Molecular phylogeny of South African abalone, its origin and evolution as revealed by two genes
The marine family Haliotidae (Mollusca: Gastropoda) includes approximately 56 extant abalone species found worldwide. None of these species are globally distributed while four areas of endemism (temperate Australia, South Africa, New Zealand and North Pacific) have been recognized. Phylogenetic relationships of 18 abalone species including five South African species were reconstructed using a combined data set containing sequence data of the mitochondrial NADH-dehydrogenase subunit 1 (ND1) gene and the nuclear hemocyanin gene. The molecular topologies confirmed former findings of two major abalone lineages with Northern and Southern Pacific distribution within the Haliotidae family. The phylogeny revealed all five South African species as a monophyletic group with a sister relationship to the Australian endemics clade. It further suggested a relatively recent radiation of the South African species and places it within the same evolutionary context as the Mediterranean/Atlantic and Australasian clades. Molecular phylogeny also revealed a split within the South African group as well as further speciation within one of the two subclades. Possible place of origin for South African abalone are discussed and ecological specialization, e.g. differential adaptation to environmental conditions, is proposed as the most likely scenario describing divergence within the South African clade. © 2012 Copyright Taylor and Francis Group, LLC.