1Department of Anthropology, University of North Carolina-Charlotte, 2Department of Anthropology, Yale University
March 26, 2015 , Archview Ballroom
Site fidelity, the tendency of individuals to stay or return to previously established natal or breeding areas, has been observed in numerous vertebrates, including primates, although cross-generational studies of the fitness consequences of site fidelity are few. Potential selective advantages of site fidelity include increased survival and reproductive success of those individuals having intimate knowledge of local resource and predator distributions as well as the presence of suitable mates.
This study tested the proposition that female residence patterns in sifaka can be differentiated according to whether social groups exhibit long-term (anchor groups; 20+ yrs.) vs. short-term (non-anchor groups; ≤ 10 yrs.) site fidelity and that female reproductive success (i.e., infant survivorship) covaries with the number of reproductive females residing in these respective groups. We predicted that females residing in anchor groups would exhibit higher fitness levels than those residing in non-anchor groups. These predictions were tested in 34 matrilocal social groups residing within Parcel 1 at Beza Mahafaly, Madagascar. 27 years of female life history and spatial data revealed that the 21 and 13 social groups were anchor and non-anchor groups.
MWW/linear regression showed a significant effect of group on the number of reproductive females/natal females residing in anchor vs. non-anchor groups and on infant survivorship, with 2.5-fold higher rates of infant survivorship observed in anchor groups composed of multiple reproductive females/daughters vs. non-anchor groups containing a single reproductive female/daughter.
These findings provide important insights into how life history can inform spatial-temporal dynamics of primate/human populations and their fitness consequences.