Developing Pressure Indicators for Europe
Edited by Anil Markandya and Nick Dale
Chapter 11: Genetic diversity in agriculture
M. Lefort 1. EROSION OF GENETIC DIVERSITY AND CONSEQUENCES FOR AGRICULTURAL DEVELOPMENT Biological diversity is an essential factor for the maintenance of the living world’s major balances. It is deﬁned by the Convention of Biological Diversity (UNEP, 1992) as ‘the variability among living organisms from all sources including, inter alia, terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are a part; this includes diversity within species, between species and of ecosystems’. In all cases, diversity is considered dynamic, and capable of evolution and adaptation under environmental constraints, thanks to a high variability at the three aforementioned levels. This chapter concentrates particularly on the consequences of a loss of genetic diversity for domestic species, and the short- and medium-term solutions which can be envisaged to reduce the loss. For centuries, animal and plant species have dispersed from their centres of origin (Frankel, 1973; Lauvergne, 1989) and have progressively adapted to highly varied environments (Harlan, 1970). These adaptations have allowed the creation and the expression of an enormous amount of genetic variation through traditional races and cultivars, subjected to very different selection pressures depending on the surroundings and human impact with which they were confronted. These cultivars evolved alongside their wild parents, allowing constant genetic exchange, either directly or via bridging species and spontaneous interspeciﬁc hybrids (Pernès, 1984). This evolutionary dynamic, the basis of peasant agriculture, allowed the long-term maintenance of a large genetic diversity, notably even within populations. More recently, agricultural intensiﬁcation...
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