title: The origin of finches on Tristan da Cunha and Gough Island, central South Atlantic ocean.
abstract: The Nesospiza finches of the Tristan da Cunha archipelago and Rowettia goughensis from Gough Island, 380 km distant, are both derived from tanager-finches (Thraupidae) that colonized the islands by crossing more than 3000 km of ocean from South America. Sequences from two mitochondrial and four nuclear genes indicate that the Patagonian bridled finches Melanodera are the closest relatives of the South Atlantic finches. Melanodera typically was sister to Rowettia, although some genes linked it more closely to Nesospiza. There was no evidence that Rowettia and Nesospiza are sister taxa, suggesting that the South Atlantic finches evolved from separate colonization events, as apparently was the case for moorhens Gallinula spp. at the two island groups. Genetic divergence between the two island finch genera thus provides an estimate of the maximum period of time they have been present at the islands, some 3-5 million years. A brief review of colonization histories suggests that island hopping by passerine birds is infrequent among islands more than 100-200 km apart.
authors.affiliation: Percy FitzPatrick Institute, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa. pryan31@gmail.com
authors.forename: Peter G
authors.initials: PG
authors.lastname: Ryan
authors.forename: Luke B
authors.initials: LB
authors.lastname: Klicka
authors.forename: Keith F
authors.initials: KF
authors.lastname: Barker
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Burns
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001267:Atlantic Ocean; D002467:Cell Nucleus / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000145:classification* / Q000235:genetics; D005260:Female; D046369:Finches / Q000145:classification* / Q000235:genetics; D049810:Genetic Speciation; D062312:Islands; D008297:Male; D010802:Phylogeny; D058974:Phylogeography; D017422:Sequence Analysis, DNA; D013997:Time Factors
chemical_list: D004272:DNA, Mitochondrial
keywords: Colonization; Island hopping; Melanodera; Nesospiza; Rowettia; Speciation