Genetic diversity and the survival of populations

In this comprehensive review, a range of factors is considered that may inf luence the significance of genetic diversity for the survival of a populati on. Genetic variation is essential for the adaptability of a population in which quantitatively inherited, fitness-related traits are crucial, Therefo re, the relationship between genetic diversity and fitness should be studie d in order to make predictions on the importance of genetic diversity for a specific population. The level of genetic diversity found in a population highly depends on the mating system, the evolutionary history of a species and the population history (the latter is usually unknown), and on the leve l of environmental heterogeneity. An accurate estimation of fitness remains complex, despite the availability of a range of direct and indirect fitnes s parameters. There is no general relationship between genetic diversity an d various fitness components. However, if a lower level of heterozygosity r epresents an increased level of inbreeding, a reduction in fitness can be e xpected. Molecular markers can be used to study adaptability or fitness, pr ovided that they represent a quantitative trait locus (QTL) or are themselv es functional genes involved in these processes. Next to a genetic response of a population to environmental change, phenotypic plasticity in a genoty pe can affect fitness. The relative importance of plasticity to genetic div ersity depends on the species and population under study and on the environ mental conditions. The possibilities for application of current knowledge o n genetic diversity and population survival for the management of natural p opulations are discussed.