| Determining the factors that affect species richness and occurrence is vital to the study of primate biogeography. In this study, I investigate the biogeographic patterns of a lemur community within a fragmented landscape in Ankarafantsika National Park, Madagascar. The landscape consists of 42 deciduous dry forest fragments ranging in size from 0.23 to 117.7 ha. I conducted a total of 1218 surveys for lemurs between June and November 2011 in the 42 fragments. I recorded a total of 1023 individual or group sightings of six species. I conducted vegetation sampling in 38 of 42 forest fragments. I measured human disturbance within each fragment and determined fragment isolation and proximity to human settlements. I explored biogeographic patterns of lemur species richness and occurrence using the species-area relationship, metapopulation dynamics, and landscape ecology. I found that lemurs in a fragmented landscape show a species-area relationship in the form of a convex power model. I did not find a sigmoidal pattern for the species-area relationship and I found no evidence of a "small island effect." Human disturbance and tree height also influence species richness, but it is unclear how. Lemur species form different metapopulations within the same landscape. Metapopulation dynamics suggest that area was a stronger factor determining individual lemur species occurrence than fragment isolation. However, for Microcebus species, area seems to have less influence than for other species (Cheirogaleus medius and Eulemur fulvus). I investigated the landscape ecology of lemur species occurrence and found species-specific scale responses to habitat amount. Area predicted species occurrence for C. medius and M. murinus, but not for M. ravelobensis. M. ravelobensis occurrence may be mediated by factors other than area, such as dispersal ability and edge tolerance. My study shows the importance of a multi-scale approach to lemur biogeography and how it is critical for understanding how lemur species respond to high amounts of forest loss and fragmentation. |
