Shifting evolutionary sands: transcriptome characterization of the Aptostichus atomarius species complex

Area of Science:

• Genomics
• Evolutionary Biology
• Arachnology

Background:

• Mygalomorph spiders are a diverse, understudied lineage.
• Genomic data is becoming accessible via high-throughput sequencing.
• The Aptostichus atomarius species complex offers insights into dune adaptation.

Purpose of the Study:

• Examine gene family conservation across the Aptostichus atomarius species complex.
• Test for positive selection in dune-adapted lineages.
• Understand transcriptomic patterns of dune adaptation.

Main Methods:

• Applied RNAseq to eight spider transcriptomes (dune, inland, outgroup).
• Utilized FUSTr and COATS pipelines for gene family and selection analysis.
• Assembled an average of ~44,000 contigs per spider.

Main Results:

• Identified over 18,000 orthologous gene clusters within the complex.
• Found 47 gene families under selection in the atomarius ingroup, including venom peptides.
• Detected six gene clusters under positive selection on branches leading to dune species.

Conclusions:

• Generated eight draft transcriptomes for ecologically diverse trapdoor spiders.
• Identified potential selection on venom gene families in the Aptostichus atomarius complex.
• Discovered selection on chemosensory-associated genes in dune endemic lineages.