The occurrence of pre-copulatory

courtship in coercively mating males has not been reported before. ITF2357 In Gluvia, coercive traits suggest that forced copulation is the exclusive mating strategy. Coercive mating strategies in camel-spiders may have evolved as an anti-predation strategy, as sexual cannibalism occurred in c. 40% of all sexual interactions. “
“Sexual size dimorphism (SSD) is often explained as the differential equilibrium between stabilizing survival selection and directional sexual/fecundity selection on the body size of males and females. Provided that survival selection is similar in both sexes, female-biased SSD is thought to occur when fecundity selection on female body size is stronger than sexual selection on male body size. However, in animals with indeterminate growth, body size depends on several life-history traits, thus, to understand why SSD has evolved, one should understand how it arises. We investigate SSD in the Tyrrhenian tree frog, Hyla sarda, by describing sexual dimorphism in age and growth and by assessing how body size affects their reproductive success. Females are 16% larger than males because they mature 1 year later, live 1 year longer and reach a larger asymptotic body size. Furthermore, body size correlates positively with female fecundity, but not with male mating success. These

results suggest that SSD arises from differential optimal trade-offs between the expected number of reproductive episodes (which decreases with prolonging growth) and the expected success in each reproductive episode (which increases with prolonging growth). “
“Reproductive Selleckchem FK506 frequency is a key component of reproductive output, and has important influences on organismal fitness and population persistence. Viperid snakes, like many other ectothermic vertebrates, generally exhibit a low frequency of reproduction (LFR), as females only 上海皓元医药股份有限公司 reproduce every second year, or even less frequently. However, for small-bodied species with constrained clutch/litter sizes, and low survival, reproductive frequency cannot be too infrequent if populations are to

persist. We assessed whether Bitis schneideri, a small, arid-adapted viperid snake from southern Africa has the LFR typical of many other viperids, despite having low survival and small litters. We calculated the reproductive frequency required to sustain a population using information gathered from recent studies of the ecology of the species. The small litter size imposed by being small-bodied, and low annual survival, require B. schneideri to reproduce frequently, probably annually, for populations to persist. We also assessed the reproductive status of all available preserved adult females. A high proportion were reproductive (up to 80% during summer), with developing or mature follicles, or developing young.