Translated material
Larbage
Why is the domesticated fox "Asterisk" and "Laechny" tail? Why is she so pathologically friendly to a person? And why should we domest the fox?
Anastasia Kharlamova , candidate of biological sciences, senior researcher at the laboratory of evolutionary genetics of the Institute of Cytology and Genetics of the SB RAS, answered Anastasia Grassmik to all these burning questions.
I graduated from the Biology Faculty of Altai State University in Barnaul. For the first time she arrived in Novosibirsk after the third year - for pre -diploma practice. There was an agreement between our universities - ten students were sent to Novosibirsk each year.
I got to the Institute of Cytology and Genetics quite by accident. I always wanted to work with animals, and when it was time to distribute in specialties - there were four of them in AGU (biochemistry, physiology, zoology and botany) - I chose zoology. In the third year, we had the practice that the dean led. After communicating with us, he already knew our interests well, and therefore directed me here.
After graduating from the university, I remained working in the same laboratory where I made a diploma. At first I was engaged in American mink - both during the thesis and the next few years. My candidate dissertation is also performed on a mink. But then I changed the object of my research on foxes.
Lisits's domestic experiment
The laboratory of evolutionary genetics was at one time led by academician D.K. Belyaev. The direction of research of the laboratory has not changed since Dmitry Konstantinovich did not become. He, being the director of the institute and at the same time head of the laboratory of evolutionary genetics, organized a selection of silver-black foxes for friendly behavior in relation to a person. This experiment was later extended to two more types - a gray rat and an American mink. As a result of selection at three model objects, manual populations were created.
An experiment on the houses of foxes today for more than fifty years. He had a fundamental goal - reproduction during the most compressed time period of that evolutionary process that all historically domesticated animals passed. The task was set - to trace the effects that were observed in the early stages of historical domestication (domestication), to understand the reasons that caused an amazing diversity among all pets, as well as explain amazing parallelism in the changes that arise during domestication.
The most important question
Belyaev’s idea was based on the issue that evolutionary scientists discussed for many years, starting with Darwin: why are all domesticated animals so much different from wild ancestral forms that are characterized by amazing uniformity?
All wild species, as a rule, have a patronizing (protective) coloring, often gray wool, all their biorhythms are clearly tied to the photoperiod (change of day and night), in other words, all physiological and morphological signs are characterized by stability. Suppose a wolf. The species is very stable both in size and in color - in all morphological indicators. And if you are talking about the dog, what do you imagine? You can imagine anything. This species is very diverse - both in shape, and in the structure of the wool, and in size ...
Almost every domesticated species is much more diverse than the original wild form. Scientists really occupied the question: “What is this connected with?” During the time of Darwin, scientists often associated such a variety with the fact that animals are taken out of their natural environment, change food, and they are often taken from the continent to the continent. A large number of parameters are changing, which are stable in the wild. This leads to the fact that many different home forms appear.
Subsequently, they began to say that a factor of behavior may play an important role here. Belyaev focused on the fact that the selection aimed at the properties of behavior may be the key mechanism that triggers the occurrence of diversity.
Unnatural selection
The experiment was started on a fox, because at that time it was divorced in large quantities in animal household farms for commercial purposes. We also have a huge array of the original wild or conditionally wild animals in order to subsequently take away the most manual from them.
The selection on some signs can only be carried out in the population in which polymorphism exists on this basis. If there is an initial diversity in a large population, then we can select animals of certain behavior and begin to select pairs of parents of the same behavior. Among their descendants, we will select the most manual and select non -treasured couples from them.
"Stars", snacks and tails twisted into the ring
The first stages of selection on behavior were the most stringent. Thousands of foxes were tested from various was farms of the former USSR. Most of the foxes were characterized by cowardly defensive behavior in relation to man, and only very small-tolerant attitude. If the fox did not try to bite and did not run away, such animals were taken into the experiment as a parental generation.
At the end of the fifties, one hundred males and thirty females for the first generation were selected. Moreover, as parents in the next generation, no more than 10% of puppies were taken. Only the most manual was selected, everyone else was rejected.
The uniqueness of behavior, as Belyaev suggested, “pulled” special features. With a high frequency, various morphological neoplasms began to occur, especially at the first stages of selection.
One of them was recorded as a semi -dominant mutation. This is a “star”, a white spot, on the head of the fox. It is characteristic of many pets and is considered one of the "markers" of domestication.
It is known that the predecessors of age cells - primary melanoblasts - migrate into the rudiments of the skin, and this process is limited in time at a certain time of embryonic development. If primary melanoblasts do not have time to reach future skin in time, then such areas will remain white. Specially conducted in our laboratory, studies in the foxes revealed that in manual animals, migration was detained in time, due to which areas of the skin-mechanical cover that are devoid of the pigment arise.
In the process of selection, other paint signs, for example, “plow” also appeared. They arose with a frequency of several orders of magnitude higher from a population selected for manual behavior.
With a high frequency, aberration (violations) of the skeletal system began to appear (in particular, the jaw put forward - the so -called snack that is abnormal for the wild population), short tails, a tail twisted into the ring. The “barish” tail characterizes the female readiness for mating in the wild population, and in manual foxes this sign can appear in both the male and the female, and also stay all year round.
As D.K. Belyaev, the frequency of aberration was much higher when selecting manual behavior. The selection of behavior caused the destabilization of the body as a whole. These facts formed the basis of the theory of destabilizing selection created by D.K. Belyaev, as opposed to the theory of stabilizing selection of Schmalgauzen, which explains the existence of species in natural conditions.
Pathological friendliness
Our model is currently very popular all over the world, since it allows you to study the molecular genetic mechanisms of behavior. The fox is a highly organized animal, and its behavior is quite complicated. You can find and interpret parallels with human behavior and study, for example, some points in human behavior.
For example, our foxes, one might say, is some kind of pathological friendliness. They can instead of food instead of playing with each other to communicate with a person.
In the genomes of different, even far from related species, you can find "common" areas. These are conservative areas, the changes in which did not occur during very long historical periods. So, they carry important genes that are so selected in evolution that they do not change for millions of years. Comparative genetic maps of animals and humans allow you to compare the genomes of the fox and dogs, foxes, dogs and humans.
It was found that one of the loci (sections in the genome), which is involved in manual behavior in foxes, is common with the locus of a person in which the gene responsible for the “William Sindr” is a syndrome of excessive friendliness in humans.
Another very important area in the fox genome, which is responsible for the formation of manual behavior, is common with the site in the dog genome, for which it was shown that it is involved in the processes of early domestication - the processes of the transition of the wolf to the ancient dog. It is quite obvious that these areas are really important if they are preserved during the evolution of different groups of both animals and humans.
Hipples
The dogs showed that as a result of domestication, they acquired the ability to contact and communicate with a person so closely that they are able to understand not only his words, but also gestures.
The experiment was as follows: a man hid some top dressing and gestured where he put it. The dog unequivocally understands this, the wolf - no. Even if this wolf was fed from the nipples, and he grew up with a man!
Our manual foxes are reliably more making the right decisions than wild foxes if a person gives them a hint. Wild foxes act randomly.
Wild animal
When we, for example, transport our foxes somewhere, in the documents we denote them as a “wild animal”. They have no other name, subspecies or form. They are not allocated systematically. The population is small, unique. She really has many features that distinguish her from the wild “ordinary fox”. All over the world they are called "Belyaevsky foxes." Everyone knows them, but they, unfortunately, have no status formally.
Of course, such a large -scale experiment, which was conceived and implemented by Dmitry Konstantinovich Belyaev, is very difficult to put to put it mildly now.
Three far -standing a friendly friend from a friend, involved in the process of experimental domestication - a representative of the Psovy family (fox), a representative of the rodent family (rat) and a representative of the Kunitsye family (American mink) - showed amazing parallelism in the changes that the selection of behavior entailed. These were the same changes that demonstrate species domesticated by man in the process of historical domestication.