Abstract Maternal age and diet can influence offspring development and fitness via maternal effects, but empirical evidence for their interactive effects remains limited. We examined how maternal age at oviposition and maternal dietary conditions influence offspring developmental responses to resource availability in the thelytokous predatory mite Amblyseius herbicolus . Mothers received either a restricted or abundant prey diet, and their offspring were exposed to varying prey availability and monitored for hatching success, survival to adulthood, developmental duration, size at maturity, and prey consumption. We asked how maternal age influences offspring development and whether maternal diet modifies these age‐related effects. Offspring of older mothers had higher survival to adulthood, developed for longer, attained a larger size at maturity, and consumed fewer prey during development. Maternal age also interacted with offspring prey availability to influence survival, while maternal diet modified age‐related effects on developmental duration, offspring size, and prey consumption. These findings demonstrate that maternal age and nutritional condition jointly shape offspring development and responses to resource availability, highlighting the importance of considering maternal age and environment when examining maternal effects and developmental plasticity.
Abstract Many organisms face alternative selective pressures across cyclically changing environments such as the diel cycle. Energetic and spatial constraints, among other issues, preclude independent day and nighttime or wakeful and sleeping responses to these contrasting sets of selective forces. We tested for behavioral similarity in microhabitat use during daytime wakeful and nighttime sleeping periods in Anolis lizards. We collected 1256 datapoints of sleeping perch height and substrate for 51 species and compared these data to published data on active perch use for these species. We demonstrate that species perch at similar heights but use significantly different perch substrates during sleep and wakefulness. The diel similarity in perch height may indicate a surfeit of adequate sleeping perches within a species' home range. The difference in perch substrate, wherein individuals tend to sleep on compliant perches, likely reflects the special predation risks encountered at night during sleep.
Abstract The drivers of plant dispersal and distribution are poorly understood. For nut‐bearing trees, interactions between seeds and caching granivores can have a strong influence on population dynamics as unrecovered caches often recruit new trees. Granivore‐seed interactions may be constrained by predators as fear alters caching and foraging behavior. We investigated how predation risk affects caching and foraging behavior in fox squirrels ( Sciurus niger ) and subsequent recruitment patterns of American turkey oak ( Quercus laevis ) acorns. We marked and tracked acorns to locate fox squirrel cache and consumption points where we assessed fox squirrel perceived predation risk, measured how caching influenced acorn survival and dispersal, and surveyed juvenile oak distributions. Fox squirrels perceived greater risk at caches than consumption points, suggesting predation risk influences caching decisions and cache distribution. Buried acorns survived at higher rates and only buried acorns germinated, though survival did not vary with dispersal distance. Juvenile oaks and cache locations showed similar hump‐shaped patterns of establishment away from nearest potential source trees. We conclude that predation risk indirectly shapes plant establishment by altering granivore behavior.
Abstract Understanding how species occupy islands and habitat patches remains a central question in biogeography, landscape ecology, conservation, and management, especially as natural and anthropogenic processes reconfigure habitat size and connectivity over time. The insular distribution function (IDF) provides a framework for predicting occupancy patterns for a species based on island area and isolation as proxies for extinction risk and colonization likelihood. While this model provides a conceptual bridge between island biogeography and metapopulation models, it has seen limited recent application in large part due to reliance on simplistic geometric measures of area and isolation. Here, we advance the implementation of the IDF by pulling from ecological niche modeling and landscape ecology to incorporate ecologically informed quantifications of area and isolation. We apply this framework to the montane sky‐islands of the Great Basin of the western United States, testing predictions for the Western Water Shrew ( Sorex navigator ). Compared with those based on traditional geometric metrics, the ecologically informed IDFs produced a discriminant function with lower classification error, stronger class separation, and different biological conclusions regarding the species' inferred response to isolation and area. The results from the ecologically informed IDF provide a contrast to IDF based on geographic axes and the classical interpretations for the system. Specifically, the steeper slope and lower intercept of the ecologically informed IDF point toward a system structured not so strongly by extinction‐driven relaxation, but by a more compensatory trade‐off in which both colonization and extinction have shaped occupancy patterns. Simulations of false‐absence rates (which affect datasets in lesser‐sampled systems) showed that the same inferences persisted in the presence of incomplete sampling. These results highlight the potential of integrating contemporary approaches with classic biogeographic models, as well as strengthening and clarifying links between island biogeography and landscape ecology. This updated analytical framework offers new opportunities for assessing subpopulation vulnerability, incorporating ecologically informed measures into occupancy‐based statistical frameworks, forecasting patchy species distributions across a full community, and studying how past and future environmental changes shape biodiversity patterns.
