Factors affecting connectivity and diversity of mouse lemur populations in northwestern Madagascar

Habitat loss and fragmentation are major ecological forces threatening animal communities across the globe. This is especially true in Madagascar, where forest loss has been rapid and widespread leading to fragmented landscapes across the island. Generally, habitat loss and fragmentation leads to decreased genetic diversity within populations and reduced connectivity between subpopulations. As a result, organisms may have an increased risk of extinction via stochastic events. However, species-specific and landscape features may mitigate the effects of habitat loss and fragmentation on persistence in fragmented landscapes. We examined the response of two sympatric mouse lemurs (Microcebus murinus and M. ravelobensis) to forest fragmentation in a dry forest landscape containing continuous forest and discrete fragments of habitat in northwestern Madagascar. We captured 717 individuals during two six-month periods in 2017 and 2018. A RADseq dataset was generated for a subset of these individuals (M. murinus: 58, M. ravelobensis: 33) for landscape genetic analyses. First, we examined the effect of fragment isolation, size, and distance to continuous forest on genetic diversity. We additionally used Mantel tests to assess the resistance of landscape features such as savannas, bushes of varying quality, and rivers on gene flow. Our preliminary results indicate that M. murinus and M. ravelobensis populations in small fragmented patches of forest still show connectivity amongst fragments and with the continuous forest, although there are species-specific differences. We suggest that these differences are due to differing dispersal abilities of the two species, with M. murinus having a greater ability to disperse between fragmented sites than M. ravelobensis.