Supplementary information of: Dynamic Evolution of Size and Color in the Highly Specialized Zodarion Ant-Eating Spiders

Ecological specialists constitute relevant case studies for understanding the mechanisms, potential and limitations of evolution. The species-rich and strictly myrmecophagous spiders of the genus Zodarion show diversified defense mechanisms, including myrmecomorphy of different ant species and nocturnality. Using hyRAD, a phylogenomic technique designed for sequencing poorly preserved specimens, we reconstructed the phylogeny of Zodarion using 52 (~ a third of the nominal) species that cover its phylogenetic and distributional diversity. We then estimated the evolution of body size and color, traits that have diversified noticeably and are linked to defense mechanisms, across the group. Our genomic matrix of 300 loci led to a well-supported phylogenetic hypothesis that uncovered two main clades inside Zodarion. Ancestral state estimation revealed the highly dynamic evolution of body size and color across the group, with multiple transitions and convergences in both traits, which we propose is likely indicative of multiple transitions in ant specialization across the genus. Our study will allow the informed targeted selection of Zodarion taxa of special interest for research into the group’s remarkable adaptations to ant specialization. It also exemplifies the utility of hyRAD for phylogenetic studies using museum material.