Low genetic diversity in captive populations of the critically endangered Blue-crowned Laughingthrush (Garrulax courtoisi) revealed by a panel of novel microsatellites.

Guoling Chen,Daoqiang Liu,Nelson Wan,Chenqing Zheng,Xu Yang,Yat-tung Yu,Vivian Wing Kan Fu,Yang Liu

doi:10.7717/peerj.6643

Guoling Chen, Daoqiang Liu + Show 6 more

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https://doi.org/10.7717/peerj.6643

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Abstract

BackgroundCaptive populations permit research and conservation of endangered species in which these efforts are hardly implemented in wild populations. Thus, analysing genetic diversity and structure of captive populations offers unique opportunities. One example is the critically endangered Blue-crowned Laughingthrush, Garrulax courtoisi, which has only two known wild populations in Wuyuan, Jiangxi and Simao, Yunnan, China. We carried out the first conservation genetic study, in order to provide useful implications that allow for successful ex situ conservation and management of the Blue-crowned Laughingthrush.MethodsUsing the novel microsatellite markers developed by whole-genome sequencing, we genotyped two captive populations, from the Ocean Park Hong Kong, which are of unknown origin, and the Nanchang Zoo, which were introduced from the Wuyuan wild population since the year 2010–2011, respectively. The genetic diversity of captive Blue-crowned Laughingthrush populations was estimated based on genetic polymorphisms revealed by a new microsatellite data set and mitochondrial sequences. Then, we characterised the population structure using STRUCTURE, principal coordinates analysis, population assignment test using the microsatellite data, and haplotype analysis of mitochondrial data. Additionally, we quantified genetic relatedness based on the microsatellite data with ML-Relate.ResultsOur results showed equally low levels of genetic diversity of the two captive Blue-crowned Laughingthrush populations. The population structure analysis, population assignment test using the microsatellite data, and haplotype analysis of the mitochondrial data showed weak population structuring between these two populations. The average pairwise relatedness coefficient was not significant, and their genetic relatedness was quantified.DiscussionThis study offers a genetic tool and consequently reveals a low level of genetic diversity within populations of a critically endangered bird species. Furthermore, our results indicate that we cannot exclude the probability that the origin of the Hong Kong captive population was the wild population from Wuyuan. These results provide valuable knowledge that can help improve conservation management and planning for both captive and wild Blue-crowned Laughingthrush populations.

Highlights

Conservation genetics applies genetic theories and techniques to assist with the conservation and management of endangered populations and reduce extinction risk (Frankham et al, 2010).Genetic factors increase species’ extinction risk through inbreeding depression, loss of genetic diversity, and loss of evolutionary potential (Frankham, 2005)
The population structure analysis, population assignment test using the microsatellite data, and haplotype analysis of the mitochondrial data showed some population structuring between these two populations
Many endangered species require captive breeding to save them from extinction through genetic rescue and reintroduction, as they are incapable of surviving in inhospitable natural environments because of direct or indirect human impacts in the form of habitat loss, overexploitation, pollution, or introduced predators, competitors, or diseases (Frankham, 2008)

Summary

Introduction

Conservation genetics applies genetic theories and techniques to assist with the conservation and management of endangered populations and reduce extinction risk (Frankham et al, 2010).Genetic factors increase species’ extinction risk through inbreeding depression, loss of genetic diversity, and loss of evolutionary potential (Frankham, 2005). Understanding genetic diversity and population structure is critically important for the conservation and management of endangered species These factors are relevant for species with small populations and/or restricted ranges, such as the critically endangered Blue-crowned. Laughingthrush, Garrulax courtoisi, which has only two wild populations left in Wuyuan, Jiangxi and. These factors are relevant for species with small populations and/or restricted ranges, such as the critically endangered Blue-crowned Laughingthrush, Garrulax courtoisi, which has only two wild populations left in Wuyuan, Jiangxi and Simao, Yunnan, China

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