Present address: Universität Basel, Zoologisches Institut, Evolutionsbiologie, Vesalgasse 1, CH-4051, Basel, Switzerland.
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Range-wide population genetic structure of Symbiodinium associated with the Caribbean Sea fan coral, Gorgonia ventalina
Article first published online: 5 MAY 2011
DOI: 10.1111/j.1365-294X.2011.05115.x
© 2011 Blackwell Publishing Ltd
Additional Information
How to Cite
ANDRAS, J. P., KIRK, N. L. and DREW HARVELL, C. (2011), Range-wide population genetic structure of Symbiodinium associated with the Caribbean Sea fan coral, Gorgonia ventalina. Molecular Ecology, 20: 2525–2542. doi: 10.1111/j.1365-294X.2011.05115.x
Publication History
- Issue published online: 8 JUN 2011
- Article first published online: 5 MAY 2011
- Received 11 November 2010; revision received 11 February 2011; accepted 15 March 2011
Keywords:
- biogeography;
- Caribbean;
- coral;
- Gorgonia ventalina;
- gorgonian;
- population genetics;
- Symbiodinium;
- zooxanthellae
Abstract
Numerous marine invertebrates form endosymbiotic relationships with dinoflagellates of the genus Symbiodinium, yet few studies have examined the population structure of these symbionts. Here, we elucidate the population genetic structure of Symbiodinium harboured by the Caribbean octocoral Gorgonia ventalina throughout the entire range of the host. We used ten microsatellite loci to survey 35 localities spanning 3124 km across the Caribbean and Western Atlantic. Diversity of Symbiodinium haplotypes was low within colonies of G. ventalina but high among colonies. Despite high haplotypic diversity, significant evidence of clonal reproduction in Symbiodinium was detected, and most clones occurred within localities, not among them. Pairwise measures of FST illustrated significant differentiation in 98% of comparisons between localities, suggesting low levels of gene flow. Clustering analyses identified six genetic groups whose distribution delimited four broad biogeographic regions. There was evidence of some connectivity among regions, corresponding with known geographic and oceanographic features. Fine-scale spatial surveys of G. ventalina colonies failed to detect differentiation among Symbiodinium at the metre scale. However, significant differentiation was observed among Symbiodinium hosted by sympatric G. ventalina colonies of different size/age classes. This cohort effect suggests that Symbiodinium may have an epidemic population structure, whereby G. ventalina recruits are infected by the locally predominant symbiont strain(s), which change over time.