Heavy metals in beetle mandibles: the first comprehensive analysis of incorporation, with evolutionary origins and implications

The first comprehensive investigation of heavy metal incorporation into the mandibles of beetles was conducted via variable pressure environmental scanning electron microscopy (VP-ESEM) and X-Ray energy dispersive spectroscopy (EDS). Mandibles from all major coleopteran lineages (117 taxa = 4/4 suborders, 16/16 superfamilies, ~25% families) were analyzed. Ancestral state reconstruction of heavy metal presence was performed on a constructed phylogeny from a pre-existing and adapted data set. Phylogenetically independent contrasts (PICs) were carried out via BayesTraits to test for correlations between metal incorporation and adult habits / food preferences. Results indicate phylogenetic signal for metal incorporation as well as correlations with adult habits.