How far can a gene disperse? Historical and contemporary gene dispersal can be estimated from spatial genetic structure and paternity analysis, and Rong et al. (pp. 285–296) find that an estimate of gene flow in Daucus carota ssp. carota based on contemporary pollen dispersal is much larger than an estimate of historical flow. The results have implications for the ease with which transgene flow might occur from cultivated GM carrots to wild carrot populations.
J. Rong, S. Janson, M. Umehara, M. Ono, K. Vrieling, 2010, 'Historical and contemporary gene dispersal in wild carrot (Daucus carota ssp. carota) populations', Annals of Botany, vol. 106, no. 2, pp. 285-296 http://dx.doi.org/10.1093/aob/mcq108