Population History Of Leishan Moustache Toad (Vibrissaphora Leishanensis)

Leishan moustache toad(Vibrissaphora leishanensis) is endemic to Chinese Mt. Leigong. Due to natural and human factors, the population of Vibrissaphora leishansis is rapidly reducing and faced with extinction. In order to create effective ways for the conservation and management of the species, we have collected48individuals from two locations for this study. Microsatellite, mitochondrial cytochrome b and MHC(Major Histocompatibility Complex) class I exon3were chosen as molecular markers to investigate genetic diversity, genetic structure and population history of Leishan moustache toad, and provided scientific basis for the protection. The main conclusions are as follow:(1) The levels of genetic diversity of two populations are relatively high. Two population’s Microsatellite results indicated that the locus heterozygosity and genetic diversity are relatively high; Cytb nucleotide diversity is comparatively low, haplotype diversity is high. All these indicate that genetic diversity is low. Differences among MHC allele are large, which indicates high genetic diversity. For the evolution rate of the three molecular markers, Cytb is the smallest, next to the microsatellite, and the largest is MHC. Generally speaking, the population has high level of genetic diversity, which means the decline of population is not owing to the decrease of genetic diversity.(2) Leishan mustache toads’genetic differentiation between the two populations is low. The microsatellite genetic differentiation value Fst of0.01200, the Cytb Fst0.02190, and P values greater than0.05, means that genetic differentiation is not severe, It is possibly because the distance between habitats of the two populations is no more than20kilometers, gene communication between populations may not been hampers by the physical distance. These two population in fact are one large united population.(3) Leishan moustache toad population in the past has experienced a population bottleneck which occurred before the population expansion, then the population began to decline. It is now at the lowest level, and MHC class I gene exon3is under the pressure of positive selection. Microsatellite detection the Leishan moustache toad population has experienced a population bottleneck, whereas the investigation of Cytb gene detected Leishan moustache toad population expansion. imbalances between MHC alleles distribution also indicates that Leishan moustache toad may have experienced a population bottleneck. Microsatellite evolution rate is faster than the mitochondrial DNA, so microsatellite provides mainly information about population genetic structure of species in recent events; while the mitochondrial DNA reflect the long-term events caused by genetic variation and gene flow condition. Thus Population bottleneck events must occur before the population expansion.(4)In conclusion, in order to keep the Leishan mustache toad’s genetic diversity and prevent the extinction of the species, a protection strategy need to be proposed to generate people’s awareness of the protection, and severely punish hunting behaviors. Conservation sites are also needed to be established in local places for the ecological supervision.