Meeting Abstract

65.4  Sunday, Jan. 6  Sibling Sea Urchin Species of the Genus Echinothrix in Hawai’i: Morphology, Genetics, & Ecology JESSOP, H.*; LESSIOS, H.A.; DEMAINTENON, M.J.; TAKABAYASHI, M.; University of Hawai’i at Hilo; Smithsonian Tropical Research Institute; University of Hawai’i at Hilo; University of Hawai’i at Hilo hollyjessop@yahoo.com

Sympatric sibling species have the potential to be especially informative regarding processes of speciation in the sea, but they must first be recognized. The sea urchin genus Echinothrix of the Indo-Pacific is currently comprised of two very similar co-existing species which can sometimes be difficult to distinguish, although they do possess some color and morphological differences. Indeed, it has been suggested that a substantial array of subtle physical differences between color morphs is indicative of additional unrecognized Echinothrix species. Furthermore, multiple independent mitochondrial DNA clades are also suggestive of possible cryptic sibling species of Echinothrix. To begin to unify genotype with phenotype in this genus, we have examined the morphology, genetics, and ecological partitioning of Echinothrix specimens from Hawai�i and nearby Kingman Reef. Our data support the hypothesis that sets of physical characteristics distinguishing Hawaiian Echinothrix species are congruent with reciprocally monophyletic mitochondrial DNA clades. However, we find no support for additional genetic divergence beyond the two currently recognized species, and color morphs in Hawai�i are the result of polymorphisms and/or plasticity instead of divergent evolutionary histories. We herein also present preliminary field survey data of interspecific differences in Echinothrix distribution patterns on Hawaiian coral reefs. Our synthesis of morphological, genetic, and ecological investigations provides improved recognition and elucidation of Echinothrix diversity in Hawai�i.