Ecological selection maintains cytonuclear incompatibilities in hybridizing sunflowers

• Published in: Ecology letters 2008-10, Vol.11 (10), p.1082-1091
• Main Authors: Sambatti, Julianno B.M, Ortiz-Barrientos, Daniel, Baack, Eric J, Rieseberg, Loren H
• Format: Article
• Language: English
• Subjects: Adaptation, Biological - genetics; Analysis of Variance; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Botany; Crosses, Genetic; Cytoplasm; Cytoplasm - genetics; ecological divergence; ecological speciation; Ecology; Ecosystem; Fertility - genetics; Flowers & plants; Fundamental and applied biological sciences. Psychology; General aspects; Genetic Speciation; Genetics, Population; Genome, Plant; Genomics; Genotype; habitat adaptation; Helianthus; Helianthus - genetics; Helianthus annuus; Helianthus petiolaris; Hybridization; Hybridization, Genetic; Models, Genetic; natural selection; Quantitative Trait, Heritable; reciprocal transplant; reproductive isolation; Selection, Genetic; Species Specificity
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/j.1461-0248.2008.01224.x

Despite the recent renaissance in studies of ecological speciation, the connection between ecological selection and the evolution of reproductive isolation remains tenuous. We tested whether habitat adaptation of cytoplasmic genomes contributes to the maintenance of reproductive barriers in hybridizing sunflower species, Helianthus annuus and Helianthus petiolaris. We transplanted genotypes of the parental species, reciprocal F1 hybrids and all eight possible backcross combinations of nuclear and cytoplasmic genomes into the contrasting xeric and mesic habitats of the parental species. Analysis of survivorship across two growing seasons revealed that the parental species' cytoplasms were strongly locally adapted and that cytonuclear interactions (CNIs) significantly affected the fitness and architecture of hybrid plants. A significant fraction of the CNIs have transgenerational effects, perhaps due to divergence in imprinting patterns. Our results suggest a common means by which ecological selection may contribute to speciation and have significant implications for the persistence of hybridizing species.