Convergence and divergence in biology. Essence and examples of phenomena

According to the theory of evolution, all living beings on the Earth developed from the simplest forms to the more complex ones. But if everything moved along one straight line, where did the 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 basic theory about the development of life on our planet, supported by science, is the theory of evolution. Its first provisions and laws were formulated in the XVII century. It implies a long natural process of changes in living organisms to a qualitatively new level.

The theory presupposes the development of organisms from the simplest to the most complex forms, which was accompanied by genetic mutations, adaptations, extinction and species formation. Modern theory is based on Charles Darwin's assumptions about natural selection and population genetics data on mutations, genetic drifts, allele frequency changes.

Evolution implies the existence of a common root in living organisms, from which their development began. In this case, the assumption of one or a pair of ancestors is not necessary. Scientists claim that there could be more ancestor organisms, but they all belonged to related groups.

The main regularities that led to the evolution are convergence and divergence. In biology, examples and features of these processes are described by Charles Darwin. More details about what they are, we will tell below.

Divergence in biology

From Latin, the term is translated as "divergence" and can be used not only in relation to living nature. Divergence in biology means the emergence of a difference in signs in organisms. In its essence, this is a multidirectional variability that arises from the adaptation of living beings to different conditions.

It manifests itself in the change of parts of the body or some organs and the acquisition of partially new functions and opportunities. Divergence in biology is a common phenomenon. It appears as a result of natural selection, that is, the struggle for existence. Acquisition of signs reduces competition - each new population can occupy its ecological niche without affecting other individuals. It also arises from isolation.

Divergence can occur at the level of a species, genus, family, and order. With its help, for example, a class of mammals was divided into rodents, carnivores, proboscis, cetaceans, primates and other detachments. They, in turn, broke up into smaller groups, which differ in their external and internal structure.

Divergences in biology: examples

Divergence leads to the appearance of organisms of different structure, which belong to the same systematic group. However, they have a common basis, the mutated parts of the body perform the same functions. For example, the ears remain ears, only in some they have become more elongated, others have rounded wings, some birds have short wings, others have long wings.

A good example is the appearance of the limbs in mammals. In different species, they differ depending on the mode of life and habitat. So, the felines have soft pads on the paws, and the primates have long and movable fingers to grip the branches, the lions developed in the sea lion , the hooves of the cows. To understand what divergence is in biology, you can use the example of whitecaps. Butterflies of this family eat different foods at the stage of the caterpillar: some eat cabbage, others - turnips, others - beets, etc.

In plants, the divergence of features is manifested in the form of leaves. In cacti they became thorns, barberry developed needles. Also, the divergence can be traced at the level of the root system. Some plants have sucker roots, potatoes have tubers, they have added thicknesses in beets and carrots and turned into root crops.

Convergence

If the divergence is characteristic of related organisms, convergence, on the contrary, is observed in remote groups. It manifests itself in the similarity of features in systematically different organisms. Like the divergence, it appeared as a result of natural selection, but in this case it is directed equally in different species, orders, etc.

Animals or plants that belong to absolutely different classes, acquire the same in structure and function organs. This is due to the overall habitat or the similarity of the way of life. But their similarity does not extend to the whole body, convergence affects only those organs that are necessary to adapt to certain conditions.

Thus, animals that travel through the air have wings. But some may refer to insects, while others may refer to vertebrates. The organisms inhabiting the water have a streamlined body shape, although they are not necessarily related to each other.

Examples of convergence

The shape of the body of dolphins, whales and fish is a typical convergence. Because of their external similarity with sharks, whales and dolphins were first ranked among the fish. Later it was proved that they are mammals, since they breathe in the lungs, they are born by viviparity and have a number of other signs.

As an example of convergence, wings of bats, birds and insects can be brought. The presence of these organs is associated with the mode of life of animals that are moved by flight. In this case, the appearance and structure of the wings are significantly different.

Another example is the presence of gills in fish and in mollusks. Sometimes convergence manifests itself in the absence of any organs. Thus, on some volcanic islands, wingless butterflies, flies and other insects live.