Genetic Diversity Of Arborophil Agingica Based On Mitochondrial And Nuclear Gene Sequences

White-browed Hill Partridge(Arborophila gingica)is an endemic bird species in the southeast of China.It was listed as a second-class national protected wildlife in China.It was previously considered as monotypic.Until recently,a new subspecies,A.g.guangxiensis,was confirmed according to morphological differences.The A.g.guangxiensis only distributed in the isolated regions of Jiuwanshan(abbreviation JWS)and Damingshan(abbreviation DMS)in Guangxi.In this study,three mitochondrial genes(COI、CYT b、ND2)and four nuclear genes(ALDOB、FGB、G3PDH、OVOG)were used to verify the taxonomic validity of A.g.guangxiensis and further to study its genetic difference between two isolated geographic populations.These information would be helpful to draw up a conservation proposal that pointed to the small populations and endangered species.The main results are as follows:1.The genetic diversity of A.gingica was analyzed by haplotype diversity(Hd)and nucleotide diversity(π).The results showed that high Hd and low π(Hd > 0.05,π < 0.005)patterns were observed at both mitochondrial and nuclear gene levels,indicating that the population experienced rapid expansion after the recent bottleneck effect,and the genetic diversity level was low.2.The phylogenetic relationship was studied by constructing phylogenetic tree and haplotype network diagram.Both phylogenetic tree and haplotype network diagram based on mitochondrial genes can divide A.gingica into two branches,one is A.g.g,and the other one is A.g.guangxiensis which contains JWS and DMS populations.These results support the taxonomic validity of A.g.g and A.g.guangxiensis,while the JWS and DMS populations did not differentiate to subspecies level,they are still treated as A.g.guangxiensis.However,the phylogenetic tree and haplotype network based on nuclear genes could not separate the two subspecies.3.Genetic structure among geographic populations was discussed based on genetic distance and nuclear gene structure analysis.Both the average genetic distance of mitochondrial genes and nuclear genes were small,indicating that there was no obvious differentiation between populations.The structure analysis based on nuclear gene data suggested that all geographical populations could be divided into A.g.g(ZM)population,JWS population and DMS population(K = 3),but the structure analysis chart showed that there was no obvious differentiation among these populations.4.The historical dynamics of population were studied by neutral test,mismatch distribution analysis and extended Bayesian skyline plots(EBSP).The results of the neutral test results of mitochondrial genes and nuclear genes were nonsignificantly negative value(P > 0.01).The mismatch distribution results showed a multi-peak distribution.These results showed that the population did not experience the recent bottleneck effect or rapid expansion,which was in a stable state.The extended Bayesian skyline plots results of the combined mitochondrial gene and nuclear gene showed that the population remained stable for a long period of time,but increased sharply at ～ 0.01 Mya.5.Combined mitochondrial gene and nuclear gene,the divergent time between subspecies and three geographic population,which was eatimated according to Bayesian algorithms.The divergent time between A.g.g and A.g.guangxiensis is 0.158 Mya before present(BP);the divergence time between JWS and DMS populations is 0.1104 Mya BP,which were in the Penultimate Glaciation(0.13 ～ 0.42 Mya).In conclusion,the results of this study indicate that A.g.g and A.g.guangxiensis have formed divergences at the molecular level,confirming the taxonomic validity of A.g.g and A.g.guangxiensis.While the geographic isolated population between JWS and DMS were not showed evolutionary distinctiveness,they are still treated as A.g.guangxiensis.The genetic diversity of A.gingica was low,and the degree of genetic differentiation of A.g.guangxiensis was low.Therefore,it is suggested to carry out a population resources survey of A.gingica to monitor the population changes;to strengthen the protection and optimization of their living environment;to strengthen public education to reduce human interference.In addition,A.g.guangxiensis is recommended to be protected as an independent unit.