Phylogenomic Analysis of Spiders Reveals Nonmonophyly of Orb Weavers
Rosa Fernández correspondenc eemail, Gustavo Hormiga, Gonzalo Giribet
•We present a phylogenomic study of spider relationships using multiple approaches
•Our results reveal that orb weavers are not monophyletic
•Either the orbicular web evolved twice or its origin is ancestral
•Potentially confounding factors in phylogenetics had no effect in our results
Spiders constitute one of the most successful clades of terrestrial predators [ 1 ]. Their extraordinary diversity, paralleled only by some insects and mites [ 2 ], is often attributed to the use of silk, and, in one of the largest lineages, to stereotyped behaviors for building foraging webs of remarkable biomechanical properties [ 1 ]. However, our understanding of higher-level spider relationships is poor and is largely based on morphology [ 2–4 ]. Prior molecular efforts have focused on a handful of genes [ 5, 6 ] but have provided little resolution to key questions such as the origin of the orb weavers [ 1 ]. We apply a next-generation sequencing approach to resolve spider phylogeny, examining the relationships among its major lineages. We further explore possible pitfalls in phylogenomic reconstruction, including missing data, unequal rates of evolution, and others. Analyses of multiple data sets all agree on the basic structure of the spider tree and all reject the long-accepted monophyly of Orbiculariae, by placing the cribellate orb weavers (Deinopoidea) with other groups and not with the ecribellate orb weavers (Araneoidea). These results imply independent origins for the two types of orb webs (cribellate and ecribellate) or a much more ancestral origin of the orb web with subsequent loss in the so-called RTA clade. Either alternative demands a major reevaluation of our current understanding of the spider evolutionary chronicle.
Received: May 1, 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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