COMPREHENSIVE SAMPLING AND INTEGRATIVE APPROACHES TO RECONSTRUCT THE EVOLUTIONARY HISTORY OF A MORPHOLOGICALLY AND ECOLOGICALLY DIVERSE GROUP OF DECAPODS (ANOMURA)

The infraorder Anomura has long captivated the attention of evolutionary biologists due to its impressive morphological diversity and ecological adaptations. To date, 2500 species have been described and, despite their monetary value in fisheries, phylogenetic relationships at high taxonomic levels remain contentious. Here, we reconstruct the evolutionary history—phylogeny, divergence times, and character evolution—of this speciose clade. For this purpose, we sequenced two mitochondrial 16S and 12S and three nuclear H3, 18S and 28S markers for 19 of the 20 extant families, using traditional Sanger and next-generation 454 sequencing methods. Molecular data are combined with 156 morphological characters in order to estimate the largest anomuran phylogeny to date. Our best phylogenetic hypothesis supports most anomuran superfamilies and families as monophyletic. However, phylogenetic relationships among three families and eleven genera are recovered as para- and polyphyletic. Hypotheses concerning the invasion of freshwater and terrestrial environments and evolution of diverse body forms are tested by ancestral state reconstruction. Results suggest crab-like form evolved multiple times during the evolution of the group and the invasion of freshwater and terrestrial environments occurred from marine ancestors. Thirty-one fossil calibration points have been included to estimate the origins and divergence times of anomuran lineages using Bayesian dating methods. Divergence time analysis dates the origins of the Anomura to the Late Permian ~259 MYA with many of the present day families radiating during the Jurassic and Early Cretaceous.