[Breeding of the Russian sable: Stages of industrial domestication and genetic variability].

Creating farms for sable breeding was associated with the commercial destruction of natural populations and, consequently, the overall decline in the species number. The gene pool of the first farm-bred sable population in Russia, established in the vicinity of Moscow ("Pushkinskiy" fur farm), was formed by crossing of animals removed from nine natural populations. In the first eight years of farm operation, approximately one thousand animals were used for sable breeding; some of these animals were able to adapt to the farm management and, subsequently, to the selection for a number of quantitative traits in the period of industrial domestication. It took about ten years for breeders to work out the breeding and selection technologies, which became successfully employed in the established affiliated sable breeding farms. The main achievement in sable breeding over the 85-year historical period of breeding in Russia is the creation of two unique breeds, black sable (1969) and Saltykovskaya 1 (2007). In general, industrial domestication in fur farming and the subsequent breeding works made the fur of many species (mink, fox, Arctic fox) obtained from natural populations uncompetitive, which undoubtedly reduced the hunting interest in the animals living in the wild. Consequently, hunting for fur-bearing animals of most species decreased and has only local importance. Owing to the specific features of sable biology, the fur of farm-bred animals cannot yet completely replace the furs obtained by hunting; however, the farm-bred sable population is constantly growing. This review presents the results of the analysis of the level of genetic variability in natural and farm populations at nuclear and mitochondrial loci. The comparative analysis makes it possible to estimate the loss of genetic diversity upon the species adaptation to the new conditions of existence.

[Influence of anthropogenous factors on the genetic variety of the sable (Martes zibellina L.)].

The genetic variety of seven geographic populations of sable has been studied; its distribution area stretches from the Urals to the Far East. It was shown using the panel of eight nuclear microsatellite markers that the sable populations from different geographical regions retain their individual genetic characteristics, despite the influence of anthropogenous factors (overhunting and introduction). There is a significant genetic similarity between the three populations of Central Siberia (Reynolds distances are 0.170-0.200) due to the influence of natural migrations that weaken genetic differentiation, while genetic difference is maximum (0.361) between populations located at the edges of the sable' habitat. The population of the Kamchatka Peninsula is isolated and exists as an independent phylogenetic group. An analysis of the topology of the phylogenetic tree suggests that the populations of Kamchatka and the Sikhote-Alin are closest to the ancestral form. Despite the existence of interspecific hybrids of sable and marten, the level of interspecific genetic differentiation between them is maximal.

[Geographical structure of the sable (Martes zibellina L.) gene pool on the basis of microsatellite loci analysis].

The genetic structure of seven natural sable populations was investigated with the use of the original panel of 10 microsatellite loci. The populations were selected on the basis of the historical data on sable numbers fluctuations for the last 300 years, as well as on data on natural and artificial migrations affecting neighboring populations. We have demonstrated that the populations are in a state of genetic equilibrium for the majority of the loci. The genetic differences between three samplings from Central Siberia populations were insignificant, and the fixation index values were relatively low. At the same time, populations from the margins of the species habitation areal were characterized by the highest fixation index values. We have shown for the first time that populations from different regions of the sable habitation areal maintain their specific features despite the influence of natural and artificial migrations. The current study, performed with nuclear genetic markers, made it possible to get insight into the genetic structure of the analyzed species as a whole.

[Genetic structure of sable (Martes zibellina L.) from Eurasia based on distribution of mitochondrial lineages].

The phylogeography of the sable, which is a commercially valuable species, is extremely complicated and poorly investigated. Specifically, the effects of factors such as the range dynamics of the sable during the Pleistocene Epoch, the localization of glacial refugia, species distribution pattern in Holocene, and recent dramatic population decline, along with massive reacclimatization measures, on the species phylogeography remain unclear. Based on the sequence analysis of the control region of mitochondrial DNA from sables that inhabit different parts of the species range, a suggestion was made of the considerably high Pleistocene genetic diversity in sable, which was subsequently lost. The initial diversity of mitochondrial lineages is mostly preserved in the Urals, while in the eastern part of the range, it seems to have been depleted as early as before the last glacial maximum. On the other hand, the even greater depletion of the mitochondrial lineages observed in some populations of central Siberia can be associated with the dramatic population decline at the turn of the 20th century.

[Mitochondrial genome variation in domesticated sable (Martes zibellina)].

The first comparison of mitochondrial variations in sables from captive and natural populations of the Urals, Central Siberia, Yakutia, Kamchatka, and Japan has been performed. The object of comparative analysis was a 427-bp 5' fragment of the mitochondrial control region, including the D-loop. Two main haplogroups of the sable mitochondrial genome have been found, which provides new data for reconstruction of the spread of the sable over its current range. Asymmetry of the haplotype abundances in the captive populations of sables has been detected. The mitochondrial haplotypes characteristic of sable breeds have been identified. The possible role of the frequent mitochondrial haplotypes of the captive population in the sable adaptation to the conditions of captivity is discussed.

[Microsatellite analysis of two captive populations of sable (Martes zibellina L.)].

The high value of sable (Martes zibellina L.) fur and stable demand for it over the centuries have led to suboptimal hunting patterns and, as a result, considerable fluctuations in the sizes of natural populations of this species. To maintain the traditional export of sable fur, efforts towards commercial domestication of sable have been made in Russia. The first farm population of sable consisted of animal from eight natural populations in 1929. After the problems related to breeding in captivity were solved, directional selection began. Eighty years of breeding have resulted in sable herds with homogeneous quantitative characters. Prospects for further breeding depend on the current level of genetic diversity in the captive populations of sables formed during the first stages of domestication. The sable populations of the Pushkinsky and Saltykovsky fur farms located in Moscow oblast, which were the objects of this study, are the progenitors of the existing captive populations. The first estimation of genetic variation of this species by means of a panel of microsatellite markers was developed for this study. Two captive sable populations were analyzed using ten microsatellite loci; a total of 75 alleles were found in both populations. Population-specific alleles were identified (6 and 13 in the Pushkinsky and Saltykovsky populations, respectively). The populations studied were found to be differentiated with respect to four microsatellite loci.

[The effect of artificial selection for coat color on fitness in a farm population of the sable (Martes zibellina)].

The relationship between the response to artificial selection for darker coat color and fitness in a farm population of the sable (Martes zibellina L.) from the Pushkinskoe Fur Farm (Moscow oblast) was studied. The selection was performed during 41 years. By the moment of the study, a response to the selection for this character had been obtained: the coat color in the selected population had become darker, and the proportion of black animals in it increased. In addition, sables with black heads, which were absent in the original population, had appeared. Artificial selection was accompanied by a decrease in the fitness of the selected population, which was expressed in decreased female reproductive capacity parameters (the fertility, maturation rate, and duration of the reproductive period). A selection technique consisting in the use of only highly fertile animals in the selection originally made it possible to restore the fitness parameters to the initial level almost without a decrease in the dark shade of the fur. However, further selection led to a drastic decrease in fitness that could not be precluded by any selection method used. The possible ways to overcome this unfavorable effect of artificial selection are discussed.

[Changes in correlations between commercially valuable characters of the sable Martes zibellina L. during artificial selection].

A farm population of the sable Martes zibellina L. has been selected for darker coat color during 40 years. Correlations between fitness characters and correlations of these characters with the selected character have been monitored. Correlation analysis has shown that the female fertility in the first year of reproduction is a promising predictor of how valuable the female will be for further breeding. Artificial directional selection has been shown to change the correlations that have been formed in natural populations of the sable. The relationship of this phenomenon with a decrease in the overall fitness during selection that has been observed in the sable population is discussed.

[Analysis of secondary sex ratio in the fox (Vulpes vulpes L.)].

Secondary sex ratio and its variability in relation to some paratypic and genetic factors were studied in the silver fox by analysis of data obtained at the Pushkinskii fur farm (Moscow oblast) in 1980-1989. A total of 17285 whelps were examined. The mean proportion of males over the ten years of observation was 0.536+/-0.004. No effect of parent age or litter size on this proportion was found. Individual analysis of the progeny of a single parent revealed 44 males and 49 females showing significant deviations from the expected sex ratio (l male : 1 female). These results can be used for reconstruction of pedigrees whose progeny yields regular deviations from the expected sex ratio.

Inheritance of litter size at birth in farmed arctic foxes (Alopex lagopus, Canidae, Carnivora).

Natural populations of the arctic fox (Alopex lagopus, Canidae, Carnivora) differ drastically in their reproductive strategy. Coastal foxes, which depend on stable food resources, produce litters of moderate size. Inland foxes feed on small rodents, whose populations are characterized by cycling fluctuation. In the years with low food supply, inland fox populations have a very low rate of reproduction. In the years with high food supply, they undergo a population explosion. To gain insight into the genetic basis of the reproductive strategy of this species, we performed complex segregation analysis of the litter size in the extended pedigree of the farmed arctic foxes involving 20,665 interrelated animals. Complex segregation analysis was performed using a mixed model assuming that the trait was under control of a major gene and a large number of additive genetic and random factors. To check the significance of any major gene effect, we used Elston-Stewart transmission probability test. Our analysis demonstrated that the inheritance of this trait can be described within the frameworks of a major gene model with recessive control of low litter size. This model was also supported by the pattern of its familial segregation and by comparison of the distributions observed in the population and that expected under our model. We suggest that a system of balanced polymorphism for litter size in the farmed population might have been established in natural populations of arctic foxes as a result of adaptation to the drastic fluctuations in prey availability.

[Effect of the hereditary characteristics of male blue foxes Alopex lagopus L. on the sex ratio of their offspring].

Family analysis of a commercial population of the blue fox (the Pushkinskoe Breeding Fur Farm, Moscow oblast) with respect to secondary sex ratio has been performed. The offspring of each individual male or female involved in crossing between 1984 and 1988 was analyzed. The study of all families formed by every male and every female has made it possible to determine a group of "outstanding" fathers (23 out of 287 males), whose offspring was predominantly male (62.1% of the offspring were males, versus 53.9% in the total population). The results of subsequent detailed study on the pedigrees of male blue foxes in whose offspring the sex ratio significantly deviates from 1:1 indicate that this character is transmitted from fathers to sons without the deterioration of other commercially valuable characters. It is presumed that the significant deviation of sex ratio from 1:1 in the offspring of some male blue foxes is determined by genetic factors.

[Signs of fitness and allozyme heterozygosity in an artificial population of sable Martez zibellinna L]. / Issledovanie priznakov prisposoblennosti i allozimnoi geterozigotonosti v iskusstvennoi populiatsii sobolia Martez zibellinna L.

Associations between some characteristics of fitness (the age of the first reproduction, life span, fertility, and number of missed pregnancies) and heterozygosity for some allozyme loci have been studied in a population of the sable Martez zibellinna L. kept in cages at a farm. Of all fitness characteristic studied, a weak correlation has only been found between heterozygosity and the age of the first reproduction (maturation rate). The age of the first reproduction is positively associated with the life span and fertility. The results obtained are discussed in terms of the relationship between the genetic variation of longevity and developmental rate and prospects of their application to breeding practice.

[A variation of secondary sex ratio in blue fox (Alopex lagopus L.)]. / Izmenchivost' vtorichnogo sootnosheniia polov u pestsa (Alopex lagopus L.).

The effects of several genotypic and paratypic factors on the secondary (at birth) sex ratio was analyzed in blue fox bred in captivity. In particular, variation of sex ratio was for the first time studied as dependent on sire's age (without considering dam's age), the ages of both sire and dam, and the lines of both parents. The initial data were obtained from the Pushkino breeding facility, Moscow oblast. In total, 15,396 puppies were analyzed. The frequency of males (P) in this population was 0.551 +/- 0.004 (confidence interval 0.543 << p << 0.559). Parents' ages and litter size had no effect on the proportion of males in the progeny. In one of the two blue fox subpopulations under study, dam's line proved to be associated with a significant departure of sex ratio to a higher proportion of males, suggesting the effect of genotypic factors on the variation of secondary sex ratio in blue fox.

[Statistical analysis of secondary sex ratio variation in sable Martes zibellina L]. / Statisticheskii analiz izmenchivosti vtorichnogo sootnosheniia polov u sobolia (Martes zibellina L.).

The secondary sex ratio in sable Martes zibellina L. maintained in captivity was estimated for the first time ever. The data obtained at the Pushkin pedigree breeding farm (Moscow oblast) in 1982 through 1987 were analyzed. In total, 1705 litters of 414 females were examined. The total frequency of male births (P) was 0.527 +/- 0.007; the 95%-confidence interval of p (the probability of birth of a male) was within the limits 0.513 << p << 0.541, and the deviation from the expected 1:1 ratio was statistically significant. No effect of parental age and litter size on the number of male progeny was found. This may indicate a small influence of the parental hormonal and immunological status on sex ratio, which was reported in many other mammal species including those related to sable. Apparently, there is an evolutionary mechanism underlying the stable excess of males in sable litters.

[Genetic variability of the sable (Martes zibellinna L.) by blood protein genes]. / Geneticheskaia izmenchivost' sobolia (Martes zibellinna L.) po genam belkov krovi.

Electrophoresis of blood proteins was used to determine, for the first time, the level of genetic variability of certain loci in the sable (Martes zibellina L.,). Variation of 23 blood proteins encoded by 25 genes was analyzed. Polymorphism was revealed in six genes. The level of heterozygosity was estimated at 0.069; the proportion of polymorphic loci was 24%. Data on the history of the sable population maintained at the farm, on geographical distribution of natural sable populations, and on the number of animals selected for reproduction in captivity is presented. The great number of animals studied and the extensive range of natural sable populations, on the basis of which the population maintained in captivity was obtained, suggest that the results of this work can be used for estimating the variability of the gene pool of sable as a species.

[Analysis of the selection process in breeding of caging populations of Arctic fox (Alopex lagopus L.)]. / Analiz selektsionnogo protsessa pri razvedenii kletochnykh populiatsii pestsa (Alopex agopus L.)]

The purpose of this research is analysis of supporting heterozygosity mechanisms in caging population of Polar fox (Alopex lagopus L.). The polymorphism of the gene, which code the blood serum protein-transferrin, was used as a genetic marker. The level of the heterozygosity was studied in the reproductive and young parts of population. As it turned out, the reproductive part is separated on some subpopulations, moreover, inbreeding lead to the decrease of heterozygosity level in this part of population. On the other hand, selection which is to be held by a number of quantitative and qualitative signs in reproductive part of population promote to increase the number of heterozygous animals.