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

Area of Science:

• Evolutionary Biology
• Genomics
• Arachnology

Background:

• Spiders are ancient, diverse terrestrial predators with poorly understood evolutionary relationships and diversification.
• Phylogenetic and diversification dynamics of spiders remain a significant challenge in evolutionary biology.

Purpose of the Study:

• To investigate spider evolution, phylogenetic relationships, and diversification dynamics using a multi-faceted approach.
• To test the "ancient orb-web hypothesis" and explore the genetic underpinnings of spider diversification.

Main Methods:

• Phylogenomics using approximately 2,500 genes from 159 spider species.
• Comparative transcriptomics and lineage diversification analyses.
• Genomic analysis of major spider lineages, including araneoids and the RTA clade.

Main Results:

• The study rejects a single origin of the orb web, suggesting multiple independent evolutions since the Triassic-Jurassic.
• No significant link was found between the loss of foraging webs and increased diversification rates.
• Distinct genomic enrichments were observed: araneoids show genes for behavior/sensory reception, while the RTA clade has genes for immunity/polyphenic determination.

Conclusions:

• Orb webs evolved multiple times independently in spiders.
• Factors beyond foraging web loss, such as habitat and biotic interactions, likely drive spider diversification.
• Transcriptomic data are crucial for robust spider phylogenetics and understanding the genetic basis of their evolutionary success.