title: Environmental selection is a main driver of divergence in house sparrows (Passer domesticus) in Romania and Bulgaria.
abstract: Both neutral and adaptive evolutionary processes can cause population divergence, but their relative contributions remain unclear. We investigated the roles of these processes in population divergence in house sparrows (Passer domesticus) from Romania and Bulgaria, regions characterized by high landscape heterogeneity compared to Western Europe. We asked whether morphological divergence, complemented with genetic data in this human commensal species, was best explained by environmental variation, geographic distance, or landscape resistance-the effort it takes for an individual to disperse from one location to the other-caused by either natural or anthropogenic barriers. Using generalized dissimilarity modeling, a matrix regression technique that fits biotic beta diversity to both environmental predictors and geographic distance, we found that a small set of climate and vegetation variables explained up to ~30% of the observed divergence, whereas geographic and resistance distances played much lesser roles. Our results are consistent with signals of selection on morphological traits and of isolation by adaptation in genetic markers, suggesting that selection by natural environmental conditions shapes population divergence in house sparrows. Our study thus contributes to a growing body of evidence that adaptive evolution may be a major driver of diversification.
authors.affiliation: Comparative Zoology Institute for Evolution and Ecology University of Tübingen Tübingen Germany.
authors.forename: Julia C
authors.initials: JC
authors.lastname: Geue
authors.affiliation: MTA-DE 'Lendület' Behavioural Ecology Research Group Department of Evolutionary Zoology and Human Biology University of Debrecen Debrecen Hungary; Evolutionary Ecology Group Hungarian Department of Biology and Ecology Babeş-Bolyai University Cluj- Napoca Romania.
authors.forename: Csongor I
authors.initials: CI
authors.lastname: Vágási
authors.affiliation: Animal Physiological Ecology Institute for Evolution and Ecology University of Tübingen Tübingen Germany.
authors.forename: Mona
authors.initials: M
authors.lastname: Schweizer
authors.affiliation: MTA-DE 'Lendület' Behavioural Ecology Research Group Department of Evolutionary Zoology and Human Biology University of Debrecen Debrecen Hungary; Evolutionary Ecology Group Hungarian Department of Biology and Ecology Babeş-Bolyai University Cluj- Napoca Romania.
authors.forename: Péter L
authors.initials: PL
authors.lastname: Pap
authors.affiliation: Comparative Zoology Institute for Evolution and Ecology University of Tübingen Tübingen Germany.
authors.forename: Henri A
authors.initials: HA
authors.lastname: Thomassen
keywords: Eastern Europe; Passer domesticus; evolutionary process; isolation by adaptation; isolation by distance; landscape genetics