Transcriptomic Insights Into the Evolution of Snake Venom: Mechanisms, Diversity, and Adaptation

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  Transcriptomic Insights Into the Evolution of Snake Venom: Mechanisms, Diversity, and Adaptation Abstract Snake venoms are evolutionarily refined biochemical arsenals composed of diverse toxins with complex functional roles in predation, defense, and competition. Over the past 2 decades, transcriptomic approaches have transformed venom research by enabling high-resolution insights into gene expression dynamics, molecular diversity, and the evolutionary mechanisms driving venom variation across lineages. In this review, we present a comprehensive synthesis of snake venom transcriptomics literature and propose a conceptual framework structured around three major axes: (1) gene family expansion through duplication and neofunctionalization; (2) regulatory complexity encompassing transcriptional, posttranscriptional, and epigenetic modulation; and (3) ecological selection pressures shaping venom profiles in response to diet, habitat, and interspecific interactions. We integrate findin...

A comparative morphology of trichobothrial bases in araneoid spiders and its significance for the phylogeny and system of the superfamily Araneoidea (Arachnida, Araneae)

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A comparative morphology of trichobothrial bases in araneoid spiders and its significance for the phylogeny and system of the superfamily Araneoidea (Arachnida, Araneae)

Abstract

Bothrial morphology was studied by SEM in 137 araneoid genera representing all 22 currently recognized extant families and all 42 conventional subfamilies of the Araneoidea. The ancestral type in the superfamily Araneoidea is a ‘hooded’ bothrium with a single well-developed transverse ridge, dividing its proximal and distal plates (‘Erigone-type’); the advanced type is a solid dome-like bothrium without vestiges of the ridge (‘Theridion-type’); there are several intermediate types reflecting various pathways and stages of the ridge reduction (united here as ‘Argiope-type’). The parallel trends in bothrial evolution, recognized as continuous series from the ancestral type up to the advanced one through some intermediate stages, are distinguished in each of the seven main phylogenetic lineages of the superfamily: ‘tetragnathoids’, ‘araneoids’, ‘cyatholipoids’, and ‘theridioids’ possess a complete set of the three types, while ‘malkariods’, ‘symphytognathoids’. and ‘linyphioids’ lack the advanced, dome-like type (‘Theridion-type’). Only three taxa have been proposed earlier as the sister group of the superfamily Araneoidea: Nicodamoidea, Deinopoidea, and Leptonetoidea; morphology of bothria, as well as other cuticular microstructures, clearly supports the araneoid-nicodamoid relationship hypothesis, purely ‘molecular’ to date. Bothrial morphology provides the additional arguments for several taxonomic acts, e.g., for the reranking the Agnarsson’s (2004) ‘clade 35’ (Theonoe, Carniella, Robertus, and Pholcomma) up to the Theonoeinae Simon, 1894, stat. nov., and for the revalidation the micropholcommatid Plectochetos Butler, 1932, gen. revalid. and zygiellid Parazygiella Wunderlich, 2004, gen. revalid.

Eskov KY, Marusik YM (2024) A comparative morphology of trichobothrial bases in araneoid spiders and its significance for the phylogeny and system of the superfamily Araneoidea (Arachnida, Araneae). ZooKeys 1219: 1-60. https://doi.org/10.3897/zookeys.1219.133002