The Evaluation Of Population Density And The Environment Adaptive Ability Of Forest Musk Deer (Moschus Berezovskii)

Forest musk deer belongs to Moschidae, Artiodactyla and dwells in the alpine forest. Once it distributed widely to most parts of China. At present, it only exists in some small fragmented habitats in southwest China due to human disturbances. Forest musk deer is listed as an endangered animal in the International Union for Conservation of Nature (IUCN) Red List of threatened species, and it is also included in the Appendices of Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The male can produce expensive musk which has the increasing market demand. Therefore, frequent poaching to acquire commercial profits threatens this endangered animal, and the current population density was needed to be estimated.The major histocompatibility complex (MHC) is an important part of immune response system, with two major subfamilies, class I and class II. Class II presents extracellular antigen to T-cell to trigger immunoreactions. The extracellular domains (al & β1) compose the antigen binding sites of MHC class II, with high polymorphism. Therefore, the gene polymorphism in antigen binding sites is used for evaluating potential adaptive viability of species, which is special important to the conservation of endangered species.Our study aimed to evaluate the current population density of the forest musk deer by detecting dung piles in several hotspots by using the distance sampling method. Then, using non-invasive method to collect the samples, we evaluated the MHC variation of forest musk deer. Our results revealed that the forest musk deer had small population density in the habitat and it had high MHC variation, and the details were listed below:(1) Population estimation(i) We found that the number of dung piles in the virgin forest (0.16 dung piles per km line transect) was markedly larger than that in secondary forest (0.04 dung piles per km line transect in secondary forest), suggesting that virgin forest is important to forest musk deer,(ii) The population density was calculated by software package Distance, and we found the density was small, with 0.16-0.24 individuals per km2.(iii) Various types of human disturbances were recorded at the survey locations, including the presence of snares (65 snares), sheds (6 sheds), and humans (49 persons) who gathered herbs, bamboo shoots, or other plants as food. Especially, poaching resulted in the low population density of forest musk deer.(2) Study on MHC variation(i) Our results suggested forest musk deer had high MHC variation. In all, there were 102 alleles in all six loci,8 alleles at DRA locus,6 alleles at DQA1 locus,8 alleles at DQA2 locus,30 alleles at DRB3 locus,28 alleles at DQB1 locus and 22 alleles at DQB2 locus.(ii) There were no significant difference in allelic richness, the number of variable amino acid residue at antigen binding sites and observation heterozygosity between captive and wild populations. Although gene diversity in the wild population was significantly larger than captive population, we found all MHC loci in captive population had high gene diversity (all over 0.5). All these results suggested captive population had high adaptive ability to changeable environment relative to wild population.(iii) Our results revealed that low latitude population had higher MHC variation compared to high latitude population. The allelic richness, gene diversity and the number of variable amino acid residue at antigen binding sites in the low latitude were significant higher than high latitude population.In summary, our study showed that forest musk deer had a low population density and was severely influenced by human disturbances, especially poaching. Therefore, our suggestions to authority were that they need to enhance investment to endangered animal conservation, and wildlife guarder should enhance their patrol time to eliminate poaching or other human influences. In addition, the pathogen in low latitude was richer compared to high latitude. Our results suggested forest musk deer with high MHC variation in low latitude may be the response to the ample pathogen to low latitude. Therefore, we need to take into account the changeable habitat if we implement ex-situ conservation to forest musk deer.