Eco‐genetic additivity of diploids in allopolyploid wild wheats

• Published in: Ecology letters 2020-04, Vol.23 (4), p.663-673
• Main Authors: Huynh, Stella, Broennimann, Olivier, Guisan, Antoine, Felber, François, Parisod, Christian, Coulson, Tim
• Format: Article
• Language: English
• Subjects: Aegilops; amplicon sequencing; Biological evolution; climate change; comparative niche modelling; comparative phylogeography; Diploids; Diploidy; Divergence; Ecological niches; Ecosystem; Environmental changes; Genetic diversity; Genomes; Geographical distribution; Humans; Hybrids; niche conservatism; Niches; Phylogeography; polyploid speciation; Polyploidy; range filling; Speciation; Species; species expansion; Triticum
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/ele.13466

Underpinnings of the distribution of allopolyploid species (hybrids with duplicated genome) along spatial and ecological gradients are elusive. As allopolyploid speciation combines the range of genetic and ecological characteristics of divergent diploids, allopolyploids initially show their additivity and are predicted to evolve differentiated ecological niches to establish in face of their competition. Here, we use four diploid wild wheats that differentially combined into four independent allopolyploid species to test for such additivity and assess the impact of ecological constraints on species ranges. Divergent genetic variation from diploids being fixed in heterozygote allopolyploids supports their genetic additivity. Spatial integration of comparative phylogeography and modelling of climatic niches supports ecological additivity of locally adapted diploid progenitors into allopolyploid species which subsequently colonised wide ranges. Allopolyploids fill suitable range to a larger extent than diploids and conservative evolution following the combination of divergent species appears to support their expansion under environmental changes. We compare genetic variation and climatic niches across distribution ranges of wild wheat species to show that additivity of differentially adapted diploids is sufficient to promote allopolyploid species that largely fill suitable space under environmental changes.