02151nas a2200241   4500008004100000020001400041245006200055210006100117300001200178520145400190653001601644653001601660653002201676653002301698653002201721653002001743653001801763100002001781700002301801700002001824700002101844856004401865       2012                        eng d  a1365-294X00aFine-scale environmental control of hybridization in oaks0 aFinescale environmental control of hybridization in oaks  an/a-n/a3 aNatural hybridization is attracting much interest in modern speciation and conservation biology studies, but the underlying mechanisms remain poorly understood. In particular, it is unclear why environmental changes often increase hybridization rates. To study this question, we surveyed mating events in a mixed oak stand and developed a spatially explicit individual-based hybridization model. This model, where hybridization is frequency-dependent, pollen is nonlimiting and which allows immigrant pollen to compete with local pollen, takes into account species-specific pollen dispersal and sexual barriers to hybridization. The consequences of pollen limitation on hybridization were studied using another simple model. The results indicate that environmental changes could increase hybridization rates through two distinct mechanisms. First, by disrupting the spatial organization of communities, they should decrease the proportion of conspecific pollen available for mating, thus increasing hybridization rates. Second, by decreasing the density of conspecifics, they should increase pollen limitation and thus hybridization rates, as a consequence of chance pollination predominating over deterministic pollen competition. Altogether, our results point to a need for considering hybridization events at the appropriate level of organization and provide new insights into why hybridization rates generally increase in disturbed environments.10adisturbance10aimmigration10amass action model10apaternity analysis10apollen limitation10aQuercus petraea10aQuercus robur1 aLagache, Lélia1 aKlein, Etienne, K.1 aGuichoux, Erwan1 aPetit, Rémy, J.  uhttps://quercus.myspecies.info/node/147