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.
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 data from population genetics about mutations, genetic drift, changeallele frequencies.
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 the Latin language, 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 are,in turn, they broke up into smaller groups that differ in external and internal structure.
Divergence in biology: examples
Divergence leads to the appearance of organisms of different structure 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, 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, potatoes have tubers, beets and carrots 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 systematicallydifferent 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.
Convergence examples
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 appearance and structure of their wings differ significantly.
Another example is the presence of gills in fish and molluscs. Sometimes convergence appears even in the absence of anyorgans. So, on some volcanic islands, wingless butterflies, flies and other insects live.
