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...

Comparative analysis of mitochondrial genomes from Buthidae (Scorpiones): gene rearrangement and phylogenetic implications

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Comparative analysis of mitochondrial genomes from Buthidae (Scorpiones): gene rearrangement and phylogenetic implications

Abstract

Scorpions, a diverse group of arachnids consisting of over 2,000 valid species, have received limited research attention in terms of their complete mitochondrial genomes (mitogenomes). To increase the taxonomic sampling frequency of species available for study based on mitogenomes, we reconstructed the complete mitogenomes of five scorpions, Androctonus amoreuxi (Audouin, 1826), Hottentotta tamulus (Fabricius, 1798), Leiurus quinquestriatus (Ehrenberg, 1828), Lychas mucronatus (Fabricius, 1798), and ­Teruelius flavopiceus (Kraepelin, 1900) within the family Buthidae. These five mitogenomes had a typical circular structure, with total sizes ranging from 14,504 to 15,083 bp. Nucleotide composition analysis indicated that the sequences were biased toward A and T. The Ka/Ks ratios within 13 protein-coding genes (PCGs) were lower than 1, suggesting that they had been subject to purifying selection in Buthidae. Our analyses provide additional evidence on that, in scorpions, the majority of mitogenome rearrangements occurred in tRNAs. Moreover, the genes tRNA-Asp, tRNA-Gln and tRNA-Ile were the hotspots of rearrangement in this order. ­Phylogenetic analyses based on PCGs supported taxonomic relationships in this taxon. Our results might provide useful insights into the gene arrangement features of scorpion mitogenomes and lay the foundation for further studies on the family Buthidae.

Xu W, Zhang G, Xu T, He K, Wang J, Liu Z, Liu H (2025) Comparative analysis of mitochondrial genomes from Buthidae (Scorpiones): gene rearrangement and phylogenetic implications. Arthropod Systematics & Phylogeny 83: 3-13. https://doi.org/10.3897/asp.83.e140421