Divergence in biology - what is it? In some cases, populations living in ecologically diverse peripheral environments may exhibit genetic differences from the rest of the population, especially where there is a wide variety of species. Genetic divergence is a process in biology in which two or more populations of an ancestral species independently accumulate genetic changes (mutations) in order to produce survivable offspring. Genetic differences among divergent populations may include mutations that do not affect the phenotype, and also lead to significant morphological and physiological changes.
Genetic divergence
At the level of molecular genetics, divergence in biology is the genetic changes that occur as a result of speciation. However, the researchers argue that it is unlikely that such a phenomenon was the result of a one-time and significant dominant mutation at the genetic locus. If this were possible, then these mutations could not be passed on to future generations. Consequently, the variant of sequential reproductive isolation, which is the result of multiple small mutations during evolution, is more likely.
Divergent evolution
According to the theory of evolution, divergence in biology is a relative phenomenon in which such populations initially accumulate differences in the process of evolutionary development and gradually become more distinct. This process is also known as "divergence" and was described in the Origin of Species (1859). Even before Darwin, many lines of departure from the central species type were described by Alfred Russell Wallace in 1858. According to the traditional theory of evolution, divergence serves two main purposes:
- It allows this type of organism to survive in an altered form through the use of new biological niches.
- This increase in diversity enhances the adaptive capabilities of the younger generation to diverse habitats.
These assumptions are purely hypothetical, since it is very difficult and almost impossible to prove them experimentally.
Molecular divergence
What is it from the point of view of molecular biology? This is the fraction of nucleotides that differ in two DNA segments. The percentage of amino acids between the two polypeptides may also vary. The term "divergence" is used in this context, since there is an assumption that two molecules are descendants of the same parent molecule. In the process of evolution, there is not only a discrepancy, but also a merger of events, such as hybridization and horizontal transport. And such events occur much more often. The molecular mechanisms of evolutionary divergence of genetic material include nucleotide substitutions, deletions, insertions, chromosomal recombinations, transpositions and inversions, duplications, transformations, and horizontal gene transfer. The number of nucleotide substitutions is a simple and useful measure of the degree of divergence between two sequences. In fact, there are several methods available for estimating the number of nucleotide substitutions and constructing a phylogenetic tree that displays the path of divergence during evolution.
Convergence Analog
Divergence in biology is an analogue of evolutionary convergence, during which organisms with dissimilar ancestors become similar due to natural selection. For example, flies and birds evolved to be similar, in the sense that they have wings and can fly, although their flightless ancestors were completely different. In fact, these two belong to different biological types. Divergence in biology is an evolutionary event in which two morphological or molecular traits arose from a common ancestor. These characteristics were initially the same, but became heterogeneous in the process of evolution. In the event of a discrepancy, there must be a certain degree of similarity between the two features in order to suggest that there was a common ancestor. For rapprochement, on the contrary, there must be a certain dissimilarity, since certain traits were borrowed from completely independent ancestors. Thus, the differences between divergence and convergence are difficult to establish.
Divergence in biology: pictures
Divergent evolution (from lat. Divergentia - discrepancy), as a rule, is a consequence of diffusion of the same species in different and isolated environments. The following examples can be cited: most creatures on the planet have upper limbs, humans and primates have arms, vertebrates have paws, birds have wings, fishes have fins and so on. All these organs are used by living organisms in different ways, but their origin is identical. Divergence can occur in any group of related organisms. The greater the number of differences, the greater the discrepancy. And there are a great many such examples in nature, for example, a fox. If its habitat is a desert, then the coat of an animal of a certain color helps to disguise itself from predators. The red fox lives in forests, where the "red coat" is combined with local landscapes. In the desert, heat makes heat transfer difficult, so the ears of the fox have evolved to large sizes, so the body gets rid of excess heat. In this case, various environmental conditions and adaptation requirements, and not genetic differences, are of decisive importance. If they lived in the same environment, it is likely that they would develop in a similar way. Divergent evolution is a confirmation of genetic proximity.
Divergence in nature: examples
Evolution is a process in which organisms change over time. The main feature is that all this happens very slowly and takes thousands or even millions of years. Divergence in biology - what is it? Consider, for example, a change in the human body: someone is tall, someone is low, some have red hair, others are black, there are fair-skinned, and dark-skinned. Like humans, other living organisms also have many variations within the same population.
Divergence is in biology (examples clearly demonstrate) the process of accumulation of gene transformations necessary for survival. You can give such an example from real life. The Galapagos Islands have many species of finches. When Charles Darwin visited these places, he noted that these animals are really similar, but they still have some key differences. This is the size and shape of their beaks. Their common ancestor underwent adaptive radiation, thus contributing to the development of new species. For example, on one island where seeds were abundant, beaks of birds were the best suited for eating this type of food. On another island, the beak structure helped the animal eat insects. In the end, many new species appeared, and each had its own unique features.
Divergent evolution occurs when it comes to the emergence of a new biological species. As a rule, this is necessary in order to adapt to various environmental conditions. A good example is the human foot, which is very different from the monkey’s foot, despite their common ancestor - the primate. A new species (in this case people) developed because there was no longer any need to climb trees. Bipedalism made the necessary changes in the foot to improve speed, balance and confident movement on the earth's surface. Although humans and monkeys are genetically similar, they have developed various physical traits necessary for survival.