title: Variation in palaeo-shorelines explains contemporary population genetic patterns of rocky shore species.
abstract: Processes driving and maintaining disjunct genetic populations in marine systems are poorly understood, owing to a lack of evidence of hard barriers that could have shaped patterns of extant population structure. Here, we map two genetically divergent lineages of an obligate rocky shore fish, Clinus cottoides, and model sea-level change during the last 110 000 years to provide the first evidence of a vicariant event along the southern coastline of Africa. Results reveal that lowered sea levels during glacial periods drastically reduced rocky intertidal habitat, which may have isolated populations in two refugia for at least 40 000 years. Contemporary coastal dynamics and oceanography explain secondary contact between lineages. This scenario provides an explanation for the origin of population genetic breaks despite a lack of obvious present-day geographical barriers and highlights the need for including palaeo-oceanography in unravelling extant population patterns.
authors: Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag XI, Matieland 7602, South Africa.
authors: Jessica A
authors: JA
authors: Toms
authors: Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa.
authors: John S
authors: JS
authors: Compton
authors: Department of Zoology, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth, South Africa.
authors: Malcolm
authors: M
authors: Smale
authors: Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag XI, Matieland 7602, South Africa svdh@sun.ac.za.
authors: Sophie
authors: S
authors: von der Heyden
mesh_terms: D000818:Animals; D057231:Climate Change; D004272:DNA, Mitochondrial / Q000235:genetics; D017753:Ecosystem; D005828:Genetics, Population; D009792:Oceans and Seas; D010473:Perciformes / Q000235:genetics*; D058974:Phylogeography; D013019:South Africa
chemical_list: D004272:DNA, Mitochondrial
keywords: sea-level change; southern Africa; vicariance