title: Eutrophication causes speciation reversal in whitefish adaptive radiations.
abstract: Species diversity can be lost through two different but potentially interacting extinction processes: demographic decline and speciation reversal through introgressive hybridization. To investigate the relative contribution of these processes, we analysed historical and contemporary data of replicate whitefish radiations from 17 pre-alpine European lakes and reconstructed changes in genetic species differentiation through time using historical samples. Here we provide evidence that species diversity evolved in response to ecological opportunity, and that eutrophication, by diminishing this opportunity, has driven extinctions through speciation reversal and demographic decline. Across the radiations, the magnitude of eutrophication explains the pattern of species loss and levels of genetic and functional distinctiveness among remaining species. We argue that extinction by speciation reversal may be more widespread than currently appreciated. Preventing such extinctions will require that conservation efforts not only target existing species but identify and protect the ecological and evolutionary processes that generate and maintain species.
authors.affiliation: Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, CH-3012 Bern, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Vonlanthen
authors.forename: D
authors.initials: D
authors.lastname: Bittner
authors.forename: A G
authors.initials: AG
authors.lastname: Hudson
authors.forename: K A
authors.initials: KA
authors.lastname: Young
authors.forename: R
authors.initials: R
authors.lastname: Müller
authors.forename: B
authors.initials: B
authors.lastname: Lundsgaard-Hansen
authors.forename: D
authors.initials: D
authors.lastname: Roy
authors.forename: S
authors.initials: S
authors.lastname: Di Piazza
authors.forename: C R
authors.initials: CR
authors.lastname: Largiader
authors.forename: O
authors.initials: O
authors.lastname: Seehausen
mesh_terms: D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D005060:Europe; D005068:Eutrophication / Q000502:physiology*; D053476:Extinction, Biological; D049810:Genetic Speciation; D060106:Lakes; D008954:Models, Biological; D010641:Phenotype; D012487:Salmonidae / Q000235:genetics / Q000502:physiology*