title: Frequent discordance between morphology and mitochondrial DNA in a species group of European water beetles (Coleoptera: Dytiscidae).
abstract: TheHydroporus memnoniusspecies group includes both widespread and range restricted diving beetle taxa in the western Palaearctic, some of which have been divided into a number of geographical subspecies. Of these,Hydroporus necopinatusis distributed in the far west of Europe, from central Spain to southern Britain, and has been split into three subspecies, occurring in Iberia (necopinatussst.), France (robertorum) and England (roni) respectively-the last of these being a rare example of an insect taxon apparently endemic to northern Europe. Here we explore inter-relationships between populations and subspecies ofH. necopinatusand related members of theHydroporus melanariussubgroup, using mitochondrial COI sequence data. We reveal widespread discordance between mitochondrial DNA sequence variation and morphology in areas whereH. necopinatusandH. melanariuscome into contact, consistent with historical introgressive hybridization between these taxa. In light of this discordance, the lack of clear genetic divergence betweenH. necopinatussubspecies, and the fact that bothrobertorumandroniare morphologically intermediate betweenH. necopinatussstr. andH. melanarius, we suggest that these taxa may be of hybridogenic origin, rather than representing discrete evolutionary lineages.
authors.affiliation: Marine Biology & Ecology Research Centre, University of Plymouth , Plymouth , United Kingdom.
authors.forename: David T
authors.initials: DT
authors.lastname: Bilton
authors.affiliation: Marine Biology & Ecology Research Centre, University of Plymouth , Plymouth , United Kingdom.
authors.forename: Lucy
authors.initials: L
authors.lastname: Turner
authors.affiliation: Aquatic Coleoptera Conservation Trust , Ayr , Scotland.
authors.forename: Garth N
authors.initials: GN
authors.lastname: Foster
keywords: Biogeography; Coleoptera; Dytiscidae; Endemics; Hydroporus; Introgression; Taxonomy; mtDNA