Cheng, L.-X. | Search bioRxiv

bioRxiv2025

Genomic signatures associated with convergent funnel-web building behavior in spiders

Spiders exhibited diverse and intricate web-building behaviors, which represent a classic model for studying the evolution of complex traits. The funnel-web, a sheet-like web with a retreat tube, has evolved independently in several spider lineages, especially in the families Agelenidae and Macrothelidae. This repeated emergence of a complex behavior offers an example of this funnel-web building behavioral convergence. Here, we present a chromosome-level genome assembly of the agelenid spider Tamgrinia laticeps, along with annotated genomes of another agelenid spider Eratigena atrica, and a macrothelid Orientothele yani which convergently evolved funnel-web building behavior. Comparative genomic analysis of 15 spider species with diverse web-types revealed convergent signatures associated with funnel-web construction. Hundreds of genes tended to experience convergent shift in selective pressure, convergent positive section, and harbored convergent amino acid substitutions. These genes are associated with synaptic transmission (e.g., SLC6A3, Gabbr1, SNAP25), neuromuscular coordination (e.g., ine, VAChT), and behavioral regulation (e.g., Crtc1, Lrrc7). Notably, we detected identical convergent amino acid changes in VAChT and ine across all three funnel-web builders. Our findings demonstrate that convergent evolution of web architecture is linked to nervous system evolution, providing genomic insights into the basis of behavioral convergence.

genomics↗

bioRxiv2024

Relaxed selection and horizontal gene transfer fuel underwater adaptation in a water spider

Spiders have primarily adapted to terrestrial life, yet a number of species have made evolutionary transitions to marine and freshwater environments. While its physiological and behavioral adaptations have been characterized, the genetic basis of semi-aquatic and aquatic adaptation in spiders remains poorly understood. Here, we provide a high-quality, chromosome-level genome assembly for the aquatic spider Argyroneta aquatica, alongside a reference transcriptome for the semi-aquatic spider Desis martensi. We performed comparative genomes analyses of 22 spider species, including a unique aquatic spider, two semi-aquatic spiders and 19 terrestrial spider species, with a focus on those in the marronoid clade. By integrating morphological, phylogenomic, comparative genomic, transcriptomic, and metabolomic analyses, we explored the genomic adaptations of aquatic and semi-aquatic spiders. Phylogenomic analysis suggests that aquatic and semi-aquatic spiders have independently evolved from their terrestrial ancestors and represent divergent evolutionary routes We found hundreds of genes tend to experience relaxed selection, positive selection, and evidence of horizontal gene transfer (HGT) associated with the transition to aquatic and semi-aquatic life in spiders. These genes are associated with respiratory, osmoregulatory, fat metabolism and digestion, hypoxia, and thermal functions, putatively facilitate the adaptations to diverse underwater life. Altogether, our findings highlight the divergent evolutionary mechanisms enabling spiders to thrive in diverse aquatic environments, providing insights into the genomic basis of adaptations to semi-aquatic and aquatic habitats.

genomics↗