Genetic diversity and interdependent crop choices in agriculture

https://doi.org/10.1016/j.reseneeco.2003.11.006Get rights and content

Abstract

The extent of genetic diversity in food crops is important as it affects the risk of attack by pathogens. A drop in diversity increases this risk. Farmers may not take this into account when making crop choices, leading to what from a social perspective is an inadequate level of diversity.

Section snippets

Trends in genetic diversity in agriculture

Are we deploying sufficient genetic diversity in agriculture? The level of genetic diversity that characterizes commercially important crops and animals is a matter of considerable concern, as it is generally agreed that access to genetic diversity has been and remains important in maintaining and increasing agricultural productivity. There are economic and epidemiological reasons to believe that the varietal choices made by farmers may lead to less genetic diversity in agriculture than is

The role of genetic diversity

What is at stake in this discussion? The key point is that a loss of genetic diversity may lead to significant risks for food supplies. A pathogen that attacks the predominant commercial variety of a food crop can inflict immense costs on society. The classic example of this is the Irish potato famine of the 19th century. More recently, the loss of a significant fraction of the Asian rice crop to the grassy stunt virus2 illustrates the same point—the extreme vulnerability of a

Genetic diversity and risk management

In growing food, as in many other areas, society faces a risk–return trade off. It can enhance the productivity and average yield of food crops at the cost of greater risk, measured by a higher standard deviation of their yields. One illustration of this is the use of crops well adapted to particular weather patterns. If a suitable weather pattern materializes these can give yields greatly in excess of more generic crops, but if the weather pattern that is realized is not that to which they are

Policy responses

The existence of external effects between farmers implies that the overall allocation of risks in society, and indeed the overall allocation of resources, will be inefficient. The analysis of Nash equilibria above indicates that under a range of parameter values farmers will make identical choices of variety and will select too little diversity. To achieve efficiency we would need to face each farmer with a cost that indicates the extent of the external effect that he is imposing on others by

Conclusions

In summary, genetic diversity in agriculture is important. Its lack can increase social vulnerability to pathogens and increase the risks that we face with our food supplies. Genetic diversity in agricultural systems is changing, and there has been a decline in traditional crop varieties and in breeds and varieties of animals. This may be associated with growing international trade in foods and in seeds. There is now perhaps an increase in the diversity of new genes included in new varieties,

References (17)

  • M. Smale

    The green revolution and wheat genetic diversity: some unfounded assumptions

    World Development

    (1997)
  • M.R. Bellon

    The dynamics of crop intraspecific diversity: a conceptual framework at the farmer level

    Economic Botany

    (1996)
  • Browning, J.A., 1988. Current thinking on the use of diversity to buffer small grains against highly epidemic and...
  • Bush, S.B. (Ed.), 2000. Genes in the Field: On-Farm Conservation of Crop Diversity. Lewis,...
  • Committee on Agriculture Science and Technology, 2003. Benefits of...
  • Ehrlich, P., Ehrlich, A., 1982. Ecoscience: preserving genetic diversity. Seed banks. Mother Earth News,...
  • K. Hammer et al.

    Estimating genetic erosion in landraces—two case studies

    Genetic Resources and Crop Production

    (1996)
  • Heal, G., Kunreuther, H., 2002. You Only Die Once: Managing Discrete Interdependent Risks. Columbia Business...
There are more references available in the full text version of this article.

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This paper was drafted at the Beijer Institute Workshop at Asko in September 2000.

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