedia of Sociology
AND; well. [from lat. convergens (convergentis) convergent] 1. Spec. What kind of coincidence signs in phenomena independent of each other. The theory of convergence. 2. Biol. The appearance in unrelated organisms of similar characteristics resulting from ... ... encyclopedic Dictionary
Convergence of state and law- a theory that has become widespread since the 50s. 20th century (P. Sorokin, J. Galbraith and others). The term is borrowed from biology, where it denotes the acquisition by various organisms of similar features due to living in the same environment. According to the theory in... Theory of state and law in schemes and definitions
I Convergence (from lat. Converge I approach, I converge) in biology, the convergence of signs in the process of evolution of non-closely related groups of organisms, their acquisition of a similar structure as a result of existing in similar conditions and equally ... ... Great Soviet Encyclopedia
- (lat. converge to converge, converge from con + verge to be directed) in biology, the similarity of the shape of the body, the structure of the organs of movement, sensory organs and other signs in groups of organisms relatively distant in origin, arising in the process ... ... Big Medical Dictionary
Books
- Living organization. The company is like a living organism. The Coming Convergence of Computer Science, Nanotechnology, Biology and Business, Christopher Meyer, Stan Davis. "A handbook for every leader who wants to understand what forces will shape the economy of the near future. In their book, Meyer and Davis give you the tools to develop" - Mike ...
According to the theory of evolution, all living beings on Earth evolved from the simplest forms to more complex ones. But if everything moved in one straight line, where did such a variety of species and populations come from? Divergence and convergence can explain this phenomenon. In biology, these concepts denote the features and patterns of development of species.
Features of evolutionary theory
The main theory about the development of life on our planet, which is supported by science, is the theory of evolution. Its first provisions and laws were formulated in the 17th century. It implies a long natural process of changes in living organisms to a qualitatively new level.
The theory assumes the development of organisms from the simplest to the most complex forms, which was accompanied by genetic mutations, adaptations, extinction and the formation of species. The modern theory is based on Charles Darwin's assumptions about natural selection and population genetics data on mutations, genetic drifts, changes in the frequency of alleles.
Evolution implies that living organisms have a common root, from which their development began. In this case, the assumption of one or a pair of progenitors is not necessary. Scientists argue that there could have been more ancestral organisms, but they all belonged to related groups.
The main patterns of evolution are convergence and divergence. In biology, examples and features of these processes were described by Charles Darwin. Read more about what they are below.
Divergence in biology
From Latin, the term is translated as "divergence" and can be used not only in relation to wildlife. Divergence in biology refers to the occurrence of differences in traits between organisms. At its core, this is multidirectional variability, which arises as a result of the adaptation of living beings to different conditions.
It manifests itself in changing parts of the body or some organs and acquiring partially new functions and capabilities. Divergence in biology is a common occurrence. It appears as a result of natural selection, that is, the struggle for existence. The acquisition of traits reduces competition - each new population can occupy its ecological niche without affecting other individuals. It also occurs as a result of isolation.
Divergence can occur at the level of species, genus, family, and order. With its help, for example, the class of mammals was divided into rodents, carnivores, proboscis, cetaceans, primates and other orders. They, in turn, broke up into smaller groups that differ in external and internal structure.
Divergences in biology: examples
Divergence leads to the fact that organisms of different structure appear that belong to the same systematic group. However, they still have a common basis, the modified parts of the body perform the same functions. For example, ears remain ears, only in some they have become more elongated, in others rounded, the wings of some birds are short, others are long.
A good example is the type of limbs in mammals. In different species, they differ depending on the way of life and habitat. So, felines have soft pads on their paws, while primates have long and movable fingers to grab branches, the sea lion has developed flippers, and cows have hooves. To understand what divergence in biology is, you can use the example of whites. Butterflies of this family eat different foods at the caterpillar stage: some eat cabbage, others eat turnips, others eat beets, etc.
In plants, the divergence of characters manifests itself in the form of leaves. In cacti, they have become thorns; in barberry, needles have developed. Also, divergence can be traced at the level of the root system. Some plants have sucker roots, in potatoes they are tubers, in beets and carrots they have added thickness and turned into root crops.
Convergence
If divergence is characteristic of related organisms, then convergence, on the contrary, is observed in distant groups. It manifests itself in the similarity of signs in systematically different organisms. Like divergence, it appeared as a result of natural selection, but in this case it is directed in the same way in different species, orders, etc.
Animals or plants that belong to completely different classes acquire the same organs in structure and function. This is due to the common habitat or the similarity of lifestyle. But their similarity does not extend to the whole body, convergence affects only those organs that are necessary for adaptability to certain conditions.
So, animals that move through the air have wings. But some may refer to insects, while others to vertebrates. Water-dwelling organisms have a streamlined body shape, although they are not necessarily related to each other.
Examples of Convergence
The body shape of dolphins, whales and fish is a typical convergence. Because of their resemblance to sharks, whales and dolphins were originally considered fish. Later it was proved that they are mammals, as they breathe with lungs, are born by live birth and have a number of other signs.
An example of convergence is the wings of bats, birds, and insects. The presence of these organs is associated with the way of life of animals that move by flight. At the same time, the type and structure of their wings differ significantly.
Another example is the presence of gills in fish and molluscs. Sometimes convergence is manifested in the absence of any organs. So, on some volcanic islands, wingless butterflies, flies and other insects live.
Date: 2011-05-11
Convergence - what is it?
M. Makhlin St. Petersburg
Convergence in biology is called the development in unrelated organisms of the same characteristics that appeared as a result of adaptation to similar living conditions. These signs can refer to both the appearance and behavioral reactions of living beings.
Usually when studying biology at school, the most obvious examples are given convergence. For example, a whale, as you know, has nothing to do with fish. This is a typical mammal, like its ancestors that lived on land. But adaptation to the aquatic environment has caused the whales to develop a "fishy" appearance with its inherent attributes: a streamlined body and fins. An equally striking example is bats, flying foxes are also mammals that acquired bird-like wings during the development of the air environment.
Photo convergence
Examples convergence can be observed in the aquarium. As such, live birth of fry can be cited. They hatch in the body of the female, the eggs receive oxygen and nutrients through her blood (that is, this is a kind of pregnancy, and not a false live birth, when the eggs simply linger in the body of the female until the offspring hatch from them), the fry are born without a yolk sac, and immediately ready for active swimming and feeding. Live birth is characteristic of both American platies and South Asian half-snouts. But guppies, platies. swordtails belong to the order cyprinodontids, and hemiramphus. dermogenis - to the detachment Sarganiformes.
An example of convergence is the bearing of offspring in a special throat pouch of one of the parent fish. It is typical for African cichlids and labyrinths (a number of species of fighting fish, chocolate gourami). The ability to knock insects off the leaves above the water is shown by laliuses and spatter fish.
Similar habitat conditions also form the convergent appearance of fish. So, flatheads, which are part of the cypriniform order, are indistinguishable in appearance from some catfish from the catfish order.
A convergent appearance was formed under similar conditions of existence in many aquatic plants. In the aquatic environment, plants need to increase the assimilating (absorbing during respiration and nutrition) surface of the leaf blade. However, if evolutionary adaptation followed the path of a simple increase in size, huge leaves would begin to obscure each other, preventing water from flowing around them.
Therefore, adaptation occurred not due to an increase in the leaf, but due to its various geometric modifications, in which the assimilating surface of the leaves increases without detriment to the light and water permeable structure of the plant as a whole.
Vallisieria, sagittaria and a number of krynums have formed long ribbon-like leaves, freely creeping with the flow. In cabombs, hottons. limnophila, myriophyllum, some ludwigia and a number of other aquatic grasses, the leaves are segmented into narrow needle-shaped segments that freely transmit light and are washed on all sides by water.
Photo convergence
Floating plants and representatives of aquatic flora with floating leaves have another problem: they need to have drying upper surfaces of the leaf (to capture light and evaporate moisture) and provide the leaf with buoyancy by including air chambers in its tissue - air-filled cavities.
Phyllanthus floating freely on the surface of the water looks like a floating salvinia fern. Nymphoides have the same floating leaves as water lilies, and those, in turn, look like hydrocleis.
Especially plants that live in nutrient-poor waters have to excel. And there are many of them in the tropics. In order not to starve, plants need to increase the leaf blade, to develop its assimilating surface to the maximum.
Nature resolved the contradiction between the desire for compactness of the leaf blade and the need to increase the absorbing surface in an original way, by “inventing” the bulloid (ie, covered with bumps and pits) leaf surface. This decision made it possible, while maintaining the dimensions of the sheet plate, to increase its total assimilation surface by 3-4 times. Bullond leaves are characteristic of the Madagascar anonogethons A.boivinianus and A.bernierianus. some forms of other species of the same genus from the island of Madagascar and A. bullosus living in Australia.
Similar "crumpled" leaves appeared in the African "floating" (in fact, it is completely submerged) Crinum natans and in a number of crintocorins (C.bullosa. C.huidoroi. C.usteriana, C.aponogetifolia), the latter even in the scientific name (apoiogetonolifolia) contains the actual recognition of its convergence with aponogetons.
As you can see, convergence is a fairly common phenomenon, not alien to the inhabitants of the aquarium, as full-fledged participants in the biokinetic, assimilation and evolutionary processes of Nature.
Magazine Aquarium 2000 №1