Journal Article

Getting a grip at the edge: recolonization and introgression in eastern Pacific Porites corals

Forsman, Zac H., Prada, Carlos, Hellberg, Michael E., Tan, Maxine H., Baums, Iliana B.

2016

Overview

Aim: To infer species identity, population isolation, and geographical variation in inter-specific hybridization among corals of the genus Pontes from the central and eastern tropical Pacific, with a focus on the timing of separation between populations of P. evermanni and P. lobata divided by the Eastern Pacific Barrier. Location: Hawaii, American Samoa, Panama and the Galapagos Islands of Ecuador. Methods: Maximum likelihood gene trees were obtained for mitochondrial DNA (COI), the internal transcribed spacer (ITS), and 5 single-copy nuclear (SCN) gene regions. Allelic networks were used to group multi-locus sen data into species clusters despite some alíele sharing. Coalescent analyses (IMa2) of the 5 sen markers were used to estimate the time of population divergence and test for introgression between P. evermanni and P. lobata. Results: Allelic networks based on sen gene sequences agreed with mtCOI and ITS designations. Divergence times between Hawaiian and eastern Pacific populations are consistent with an early Pleistocene recolonization of the eastern Pacific by P. evermanni followed by a more recent arrival of P. lobata. The two species were fully isolated in Hawaii/American Samoa populations, but introgression from P. evermanni into P. lobata was evident in the eastern Pacific. Main conclusions: These results are consistent with a scenario where a bout of introgression with P. evermanni> an early-arriving colonizer of the eastern Pacific suited to marginal environmental conditions, facilitated the later colonization of the more sensitive P. lobata.

• Publisher: Blackwell Publishing Ltd,John Wiley & Sons Ltd,Wiley Subscription Services, Inc
• Subject: alleles / American Samoa / coalescence / coral reef / corals / Eastern Pacific Barrier / Ecuador / Environmental conditions / environmental factors / Galapagos Islands / geographical variation / Hawaii / internal transcribed spacers / interspecific hybridization / introgression / marginal population / Mitochondrial DNA / Panama / phylogeny / Pleistocene / Quantifying biodiversity / Recolonization / transcription (genetics)