Genetic diversity
Genetic diversity refers to the variety and variability within and between species. It can refer to the naturally occurring genetic variability within and between populations of a species, for example wild relatives of food crops, or to the variability created by humans, for example farmer-developed traditional crop varieties called landraces, or commercially bred varieties of a crop (e.g. different apple varieties: Fuji, Golden Delicious, Golden Pippin, etc.). There is considerable genetic diversity within all food crop species, particularly in centres of origin, which are the geographical areas where species were originally developed. For example, the Andean region of Peru is a centre of origin for certain tuber species, and over 1,483 varieties of these species can be found there. Genetic diversity is important as different genes give rise to important traits, such as nutrient composition, hardiness to different environments, resistance to pests, or ample harvests. Genetic diversity is decreasing due to agricultural modernization, changing land use and climate change, among other factors. (It is even possible that breeding narrowly for the pest- and disease-resistance necessary to deal with climate change will, itself, reduce agrobiodiversity.) Genetic diversity is not static but is constantly evolving in response to changes in the environment and according to human intervention, whether farmers or breeders.