Polyandry Research Paper

Polyandry in Anuran Amphibians Polyandry is a breeding pattern where the female mates with multiple males in one mating season, this topic is described by Byrne and Roberts (2012) as a poorly understood topic in evolutionary biology. Polyandry has two types in taxa with external fertilization, e.g. anuran amphibians: simultaneous and sequential polyandry. Simultaneous polyandry occurs when sperm from multiple males compete to fertilize eggs. Sequential polyandry occurs when the eggs from a single female are fertilized by multiple males and sperm competition is absent (Byrne and Roberts 2012). These two types are not mutually exclusive; a species can display traits from both types. Polyandry can provide a species with better reproductive success, in the case of Salamandra salamandra, or insure against nest failure as studied in the Australian toadlet Pseudophryne bibronii, or increase the fitness of the offspring as studied in Chiromantis xerampelina. However, females can be forced into polyandrous mating by male harassment, as studied in Bufo bufo. Sexual

In passive polyandry the females are forced to copulate with multiple males against their interests. In active polyandry the females choose to mate with multiple males. In the common toad, Bufo bufo, the female benefits are commonly lacking which is indicative of passive polyandrous mating. Sztatecsny, Jehle, Burke, and Hödl (2006) hypothesized that due to the variance in reproductive success among B. bufo polyandrous mating would be rare, however, the prevalence of polyandry in B. bufo is similar to other anurans. Benefits from polyandrous mating for the females is severely lacking and Sztatecsny et al. (2006) concluded that sexual selection in the common toad was driven by direct costs as opposed to direct or indirect benefits since polyandrous mating provides no advantage to the female but largely results from male