Is inaccurate mimicry ancestral to accurate in myrmecomorphic spiders (Araneae)?

Abstract

Batesian mimicry, in which a palatable organism resembles an unpalatable model, is widespread among taxa. Batesian mimics can be classified based on their level of accuracy (inaccurate or accurate). Using data on defensive strategies in more than 1000 species of spiders I investigated whether inaccurate myrmecomorphy is ancestral to accurate myrmecomorphy. I classified 233 myrmecomorphic species into four accuracy levels based on morphology, from poor inaccurate mimics to very accurate ones. I found that myrmecomorphy has evolved independently in 16 families and 85 genera. On the family-level phylogeny, the occurrence of myrmecomorphy is confined mainly to families branching later on the tree, from the RTA clade. On the generic-level phylogenies in Corinnidae and Salticidae, myrmecomorphy is not only of derived origin. Estimated ancestral state was non-mimetic in Salticidae and poor inaccurate myrmecomorphy in Corinnidae. Thus, inaccurate myrmecomorphic spider mimics seem rather ancestral to accurate but additional analysis on species-level phylogenies is needed to support this conclusion. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 97–111.