MEPS 468:203-215 (2012)  -  DOI: https://doi.org/10.3354/meps09956

ABSTRACT: To enhance our current understanding of the evolution of intertidal marine species, we investigated the phylogeographic population structure of the Cape sea urchin Parechinus angulosus using cytochrome c oxidase subunit I (COI) mitochondrial and receptor for egg jelly protein 9 (SpREJ9) nuclear DNA (nDNA) sequence data. The species shows variation in colour form, has a wide distribution along the southern African coastline, a broadcast mode of reproduction and probably a fairly long post larval development. Despite the prediction that species with such life history traits will show shallow genetic differentiation among sampling sites, high levels of population differentiation were obtained among many of the 18 sampling localities. The trend was particularly strong along the west coast Namaqua biogeographic province of southern Africa where the structure was also correlated with local upwelling. Larval dispersal broadly corresponded with oceanic currents and 2 distinct geographic genetic groupings were detected. The first grouping represents most individuals sampled along the cool temperate west coast, while the second comprises individuals sampled from the south and east coasts of southern Africa. The genetic separation of P. angulosus individuals is in the vicinity of a recognized biogeographic barrier (Cape Point), and is supported by geneflow analyses, parsimony haplotype networks for both nDNA and mtDNA data, and a mtDNA Bayesian analyses of population structure. Expansion events for the Cape sea urchin, and the divergence time estimates between the 2 assemblages, centre around the last glacial maximum and provide substantial support that glaciations and associated lowering and rising of sea levels significantly affected marine rocky shore organisms along the southern African coastline.

KEY WORDS: Southern Africa · Echinodermata · Phylogeography · Geneflow · Sea-level change · SpREJ · mtDNA COI