Meeting Abstract

S3.5  Tuesday, Jan. 4  Diversification of sympatric broadcast-spawning limpets (Cellana spp.) within the Hawaiian archipelago BIRD, C E*; HOLLAND, B S; BOWEN, B W; TOONEN, R J; University of Hawai’i at Manoa cbird@hawaii.edu

Speciation remains a central enigma in biology, and nowhere is this more apparent than in shallow tropical seas where biodiversity rivals or exceeds that of tropical rainforests. Obvious barriers to gene flow are few, most marine species have a highly dispersive larval stage, and these circumstances greatly reduce opportunities for geographic isolation and speciation. Hawaiian biodiversity includes many spectacular radiations in the terrestrial realm where opportunities for geographic isolation abound. In contrast, marine colonizers are believed to not diversify and produce a single endemic species or population. Here we examine the evolutionary origin of three endemic Hawaiian limpets (Cellana exarata, C. sandwicensis, and C. talcosa), and formally test the assertion that marine species do not diversify within the archipelago. Analysis of three mtDNA (12S, 16S, COI; 1565 bp) and two nDNA sequences (ATPSb, H3; 709 bp) demonstrates that the Hawaiian limpets (N=414) are monophyletic sister species. There is substantial reproductive isolation among the species, but mitochondrial introgression is evident and one F1 hybrid was sampled. The archipelago was colonized approximately 5.1 (3.4-7.2) Mya from the West Pacific (vicinity of Japan) by a single limpet species which subsequently radiated into three endemic species – the first insular broadcast-spawning lineage known to do so world-wide. The species are partitioned along the well-known vertical environmental gradients on basaltic intertidal shores, a strong suggestion of ecological influence on their diversification. Inhabiting the high shore is an ancestral character, indicating that the high shore was colonized initially, followed by diversification as the lower shore regions were invaded – a potential case of sympatric speciation.