Phylogenomics Resolves a Spider Backbone Phylogeny and Rejects a Prevailing Paradigm for Orb Web Evolution
Jason E. Bond 4 correspondence email, Nicole L. Garrison4, Chris A. Hamilton, Rebecca L. Godwin, Marshal Hedin, Ingi Agnarsson
4Co-first author
Open Archive
Highlights
•Phylogenomic data are presented for taxa representing all major spider lineages
•Concatenation and species tree analyses resolve a consistent backbone phylogeny
•The orb web is reconstructed as ancestral for a clade including most spider diversity
•Divergence time estimates place the origin of orb webs in the Lower Jurassic
Summary
Spiders represent an ancient predatory lineage known for their extraordinary biomaterials, including venoms and silks. These adaptations make spiders key arthropod predators in most terrestrial ecosystems. Despite ecological, biomedical, and biomaterial importance, relationships among major spider lineages remain unresolved or poorly supported [ 1 ]. Current working hypotheses for a spider “backbone” phylogeny are largely based on morphological evidence, as most molecular markers currently employed are generally inadequate for resolving deeper-level relationships. We present here a phylogenomic analysis of spiders including taxa representing all major spider lineages. Our robust phylogenetic hypothesis recovers some fundamental and uncontroversial spider clades, but rejects the prevailing paradigm of a monophyletic Orbiculariae, the most diverse lineage, containing orb-weaving spiders. Based on our results, the orb web either evolved much earlier than previously hypothesized and is ancestral for a majority of spiders or else it has multiple independent origins, as hypothesized by precladistic authors. Cribellate deinopoid orb weavers that use mechanically adhesive silk are more closely related to a diverse clade of mostly webless spiders than to the araneoid orb-weaving spiders that use adhesive droplet silks. The fundamental shift in our understanding of spider phylogeny proposed here has broad implications for interpreting the evolution of spiders, their remarkable biomaterials, and a key extended phenotype—the spider web.
Received: April 23, 2014; Received in revised form: June 12, 2014; Accepted: June 12, 2014; Published Online: July 17, 2014
© 2014 Elsevier Ltd. Published by Elsevier Inc.
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