Landscape gene flow, coexistence and threshold effect: The case of genetically modified herbicide tolerant oilseed rape (Brassica napus)

M. Graziano Ceddia, Mark Bartlett, Charles Perrings

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Globally there have been a number of concerns about the development of genetically modified crops many of which relate to the implications of gene flow at various levels. In Europe these concerns have led the European Union (EU) to promote the concept of 'coexistence' to allow the freedom to plant conventional and genetically modified (GM) varieties but to minimise the presence of transgenic material within conventional crops. Should a premium for non-GM varieties emerge on the market, the presence of transgenes would generate a 'negative externality' to conventional growers. The establishment of maximum tolerance level for the adventitious presence of GM material in conventional crops produces a threshold effect in the external costs. The existing literature suggests that apart from the biological characteristics of the plant under consideration (e.g. self-pollination rates, entomophilous species, anemophilous species, etc.), gene flow at the landscape level is affected by the relative size of the source and sink populations and the spatial arrangement of the fields in the landscape. In this paper, we take genetically modified herbicide tolerant oilseed rape (GM HT OSR) as a model crop. Starting from an individual pollen dispersal function, we develop a spatially explicit numerical model in order to assess the effect of the size of the source/sink populations and the degree of spatial aggregation on the extent of gene flow into conventional OSR varieties under two alternative settings. We find that when the transgene presence in conventional produce is detected at the field level, the external cost will increase with the size of the source area and with the level of spatial disaggregation. On the other hand when the transgene presence is averaged among all conventional fields in the landscape (e.g. because of grain mixing before detection), the external cost will only depend on the relative size of the source area. The model could readily be incorporated into an economic evaluation of policies to regulate adoption of GM HT OSR.

Original languageEnglish (US)
Pages (from-to)169-180
Number of pages12
JournalEcological Modelling
Volume205
Issue number1-2
DOIs
StatePublished - Jul 10 2007

Fingerprint

Brassica napus
coexistence
transgenes
gene flow
herbicide
herbicides
crop
crops
pollen flow
plant characteristics
self-pollination
crop models
economic analysis
European Union
biological characteristics
growers
autogamy
cost
genetically modified organisms
markets

Keywords

  • Coexistence
  • Gene flow
  • Oilseed rape (B. napus)
  • Spatial aggregation
  • Threshold effect

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecological Modeling
  • Ecology

Cite this

Landscape gene flow, coexistence and threshold effect : The case of genetically modified herbicide tolerant oilseed rape (Brassica napus). / Ceddia, M. Graziano; Bartlett, Mark; Perrings, Charles.

In: Ecological Modelling, Vol. 205, No. 1-2, 10.07.2007, p. 169-180.

Research output: Contribution to journalArticle

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