No evidence for mitochondrial genetic variability in the largest population of critically endangered Tonkin snub-nosed monkeys in Vietnam

Recent Advances in Genetics and Genomics of Snub-Nosed Monkeys (Rhinopithecus) and Their Implications for Phylogeny, Conservation, and Adaptation

The snub-nosed monkey genus Rhinopithecus (Colobinae) comprises five species (Rhinopithecus roxellana, Rhinopithecus brelichi, Rhinopithecus bieti, Rhinopithecus strykeri, and Rhinopithecus avunculus). They are range-restricted species occurring only in small areas in China, Vietnam, and Myanmar. All extant species are listed as endangered or critically endangered by the International Union for Conservation of Nature (IUCN) Red List, all with decreasing populations. With the development of molecular genetics and the improvement and cost reduction in whole-genome sequencing, knowledge about evolutionary processes has improved largely in recent years. Here, we review recent major advances in snub-nosed monkey genetics and genomics and their impact on our understanding of the phylogeny, phylogeography, population genetic structure, landscape genetics, demographic history, and molecular mechanisms of adaptation to folivory and high altitudes in this primate genus. We further discuss future directions in this research field, in particular how genomic information can contribute to the conservation of snub-nosed monkeys.

The Genetic Status of the Critically Endangered Hainan Gibbon (Nomascus hainanus): A Species Moving Toward Extinction

The Hainan gibbon (Nomascus hainanus), once widespread across Hainan, China, is now found only in the Bawangling National Nature Reserve. With a remaining population size of 33 individuals, it is the world's rarest primate. Habitat loss and fragmentation are the primary drivers of Hainan gibbon population decline. In this study, we integrated data based on field investigations and genotype analyses of 10 microsatellite loci (from fecal samples) to assess genetic diversity in this Critically Endangered primate species. We found that the genetic diversity of the Hainan gibbon is extremely low, with 7 of 8 microsatellite loci exhibiting decreased diversity. Additional molecular analyses are consistent with field observations indicating that individuals in groups A, B, and C are closely related, the female-male sex ratios of the offspring deviates significantly from 1:1, and the world's remaining Hainan gibbon population is expected to experience continued high levels of inbreeding in the future. Given extensive habitat loss (99.9% of its natural range has been deforested) and fragmentation, this rarest ape species faces impending extinction unless corrective measures are implemented immediately.

Population genetic structure of the thick-tailed bushbaby (Otolemur crassicaudatus) from the Soutpansberg Mountain range, Northern South Africa, based on four mitochondrial DNA regions

Greater bushbabies, strepsirrhine primates, that are distributed across central, eastern and southern Africa, with northern and eastern South Africa representing the species' most southerly distribution. Greater bushbabies are habitat specialists whose naturally fragmented habitats are getting even more fragmented due to anthropogenic activities. Currently, there is no population genetic data or study published on the species. The aim of our study was to investigate the genetic variation in a thick-tailed bushbaby, Otolemur crassicaudatus, population in the Soutpansberg mountain range, Limpopo Province, South Africa. Four mitochondrial regions, ranging from highly conserved to highly variable, were sequenced from 47 individuals. The sequences were aligned and genetic diversity, structure, as well as demographic analyses were performed. Low genetic diversity (π = 0.0007-0.0038 in coding regions and π = 0.0127 in non-coding region; Hd = 0.166-0.569 in coding regions and Hd = 0.584 in non-coding region) and sub-structuring (H = 2-3 in coding regions and H = 4 in non-coding region) was observed with two divergent haplogroups (haplotype pairwise distance = 3-5 in coding region and 6-10 in non-coding region) being identified. This suggests the population may have experienced fixation of mitochondrial haplotypes due to limited female immigration, which is consistent with philopatric species, that alternative haplotypes are not native to this population, and that there may be male mobility from adjacent populations. This study provides the first detailed insights into the mitochondrial genetic diversity of a continental African strepsirrhine primate and demonstrates the utility of mitochondrial DNA in intraspecific genetic population analyses of these primates.

Genetic and genomic monitoring with minimally invasive sampling methods

The decreasing cost and increasing scope and power of emerging genomic technologies are reshaping the field of molecular ecology. However, many modern genomic approaches (e.g., RAD-seq) require large amounts of high-quality template DNA. This poses a problem for an active branch of conservation biology: genetic monitoring using minimally invasive sampling (MIS) methods. Without handling or even observing an animal, MIS methods (e.g., collection of hair, skin, faeces) can provide genetic information on individuals or populations. Such samples typically yield low-quality and/or quantities of DNA, restricting the type of molecular methods that can be used. Despite this limitation, genetic monitoring using MIS is an effective tool for estimating population demographic parameters and monitoring genetic diversity in natural populations. Genetic monitoring is likely to become more important in the future as many natural populations are undergoing anthropogenically driven declines, which are unlikely to abate without intensive adaptive management efforts that often include MIS approaches. Here, we profile the expanding suite of genomic methods and platforms compatible with producing genotypes from MIS, considering factors such as development costs and error rates. We evaluate how powerful new approaches will enhance our ability to investigate questions typically answered using genetic monitoring, such as estimating abundance, genetic structure and relatedness. As the field is in a period of unusually rapid transition, we also highlight the importance of legacy data sets and recommend how to address the challenges of moving between traditional and next-generation genetic monitoring platforms. Finally, we consider how genetic monitoring could move beyond genotypes in the future. For example, assessing microbiomes or epigenetic markers could provide a greater understanding of the relationship between individuals and their environment.