Evolution of corallivory in the gastropod genus Drupella

Abstract

Although muricid gastropods in the genus Drupella are well-known consumers of Indo-Pacific corals, their evolutionary and ecological history is unclear, as is their relationship to the apparently facultative coral-feeder Ergalatax margariticola, which has been reported to feed upon corals in Hong Kong. We use a well resolved molecular phylogeny (reconstructed from one nuclear and two mitochondrial genes) to show that the monophyletic genus Drupella falls into the muricid subfamily Ergalataxinae and that the genus includes ‘E. margariticola’, which is composed of two cryptic species. We show that genetic structure within the here reassigned ‘Drupella margariticola’ species complex does not relate to feeding mode, but instead seems to correspond to broad patterns of habitat ecology found in other gastropod taxa. Our analyses suggest that Drupella originated in the late Miocene (approximately 9.6 Ma) and diversified approximately 5.0 Ma, much later than the appearance of modern coral reefs in the early Cenozoic. Thus, it is possible that corallivory in Drupella evolved in response to the major expansion and reorganization of reefs that took place in the early Miocene.