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Genetics Section

Campbell, Lesley G. [2], Waite, Thomas A. [2], Bartsch, Detlef [1].

Impacts of crop-to-wild gene flow: beyond conventional metrics of genetic diversity.

Agricultural practices routinely increase interactions between crops and their wild relatives, often resulting in hybridization. Such introgression of crop genes into a wild plant genome is of particular concern when the wild species is of conservation interest. Crop-to-wild gene flow is generally high when wild populations are small and the typical concern is that high rates of introgression may decrease or homogenize the genetic diversity of wild populations, as measured using conventional population genetics metrics. Here, we address another potentially undesirable outcome, namely that genetic diversity is increased or made more heterogeneous by introgression. Crop-to-wild gene flow is analogous to species invasion into an ecological community, so we use species diversity indices (Shannon-Weiner’s H, Simpson’s D and McIntosh’s E) to measure the impact of introgression of crop alleles on genetic diversity. We illustrate this approach using multi-locus genotype data on wild (Beta vulgaris ssp. maritima) and crop-wild hybrid beet populations (B. v. ssp. maritima x vulgaris) scattered throughout Europe (Bartsch et al. 1999). Each hybrid population was located near one of three types of crop populations – sugar beet, table beet or swiss chard. We asked whether genetic diversity of hybrid populations was affected by the introgression of crop alleles. We used allozyme data from 12 loci across 10 wild and 8 hybrid beet populations to estimate changes in diversity following introgression. Conventional population genetics metrics were generally unable to detect any changes in genetic diversity. However, our locus-by-locus analysis revealed that genetic diversity, as estimated by species diversity indices, was usually greater within hybrid than wild populations. We encourage other workers to use species diversity indices where the goal is to measure the impacts of allelic invasion on wild populations.

1 - Aachen University of Technology – RWTH, Ecology, Ecochemistry, and Ecotoxicology, Aachen, D-52056, Germany
2 - Ohio State University, Depatment of Evolution, Ecology and Organismal Biology, 318 W. 12th Ave., Columbus, Ohio, 43210-4321, United States

Beta vulgaris
Species diversity indices
genetic diversity
crop-to-wild gene flow.

Presentation Type: Paper
Session: 53-15
Location: Peruvian (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 4:45 PM
Abstract ID:292

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