Ling Ming Tsang and Benny Kwok Kan Chan contributed equally to this work.
Host-associated speciation in the coral barnacle Wanella milleporae (Cirripedia: Pyrgomatidae) inhabiting the Millepora coral
Article first published online: 27 FEB 2009
© 2009 Blackwell Publishing Ltd
Volume 18, Issue 7, pages 1463–1475, April 2009
How to Cite
TSANG, L. M., CHAN, B. K. K., SHIH, F.-L., CHU, K. H. and ALLEN CHEN, C. (2009), Host-associated speciation in the coral barnacle Wanella milleporae (Cirripedia: Pyrgomatidae) inhabiting the Millepora coral. Molecular Ecology, 18: 1463–1475. doi: 10.1111/j.1365-294X.2009.04090.x
- Issue published online: 19 MAR 2009
- Article first published online: 27 FEB 2009
- Received 11 August 2008; revision revised 11 December 2008; accepted 15 December 2008
- coral reef;
- cryptic species;
- ecological speciation;
- fire coral;
- sympatric speciation
Speciation by host shift is a common phenomenon observed in many symbiotic animals. The symbiont–host interaction is highly dynamic, but it is poorly documented in the marine realm. In the present study, we examined the genetic and morphological differentiation of the coral barnacle Wanella milleporae (obligate to fire corals) collected from four different Millepora host species in Taiwan to investigate the host specificity of this barnacle. Phylogenetic analysis of mitochondrial COI gene for 241 individuals of Wanella revealed five distinct clades, whose sequence divergences are comparable to values between other cogeneric barnacle species. The five clades also differ in shell and opercular plate morphology and colour. Genetic and morphological differentiations together strongly suggest the presence of cryptic species. Although the five clades do not display species-level host specificity, they showed a significant difference in preference on host growth form. Clades 1 and 2 were predominantly found on encrusting Millepora exaesa and Millepora platyphylla, while clades 3, 4 and 5 live exclusively on branching-form fire corals Millepora dichotoma and Millepora tenella. Phylogeny inferred from the combined mitochondrial COI, 16S and 12S (2182 bp) analysis suggests the division of the five clades into two major lineages congruent with the morphology of the host coral. Multiple independent invasions to the same form of host and subsequent speciation are evident in the Red Sea and Taiwan. Our results indicate that ecological/sympatric speciation could occur in marine symbiotic invertebrates through host shift and specialization. It appears that, as in their terrestrial counterparts, host–symbiont radiations in the marine realm are more prevalent than we expected and thus warrant further investigation.