| The diversity on coral reefs has long captivated observers. We examine the mechanisms of speciation, role of ecology in speciation, and patterns of species distribution in a typical reef-associated clade-the diverse and colorful Calcinus hermit crabs-to address the origin of tropical marine diversity. We sequenced COI, 16S, and H3 gene regions for similar to 90% of 56 putative species, including nine undescribed, "cryptic" taxa, and mapped their distributions. Speciation in Calcinus is largely peripatric at remote locations. Allopatric species pairs are younger than sympatric ones, and molecular clock analyses suggest that > 2 million years are needed for secondary sympatry. Substantial niche conservatism is evident within clades, as well as a few major... |
