Broad-Scale Climatic Gradients Drive Multiple Facets of Scorpion Beta Diversity in Northeastern Brazil

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  Broad-Scale Climatic Gradients Drive Multiple Facets of Scorpion Beta Diversity in Northeastern Brazil ABSTRACT Aim Beta diversity analyses clarify mechanisms structuring ecological communities, but their multidimensional facets remain poorly explored in arthropods. Here, we quantified taxonomic, phylogenetic, and functional beta diversity in scorpions, partitioned these facets into species replacement and richness differences, and evaluated the relative importance of spatial structure and environmental conditions in driving community assembly. Location Northeastern Brazil, South America. Taxon Scorpions (Arachnida: Scorpiones). Methods Taxonomic beta diversity was estimated using species presence across 70 sites in northeastern Brazil. Phylogenetic turnover was calculated from a multi-locus molecular tree, and functional beta diversity was derived from morphometric and ecological traits. All beta diversity facets were decomposed into replacement and richness-difference component...

Sexual dimorphism in bite force performance and cheliceral muscle morphology in a wandering spider (Araneae, Ctenidae)

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Sexual dimorphism in bite force performance and cheliceral muscle morphology in a wandering spider (Araneae, Ctenidae)

Abstract

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Bite force is a key performance trait in many animal taxa, directly influencing ecological and behavioral interactions such as predation, defense, and mating. In spiders, this trait could be modulated by both morphological and environmental factors, yet few studies have measured it directly. Here, we provide the first in vivo measurements of bite force in the wandering spider Phoneutria depilata and test the effects of sex, body size, diet, and predator-induced stress on bite force. We also investigate the volume and mechanical advantage of cheliceral muscles using μCT scans of male and female specimens. Our results show that females exhibit significantly higher bite forces than males, even after correcting for body size. This difference is primarily associated with sexual size dimorphism but is likely also influenced by the greater volume of specific adductor muscles (Anterior medial and Anterior medial outer). In contrast, neither dietary composition nor predator exposure had a significant impact on bite performance. These findings suggest that while environmental conditions may influence other traits, bite force in P. depilata is mainly determined by intrinsic morphological features. This study highlights the role of sexual dimorphism in shaping biomechanical traits and provides a basis for future research on functional performance in arachnids.

González-Gómez, J. C., Simone, Y., Herrel, A., Guevara, G., & F. Pérez, L. M. Sexual dimorphism in bite force performance and cheliceral muscle morphology in a wandering spider (Araneae, Ctenidae). Journal of Zoology. https://doi.org/10.1111/jzo.70106