Non-invasive conservation genetics of the critically endangered golden-crowned sifaka (Propithecus tattersalli): high diversity and significant genetic differentiation over a small range

Abstract

The genetic structure of the golden-crowned sifaka (Propithecus tattersalli) was evaluated in three forest types in the Daraina region between the Loky and Manambato Rivers in northeastern Madagascar. This critically endangered lemur species, only found within this restricted region (~1,300 km2), comprises populations which survive in forest fragments of varying size. While this remote region is already affected by human deforestation, the scheduled paving of the national road can potentially bring significant changes in the near future. In 2006, sifakas feces from 82 putative individuals were collected immediately after defecation. DNA samples were genotyped at 13 microsatellite loci to characterize patterns of genetic diversity within and among three sets of forest fragments representing different ecological types. The recent 2CTAB/PCI extraction method and the ‘comparative’ genotype validation approach allowed us to significantly improve the efficiency of amplification procedures. We found that golden-crowned sifaka genetic diversity was surprisingly high despite its narrow distribution and the current level of habitat fragmentation. We used both spatial and non-spatial Bayesian clustering methods to determine if forest edges correlated with cryptic genetic clusters and found that it was overall the case. However, the results also indicate that migrations are possible between two of the three studied forest complexes despite the presence of the national road. This is probably due to remaining riparian and small forest patches between these two forest complexes. The third forest complex is more differentiated although some migrations/connections may still exist through non-sampled fragments. This strongly suggests that it is necessary to maintain corridors and small patches, and also to explore the genetic diversity of the fragments outside the protected area.