Hidden in the wrack: spider (Arachnida, Araneae) diversity and new records for Italy from Posidonia banquettes

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  Hidden in the wrack: spider (Arachnida, Araneae) diversity and new records for Italy from Posidonia banquettes ABSTRACT Posidonia oceanica (L.) Delile beach wrack deposits (banquettes) are a characteristic coastal habitat of the Mediterranean Sea, yet their invertebrate communities remain poorly studied. Here we report the results of a survey from January to November 2024 of the spider fauna (Order Araneae) associated with Posidonia banquettes at Sant’Agostino beach (Civitavecchia, Latium, central Italy), using four complementary sampling methods (surface and underground pitfall traps, Berlese-Tullgren funnel extraction, and visual census). A total of 161 specimens were collected, with 17 species assigned to 11 families among adult individuals. The dominant families were Argyronetidae (39.4%), represented exclusively by Chaerea maritimus Simon, 1885, and Gnaphosidae (33.8%). Three species are recorded for the first time in Italy: Dysdera gamarrae Ferrández 1984, Gnaphosa jucu...

Venom Variation as a Window into the Ecology and Evolution of Snakes

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Venom Variation as a Window into the Ecology and Evolution of Snakes

Abstract

Snake venoms are complex biochemical systems that function primarily in prey subjugation and defense, yet their composition varies extensively across individuals, populations, species, and environments. This variation provides a powerful framework for investigating ecological and evolutionary processes. Here, we offer a forward-looking synthesis of snake venom diversity that proposes new research directions and highlights how venom variation can illuminate eco-evolutionary dynamics across biological scales. We review evidence for ten key contexts in which venom variation arises, including within-population differences, sexual dimorphism, geographic structuring, ontogenetic shifts, seasonal changes, interspecific divergence, hybridization, convergent evolution, prey specificity, and venom resistance. Together, these processes demonstrate that venom phenotypes are shaped by interacting selective pressures such as trophic ecology, predator–prey coevolution, environmental heterogeneity, and gene flow. While phylogenetic history establishes broad toxin composition patterns, ecological factors frequently drive rapid and repeated shifts in venom phenotype. We further outline the historical development of venom research, from early descriptive studies to modern integrative approaches enabled by advances in proteomics, transcriptomics, genomics, and functional assays. These methodological innovations increasingly allow venom composition to be linked directly to ecological performance and evolutionary outcomes. Despite this progress, major gaps remain, including limited taxonomic coverage, incomplete integration of ecological data, and insufficient experimental tests of adaptive hypotheses. Future research combining molecular, functional, and field-based approaches will be essential for resolving the mechanisms that generate and maintain venom diversity. As complex traits shaped by interacting ecological and evolutionary forces, snake venoms provide an exceptional model system for understanding how selection, constraint, and environmental context interact to produce phenotypic diversity across time and space.

Balchan, N. R., Mackessy, S. P., Wogan, G. O., Esquerré, D., & Avella, I. Venom Variation as a Window into the Ecology and Evolution of Snakes. Integrative and Comparative Biology. https://doi.org/10.1093/icb/icag056