Molecular mechanisms of genetic isolation

Darwin is non in unserviceable c alled his major mold The Origin of Species. He understood that speciation - the rudimentary process of biological developing. It seems strange that in biology thither is still no universally pass judgment definition of species. We all understand that a horse and a zebra, hard and fluffy wheat - divergent kinds. exactly attempts to ready this structural straighten out units, the total for the al genius of nature, encounter knockout difficulties. \nThe term scene was first proposed by Aristotle as a collection of objects united by the similarity. sole(prenominal) 2000 years later, in 1693, the English naturalist Dzh.Rey gave the concept of grade biological sense. jibe to Ray, a species - a collection of individuals who bring forth together on two criteria: the concrete identity of geo morphological features and free crossing with reproduction traits in the progeny. \nMost researchers outright conclude that the morphological cr iteria for determining species is insufficient. Geneticists atomic number 18 inclined to the insurgent criterion, on the buttocks of which it follows that the independence of the make supported by genetic closing off. thither can be no evolution without genetic closing off - limited the re-sentencing of genes between the rising species. This is true, but thither are different mechanisms to prevent carrefour in nature. \n angiotensin-converting enzyme of these mechanisms - geographic isolation, ie territorial isolation of species. In 1870 M.Vagner conclude that in one habitat may be alone one species, and therefore, in different - different. This he called geographic speciation. at once it is called allopatric (allos - other, patris - birth impersonate). Darwin, however, admitted that the transfigure of genes may be limited non only geographically separated populations of the founding. \nsometimes in an free dwelling place of the original produce arise whole swarms or, as they are called, bouquets of new species. Examples of this sort - Darwins finches from the Galapagos Islands, lean and crustaceans Baikal fish cichlid fishes of the dandy Lakes. They all consist in the like habitat, not interbreeding, as they developed particular(prenominal) mechanisms of genetic isolation: reproduction at different times, the differences in terms of conglutination behavior. Typically, males and females of different species do not circuit board each other. But this barrier is easy overcome, for example, by influence (imprinting). It is known that in Eurasia inhabited by various species of dodges, and in the wild they intimately do not interbreed. But if one kind of duck egg is primed(p) to the nest of another, who came to the duckling would bump kind of deterrent example adoptive mother, and as an adult gentlewoman will foil only with individuals, be to him. Sometimes it comes to paradoxes. K.Lorents wrote that maam white peacock, who grew u p in the babys room of reptiles, then behavior trying to work care of the monstrosity tortoises, not paying(a) attention to the or so beautiful pavilion. This isolation is called prekopulyatsionnoy. Different species do not mark hybrids and retain their independence, because it hardly does not mate. This manner is most predominant in high organisms, especially mammals and birds.