Evolution of Pair-Living in Phaner furcifer

Abstract

Pair-living evolved several times independently in the primate lineage and most likely for more than one reason. Currently, there are 7 hypotheses regarding the evolution of pair-living in primates. They may explain several but not all cases. I investigated the applicability of the explanations to fork-marked lemurs Phaner furcifer. I used information from a long-term study on 8 fork-marked lemur families in Kirindy Forest to evaluate the hypotheses. Fork-marked lemurs live in uniform dispersed pairs, which share and defend a territory but spend three-quarters of their activity time apart from each other. Unconditional female dominance and lack of permanent close association between pair-partners disqualify most hypotheses. Lack of male parental care and long travel distances in small home ranges disqualify other explanations. I conclude that there is no support a priori for any current pair-living hypothesis and that the newly formulated intersexual-feeding-competition hypothesis best explains the evolution of pair-living in fork-marked lemurs. Accordingly, female range exclusivity evolved first as a consequence of intense feeding competition. Subsequently, indirect feeding competition drove females to accept a single male to share their territory as a defense against feeding competition from males whose ranges unsystematically overlap those of several females. This situation led to pair-living because formation of dispersed one-male-multifemale-units was too costly for males in terms of reduced foraging efficiency.