Reconciling gene trees with organism history: the mtDNA phylogeography of three Nesotes species (Coleoptera : Tenebrionidae) on the western Canary Islands

The processes of island colonization and speciation are investigated throug h mtDNA studies on Canary Island beetles. The genus Nesotes (Coleoptera: Te nebrionidae) is represented by 19 endemic species on the Canary Islands, th e majority of which are single island endemics. Nesotes conformis is the mo st widespread, occurring on Gran Canaria, Tenerife, La Palma and El Hierro. Nesotes conformis forms a paraphyletic assemblage, with a split between Gr an Canaria and the other three islands. Nesotes conformis of the western Ca nary Islands cluster with Nesotes altivagans and Nesotes elliptipennis from Tenerife. Fifty-two individuals from this western islands species complex have been sequenced for 675 base pairs of the mtDNA cytochrome oxidase II g ene, representing Tenerife, La Palma and El Hierro. A neighbour joining ana lysis of maximum likelihood distances resulted in three distinct mtDNA line ages for N. conformis, two of which also include mitotypes of N. altivagans and N. elliptipennis. Through application of parametric bootstrap tests, w e are able to reject hypotheses of monophyly for both N. conformis and N. a ltivagans. Nesotes altivagans and N. elliptipennis are poorly separated mor phologically and mtDNA sequence data adds support to this being one species with a highly variable morphology. We propose that N. altivagans/N. ellipt ipennis is recently derived from two ancestral mtDNA lineages within N. con formis from the Teno region of Tenerife. We further propose colonization of the younger islands of La Palma and El Hierro by N. conformis from a mitoc hondrial lineage within the Teno massif (colonization; diversification; mit ochondrial DNA; Canary Islands; Coleoptera).