title: Is hybridization driving the evolution of climatic niche in Alyssum montanum.
abstract: After decades of interest, the contribution of hybridization to ecological diversification remains unclear. Hybridization is a potent source of novelty, but nascent hybrid lineages must overcome reproductive and ecological competition from their parental species. Here, we assess whether hybrid speciation is advantageous over alternative modes of speciation, by comparing the geographical and ecological ranges and climatic niche evolutionary rates of stabilized allopolyploid vs. autopolyploids in the Alyssum montanum species complex.
  
  
  
  We combined an extensive review of studies addressing the systematics and genetic diversity of A. montanum s.l., with flow cytometry and cloning of nuclear markers, to establish the ploidy level and putative hybrid nature of 205 populations. The respective geographic distribution and climatic niche evolution dynamics of the allo- and autopolyploids were investigated using multivariate analyses and comparative phylogenetic approaches.
  
  
  
  As expected by theory, allopolyploids occur mainly along contact zones and are generally spatially overlapping with their diploid counterparts. However, they demonstrate higher rates of niche evolution and expand into different climatic conditions than those of their diploid congeners. In contrast, autopolyploids show lower rates of niche evolution, occupy ecological niches similar to their ancestors and are restricted to less competitive and peripheral geographic areas.
  
  
  
  Hybridization thus seems advantageous by promoting ecological niche evolution and more readily allowing escape from competitive exclusion.
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland Nils.Arrigo@unil.ch.
authors.forename: Nils
authors.initials: N
authors.lastname: Arrigo
authors.affiliation: Unit of Ecology & Evolution, Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland.
authors.forename: Marylaure
authors.initials: M
authors.lastname: de La Harpe
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Glenn
authors.initials: G
authors.lastname: Litsios
authors.affiliation: Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovakia.
authors.forename: Judita
authors.initials: J
authors.lastname: Zozomová-Lihová
authors.affiliation: Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovakia Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-12801 Praha 2, Czech Republic.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Španiel
authors.affiliation: Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovakia Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-12801 Praha 2, Czech Republic.
authors.forename: Karol
authors.initials: K
authors.lastname: Marhold
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, P.O. Box 210088, Tucson, Arizona 85721 USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Barker
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Nadir
authors.initials: N
authors.lastname: Alvarez
mesh_terms: D005075:Biological Evolution; D019607:Brassicaceae / Q000235:genetics*; D002980:Climate; D004171:Diploidy; D004463:Ecology; D014644:Genetic Variation; D005843:Geography; D006824:Hybridization, Genetic; D010802:Phylogeny; D011003:Ploidies
keywords: Brassicaceae; allopolyploidy; autopolyploidy; competition; diversification; ecological novelty; local adaptation; minority cytotype disadvantage; transgressive segregation