Su-Jen Roberts
Drivers of variation in paternity concentration in wild blue monkeys
Variation in the relative reproductive success of
males has been attributed to a number of factors, including: behavioral
variables (e.g., dominance rank, male and female preferences, coalitions, consortship), demographic variables (e.g., number of
competitors, female estrus synchrony), and individual characteristics (e.g.,
condition, size). I study
blue monkeys (Cercopithecus mitis stuhlmanni) in Kakamega Forest,
Kenya. This species exemplifies a
one-male polygynous mating system, with groups
comprising one resident male, multiple adult females, and offspring. As resident males are the highest-ranking
males in a one-male social system, they are assumed to monopolize paternity
within their group. Researchers,
however, have observed influxes of non-resident males into groups during the
breeding season, leading to extra-group copulations, thereby challenging the
assumption that resident males sire all the infants in their groups (see also
Hatcher). My study will evaluate
the hypothesis that male residency contributes to reproductive success in
one-male groups, and will focus on the role of behavioral and demographic
factors in influencing paternity concentration by residents.
Genetic
and behavioral tools have been applied separately in the past to investigate
male reproductive skew, however, their combination allows for a closer
examination of fitness. I will
observe the activity patterns and social behavior of non-resident and resident
males and monitor several social groups throughout the breeding season to
observe copulations, influxes of males, and male-female social
interactions. Long-term data on
resident male tenure and female reproductive synchrony will allow me to extend
this study to address male mating monopolization across a period of up to 6
years.
In
the Molecular Anthropology Lab at New York University, I am working to assign
paternity through molecular analysis of DNA extracted from fecal samples of
infants, resident and non-resident males.
Determining correlations between behavioral and demographic variables
and paternity make it possible to investigate the respective roles that these
variables play in male reproductive output, an evaluation which is integral in
placing behaviors within an evolutionary framework. Ultimately, this work will
contribute to knowledge of factors that influence a male's reproductive success
in wild, long-lived animals.