From missionary maps to molecular markers: investigating genetic diversity of the black-and-white snub-nosed monkey ( Rhinopithecus bieti ) from museum collections

Historical collections offer a unique opportunity to reconstruct baselines of genetic diversity in taxa, particularly important for species that have been historically under-studied and now face severe conservation threats. The black-and-white snub-nosed monkey (Rhinopithecus bieti) is endemic to the high-altitude forests of China’s Hengduan Mountains and is among the most endangered non-human primates. Yet little is known about the historical extent of its genetic variation. In this study we combined archival, cartographic and field-based investigations to georeference seven type specimens collected in the nineteenth century and housed at the National Museum of Natural History in Paris, France. These specimens were compared with twentieth century specimens preserved in Kunming, China, to examine temporal changes in mitochondrial and nuclear genetic diversity. Mitochondrial HVI sequencing showed novel haplotypes not found in contemporary datasets, whereas microsatellite genotyping showed a significant decline in heterozygosity over the past century. Although several factors including DNA degradation may be affecting our results, they are nevertheless consistent with a loss of genetic diversity over time, which can result from habitat fragmentation. This study highlights both the value and constraints of using historical collections to inform conservation genetics.