"Reproductive Success and Genetic Population Structure in Wedge -Capped Capuchin Monkeys" by Maria Ximena Corina Valderrama Aramayo

Maria Ximena Corina Valderrama Aramayo

Deposited 2002

Abstract
The central question in this study was whether an unusual breeding system observed in wedge-capped capuchin monkeys would be supported by genetic paternity analysis. Long-term demographic data for a large capuchin group were incorporated with neutral autosomal markers. The dataset was used to examine the relative influence of male dominance rank and female preference on reproductive output. Each alpha male sired more offspring than did other males, and two consecutive alpha males collectively sired slightly more than half the offspring. This result indicated an important role of discreet mating and sexual coercion as reproductive strategies by subordinate and extragroup males. In addition, the alpha male sired an increasing proportion of offspring in lower-ranking matrilines. These females may have targeted alpha males as a strategy to offset higher rates of offspring loss in these matrilines.

Estimates of genetic relatedness and variability, together with rates of demographic parameters, were used to examine how kin, group, and genetic structure evolved in one large and one small capuchin group.

Demographic and genetic information was incorporated with mitochondrial DNA haplotypes to assess local and regional genetic diversity and the demographic history of capuchins in the llanos of Venezuela. Relatedness within hierarchical demographic units reflected breeding and dispersal patterns. Spatial distributions of uncommon autosomal alleles also showed an association with dispersal patterns within the local population. In contrast, there was lack of phylogenetic resolution and absence of mutation-drift equilibrium in the regional population. In addition, mitochondrial DNA haplotypes were depauperate in variability within and among populations, only showing structure across a riverine dispersal barrier. These results indicated a recent founder event followed by rapid population expansion.

Incorporating genetic information into the long-term demographic study of capuchins was essential for testing models of male reproductive variance. The combined dataset also showed that short-term results could not be extrapolated over the long-term, for example in male reproductive variance and in matrilineal relatedness estimates. Information regarding dominance rank differentiation was critical for understanding how it led to female reproductive differentiation and lineage sorting, a principal mechanism of microevolution in this capuchin population. Similarly, collecting genetic data from two genomes proved indispensable for identifying the demographic and genetic determinants of the regional population's current genetic structure.