Shifting Biogeographic Patterns of Microcebus ravelobensis and M. murinus.

It is important to understand how sympatric congeners can co-occur within the same landscapes to better understand niche differentiation and how each species respond to habitat modification. We compiled previously published, long-term data from several studies on encounter rates of two sympatric mouse lemurs (Microcebus ravelobensis and M. murinus) in different survey sites (surveyed portions of continuous forest and individual fragments) using trapping (N = 16 sites; 42 samples) and visual (N = 42 sites; 73 samples) survey methods in Ankarafantsika National Park, Madagascar (total N = 58 sites; 115 samples). A sample reflects multiple surveys, visual, and/or trapping (N = 2–21) along a line-transect and/or trapline within 1 year. We found higher encounter rates of M. ravelobensis and M. murinus in continuous forests and fragmented forests, respectively. Contrary to studies conducted at a smaller scale, yearly encounter rates for M. ravelobensis were negatively associated with rainfall but were positively associated with rainfall for M. murinus. Like previous studies, we found a negative correlation in encounter rates between M. ravelobensis and M. murinus in continuous forests. However, in fragmented forests there was a significant positive relationship between the two species. Our data suggest that M. ravelobensis preferred continuous forest habitat, whereas the congeneric M. murinus preferred fragmented forest habitat. Such results are likely related to species-specific ecological requirements: whereas the continuous forest has conditions that M. ravelobensis finds preferential (i.e., wetter, taller, and denser forests), the forest fragments are drier, habitat that is preferred by M. murinus. [ABSTRACT FROM AUTHOR]