title: An ecological approach to measuring the evolutionary consequences of gene flow from crops to wild or weedy relatives.
abstract: OBJECTIVE
  Agricultural practices routinely create opportunities for crops to hybridize with wild relatives, leading to crop gene introgression into wild genomes. Conservationists typically worry this introgression could lead to genetic homogenization of wild populations, over and above the central concern of transgene escape. Alternatively, viewing introgression as analogous to species invasion, we suggest that increased genetic diversity may likewise be an undesirable outcome.
  
  
  METHODS
  Here, we compare the sensitivity of conventional population genetic metrics with species diversity indices as indicators of the impact of gene flow on genetic diversity. We illustrate this novel approach using multilocus genotype data (12 allozyme loci) from 10 wild (Beta vulgaris subsp. maritima) and eight putative crop-wild hybrid beet populations (B. vulgaris subsp. vulgaris × B. vulgaris subsp. maritima) scattered throughout Europe.
  
  
  RESULTS
  Conventional population genetic metrics mostly failed to detect shifts in genetic composition of putative hybrid populations. By contrast, species diversity indices unambiguously revealed increased genetic diversity in putative hybrid populations.
  
  
  CONCLUSIONS
  We encourage other workers to explore the utility of our more sensitive approach for risk assessment prior to the release of transgenic crops, with a view toward widespread adoption of our method in studies aimed at detecting allelic invasion.
authors.affiliation: Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada.
authors.forename: Lesley G
authors.initials: LG
authors.lastname: Campbell
authors.affiliation: Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Lee
authors.affiliation: Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada.
authors.forename: Kruti
authors.initials: K
authors.lastname: Shukla
authors.affiliation: Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, Ohio 43210 USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Waite
authors.affiliation: Abteilung Gentechnik, Bundesamt für Verbraucherschutz und Lebensmittelsicherheit, Mauerstr. 39-42, 10117 Berlin, Germany.
authors.forename: Detlef
authors.initials: D
authors.lastname: Bartsch
keywords: Beta vulgaris; biotic homogenization; crop–wild gene flow; genetic diversity; genetic homogenization; genetically engineered plants; risk assessment