Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon

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  Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon Abstract Snakes exhibit extreme cranial kinesis that facilitates ingestion of prey with large cross-sectional area, but this ability is widely predicted to reduce bite performance due to decreased structural rigidity. Consequently, most large-bodied snakes rely on envenomation or constriction to subdue prey prior to ingestion. Species within the genus Drymarchon represent a notable exception: these large, non-venomous, non-constricting snakes routinely consume a wide range of prey, including large and potentially dangerous vertebrates, using only simple seizing and pinioning behaviors. Here, we quantify bite performance in three species of Drymarchon ( D. corais, D. couperi, and D. melanurus ), examine morphological predictors of biting performance, compare biting pressure to constriction pressure in similarly sized snakes, and synthesize dietary records across the genus. Our results sh...

A revised classification system of the marronoid clade of spiders (Araneae), based on dense sampling phylogenomics and comparative morphology

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A revised classification system of the marronoid clade of spiders (Araneae), based on dense sampling phylogenomics and comparative morphology

Abstract

The marronoid clade is a globally distributed, ecologically diverse group of spiders. It is an important faunal component in both natural and synanthropic environments, and even found in aquatic and extreme habitats such as desert salt flats. The systematics of the marronoid clade has been notoriously unstable due to the widespread character homoplasy and phenotypic variation found across the group, resulting in vague family concepts. The present work aims to mitigate this problem by conducting the thus far most densely sampled phylogenetic study (including 58% of all known genera), combining genomic subsampling (ultraconserved elements) and marker sequencing approaches. Our study especially focused on the so-called Austral marronoids, which have not been sufficiently treated in recent revisionary works. Our results find robust evidence for a biogeographic separation of most marronoid families, which generally exhibit their highest diversity in temperate regions of both hemispheres and are poorly represented in the tropics. Based on our phylogenetic and comparative morphological study, we propose a revised classification system of the marronoid clade, comprising 18 families. We provide descriptions of each family, notes on their natural history and explain the gaps that persist in biodiversity documentation, delivering a robust foundation for future ecological, macro-evolutionary and taxonomic works.

Wolff, J. O., J. Kelly, M. B., Cala-Riquelme, F., Gorneau, J. A., Montana, K. O., Smith, H. M., Sirvid, P. J., Vink, C. J., Esposito, L. A., Ramírez, M. J., & Griswold, C. E. A revised classification system of the marronoid clade of spiders (Araneae), based on dense sampling phylogenomics and comparative morphology. Cladistics. https://doi.org/10.1111/cla.70057