Benefits of polyandry: molecular evidence from field-caught dung beetles

When females mate with multiple males, they set the stage for post-copulatory sexual selection via sperm competition and/or cryptic female choice. Surprisingly little is known about the rates of multiple mating by females in the wild, despite the importance of this information in understanding the potential for post-copulatory sexual selection to drive the evolution of reproductive behavior, morphology, and physiology. Dung beetles in the genus Onthophagus have become a laboratory model for studying pre- and post-copulatory sexual selection, yet we still lack information about the reproductive behavior of female dung beetles in natural populations. Here, we develop microsatellite markers for Onthophagus taurus, and use them to genotype the offspring of wild-caught females, and to estimate natural rates of multiple mating and patterns of sperm utilization. We found that O. taurus females are highly polyandrous: 88% of females produced clutches sired by at least two males, and 5% produce...