|Title||Getting a grip at the edge: recolonization and introgression in eastern Pacific Porites corals|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Hellberg M.E, Prada C., Tan M.H, Forsman Z.H, Baums I.B|
|Journal||Journal of Biogeography|
|Type of Article||Article|
|Keywords||coalescence; coral reef; divergence; Eastern Pacific Barrier; evolutionary history; gene flow; geographic-distribution; hybridization; introgression; marginal population; phylogenetic analysis; pleistocene; pocillopora corals; population; reef fishes; tropical pacific|
Aim To infer species identity, population isolation, and geographical variation in inter-specific hybridization among corals of the genus Porites 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 scn data into species clusters despite some allele sharing. Coalescent analyses (IMa2) of the 5 scn 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 scn 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.