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...

Spatial Scale Modulates the Effect of Habitat Amount on Diversity Patterns of Arachnid Assemblages Across Different Brazilian Ecosystems

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Spatial Scale Modulates the Effect of Habitat Amount on Diversity Patterns of Arachnid Assemblages Across Different Brazilian Ecosystems

ABSTRACT

Aim

We evaluated how native vegetation cover influences the diversity of arachnid assemblages across multiple spatial scales in major Brazilian ecosystems.

Location

Brazil (Amazon and Atlantic rainforests, Cerrado savanna and Caatinga dry forest).

Taxon

Arachnida (Opiliones, Pseudoscorpiones and Scorpiones).

Methods

We sampled arachnids at 120 sites using active search and litter sifting. Native vegetation cover was quantified at three spatial scales (100, 200 and 300 m buffers) using GIS data. Assemblage structure was assessed using abundance, species richness, and Hill numbers (q = 0, 1 and 2). Generalized linear mixed models were used to evaluate responses across taxonomic groups and ecosystems.

Results

We recorded 3986 individuals from 179 species. Diversity responses to native vegetation cover were taxon-, ecosystem- and scale-dependent. Positive effects of vegetation cover were stronger and more consistent in rainforest than in savanna and dry forest ecosystems. In rainforests, most responses occurred at smaller spatial scales (100–200 m), whereas no significant effects were detected in the savanna. Opiliones richness showed limited variation with vegetation cover but differed in dominance structure among ecosystems. Scorpion assemblages were characterized by low richness and high dominance, while pseudoscorpions exhibited low evenness in more species-rich sites, particularly in the Amazon.

Main Conclusions

Native vegetation cover plays an important role in structuring arachnid diversity in Brazil, but its effects vary across taxa, ecosystems and spatial scales. These findings highlight the need for taxon- and scale-specific conservation strategies and reinforce the importance of multi-scale approaches to biodiversity conservation in Neotropical landscapes under increasing anthropogenic pressure.


A. Lira, A. F., DeSouza, A. M., Brito-Almeida, T. R., L. Neves, H. L., Rodrigues, G. G., De-Oliveira-Nogueira, C. H., Souza, U. F., S. Andrade, A. R., Jansen, R. G., Tourinho, A. L., Carvalho, L. S., Pordeus, L. M., Cunha, H. P., Silva, A. A., Chaves, M. F., Tizo-Pedroso, E., C. Lima, L. R., A. Lins, A. H., A. Correa, C. M., . . . Viana-Junior, A. B. (2026). Spatial Scale Modulates the Effect of Habitat Amount on Diversity Patterns of Arachnid Assemblages Across Different Brazilian Ecosystems. Journal of Biogeography, 53(8), e70320. https://doi.org/10.1111/jbi.70320