Inbreeding in the breeding of British cats.
 
BRITISH KITTEN

MAPE SITE

RUS

BRITISH KITTEN BRITISH KITTEN BRITISH KITTEN BRITISH KITTEN BRITISH KITTEN BRITISH KITTEN BRITISH KITTEN BRITISH KITTEN
Copyright© 09.03.2008 Ridolina    Web design: Tipikina Galina Sergeevna  ® 2007, Russia, Moscow tel. +7 495 3877549 mob. +7 985 2589172 e-mail: ridolina@yandex.ru
Photos © Tipikina Galina Sergeevna Use of materials of a site probably only from the sanction of the owner and the direct reference to a site.

Rambler's Top100 Яндекс цитирования
"Inbreeding - a method of breeding,
used for improvements to the physical or mental characteristics "
CONCLUSIONS:

Breeders are often asked, is it possible to carry out hard or average inbreeding?
Answer. If the animals carry genetic abnormalities, they show up, and it does not depend on the degree of kinship. Even if you are absolutely unrelated povyazhete cat cat from another planet, and in his or her genes are fixed or there are any deformities and ailments, you will certainly get them in the children and vice versa, tying her sister with a brother who do not have such problems, they never will be. Incest should not be confused with inbreeding. In animals and humans are different programs of evolution.

Information that you can not buy kittens, whose parents are relatives - complete nonsense! The lack of inbred matings in the nursery - not a guarantee of health and lack of various anomalies and defects in cats, and even suggestive of the fact that the producers of these informants are carriers of genetic abnormalities, so inbreeding and do not use.

According to the rules of breeding such matings recommended to carry out in consultation with the tribal committee. Need to know what hereditary abnormalities have these manufacturers. There are those who are contraindicated for inbreeding. Newcomers to breed just need to resolve such issues with their plemennikom.

Furthermore, inbreeding is absolutely contraindicated in species of cats, which were used at a dilution of fixation of mutation of genes that are in the homozygous form leads to the manifestation of the harmful effects of this mutation - Congenital and hereditary diseases.

Inbreeding quickly identifies weaknesses and manufacturers to accelerate the process of selecting the best breed characteristics. Producers who do not have lethal, poluletalnyh, and other harmful mutant genes will produce healthy offspring with inbreeding, and their descendants continue to flat stable litters.

Tipikina Galina, owner of the cattery British Shorthair Ridolina
IHDBRIDIHG - PRO ET CONTRA

This article is addressed to lovers and cat owners cat kennels, as well as the chairmen of the clubs and associations which have as their main goal of strengthening and improving the quality of their animals breed, by pure breeding and selection (breeding). Immediately, we emphasize that because the selection includes a rigid culling, this goal is in conflict with the commercial breeding of cats, where the main goal - profit.

Inbreeding as a component of pure breeding

In its work, the breeder, the breeder must decide which of females with which males should be selected from the pair to their offspring combined the definite signs of acquired and improved features. This event is called a selective choice of pairs for mating. Matching should be done gradually and systematically, and the purpose of its change of genetic structure of populations of animals kennel in the desired direction, or the preservation and consolidation in the progeny of a combination of valuable features. Sometimes, to develop new breeds or breed of bringing in entirely new features previously not peculiar to her, or even apply interbreed interbreeding, but usually the main focus of the breeder is the so-called thoroughbred breeding - mating of individuals of the same breed.
Thoroughbred breeding is divided into two types: outbreeding - a system of pairings of unrelated animals within the breed, and inbreeding - mating system of individuals having a close family relationship, such as brother-sister, father-daughter, mother-son, cousins, etc. . In general, inbreeding suggests that the paired specimens - the future father and mother - have a common ancestor or at least one common ancestor. Although the importance and need for specialists inbreeding in purebred breeding obvious, among the amateurs, there are many myths and prejudices, both against the most inbred, and the use of inbred producers in breeding. (Pre say that the latter is especially a big mistake, because inbridirovannye elite producers are usually prepotent - their children are largely "a father" - and often give very strong offspring.)

Genetic basis of inbreeding

What is the biological (genetic) nature of inbreeding? All modern breeds of animals, including cats, are heterozygous for many genes. This means the following. Zygote - a fertilized egg - and receives from his father, and mother of one complete set of genes, so that they have a double set. If both genes are responsible for this trait - one from the father and the other from the mother - are identical, this condition is called homozygous for this gene and will develop from eggs homozygous for that gene individual. If the genes are equivalent to the pair, for example, determining the formation of black pigment of hair, different (say, a father gave a gene with black and his mother - a modified, such as Himalayan gene Cs), then the individual will heterozygous for this gene (CCS). In the latter case, the gene is dominant black, and the animal looks (phenotype) can be obtained in black, but will be a carrier of recessive (hidden) Himalayan gene. If such animal is heterozygous - albeit it was a black cat carrier Himalayan gene to cross with his sister, also a black cat carrying a hidden Himalayan gene, the progeny will be observed splitting (Fig. 1) of the offspring will be black color (CC - homozygous and CCS - heterozygous genotypes), while the other part - the Himalayan (homozygous genotype ssss) This is because in the crossing of a black cat with his black nurse their sex cells gametes (sperm and egg) - carry on a single set of genes that are occur in all four possible combinations: with the cat and the cat C, C of Cs from the cat and the cat, the cat and Cs with the cat, the cat Cs and Cs from the cat. Consequently, with probability 1 / 4 two Himalayan gene (one from the father and the other from the mother) will converge in one zygote and give homozygous genotype and the Himalayas, therefore, part of the phenotype in the Himalayan kitten litter. Another part of the litter, with the same probability 1 / 4 turns out to be homozygous for the gene of a continuous black color (CC). Thus, the genetic nature of inbreeding is reduced to the process of decomposition of the population in line with different homozygous genotypes, inbreeding Since the genes were in heterozygous state, are transferred to the homozygous state in the next generation, by crossing homozygous animals of the same color will not be observed splitting. This way by inbreeding by revealing hidden features, fixing desirable traits from generation to generation and creation of stable genetic lines.
The fastest practical way to increase homozygosity in higher animals is the pairing of brother and sister (siblings) who have a common father and mother (do not make any difference whether the siblings are taken, littermates, or from different litters), as well as father and daughter pairing or mother and son. It is sometimes argued among lay people felt that, say, father and daughter pairing is possible, and the mother and son can not be - a myth that does not have any reason; the effect of these two types of inbreeding is quite similar. If the exercise of such close inbreeding (incest) for 1b generations in a row, reached 98% of homozygosity for all genes and, consequently, in the absence of cleavage, all the individuals of these litters are almost identical in genotype and phenotype - all children are identical, like twins, of course in practice is usually applied inbreeding is much less, and thus achieved a much lower degree of homozygosity.
It should be noted that the pairing of second cousins ??and sisters (the general's great-grandfather) leads to increased homozygosity, only 2% with an infinite number of generations, therefore, this type of inbreeding is fundamentally different from a closer degree of inbreeding and in fact does not lead to the achievement of the goals that facing a system of inbreeding. Breeders, for whatever reason to avoid inbreeding, may not be afraid to mate twice removed relatives.

Determining the degree of inbreeding and inbreeding coefficient

Based on the analysis of animal pedigree can be qualitatively assess the degree of inbreeding, which is expressed by the saturation of pedigree common ancestors (nicknames) for maternal and paternal lines. By Shaporuzhu, Roman numerals denote generation (number of ancestors), assuming the parent for the first, his grandfather for the second, etc. If the common ancestor is repeated in the maternal and paternal in the pedigree, it is first put its occurrence in the maternal lineage, and then, with a hyphen - in his father's. Then crossing son x mother will be denoted as I-II, father x daughter as II-I, brother, sister, as x II-II, grandfather granddaughter as x III-I, cousins ??sister as x IIIIII, etc. Inbreeding type father x daughter (II-I), son x mother (I-II) and brother x sister (II-II) is designated as very close, or incest, inbreeding type II-III or III-II - it's close inbreeding, and cross III-IV, IV-III, IV-IV, II-V, and so n - moderate inbreeding. Given the lack of tangible effects of the more distant inbreeding in practice can not be regarded as the true inbreeding. Owners of high-pedigreed cats, picking up a pedigree cat, can estimate how often and how much inbreeding is used by breeders who participated in the removal of the pet.
For quantifying the degree of inbreeding in the pedigree of an animal and thereby determine the measure of its homozygosity English geneticist C. Wright introduced the concept of inbreeding coefficient (F). This ratio is calculated as follows. First is the number of generations from the common ancestor of A father and mother to the father of the animal (p), then the number of generations (arrows) from the same ancestor A to the mother (t). These numbers are added up and added to the sum of unit: n = p + m + 1. The inbreeding coefficient of the analyzed animal (proband A) of this ancestor is 1 / 2 to the power n: ha = (1 / 2) n. If the father and mother is a few common ancestors, the coefficients are summed up:
Fx = EF, = E (1 / 2) n, where i - the common ancestors of A, B, C, etc.
For example, calculate the inbreeding coefficient of animal (proband X) obtained by crossing siblings. In genealogical distance (path) from grandfather to father - a generation, from grandfather to the mother - a generation hence, n = 1 + 1 + 1 = 3, and hence fb = (1 / 2) 3 = 1 / 8. But they have one common ancestor - their grandmother, from her father before - a generation, from mother to her the same - a generation, and therefore will also Fa 1 / 8. The total inbreeding coefficient for X is obtained by Fx = Fa + Fb = 1 / 8 +1 / 8 = 1 / 4, or 0.25.
Another example - crossing his grandfather with his granddaughter. Here, the offspring's paternal generations do not, ie 0 generations through the maternal line - two generations, where n = 0 + 2 + 1 = 3, then Fx = (1 / 2) 3 = 1 / 8, or 0.125.
Finally, an example of crossing cousins ??and sister. Common ancestors of their offspring - the great-grandfather and great-grandmother. From grandparents to my father - two generations from him to the mother of 2nd generation, ie n = 2 + 2 + 1 = 5, respectively, and Fb = (1 / 2) '1 / 32. The same is obtained by calculating the coefficient of inbreeding in the common ancestor of the other - the great-grandmother: Fa = (1 / 2) 3 = 1 / 32. Consequently, the total inbreeding coefficient Fx = Fa + Fb = 1 / 32 +1 / 32 = 1 / 16, or 0.0625.
From the available pedigrees, each breeder or owner of a purebred animal is able to calculate the inbreeding coefficient of their pets or their parents and grandparents - if used in their production of inbreeding. As mentioned earlier, this ratio is a measure of the degree of purity (homozygous) lines participating in the pedigree, as well as an indication of a possible prepotent respective manufacturers and / or proizvoditelnits (see below). The higher the inbreeding coefficient of animal, the greater the gene is homozygous. Naturally, it follows from the formula, the inbreeding coefficient can not exceed unity,



Inbreeding depression and heterosis

Why is it that human society exists in most civilizations, or an express prohibition on incest, or his conviction? Moreover, why in the wild, too, are adjusted so that as far as possible to avoid inbreeding and homozygosity? The main reason is that wildlife and human society for the successful survival and adaptation to changing environmental conditions (including social and economic in the case of human society) should be a variety of genotypes and individuals in the population. In the diverse community there will always be individuals best adapted to the specific situation, but the situation is changing - and other individuals with other signs of swim to the surface. The monotony of the population, although well adapted to these specific conditions of its existence, doomed to extinction species by changing the conditions of existence, thus the desire to create diversity should not separate individuals, and the species to meet the diverse and changing needs of the environment and the historical process .
But there is also a direct risk of inbreeding for individuals. The fact that, as in the individual life of the animal (and human), and on through the generations from time to time there are mutations - changes in the genes. Most of the mutations - harmful, and if they manifested themselves immediately, it would lead to death (lethal mutations), deformities, abnormal behavior, inconsistencies environment, etc. However, most mutations at the same time has a recessive character, ie in combination with a normal pair genome through a double set of genes not expressed in the heterozygous state. The cargo of noxious, but not shown, hidden mutation is present in every heterozygous individual, including each person creates inbreeding homozygosity, including homozygosity of harmful genes, and thus leads to their phenotypic expression in the offspring - intrauterine or early death, deformities , decreased viability, etc. This is called inbreeding depression.
We define the reverse question - why, despite the risk of inbreeding depression, breeders, carve and perfecting the domestic animals, so often resort to inbreeding and are not afraid of him? The answer is simple: Breeders do not tend to maximize the survival, vitality and high quality offspring of all individuals, and lead selection of the best, vybrakovyvaya (eg kastriruya) defective, weak, and just with undesirable traits. Thus, when inbreeding, when the decomposition of the genotype homozygous for the line, the harmful recessive genes appear and are removed from further breeding, and all the "good" genes and their combinations are fixed in the homozygous state and are left for future generations. Thus, inbreeding in the hands of the breeder - a way to remove the cargo from the genotype of deleterious mutations, on the one hand, and create the necessary combinations of valuable genes and traits, on the other. In addition, homozygosity created the need for removing any of the new breed uniformity that meets the requirements of this species, and the relevant securities are fixed signs in their offspring. It should be noted that as inbreeding and selection of the best, due to disposal of hazardous cargo hidden mutations, the risk of inbreeding depression in inbreeding of selected inbred animals is reduced.
In crosses between different inbred lines of independent phenomenon can be observed, in a sense the opposite of inbreeding depression - heterosis, also known as a "hybrid force". These hybrids of two inbred animals usually show increased viability, growth, fertility, etc. This is because in crosses between two inbred lines, selected, and therefore similar to a typical hallmark of the breed is preserved in the offspring homozygous for these selected features, while not culled the remaining harmful mutations in heterozygous state are transferred and thus become recessive, ie not occur.


Practice and purpose of inbreeding

Consider the whole sum and tasks that are performed, and the goals that are pursued livestock, including breeders, cat breeders, the use of inbreeding.
First, inbreeding is required when a new breed or a new group within the breed. To increase the genetic diversity and to attract new characters breeder crosses of animals of different breeds. The resulting hybrid offspring are heterozygous and therefore will be given in subsequent generations of splitting. To consolidate the desirable combination of traits and inbreeding is used mostly close, like brother x sister, father, mother and daughter x x son. As a result of inbreeding are homogeneous family and reached a constant manifestation of symptoms. Among the inbred descendants of a strict culling of up to 80% - defective, weak, and do not meet the standards outlined animals.
Fig. 3 shows an example of very close inbreeding in the breeding Himalayan cats with mauve markings (laylakpoynt) in an English nursery Mingchyu. The cat with the color chocolate-point - Snuff - was obtained by mating a cat Troma, the color of the seal point, chocolate and blue carrier geyov from the American Kennel Breyer, with Siamese Trayviey also seal point and also the bearer of chocolate and a blue gene from Mingchsch kennel, the cat chocolate point (Snuff) was mated with his father, a cat Throm. Born of their cat Chalk, seal-point, was tied with his mother, a cat Snuff, chocolate-point. They are the first cat was born with violet markings (lilac-point) - Sulatri. It is worth noting a very high coefficient of inbreeding Sulatri: R 3 / 8, or 0.375, ie higher than in crosses brother and sister.
Second, a close (very close), inbreeding is used when necessary to identify the manufacturers - the carriers of lethal, poluletalnyh and other undesirable genes. This so-called test of inbreeding. According to the results of test of inbreeding may be adopted various decisions, either by manufacturers such discarded or used to produce homozygous offspring (through inbreeding) with culling and selection of defective better than achieved purification of the genotype of undesirable genes.
Thirdly, the purpose of inbreeding may be vysokoprepotentnogo excretion, ie, effectively transferring their children to the features, the manufacturer. It is known that inbred animals have higher self-prepotentsiey compared with specimens derived from unrelated matings. In this regard, in cattle there is a widely accepted practice inbred male mate with females neinbrednymi, this practice is called top-crossing. It is important that a good producer of inbred, selected to convey the quality of seeds, can significantly improve the livestock nursery and give it its face, the feature, its type.
Fourth, some breeders are going to create inbred lines in their kennels, so that later, crossing from different lines (often this is done in the manner of cooperation between the different nurseries), to obtain the effect of heterosis - a powerful, large, viable and fertile offspring.
Finally, we wish to stress that to maintain breeding - including the cats - it is necessary to apply the system of selection and recruitment of competent animals. We differentiate between selection on the phenotype and genotype. Cat lovers are familiar with the different levels of Cat Show, which is carried out classroom assessment (in professional language - valuation of) cats. This is the assessment of the phenotype. Estimate of the genotype should be performed on pedigrees of animals and the quality of their offspring. In general, the breeding value of an animal can be explained only by evaluating the manufacturer of the quality of his offspring. Beautiful animal phenotype is not always a good producer. In cattle there is popular expression: "A good bull polstada worth it." The same is true with cats producers: quality kennel and his face is largely determined by the manufacturer's cat (or cats, the producers, if more than one). This cat-maker should be highly prepotent and, therefore, breeders must pay attention to the inbred manufacturers. Moreover, it is impossible to create a good nursery, just bought abroad expensive animals and the champion grandchempionskimi titles. It is necessary that in the kennel and the kennel from the manufacturers on the side of the animals were born a champion and an international level grandchempionskogo. And this requires a competent breeding, which plays an essential role of inbreeding.

Marlene Mkrtichovich Aslanian,
Professor of Genetics
and selection, Sc.D.;
Alexander Spirin,
Professor of Molecular
Biology, Doctor of Biology
Science, Member
Russian Academy of Sciences
Head of the Department of Molecular Biology, Biological Faculty, Moscow State University. MV Alexander Spirin University
Doctor of Biological Sciences, Department of Genetics prfessor Moscow State University. MV University Aslanian Marlene Mkrtichovich
Inbreeding
Introduction: Tipikina Galina, owner of the cattery of British cats Ridolina

"Inbreeding - this dilution method used for improvements to the physical or mental characteristics" - written in today's "Encyclopedic Dictionary of Terms dog."

Any breed of animals created by inbreeding, there is no other way. His aim to consolidate breed characteristics at the genetic level. In the animal world there is protection from degradation by inbreeding, and protection from interspecific crosses. Therefore, in wild populations of species preserved in its original form, and inbreeding, which is inevitable in nature, does not interfere with the reproduction of sound generation. If it had been otherwise, we would have lost their animals.


Inbreeding and its role in breeding, inbreeding depression, prepotent.

Inbreeding (from English inbreeding: in - in, inside, breeding - breeding) - one of the methods of breeding, in which a pair reduce animal originating from a common ancestor, that is relative.

Inbreeding depression - the weakening of the viability of offspring as a result of the accumulation and display of lethal and poluletalnyh genes and other negative traits available to the pioneers of the population.

Prepotent - the ability of manufacturers steadfastly bequeath its features (as desirable and undesirable).

"Pure Line" - a limited collection of animals, long-term breeding by close inbreeding.

Allele - a fragment of the gene "responsible" for a particular trait.
Phenotype - a set of external and internal features.
Genotype - a set of hereditary germs that the body receives from the parents.

Homozygosity - the ability of individuals to form a sort of germ cells, which contain two of the same hereditary, either both dominant (eg, explosives) or both recessive (bb).

Heterozygosity - the ability of individuals to form different germ cells carrying a dominant gene, and the other, the corresponding recessive (Bb).
Positive and negative aspects of inbreeding are constantly conducted endless debates, and this issue deserves special consideration. Opponents of this method indicate that the mating of close relatives leads to a decrease in fertility of their offspring, the descendants of the general weakening of body, a large percentage of stillbirths and increased mortality from disease, the frequent appearance of the puppies, suffering from genetic (hereditary) diseases and disabilities. Belief is so strong that most breeders to mate brother and sister among purebred dogs are viewed as completely unacceptable and criminal phenomenon. Proponents are reminded that all or nearly all species, not only dogs but other animals were bred with close inbreeding. At the same time they point out that inbreeding can fix in the desired quality of the descendants of the original manufacturers.


Indeed, most populations of wild animals in nature arises from a single pair or a few individuals caught accidentally in a new and not yet inhabited this type of place. It is clear that even if the original manufacturers were chuzhekrovnymi, then after a few generations the whole population will be composed of relatives. But the selection of a regulator in this case is the very nature of which is to allow the continuation of the species most adapted to the area. Some part of the world's best stock horses, cows, pigs, dogs and other animals was also obtained by inbreeding, which is actively used in our time to formulate a more productive breeds of livestock.


In practical dog breeding is very common notion of "line", as used in a variety of meanings. In this regard, we deem it necessary to acquaint readers with the notion of "pure line." Feature of line breeding is that all individuals of each generation of this line are descended from one pair of animals, a brother and sister, of which, in turn, only one pair, a brother and sister, is the ancestor of the next generation. To create a pure line breeding is necessary for this scheme for at least 20 generations. Inbreeding leads to genetic uniformity of such animals within the lines, which occurs, for example, in identical twins. In this way, created a line of laboratory animals used in medical and biological experiments. One of the first researchers to apply the method to study the pure lines of the problems of oncology, in an experiment using mice that had been known Clarence Little. The essence of the processes that occur when inbreeding - a shift from heterozygosity to homozygosity. Unrelated mating, conversely, help to increase the degree of heterozygosity.


The process of removing the inbred line is clearly divided into two periods. Initially, increases the formation of homozygotes. It lasts a long time, because alleles that are latent in the original specimens, it happens quite a lot. Because of this inevitably increases the variability in the population. During the same period the detection poluletalnyh, lethal, and other harmful mutant genes that are earlier in the heterozygous state, which is manifested in the form of so-called inbreeding depression. If the genotype of the original specimens of these genes are many, the attempt to create a line may not be successful, and it will end its existence, when most of these genes will move in the homozygous state. The practice of breeding pure lines of laboratory animals shows that the 5-6th generation of inbreeding, identifies the main lethal and sublethal genes in the genotype with its founders. If the line had shifted in six generations, the inbred breeding its future is not an issue. Finally, after another 10-12 generations, there comes a time when all genes are transferred in the homozygous state, the line is consolidated, and now, no matter how many generations of inbreeding did not occur, the line maintains its hereditary characteristics. It may change now only in the case of mutations. However, it is impossible to achieve absolute homozygosity, even in clean lines, since the appearance of mutations is a continuous process. Creating and maintaining clear lines requires a long time, the large number of animals, and accordingly, and large, specially equipped areas. Obviously, a clean line of dog or cat is almost impossible, so use this concept in the dog quite ill.


Thus, reproduction is akin to a tool for moving population's gene pool in the homozygous state. But the fact of deterioration of the lines in the process of inbreeding only shows that many of the alleles were hiding in the heterozygous state in the founders of the lines, could give homozygous negative effect. This increases the chance of external manifestations of the lethal and sublethal genes, respectively, the birth of dead or defective puppies. And the frequency of such cases depends entirely on the incidence of adverse alleles in the population.


Experiments on inbreeding albino rats were initiated by the American scholar Helen King in 1909, with several pairs of rats, originating from the same litter. From these pairs of rats by continuous breeding brother and sister from the same litter were obtained by separate lines, led to the closest degree of kinship. After some time in there were only two lines, and the rest have completed their existence as a result of strong inbreeding depression associated with the presence of the pioneers in the genotype of these lines a large number of lethal and sublethal genes. Until 1923, all received over seven thousand litters, including more 50tys. rats, and data about the inbreeding stretch of 40 consecutive generations. When breeding was carried out rigorous selection process. All weak, petty and vicious animals are removed, and allowed to mate the largest and most powerful individuals. The end result is all the inbred animals had a greater weight than the controls, higher fertility, etc. With all this progeny of one pair, though small, but very clearly differed from the offspring of another pair.


What gives us the experience? It shows that inbreeding followed by selection, quickly leads to an improvement of this group of animals in relation to the criteria selected by, by the affirmation of those genetic features that were present in the original ancestors. This explains the slight difference between the offspring of the first and second original pair of rats, which crossed the line of inbreeding depression. The importance of hereditary peculiarities combined for inbreeding manufacturers with even greater clarity stems from the experience akin to breeding guinea pigs, a detailed study by the American scientist C. Wright. The experiments were started in 1906 with 35 pairs of guinea pigs by mating brothers and sisters. Prior to 1921 inclusive were obtained over 30 thousand animals in 20 generations. In contrast to the experience with the rats no screening was conducted. In the analysis of the obtained material was installed lowering fertility and viability of offspring. A detailed examination of individual families showed that among them there are very strong differences in many aspects, but within families there was a complete similarity with respect to all hereditary traits - physiological as: fertility, the rate and pattern of growth and development, general vitality, resistance to diseases, and so n. and vneshnemorfologicheskih: color, colors, and signs the form.


If parents have hereditary factors contributing to the manifestation of negative symptoms, the whole inbred family obtained from these producers, bravely shows the corresponding negative symptoms, which entails a negative attitude is closely related to breeding in general. If the original parent pair has a positive sign of the genes, it is precisely these characteristics are embodied in their inbred offspring.
Manufacturers of inbridirovannoy families have a much greater degree of homozygosity and, hence, prepotent, rather than producers, obtained by selection with an unrelated breeding. The practical value of the producer, the higher the better he is able to produce offspring with different combinations of pairs. We must distinguish between the ability to increase the number of animals and the ability to improve their quality. In evaluating this manufacturer should bear in mind both the quality of his descendants and the descendants of the ratio of good to poor. Analyzing the resulting material can determine the degree of prepotent producer and its main prepotent traits, both positive and negative.


Thus, one could argue that with the help of inbreeding in the breeding of animals solve many problems. Inbreeding on the outstanding producers, followed by selection, eroding their valuable properties in the progeny. It is used to create the breed clearly different lines or families. Inbreeding reveals the genetic properties of individuals and to select against harmful recessive alleles in the population, helping to improve the quality of livestock. But it is necessary to emphasize that inbreeding - a "tool" extremely serious and requires the use of it is sufficient knowledge and experience, lack of which could cause considerable harm to the breed.


Many thanks to Maria Nikolaevna Sotskov, Ph.D., assistant professor of Moscow State Psychological-Pedagogical University, the owner of "The White Flock" kindly provided us with material from the new upcoming book "Breeding", co-authored with N. Moskovkin


This article was prepared Rusakova M.

Reviewer - Maria Sotskov.

Inbreeding and its role in breeding, inbreeding depression, prepotent. IHDBRIDIHG - PRO ET CONTRA

This article is addressed to lovers and cat owners cat kennels, as well as the chairmen of the clubs and associations which have as their main goal of strengthening and improving the quality of their animals breed, by pure breeding and selection (breeding). Immediately, we emphasize that because the selection includes a rigid culling, this goal is in conflict with the commercial breeding of cats, where the main goal - profit.

Inbreeding as a component of pure breeding

In its work, the breeder, the breeder must decide which of females with which males should be selected from the pair to their offspring combined the definite signs of acquired and improved features. This event is called a selective choice of pairs for mating. Matching should be done gradually and systematically, and the purpose of its change of genetic structure of populations of animals kennel in the desired direction, or the preservation and consolidation in the progeny of a combination of valuable features. Sometimes, to develop new breeds or breed of bringing in entirely new features previously not peculiar to her, or even apply interbreed interbreeding, but usually the main focus of the breeder is the so-called thoroughbred breeding - mating of individuals of the same breed.
Thoroughbred breeding is divided into two types: outbreeding - a system of pairings of unrelated animals within the breed, and inbreeding - mating system of individuals having a close family relationship, such as brother-sister, father-daughter, mother-son, cousins, etc. . In general, inbreeding suggests that the paired specimens - the future father and mother - have a common ancestor or at least one common ancestor. Although the importance and need for specialists inbreeding in purebred breeding obvious, among the amateurs, there are many myths and prejudices, both against the most inbred, and the use of inbred producers in breeding. (Pre say that the latter is especially a big mistake, because inbridirovannye elite producers are usually prepotent - their children are largely "a father" - and often give very strong offspring.)

Genetic basis of inbreeding

What is the biological (genetic) nature of inbreeding? All modern breeds of animals, including cats, are heterozygous for many genes. This means the following. Zygote - a fertilized egg - and receives from his father, and mother of one complete set of genes, so that they have a double set. If both genes are responsible for this trait - one from the father and the other from the mother - are identical, this condition is called homozygous for this gene and will develop from eggs homozygous for that gene individual. If the genes are equivalent to the pair, for example, determining the formation of black pigment of hair, different (say, a father gave a gene with black and his mother - a modified, such as Himalayan gene Cs), then the individual will heterozygous for this gene (CCS). In the latter case, the gene is dominant black, and the animal looks (phenotype) can be obtained in black, but will be a carrier of recessive (hidden) Himalayan gene. If such animal is heterozygous - albeit it was a black cat carrier Himalayan gene to cross with his sister, also a black cat carrying a hidden Himalayan gene, the progeny will be observed splitting (Fig. 1) of the offspring will be black color (CC - homozygous and CCS - heterozygous genotypes), while the other part - the Himalayan (homozygous genotype ssss) This is because in the crossing of a black cat with his black nurse their sex cells gametes (sperm and egg) - carry on a single set of genes that are occur in all four possible combinations: with the cat and the cat C, C of Cs from the cat and the cat, the cat and Cs with the cat, the cat Cs and Cs from the cat. Consequently, with probability 1 / 4 two Himalayan gene (one from the father and the other from the mother) will converge in one zygote and give homozygous genotype and the Himalayas, therefore, part of the phenotype in the Himalayan kitten litter. Another part of the litter, with the same probability 1 / 4 turns out to be homozygous for the gene of a continuous black color (CC). Thus, the genetic nature of inbreeding is reduced to the process of decomposition of the population in line with different homozygous genotypes, inbreeding Since the genes were in heterozygous state, are transferred to the homozygous state in the next generation, by crossing homozygous animals of the same color will not be observed splitting. This way by inbreeding by revealing hidden features, fixing desirable traits from generation to generation and creation of stable genetic lines.
The fastest practical way to increase homozygosity in higher animals is the pairing of brother and sister (siblings) who have a common father and mother (do not make any difference whether the siblings are taken, littermates, or from different litters), as well as father and daughter pairing or mother and son. It is sometimes argued among lay people felt that, say, father and daughter pairing is possible, and the mother and son can not be - a myth that does not have any reason; the effect of these two types of inbreeding is quite similar. If the exercise of such close inbreeding (incest) for 1b generations in a row, reached 98% of homozygosity for all genes and, consequently, in the absence of cleavage, all the individuals of these litters are almost identical in genotype and phenotype - all children are identical, like twins, of course in practice is usually applied inbreeding is much less, and thus achieved a much lower degree of homozygosity.
It should be noted that the pairing of second cousins ??and sisters (the general's great-grandfather) leads to increased homozygosity, only 2% with an infinite number of generations, therefore, this type of inbreeding is fundamentally different from a closer degree of inbreeding and in fact does not lead to the achievement of the goals that facing a system of inbreeding. Breeders, for whatever reason to avoid inbreeding, may not be afraid to mate twice removed relatives.

Determining the degree of inbreeding and inbreeding coefficient

Based on the analysis of animal pedigree can be qualitatively assess the degree of inbreeding, which is expressed by the saturation of pedigree common ancestors (nicknames) for maternal and paternal lines. By Shaporuzhu, Roman numerals denote generation (number of ancestors), assuming the parent for the first, his grandfather for the second, etc. If the common ancestor is repeated in the maternal and paternal in the pedigree, it is first put its occurrence in the maternal lineage, and then, with a hyphen - in his father's. Then crossing son x mother will be denoted as I-II, father x daughter as II-I, brother, sister, as x II-II, grandfather granddaughter as x III-I, cousins ??sister as x IIIIII, etc. Inbreeding type father x daughter (II-I), son x mother (I-II) and brother x sister (II-II) is designated as very close, or incest, inbreeding type II-III or III-II - it's close inbreeding, and cross III-IV, IV-III, IV-IV, II-V, and so n - moderate inbreeding. Given the lack of tangible effects of the more distant inbreeding in practice can not be regarded as the true inbreeding. Owners of high-pedigreed cats, picking up a pedigree cat, can estimate how often and how much inbreeding is used by breeders who participated in the removal of the pet.
For quantifying the degree of inbreeding in the pedigree of an animal and thereby determine the measure of its homozygosity English geneticist C. Wright introduced the concept of inbreeding coefficient (F). This ratio is calculated as follows. First is the number of generations from the common ancestor of A father and mother to the father of the animal (p), then the number of generations (arrows) from the same ancestor A to the mother (t). These numbers are added up and added to the sum of unit: n = p + m + 1. The inbreeding coefficient of the analyzed animal (proband A) of this ancestor is 1 / 2 to the power n: ha = (1 / 2) n. If the father and mother is a few common ancestors, the coefficients are summed up:
Fx = EF, = E (1 / 2) n, where i - the common ancestors of A, B, C, etc.
For example, calculate the inbreeding coefficient of animal (proband X) obtained by crossing siblings. In genealogical distance (path) from grandfather to father - a generation, from grandfather to the mother - a generation hence, n = 1 + 1 + 1 = 3, and hence fb = (1 / 2) 3 = 1 / 8. But they have one common ancestor - their grandmother, from her father before - a generation, from mother to her the same - a generation, and therefore will also Fa 1 / 8. The total inbreeding coefficient for X is obtained by Fx = Fa + Fb = 1 / 8 +1 / 8 = 1 / 4, or 0.25.
Another example - crossing his grandfather with his granddaughter. Here, the offspring's paternal generations do not, ie 0 generations through the maternal line - two generations, where n = 0 + 2 + 1 = 3, then Fx = (1 / 2) 3 = 1 / 8, or 0.125.
Finally, an example of crossing cousins ??and sister. Common ancestors of their offspring - the great-grandfather and great-grandmother. From grandparents to my father - two generations from him to the mother of 2nd generation, ie n = 2 + 2 + 1 = 5, respectively, and Fb = (1 / 2) '1 / 32. The same is obtained by calculating the coefficient of inbreeding in the common ancestor of the other - the great-grandmother: Fa = (1 / 2) 3 = 1 / 32. Consequently, the total inbreeding coefficient Fx = Fa + Fb = 1 / 32 +1 / 32 = 1 / 16, or 0.0625.
From the available pedigrees, each breeder or owner of a purebred animal is able to calculate the inbreeding coefficient of their pets or their parents and grandparents - if used in their production of inbreeding. As mentioned earlier, this ratio is a measure of the degree of purity (homozygous) lines participating in the pedigree, as well as an indication of a possible prepotent respective manufacturers and / or proizvoditelnits (see below). The higher the inbreeding coefficient of animal, the greater the gene is homozygous. Naturally, it follows from the formula, the inbreeding coefficient can not exceed unity,



Inbreeding depression and heterosis

Why is it that human society exists in most civilizations, or an express prohibition on incest, or his conviction? Moreover, why in the wild, too, are adjusted so that as far as possible to avoid inbreeding and homozygosity? The main reason is that wildlife and human society for the successful survival and adaptation to changing environmental conditions (including social and economic in the case of human society) should be a variety of genotypes and individuals in the population. In the diverse community there will always be individuals best adapted to the specific situation, but the situation is changing - and other individuals with other signs of swim to the surface. The monotony of the population, although well adapted to these specific conditions of its existence, doomed to extinction species by changing the conditions of existence, thus the desire to create diversity should not separate individuals, and the species to meet the diverse and changing needs of the environment and the historical process .
But there is also a direct risk of inbreeding for individuals. The fact that, as in the individual life of the animal (and human), and on through the generations from time to time there are mutations - changes in the genes. Most of the mutations - harmful, and if they manifested themselves immediately, it would lead to death (lethal mutations), deformities, abnormal behavior, inconsistencies environment, etc. However, most mutations at the same time has a recessive character, ie in combination with a normal pair genome through a double set of genes not expressed in the heterozygous state. The cargo of noxious, but not shown, hidden mutation is present in every heterozygous individual, including each person creates inbreeding homozygosity, including homozygosity of harmful genes, and thus leads to their phenotypic expression in the offspring - intrauterine or early death, deformities , decreased viability, etc. This is called inbreeding depression.
We define the reverse question - why, despite the risk of inbreeding depression, breeders, carve and perfecting the domestic animals, so often resort to inbreeding and are not afraid of him? The answer is simple: Breeders do not tend to maximize the survival, vitality and high quality offspring of all individuals, and lead selection of the best, vybrakovyvaya (eg kastriruya) defective, weak, and just with undesirable traits. Thus, when inbreeding, when the decomposition of the genotype homozygous for the line, the harmful recessive genes appear and are removed from further breeding, and all the "good" genes and their combinations are fixed in the homozygous state and are left for future generations. Thus, inbreeding in the hands of the breeder - a way to remove the cargo from the genotype of deleterious mutations, on the one hand, and create the necessary combinations of valuable genes and traits, on the other. In addition, homozygosity created the need for removing any of the new breed uniformity that meets the requirements of this species, and the relevant securities are fixed signs in their offspring. It should be noted that as inbreeding and selection of the best, due to disposal of hazardous cargo hidden mutations, the risk of inbreeding depression in inbreeding of selected inbred animals is reduced.
In crosses between different inbred lines of independent phenomenon can be observed, in a sense the opposite of inbreeding depression - heterosis, also known as a "hybrid force". These hybrids of two inbred animals usually show increased viability, growth, fertility, etc. This is because in crosses between two inbred lines, selected, and therefore similar to a typical hallmark of the breed is preserved in the offspring homozygous for these selected features, while not culled the remaining harmful mutations in heterozygous state are transferred and thus become recessive, ie not occur.


Practice and purpose of inbreeding

Consider the whole sum and tasks that are performed, and the goals that are pursued livestock, including breeders, cat breeders, the use of inbreeding.
First, inbreeding is required when a new breed or a new group within the breed. To increase the genetic diversity and to attract new characters breeder crosses of animals of different breeds. The resulting hybrid offspring are heterozygous and therefore will be given in subsequent generations of splitting. To consolidate the desirable combination of traits and inbreeding is used mostly close, like brother x sister, father, mother and daughter x x son. As a result of inbreeding are homogeneous family and reached a constant manifestation of symptoms. Among the inbred descendants of a strict culling of up to 80% - defective, weak, and do not meet the standards outlined animals.
Fig. 3 shows an example of very close inbreeding in the breeding Himalayan cats with mauve markings (laylakpoynt) in an English nursery Mingchyu. The cat with the color chocolate-point - Snuff - was obtained by mating a cat Troma, the color of the seal point, chocolate and blue carrier geyov from the American Kennel Breyer, with Siamese Trayviey also seal point and also the bearer of chocolate and a blue gene from Mingchsch kennel, the cat chocolate point (Snuff) was mated with his father, a cat Throm. Born of their cat Chalk, seal-point, was tied with his mother, a cat Snuff, chocolate-point. They are the first cat was born with violet markings (lilac-point) - Sulatri. It is worth noting a very high coefficient of inbreeding Sulatri: R 3 / 8, or 0.375, ie higher than in crosses brother and sister.
Second, a close (very close), inbreeding is used when necessary to identify the manufacturers - the carriers of lethal, poluletalnyh and other undesirable genes. This so-called test of inbreeding. According to the results of test of inbreeding may be adopted various decisions, either by manufacturers such discarded or used to produce homozygous offspring (through inbreeding) with culling and selection of defective better than achieved purification of the genotype of undesirable genes.
Thirdly, the purpose of inbreeding may be vysokoprepotentnogo excretion, ie, effectively transferring their children to the features, the manufacturer. It is known that inbred animals have higher self-prepotentsiey compared with specimens derived from unrelated matings. In this regard, in cattle there is a widely accepted practice inbred male mate with females neinbrednymi, this practice is called top-crossing. It is important that a good producer of inbred, selected to convey the quality of seeds, can significantly improve the livestock nursery and give it its face, the feature, its type.
Fourth, some breeders are going to create inbred lines in their kennels, so that later, crossing from different lines (often this is done in the manner of cooperation between the different nurseries), to obtain the effect of heterosis - a powerful, large, viable and fertile offspring.
Finally, we wish to stress that to maintain breeding - including the cats - it is necessary to apply the system of selection and recruitment of competent animals. We differentiate between selection on the phenotype and genotype. Cat lovers are familiar with the different levels of Cat Show, which is carried out classroom assessment (in professional language - valuation of) cats. This is the assessment of the phenotype. Estimate of the genotype should be performed on pedigrees of animals and the quality of their offspring. In general, the breeding value of an animal can be explained only by evaluating the manufacturer of the quality of his offspring. Beautiful animal phenotype is not always a good producer. In cattle there is popular expression: "A good bull polstada worth it." The same is true with cats producers: quality kennel and his face is largely determined by the manufacturer's cat (or cats, the producers, if more than one). This cat-maker should be highly prepotent and, therefore, breeders must pay attention to the inbred manufacturers. Moreover, it is impossible to create a good nursery, just bought abroad expensive animals and the champion grandchempionskimi titles. It is necessary that in the kennel and the kennel from the manufacturers on the side of the animals were born a champion and an international level grandchempionskogo. And this requires a competent breeding, which plays an essential role of inbreeding.

Marlene Mkrtichovich Aslanian,
Professor of Genetics
and selection, Sc.D.;
Alexander Spirin,
Professor of Molecular
Biology, Doctor of Biology
Science, Member
Russian Academy of Sciences
Head of the Department of Molecular Biology, Biological Faculty, Moscow State University. MV Alexander Spirin University
Doctor of Biological Sciences, Department of Genetics prfessor Moscow State University. MV University Aslanian Marlene Mkrtichovich