Genetic Structure Of The Saxaul Sparrow That Inhabits The Extremely Arid Desert

Population genetic structure refers to the temporal and spatial distribution of genetic variation of the population.Investigations of the genetic variation and genetic structure of population may be helpful to demonstrate the evolution of animal life history traits,as well as their adaptive responses to environmental changes.That means,animals will exhibit distinct genetic structure under different environments.To examine how Saxaul Sparrows?Passer ammodendri?adapt to extreme arid desert,this study explored the genetic structure of a population that bred in the Anxi Extreme Arid National Natural Reserve in 2017-2018.A total of 506 smaples were collected in four successive seasons,of which genotyping was carried out based on 12polymorphic microsatellite loci.The seasonal variation of genetic diversity was examined using software POPGENE.Genetic differentiation of populations in different seasons were tested using software Arlequin and Structure.Fine-scale spatial genetic structure of the population were identified using spatial autocorrelation analysis.By integrating life history traits,breeding strategies and dispersal patterns of this sparrow,I tried to determine what factors play the key role in driving the gene pool to change in this extreme environment.My main results are listed below one-by-one.First of all,this Saxaul Sparrow population exhibited low levels of genetic diversity.The average observed heterozygosity of was 0.484?raning 0.281-0.776?,and the average expected heterozygosity was 0.810?raning 0.726-0.920?.Inbreeding coefficient(F_IS)was 0.407?raning 0.157-0.641?.Each one of the twelve microsatellite loci deviated significantly from the Hardy-Weinberg Equilibrium,perhaps due to the high level of inbreeding occurred in this population.Genetic diversity of the Saxaul Sparrow population exhibited overt seasonal variation.The values of heterozygosity,allele richness and Shannon's information index indicated that the genetic diversity was highest in summer but lowest in winter.Genetic differentiation among four seasons mainly occurred at interpopulation level,with little at intra-population level.Genetic similarities among Saxaul Sparrow populations in different seasons indicated that seasonal variations were not significant.During the breeding season,there existed a positive spatial genetic structure at the fine scale,the closer the spatial distance between two nests,the greater the genetic relatedness between them.This fine-scale spatial genetic structure was uncovered by separately carrying out the spatial autocorrelation analysis for male and female.But the structure of males had a larger scale than thata of females.This finding indicates that both sexes of Saxaul Sparrow prefer to build kin clusters in a small area,which may be the main reason for the occurrence of inbreeding and low level of genetic diversity in this Saxaul Sparrow population.Moreover,a certain degree of female-biased dispersal can be identified because of the smaller scale of female structure than male structure.We also deduce from the spatial genetic structure analysis that the Saxaul Sparrow has.In conclusion,this study suggests that the seasonal variation of genetic diversity in the extreme arid population of Saxaul Sparrow may be related to its breeding strategy and dispersal pattern.