title: Quantifying temporal isolation: a modelling approach assessing the effect of flowering time differences on crop-to-weed pollen flow in sunflower.
abstract: Flowering time divergence can be a crucial component of reproductive isolation between sympatric populations, but few studies have quantified its actual contribution to the reduction of gene flow. In this study, we aimed at estimating pollen-mediated gene flow between cultivated sunflower and a weedy conspecific sunflower population growing in the same field and at quantifying, how it is affected by the weeds' flowering time. For that purpose, we extended an existing mating model by including a temporal distance (i.e. flowering time difference between potential parents) effect on mating probabilities. Using phenological and genotypic data gathered on the crop and on a sample of the weedy population and its offspring, we estimated an average hybridization rate of approximately 10%. This rate varied strongly from 30% on average for weeds flowering at the crop flowering peak to 0% when the crop finished flowering and was affected by the local density of weeds. Our result also suggested the occurrence of other factors limiting crop-to-weed gene flow. This level of gene flow and its dependence on flowering time might influence the evolutionary fate of weedy sunflower populations sympatric to their crop relative.
authors: INRA, UMR 1334, Amélioration Génétique et Adaptation des Plantes méditerranéennes et tropicales (AGAP) Montpellier Cedex 1, France ; ETH Zurich, Institute of Integrative Biology (IBZ) Zurich, Switzerland.
authors: Marie
authors: M
authors: Roumet
authors: INRA, UMR 1334, Amélioration Génétique et Adaptation des Plantes méditerranéennes et tropicales (AGAP) Montpellier Cedex 1, France.
authors: Adeline
authors: A
authors: Cayre
authors: INRA, UMR 1334, Amélioration Génétique et Adaptation des Plantes méditerranéennes et tropicales (AGAP) Montpellier Cedex 1, France.
authors: Muriel
authors: M
authors: Latreille
authors: INRA, UMR 1334, Amélioration Génétique et Adaptation des Plantes méditerranéennes et tropicales (AGAP) Montpellier Cedex 1, France.
authors: Marie-Hélène
authors: MH
authors: Muller
keywords: crop-to-weed gene flow; paternity analysis; phenology; pollen dispersal; sunflower (Helianthus annuus); temporal isolation