Loss of sea turtle eggs drives the collapse of an insular reptile community.

Marine subsidies are vital for terrestrial ecosystems, especially low-productivity islands. However, the impact of losing these subsidies on the terrestrial food web can be difficult to predict. We analyzed 23 years of survey data from Orchid Island to assess the consequences of the abrupt loss of an important marine subsidy. After climate-driven beach erosion and predator exclusion efforts resulted in the abrupt loss of sea turtle eggs from the terrestrial food web, predatory snakes altered their foraging habitats. This increased predation on other reptile species in inland areas, resulting in population declines in most terrestrial reptile species. Comparisons with sea turtle-free locations where lizard populations remained stable supported these findings. Our study emphasizes the cascading effects of generalist predators and the unintended consequences of single-species conservation, highlighting the importance of understanding species interconnectedness and considering potential ripple effects in marine-dependent insular ecosystems.

Why do ovigerous females approach courting males? Female preferences and sensory biases in a fiddler crab.

Perceptual biases explain the origin and evolution of female preference in many species. Some responses that mediate mate choice, however, may have never been used in nonmating contexts. In the fiddler crab, Uca mjoebergi, mate-searching females prefer faster wave rates and leading wave; however, it remains unclear whether such responses evolved in a mating context (i.e., the preference has effect on the fitness of the female and her offspring that arise from mating with a particular male) or a nonmating contexts (i.e., a female obtains direct benefits through selecting the male with a more detectable trait). Here, we compared the preferences of mate-searching with those of ovigerous females that are searching for a burrow and do not concern about male "quality." Results showed that as both mate-searching and ovigerous females preferentially approached robotic males with faster wave rates. This suggests that wave rate increases detectability/locatability of males, but the mating preference for this trait is unlikely to evolve in the mating context (although it may currently function in mate choice), as it does not provide fitness-related benefit to females or her offspring. Wave leadership, in contract, was attractive to mate-searching females, but not ovigerous females, suggesting that female preference for leadership evolves because wave leadership conveys information about male quality. We provide not only an empirical evidence of sensory biases (in terms of the preference for faster wave), but the first experimental evidence that mating context can be the only selection force that mediates the evolution of male sexual traits and female preference (in terms of the preference for leading wave).

Incorporating an ontogenetic perspective into evolutionary theory of sexual size dimorphism.

Sexual size dimorphism (SSD) describes divergent body sizes of adult males and females. While SSD has traditionally been explained by sexual and fecundity selection, recent advances in physiology and developmental biology emphasize that SSD would occur proximately because of sexual differences in ontogenetic growth trajectories (i.e., growth rate and duration). Notably, these ontogenetic traits are subject to energetic or time constraints and thus traded off with fitness components (e.g., survival and reproduction). To elucidate the importance of such ontogenetic trade-offs in the evolution of SSD, we developed a new theoretical framework by extending quantitative genetic models for the evolution of sexual dimorphism in which we reinterpret the trait as body size and reformulate sex-specific fitness in size-dependent manners. More specifically, we assume that higher growth rate or longer growth duration leads to larger body size and higher reproductive success but incurs the cost of lower survivorship or shorter reproduction period. We illustrate how two sexes would optimize ontogenetic growth trajectories in sex-specific ways and exhibit divergent body sizes. The present framework provides new insights into the evolutionary theory of SSD and predictions for empirical testing.