If animals increase inclusive fitness by cooperating with relatives, nepotism should involve maternal and paternal kin equally, all else being equal. Evidence of a behavioral bias toward paternal ...half‐siblings in primates is both limited and mixed, with most positive reports from papionins. To expand knowledge of paternal kin recognition, particularly in cercopithecine monkeys, we examined evidence for paternal kin bias in wild blue monkeys (Cercopithecus mitis), a species living mostly in one‐male groups. Seasonal breeding and the amount of male reproductive skew in blue monkeys suggests that opportunities to distinguish paternal kin are plentiful, and their social system would make such discrimination beneficial. We compared spatial association and social contact (grooming and contact‐sitting) of 20 adult females with at least one paternal half‐sibling and at least one non‐relative that were present at the same time. We used two data sets, one in which social partners were other parous females, the other in which they were juveniles. Data came from a 7‐year period. When interacting with other adult females, subjects groomed and sat in contact with paternal half‐siblings significantly more than with known non‐kin, and there was a similar trend for spatial association. We detected no paternal kin bias in interactions with juvenile partners. Kin‐biased affiliative contact with adult female partners did not appear to be based on age proximity, measured by birth cohort. The study species’ social system suggests phenotype matching as the most likely alternative mechanism, though we could not test it directly. Across both behaviors, there was no significant relationship between the number of matrilineal kin a subject had and the degree to which she preferred paternal half‐siblings over non‐kin as affiliative partners. These findings contribute to a comparative understanding of paternal kin recognition in primates.
HIGHLIGHTS
• Blue monkey adult females interacting with peers prefer to socialize with paternalhalf‐siblings over known non‐relatives, suggesting an ability to recognize thesepaternal kin.• The mechanism of kin recognition does not appear to be based on age similarity.• The degree to which females preferred paternal half‐siblings was not related to thenumber matrilineal kin they had, or to the number of very close maternal relatives.
Adult female blue monkeys show higher rates of social contact and association with paternal half‐siblingsthan with non‐relatives. Each line shows data for one adult female, and connects her average value forsocializing with partners in each class.
Examining seasonal mortality patterns can yield insights into the drivers of mortality and thus potential selection pressures acting on individuals in different environments. We compiled adult and ...juvenile mortality data from nine wild non-human primate taxa to investigate the role of seasonality in patterns of mortality and address the following questions: Is mortality highly seasonal across species? Does greater environmental seasonality lead to more seasonal mortality patterns? If mortality is seasonal, is it higher during wet seasons or during periods of food scarcity? and Do folivores show less seasonal mortality than frugivores? We found seasonal mortality patterns in five of nine taxa, and mortality was more often tied to wet seasons than food-scarce periods, a relationship that may be driven by disease. Controlling for phylogeny, we found a positive relationship between the degree of environmental seasonality and mortality, with folivores exhibiting more seasonal mortality than frugivores. These results suggest that mortality patterns are influenced both by diet and degree of environmental seasonality. Applied to a wider array of taxa, analyses of seasonal mortality patterns may aid understanding of life-history evolution and selection pressures acting across a broad spectrum of environments and spatial and temporal scales.
(1) A log-linear model of variance in the consumption of fruit, leaves, insects and other plant foods by sympatric Kenyan guenons showed that species identity, age-sex class, time of year, and all ...two-way interactions of these factors were significant sources of dietary variation. (2) Blue monkeys were more folivorous and less frugivorous and insectivorous than redtails. The two species used different plant species and substrates as sources of insect prey. Redtails used capture methods more appropriate for mobile prey more often than blue monkeys. Both species showed a bimodal annual seasonality in their consumption of fruit, leaves and insects, but differed in how the proportions of these items in the diet inter-relate. (3) In both species, adult males were highly frugivorous, whereas adult females were more insectivorous and/or folivorous. Juvenile size was directly related to the proportions of leaves and of insects in the diet, but inversely related to the proportion of fruit. The largest juveniles were more folivorous and insectivorous than adults. Some age-sex differences were found in the plant species and substrates used for insect capture, and in capture methods. (4) The diets of some heterospecific age-sex classes were more similar than those of some conspecific age-sex classes in degree of frugivory and insectivory, and in how the monthly proportions of the three major dietary components covaried. Dietary similarity of conspecifics tended to exceed that of heterospecifics, however, when plant species-specific items and the number of individuals in each species-age-sex class were taken into consideration. (5) These results and comparisons with other Cercopithecus communities suggest that dietary variation between species and between species-age-sex classes is related to body size, the physiological demands of reproduction and growth, social constraints, and competition, especially for fruit.
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