Phylogenomics, Diversification Dynamics, and Comparative Transcriptomics across the Spider Tree of Life

• Published in: Current biology 2018-05, Vol.28 (9), p.1489-1497.e5
• Main Authors: Fernández, Rosa, Kallal, Robert J., Dimitrov, Dimitar, Ballesteros, Jesús A., Arnedo, Miquel A., Giribet, Gonzalo, Hormiga, Gustavo
• Format: Article
• Language: English
• Subjects: Araneae; Arthropoda; Chelicerata; lineage diversification; orb web; transcriptomics
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2018.03.064

Dating back to almost 400 mya, spiders are among the most diverse terrestrial predators [1]. However, despite considerable effort [1–9], their phylogenetic relationships and diversification dynamics remain poorly understood. Here, we use a synergistic approach to study spider evolution through phylogenomics, comparative transcriptomics, and lineage diversification analyses. Our analyses, based on ca. 2,500 genes from 159 spider species, reject a single origin of the orb web (the “ancient orb-web hypothesis”) and suggest that orb webs evolved multiple times since the late Triassic–Jurassic. We find no significant association between the loss of foraging webs and increases in diversification rates, suggesting that other factors (e.g., habitat heterogeneity or biotic interactions) potentially played a key role in spider diversification. Finally, we report notable genomic differences in the main spider lineages: while araneoids (ecribellate orb-weavers and their allies) reveal an enrichment in genes related to behavior and sensory reception, the retrolateral tibial apophysis (RTA) clade—the most diverse araneomorph spider lineage—shows enrichment in genes related to immune responses and polyphenic determination. This study, one of the largest invertebrate phylogenomic analyses to date, highlights the usefulness of transcriptomic data not only to build a robust backbone for the Spider Tree of Life, but also to address the genetic basis of diversification in the spider evolutionary chronicle. •We present the largest phylogenomic analysis for spiders to date•We show a robust backbone for spider relationships with novel phylogenetic placements•Our analyses reject the single origin of the orb web•Genomic differences may have contributed to differential lineage diversification Fernández et al. use a synergistic approach to study spider evolution through phylogenomics, comparative transcriptomics, and lineage diversification analyses. The “ancient orb web” hypothesis was rejected. Loss of foraging webs was not strongly associated to spider diversification. Notable genomic differences were found between main spider clades.