Behavioral evidence for two-stage sleep in spiders

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  Behavioral evidence for two-stage sleep in spiders Abstract Sleep is a fundamental behavioral state found across the animal kingdom, yet most of what we know about sleep is heavily vertebrate-biased. Studies are scarce or nonexistent in all but a few invertebrate lineages. A recent study of an REM sleep-like behavior in a jumping spider has reported unexpected parallels to sleep expression in vertebrates. So far, experimental evidence that these behavioral indicators truly represent sleep was lacking in spiders. Here, we present a comprehensive investigation into sleep behavior in the spider Portia fimbriata (Salticidae). We demonstrate diurnal activity, a free-running circadian rhythm, robust sleep architecture, regularly occurring REM-like behaviors, elevated arousal thresholds during those REM-like states, as well as rebound effects following sleep disruption. We conclude that the behavior we observe in spiders is behavioral sleep, providing evidence for an REM-like sleep sub...

Sex Role–Dependent Behavioral and Architectural Divergence in a Jumping Spider

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Sex Role–Dependent Behavioral and Architectural Divergence in a Jumping Spider

ABSTRACT

Sex differences in behavior and functional traits are often attributed to differences in mating effort intensity, but the role of sex-specific parental demands remains poorly understood. Using the jumping spider Toxeus maxillosus—where males engage in mate searching and courtship without providing parental care, while females provide extended maternal care from egg attendance to offspring maturity (around 3 months)—we conducted an exploratory investigation into whether these distinct selective pressures led to divergence in spatial behaviors and nest architecture. Results revealed that males and females showed equivalent accuracy, latency, and learning-related performance in both a route-planning test under water stress and a color-pattern associative memory task. In contrast, during nest-construction assays, females built complex, multi-entrance structures that closely matched the container's corner geometry, whereas males constructed only simple nests. Moreover, females built significantly larger and denser nests in both tube-present and tube-absent conditions. These findings indicate that when spatial or signal-processing abilities are equally critical for both sexes’ survival and reproduction, sexual and parental selection can converge on similar phenotypic performance; however, when trait functionality is strongly sex-limited (as in nest construction), divergence emerges. Our results reconcile conflicting reports of sex differences in spatially related traits by demonstrating that ecological necessity, rather than selective pressures alone, predicts the extent of divergence.

Wang, Y., Jiang, C., Liu, J. X., Jiao, X., & Chen, Z. Sex Role–Dependent Behavioral and Architectural Divergence in a Jumping Spider. Integrative Zoology. https://doi.org/10.1111/1749-4877.70127