Genetic diversity of Yangtze finless porpoises population in Poyang Lake Basin
[Objective]The Yangtze finless porpoise(Neophocaena asiaeorientalis asiaeorientalis)is the only extant cetacean in the Yangtze River,the flagship species of the Yangtze River aquatic ecosystem,and the first-class wild protected animal in China.It is listed as a critically endangered(CR)species on the IUCN Red List.The results of the national Yangtze finless porpoise scientific expedition in 2022 showed that the existing number was 1 249,of which 492 were in Poyang Lake,accounting for about 40%.Currently,under the background of"jointly focusing on large-scale protection and not engaging in large-scale development"in the Yangtze River basin,the living environment of the Yangtze finless porpoise has been improved,but it is still affected by extremely low water levels,making the Yangtze finless porpoise population diffusely distributed to the main stream of the five rivers and even isolated seasonally,which affected the variation of genetic diversity.This study aims to analyze the genetic difference characteristics of its population through whole-genome re-sequencing technology.It provides reference for the protection of genetic diversity of the Yangtze finless porpoise population in the Poyang Lake Basin,and provides theoretical guidance for maintaining the genetic integrity and adaptation potential of the finless porpoise species.[Method]The whole genome data of three Yangtze finless porpoise(PY)muscle samples from Poyang Lake were obtained by resequencing technology.Combined with the whole genome data of three narrow-ridged finless porpoises from Tongling,Anhui(TL)and Ningbo,Zhejiang(NB),the genetic diversity and population structure were compared and analyzed to explore the genetic differentiation of the Yangtze finless porpoise population in Poyang Lake in a specific geographical area.[Result]The results showed that:(1)Compared with the TL and NB populations,the PY population had higher single-nucleotide polymorphism(Pi value=2.65×10-5)and some differences existed between PY and TL populations(Fst=0.32);(2)The PY population had a lower degree of inbreeding(Inbreed coefficient=0.21);(3)The phylogenetic tree indicated that the PY population formed an independent branch within the finless porpoise populations;(4)Structure and PCA results revealed that the PY population was genetically closer to the TL population and distant from the NB population.[Conclusion]The PY population exhibited relatively higher genetic diversity and was distinct from the other two populations.Additionally,there was some genetic diversity difference among the different populations of finless porpoises.It was recommended to strengthen the genetic exchange between the populations of finless porpoises in the Yangtze River Basin,which was of significance for enhancing the adaptation and evolution of the species.
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