The law, which was discovered by the outstanding domestic scientist N. I. Vavilov, is a powerful stimulator of the selection of new species of plants and animals that are beneficial to humans. Even at present, this pattern plays a large role in the study of evolutionary processes, the development of an acclimatization base. The results of Vavilov's research are also important for the interpretation of various biogeographic phenomena.
The essence of the law
Briefly, the law of homologous series is as follows: the variability spectra of related plant types are similar to each other (often this is a strictly fixed number of various variations). Vavilov presented his ideas at the III selection congress, which was held in 1920 in Saratov. To demonstrate the effect of the law of homologous series, he collected the entire set of hereditary characters of cultivated plants, arranged them in one table and compared the varieties and subspecies known at that time.
Plant study
Together with the cereal, Vavilov also considered legumes. In many cases, parallelism has been discovered. Despite the fact that each family had phenotypic characters, they had their own characteristics, and a form of expression. For example, the color of the seeds of almost any cultivated plant ranged from lightest to black. In well-studied researchers of cultivated plants, up to several hundred characters were found. Others, who were at that time less studied or wild relatives of cultivated plants, showed much less signs.
Geographical distribution centers of species
The basis for the discovery of the law of homologous series was the material that Vavilov collected during his expedition to Africa, Asia, Europe and America. The first assumptions that there are some geographical centers where biological species originate from were made by the Swiss scientist A. Dekandol. According to him, once these species covered large territories, sometimes entire continents. However, it was Vavilov who was the researcher who was able to study the diversity of plants on a scientific basis. He used a method called differentiated. The entire collection that was collected by the researcher during the expeditions was subjected to careful analysis using morphological and genetic methods. So it was possible to determine the final area of concentration of the diversity of forms and attributes.
Plant map
During these trips, the scientist was not entangled in the variety of species of various plants. He put all the information with colored pencils on the cards, then translating the material into a schematic view. Thus, he was able to discover that on the whole planet there are only a few centers of diversity of cultivated plants. The scientist showed directly with the help of maps how from these centers the species “spread” to other geographical regions. Some of them go a short distance. Others conquer the whole world, as happened with wheat and peas.
The consequences
According to the law of homologous variation, all plant varieties genetically related to each other have approximately equal series of hereditary variation. At the same time, the scientist admitted that even features that are similar in appearance can have a different hereditary basis. Considering the fact that each of the genes has the ability to mutate in different directions and that this process can proceed without a specific direction, Vavilov suggested that the number of gene mutations in related species will be approximately the same. The law of homologous series of N. I. Vavilov reflects the general laws of the processes of gene mutation, as well as the morphogenesis of various organisms. It is the main basis for the study of biological species.
Vavilov also showed a corollary that followed from the law of homological series. It reads as follows: hereditary variability in almost all plant species varies in parallel. The closer the species are to each other, the more this homology of characters is manifested. Now this law is universally applied in breeding crops, as well as animals. The discovery of the law of homologous series is one of the greatest achievements of the scientist, which brought him world fame.
Origin of plants
The scientist created a theory about the origin of cultivated plants in points of the globe that are distant from each other in various prehistoric eras. According to the law of Vavilov’s homologous series, similar variations in character variability are found in related plant and animal species. The role of this law in crop production and animal husbandry can be compared with the role played by the periodic table of D. Mendeleev in chemistry. Using his discovery, Vavilov came to the conclusion about which territories are the primary sources of certain types of plants.
- To the Sino-Japanese region, the world owes its origin to rice, millet, bare-grain forms of oats, and many types of apple trees. Also, the territory of this region is home to valuable varieties of plums, eastern persimmons.
- The birthplace of bananas, coconut palm and sugarcane is the Indonesian-Indochinese Center.
- Using the law of homological series of variability, Vavilov was able to prove the enormous importance of the Hindustan Peninsula in the development of crop production. These territories are home to some types of beans, eggplant, and cucumbers.
- Walnuts, almonds, and pistachios were traditionally grown on the territory of the Central Asian region. Vavilov discovered that this territory is the birthplace of onions, as well as primary types of carrots. In ancient times, the inhabitants of Tajikistan grew apricots. One of the best in the world are melons, which were bred in the territories of Central Asia.
- Grapes first appeared in the Mediterranean territories. The evolution of wheat, flax, and various varieties of oats also took place here. Also quite typical of the Mediterranean flora is the olive tree. Here also began the cultivation of lupine, clover and flax.
- Flora of the Australian continent gave the world eucalyptus, acacia, cotton.
- The African region is the birthplace of all types of watermelons.
- In the European-Siberian territories, the cultivation of sugar beets, Siberian apple trees, and forest grapes took place.
- South America is the birthplace of cotton. The Andean Territory is home to potatoes and some types of tomatoes. In the territories of ancient Mexico, corn and some types of beans were grown. Tobacco also originated here.
- In Africa, an ancient man first used only native plant species. The black continent is home to coffee. In Ethiopia, wheat first appeared.
Using the law of homologous series of variability, a scientist can identify the center of origin of plants by those characteristics that are similar to the forms of species from another geographical area. In addition to the necessary variety of flora, in order for a large outbreak of various cultivated plants to arise, an agricultural civilization is also needed. So N.I. Vavilov considered.
Domestication of animals
Thanks to the discovery of the law of homologous series of hereditary variability, it became possible to discover those places where the domestication of animals once occurred for the first time. It is believed that it happened in three ways. This is a rapprochement between man and animals; forced taming of young individuals; Domestication of adults. The territories on which domestication of wild animals took place are presumably located in the habitats of their wild relatives.
Taming in different eras
It is believed that the dog was domesticated during the Mesolithic. Man began to breed pigs and goats in the Neolithic era, and a little later wild horses were tamed. However, the question of who the ancestors of modern domestic animals were still not clear. It is believed that the ancestors of cattle were tours, horses - tarpans and horses of Przhevalsky, domestic goose - wild gray goose. Now the process of domestication of animals cannot be called completed. For example, in the process of taming are arctic foxes and wild foxes.
The meaning of the law of homologous series
With the help of this law, it is possible not only to establish the origin of certain types of plants and foci of domestication of animals. It allows you to predict the appearance of mutations by comparing the patterns of mutation in other types. Also, with the help of this law, it is possible to predict the variability of the trait, the possibility of the appearance of new mutations by analogy with those genetic deviations that were found in other species related to this plant.