This chapter discusses speciation and the factors distinguishing its major modes in sexual plants: allopatric (geographical and peripatric), parapatric and sympatric. The genetic differentiation during speciation and the risk of transgene escape into the environment are described. The role of...

The extent to which transgene flow from plantations can be effectively predicted, managed and monitored will be a critical factor influencing the adoption of transgenic plantations. Studies of historical and contemporary gene flow levels, via genetic structure surveys and parentage analyses,...

Cultivated and wild carrots can hybridize spontaneously, and transgenes may therefore potentially spread from genetically modified carrots into wild populations. This can happen by several different routes. Flowering cultivated carrots may send out pollen to neighbouring populations of wild carrots ...

This contribution is based mainly on ongoing research in an EU Framework 5 research programme. Wheat is a self-compatible, wind-pollinated species whose flowers are often cleistogamous. Crop to crop gene flow is very limited. Field experiments demonstrate that the distance of wheat pollen dispersal ...

Transgenes may be transferred from genetically modified (GM) crops to the wider environment through crosses with compatible wild or weedy relatives. For oilseed rape (Brassica napus), we found extensive transfer of nuclear as well as plastid DNA (cpDNA) to Brassica rapa in an environment with poor...

The level of transgene expression in crop × weed hybrids and the degree to which crop-specific genes are integrated into hybrid populations are important factors in assessing the potential ecological and agricultural risks of gene flow associated with genetic engineering. The average transgene...

Concerns about the introduction of genetically modified crops frequently centre on the possibility of gene transfer to wild relatives, resulting either in the disruption of natural patterns of genetic diversity by introgressing into species gene pools or in the addition of traits which may cause...

The formation of F₁ hybrids between a genetically modified (GM) crop and a wild or weedy relative represents the first of a series of exposure events that could ultimately result in an undesirable change to the environment (hazard). The abundance of hybrids directly influences the dynamics of...