Mating systems and relative reproductive success inferred via PBT
Outputs from parentage analysis were used to generate individual profiles for each adult which included the number of offspring produced, the number of unique mates, and the number of offspring produced per mating. These data were then used to describe the mating system by looking for evidence of monogamy (one male mates with one female or vice versa), polygyny (one male mates with multiple females), or polyandry (one female mates with multiple males). Because Roth et al. (2018) did not quantify total offspring production and only a subset of offspring were analyzed for genetic analysis, we present measures of relative reproductive success among adults and relative production by different sexes. We quantified the correlation between the number of mates an adult acquired and the number of offspring produced using a Pearson’s correlation coefficient.
Although we expected the incidence of false positive and false negative rates for parentage assignment to be low because we used stringent criteria to limit error (see above), we elected to use a complimentary analysis, sibship assignment (SA), to confirm PBT results. Briefly, we estimated full-sibling relationships among our juvenile collection using the sibship assignment approach implemented in the software program COLONY (Jones and Wang 2010), and compared the outputs from SA and parentage analysis. COLONY employs a full-likelihood approach to estimate sibship and has been shown to outperform other sibship reconstruction methods (Lepais et al. 2010). For comparison purposes, we determined the proportion of full sibling pairs that were identical based on the two estimation procedures. Additionally, we examined the number of full-sibling pairs that were detected by one program and not the other. Lastly, we report on the number of single children families detected via sibship assignment and parentage analysis.