Evaluation of genetic diversity and its use in conservation programmes

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Intraspecific variation is the requirement for evolution and adaptation of a species to new conditions, since it offers the possibility of different responses to selective forces. The quantification of variability is then highly desirable. For assessing variability, several approaches have been used. Phenotypic characters are easily recordable, but show a strong environmental influence and their genetic control is unclear. Molecular markers allow the direct study of genetic material variation but usually traits without phenotypic value are recorded. Two types of variation can be distinguished: Neutral variability, those traits not influenced by selective forces, and adaptive variation, features with selective value. Neutral genetic diversity is estimated mainly by molecular markers. In the last years several techniques have been developed to study both proteins (products of genes) or DNA (hereditary material). A review of the most commonly used techniques is offered, as well as their main applications. The classic method for the study of adaptive variation are provenance/progeny trials, in which levels of variation and the amount corresponding to genetic variabiltiy are analyzed. The basis is to test different genotypes in the same site, in order to minimize the environmental variation. The knowledge of diversity is a prerrequisite in any conservation programm. It is a component of biodiversity that must be preserved, but, also, it is a useful tool for many aspects, specially for determining what processes are involved in the genetic structure of the target species.