Tema- 10. Methods of studying the evolutionary process.

The principal methods of studying the evolutionary process by biological disciplines in a sequence that reflects the penetration of evolutionary ideas in these disciplines: first paleontological, biogeographical, morphological, embryological and systematic, and then the data of genetics, biochemistry, and molecular biology.

Paleontological methods. Essentially, without exception, the methods of science as paleontology fossil record can be viewed as methods for studying the evolutionary process. We consider in detail only the most important paleontological methods of study of evolution: the identification of fossil intermediate forms, recovery phylogenetic series and the detection sequence of fossil forms.

Transitional fossils -shaped organisms that combine features of the older and younger groups. Bright representative transitional forms - fossil Ichthyostega, allowing the fish to associate with terrestrial vertebrates.

Biogeographic methods. Biogeography puts into the hands of researchers methods to analyze the overall progress of the evolutionary process at different scales.

Comparison of flora and fauna. The scale of evolution associated with the emergence of entire flora and fauna, you can talk on the basis of studying the characteristics of the modern continents of the Earth in relation to the analysis of their population.

Insular forms. The fauna and flora of islands is even more peculiar than the deeper and longer these islands were isolated from the main land. For example, comparatively recently lost contact with the mainland British Isles have a fauna with a small number of autochthonous (arisen precisely here) species. The latter include partridge - Grouse (Lagopus scoticus), two species of voles, some already mentioned freshwater whitefish, some snails and a number of species of bugs.

Relics. The flora and fauna of the distant past of the Earth and indicates relict forms. Relics - individual species or small groups of species with the complex character of extinct groups of past eras. Among animals, one of the most striking is the relict forms tuatara (sphenodon punctatus) - the only representative of a whole subclass of reptiles.

Among the plants can be considered a relic of the ginkgo (Gingko biloba), now common in China and Japan only as an ornamental plant. Look this plant gives us an idea of the wood forms, extinct in the Jurassic period.

The study of relict forms allows you to build reasonable assumptions on the shape of long-extinct groups, their way of life, conditions that existed millions of years ago.

Morphological methods. Using morphological (comparative anatomical, histological, and others.) Methods for the study of evolution is based on a simple principle: the deep inner similarity of organisms can show kinship forms compared.

Homology bodies. Bodies with the general plan of the structure, developing from similar primordia, in similar proportion to other organs and operating as similar and different functions are called homologous. In other words, it's bodies that have a profound similarity in the structure based on the unity of origin of the organisms.

Different in appearance and function of mammalian limbs consist of similar elements: the scapula, shoulder bones, forearm, wrist, metacarpus, phalanges. In all cases, maintain a single plan structure, the similarities in the relationship with the rest of the limbs and organs of ontogenetic development.

The phenomenon of homology, similarity or homologous, to be distinguished from similar phenomena, or similar affinities. Similar bodies only superficially similar, which is caused by performing similar functions, and not a common origin. To establish the relationship and finding ways of evolution of the studied groups, these bodies do not matter. Compare the thorn acacia, barberry, hawthorn and blackberry - these organs are similar and do not indicate a relationship of a form, showing only a similar direction adaptations induced in the evolution of the action of natural selection (store and retrieve the development of forms of plants are protected from eating large herbivorous vertebrates).

Rudimentary organs and atavism. Data of homology sufficient to restore the path of one or the other group, it is difficult to determine, for example, which of the compared homologous The parent form.

The structure of almost any organism can be found bodies or structures, relatively undeveloped (devoid of any important parts in comparison with homologous structures related forms) and lost their former primary importance in the process of phylogeny; such bodies or entities are called vestigial.

Sometimes vestigial organs can reach (in some individuals within a species) of such significant size that resemble the structural features of the ancestral forms. Organ or structure, showing the "age of the ancestors', called atavistic (from Lat. Atavus - ancestor).

Unlike rudimentary organs of atavism is the first found in almost all members of a given population, the second - only a few individuals.

Comparative anatomical series. Consider the number of limbs modern equines Mammals: tapir, rhinoceros, horse, - showing the path of evolution that led to the emergence odnopaloy legs of a horse. In the transition from living in tropical rain forests (tapir) to life in the savannah (Rhino) is a reduction of up to three fingers. In the transition to life in the open spaces (horse) reduction finger goes even further - to save only a single central finger (from a biomechanical point of view walking on one finger is extremely profitable for instant repulsion and fast running). Comparison of modern monotremes, marsupials and placental mammals allows us to represent the main path of evolution of beasts-from laying eggs (the platypus and echidna) to the birth of the living, but very immature babies (marsupials), and finally to the connection of the body of the embryo with the mother (placenta).

Population morphology. A.Uolles in 1 in. led variational series of values studied attributes for small groups of individuals. With the spread of population thinking morphological studies have also proved a convenient weapon for the study of current processes of microevolution. Population-morphological methods allow to capture the direction of natural selection to change the nature of the distribution of characteristic values in the population at different stages of its existence, or when comparing different populations.

Embryological techniques. Embryology has two main methods of studying the evolutionary process: the identification and study of embryonic similarity of recapitulation.

After the discovery of the phenomenon of embryonic similarity K.Berom Charles Darwin showed that it indicates a common origin and unity of the initial stages of the evolution of the forms compared.

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