6 research outputs found
The evolution of food sharing in primates
The aim of this study is to explain the occurrence
of food sharing across primates. Defined as the unresisted
transfer of food, evolutionary hypotheses have to explain
why possessors should relinquish food rather than keep it.
While sharing with offspring can be explained by kin
selection, explanations for sharing among unrelated adults
are more controversial. Here we test the hypothesis that
sharing occurs with social partners that have leverage over
food possessors due to the opportunity for partner choice in
other contexts. Thus, we predict that possessors should
relinquish food to potential mates or allies, who could
provide or withhold matings or coalitionary support in the
future. We used phylogenetic analyses based on both
maximum likelihood and Bayesian approaches in a sample
of 68 primate species to test these predictions. The analyses
strongly indicate that (1) sharing with offspring is predicted
by the relative processing difficulty of the diet, as measured by the degree of extractive foraging, but not overall diet
quality, (2) food sharing among adults only evolved in
species already sharing with offspring, regardless of diet,
and (3) male–female sharing co-evolved with the opportunity
for female mate choice and sharing within the sexes
with coalition formation. These results provide comparative
support for the hypothesis that sharing is “traded” for
matings and coalitionary support in the sense that these
services are statistically associated and can thus be selected
for. Based on this, we predict that sharing should occur in
any species with opportunities for partner choice
Female Reproductive Seasonality and Male Influxes in Wild Mandrills (Mandrillus sphinx)
The correlates of variation in the number of males in primate groups form a long-standing question in primatology. We investigated female reproductive seasonality and the numbers of males in groups of wild mandrills (Mandrillus sphinx) in a 25-month camera-trap survey with 160 camera locations in Moukalaba-Doudou National Park, Gabon. We used 1760 videos to analyze group composition, including the presence of females with newborn infants and with sexual swellings, the number of males present in groups, and male spatial positioning in groups. Female reproduction was seasonal, with a peak in the number of newborns in the mid-rainy season and a peak in the number of females with sexual swellings in the early dry season. The number of males in the group increased in the dry season, with a much greater increase in the number of mature males (sevenfold) than in submature males (twofold). The peak number of mature males, but not submature males, in the group lagged significantly behind the peak in the number of females with sexual swellings, suggesting that submature males enter groups before mature males and/or that mature males stay in the group longer after the peak of females with sexual swellings. Mature, but not submature, males appeared frequently near females with sexual swellings. In conclusion, we found a clear relationship between the presence of receptive females and the number of males in the group, and evidence that male competitive ability influences male strategies