title: Environmental (in)dependence of a hybrid zone: Insights from molecular markers and ecological niche modeling in a hybrid zone ofOriganum(Lamiaceae) on the island of Crete.
abstract: The role of environment and the relative significance of endogenous versus exogenous selection in shaping hybrid zones have been crucial issues in the studies of hybridization. Recent advances in ecological niche modeling (ENM) offer new methodological tools, especially in combination with the genotyping of individuals in the hybrid zone. Here, we study the hybrid zone between the widely known spicesOriganum onitesandOriganum vulgaressp.hirtumin Crete. We analyze the genetic structure of both parental taxa and their hybridOriganum×intercendensusing AFLP markers on 15 sympatric and 12 allopatric populations and employ ecological niche modeling and niche similarity tests to study their niche patterns. We complement these analyses with seed viability measurements. Our study revealed that the hybridizing taxaO. onitesandO. vulgaressp.hirtumand the resulting genotypic classes showed geographical and environmental niche similarities based on the predictions of ENMs and the subsequent similarity tests. The occurrence of the hybrid zone is not directly dependent on environmental factors which favor the fitness of the hybrid compared to the parental taxa, but rather on aspects such as historical factors and management practices, which may contribute to the localization and maintenance of the contact zone between parental species. Our results suggest that if a minimum required niche differentiation between genotypic classes is not achieved, environmental dependence might not have a prominent role on the outcome of the hybridization.
authors.affiliation: Department of Biology University of Crete Heraklion Greece.
authors.forename: Michael
authors.initials: M
authors.lastname: Bariotakis
authors.affiliation: Department of Biology University of Crete Heraklion Greece; Present address: Department of Systematic and Evolutionary Botany University of Zürich Zürich Switzerland.
authors.forename: Konstantina
authors.initials: K
authors.lastname: Koutroumpa
authors.affiliation: School of Biology Aristotle University of Thessaloniki Thessaloniki Greece.
authors.forename: Regina
authors.initials: R
authors.lastname: Karousou
authors.affiliation: Department of Biology University of Crete Heraklion Greece; Botanical Garden University of Crete Rethymnon Greece.
authors.forename: Stergios A
authors.initials: SA
authors.lastname: Pirintsos
keywords: Origanum; contact zone; genotypic classes; hybridization; management practices; niche modeling; spices