Abstract
p ]Genetic erosion occurs as a result of disruption of the natural habitat by humankind or through the replacement of traditional landraces or ecotypes by modern cultivars. It may occur because of a decline in a species’ diversity through the reduction of its geographical distribution or through the complete loss of a species. Within a species a decline in genetic diversity is caused by the loss of genetic information through the reduction of its distribution and population size. Comparison of the current geographical distribution of a species with its past distribution can be used to assess the degree of genetic erosion that has occurred. Quantified assessment of genetic erosion is possible using species diversity indices and measures of genetic diversity.
Although there is some evidence of genetic erosion in pasture and forage legumes of the Mediterranean, it is only circumstantial. Much of this evidence is from observations of loss of habitats to development and intensification of agriculture, and in particular, the increase of grazing pressure in many areas where it has been equated with a reduction in the distribution of species. There is an urgent need to quantify the extent of genetic erosion in the Mediterranean more accurately by determining a baseline of the original species distributions in the region and precisely defining the current distribution of species. Genetic diversity of older original collections of species should be quantified and compared with that of current natural populations to determine if there has been a reduction in the genetic diversity of natural populations.
Pasture and forage species within a genus have different ecological niches, and as such are not interchangeable. Increasing genetic erosion may result in the loss of species or genes that may have potential in Mediterranean agricultural systems, or could be useful in extending the geographical range of a species currently used in agriculture.
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Robertson, L.D., Bounejmate, M. (1999). Genetic erosion of pasture and forage legumes in the Mediterranean basin. In: Bennett, S.J., Cocks, P.S. (eds) Genetic Resources of Mediterranean Pasture and Forage Legumes. Current Plant Science and Biotechnology in Agriculture, vol 33. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-4776-7_6
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