Low genetic diversity and strong population structure shaped by anthropogenic habitat fragmentation in a critically endangered primate, Trachypithecus leucocephalus

Abstract

Habitat fragmentation may strongly impact population genetic structure and reduce the genetic diversity and viability of small and isolated populations. The white-headed langur (Trachypithecus leucocephalus) is a critically endangered primate species living in a highly fragmented and human-modified habitat in southern China. We examined the population genetic structure and genetic diversity of the species and investigated the environmental and anthropogenic factors that may have shaped its population structure. We used 214 unique multi-locus genotypes from 41 social groups across the main distribution area of T. leucocephalus, and found strong genetic structure and significant genetic differentiation among local populations. Our landscape genetic analyses using a causal modelling framework suggest that a large habitat gap and geographical distance represent the primary landscape elements shaping genetic structure, yet high levels of genetic differentiation also exist between patches separated by a small habitat gap or road. This is the first comprehensive study that has evaluated the population genetic structure and diversity of T. leucocephalus using nuclear markers. Our results indicate strong negative impacts of anthropogenic land modifications and habitat fragmentation on primate genetic connectivity between forest patches. Our analyses suggest that two management units of the species could be defined, and indicate that habitat continuity should be enforced and restored to reduce genetic isolation and enhance population viability.

Fine‐scale genetic structure analyses reveal dispersal patterns in a critically endangered primate, Trachypithecus leucocephalus

“…The FS and CZ areas are separated by 40–50 km of flat area containing farmlands, roads, and villages. Previous population genetic analyses indicate high levels of genetic differentiation and very low levels of gene flow between the FS and CZ populations, suggesting genetic isolation, and demographic independence (Wang et al, ). Therefore, we analyzed the FS and CZ populations separately in the genetic analyses reported in this study.…”

“…A detailed description of the genetic diversity parameters of the microsatellite loci was reported previously (Wang et al, ). Genotyping data are available online (Dryad entry DOI will be provided later).…”

“…In a previous study, we found lower genetic diversity and stronger population structure in T. leucocephalus via assessments of maternally inherited mitochondrial DNA (mtDNA) in comparison with the genetic diversity and population structure indicated by bi‐parentally inherited microsatellite markers, suggesting that female philopatry and gene flow are mediated predominantly through male dispersal (Wang, Qiao, Pan, & Yao, ; Wang, Qiao, Li, Pan, & Yao, ). However, analyses at the population level cannot reveal the fine genetic structure and sex‐specific processes of T. leucocephalus .…”

Population‐level assessment of genetic diversity and habitat fragmentation in critically endangered Grauer's gorillas

“…Generally, increased levels of inbreeding and loss of genetic diversity threaten long‐term population survival and may lead to population extinction through decreased fertility, reduced ability to adapt to environmental changes, and enhanced susceptibility to infectious disease (Evans & Sheldon, ; Keller & Waller, ; O'Grady et al, ; Smith, Sax, & Lafferty, ; Willi, Van Buskirk, & Hoffmann, ). Threatened populations are frequently impacted by a multitude of factors starting with small long‐term effective population size (Abascal et al, ; Xue et al, ), low genetic diversity, habitat fragmentation and loss (Bergl, Bradley, Nsubuga, & Vigilant, ; Casas‐Marce, Soriano, López‐Bao, & Godoy, ), and other anthropogenic pressures (Brown, Peacock, & Ritchie, ; Wang, Qiao, Li, Pan, & Yao, ).…”

Population Genetics Analyses of the Endangered Proboscis Monkey from Malaysian Borneo

“…However, geographic distance and fragmented habitat are often said to be barriers to allowing gene flow to occur and result in a lack of shared haplotype numbers, with many unique haplotypes restricted to single localities [Whitlock and McCauley, 1999;Warren et al, 2001;Ogata and Seino, 2015;Wang et al, 2017]. The current study showed only 8 haplotypes defined by 10 segregating sites from 1,434 bp.…”