Genetic Diversity and Erosion—A Global Perspective

Abstract

Biodiversity is continually declining, according to global biodiversityindicators (Butchart et al. in Science 328: 1164-1168, 2010). Populationtrends, habitat extent, habitat condition, and composition of speciescommunities-indicators of the state of diversity-are declining, while atthe same time pressures on biodiversity posed by resource consumption,invasive alien species, pollution, overexploitation, and climate changeare increasing. The rate of current loss of species is reported to be100-1000 times the natural background rate (Chivian and Berstein inSustaining life on earth. How human health depends on biodiversity.Oxford University Press, New York, 2008, Chivian and Berstein in How ourhealth depends on biodiversity. Center for Health and the globalenvironment. Harvard medical school, Boston, 2010; Pimm et al. inScience 344, 2014). Dramatic though that figure is, it underestimatesthe full loss of diversity because it ignores loss at both genetic andpopulation level (Myers in Seeds and sovereignty. The use and control ofplant genetic resources. Duke University Press, Durham, 1988; Mendenhallet al. in Biol Conserv 151: 32-34, 2012). One of the first publicationsalerting the world about the losses of genetic diversity within species,later termed ``genetic erosion,{''} was published in 1914 (Baur in DieBedeutung der primitiven Kulturrassen und der wilden Verwandten unsererKulturpflanzen fuer die Pflanzenzuechtung; Jahrbuch Deutsche Landwirt,1914). The first concern about loss of diversity regarded agriculturallyimportant species, as these are of direct and daily use to people. Onehundred years later, genetic erosion is addressed at the global level ininternational agendas that set targets and propose actions to reduce theloss of genetic diversity, such as the Global Plan of Action (GPA) forPlant Genetic Resources for Food and Agriculture (PGRFA) of the FAOCommission on Genetic Resources for Food and Agriculture (CGRFA) and theAichi biodiversity targets of the Convention on Biodiversity (CBD). Thefact that genetic erosion today is addressed at global level impliesthat the crucial importance of genetic diversity for sustaining life onearth has been recognized. Strategies and actions to reduce the ongoingloss of genetic diversity are now in place. However, these measures havebeen found only partially successful as only few significant reductionsin rates of decline were observed (Butchart et al. in Science 328:11641168, 2010), and global estimates of the extent of genetic erosionare still lacking. This chapter focuses on the importance of geneticdiversity in PGRFA, how diversity of PGRFA is affected by geneticerosion, development of activities undertaken by international bodies toaddress genetic erosion, options to improve knowledge about theunderlying processes that lead to genetic erosion, and the need forsystematic monitoring of genetic diversity to better safeguard,conserve, and use PGRFA.