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Résumé :
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The development of electrophoresis applied to enzymes revolutionized population genetics in the early 1970s. Although the theoretical aspects of this field were already largely developed, notably by the Sewall Wright school (1968, 1969), they could hardly be confirmed with experimental data in the absence of numerous and variable genetic markers. Over the past thirty years, results on allozymic polymorphism accumulated by the hundreds, several bibliographic syntheses were compiled for the plant and animal kingdoms (Nevo et al., 1984; Hamrick and Godt, 1989). The advent of molecular markers considerably accelerated the development of population genetics (Powell, 1994). While allozymes pertain only to a relatively uniform family of markers, access at the DNA level has revealed a considerable heterogeneity of the genome with respect to polymorphism (Chapter 1) and the mode of evolution of different genomic regions. Moreover, polymorphism could be analysed in new compartments (chloroplasts, mitochondria) having their own heredity and evolution. The more traditional field of population genetics, the analysis of the genetic structure of natural populations was considerably consolidated as a result of information drawn from new molecular markers. But the availability of new markers, and particularly the access to DNA sequence data permitted not only to open new fields of application, but also to infer more refined conclusions on the history and evolution of populations. Phylogenetics is certainly one field has benefited from the improvement of the DNA marker technology. But the additional comparison of genealogical information with the geographic distribution of species and population (phylogeography) has further permitted to integrate population genetics into a larger historical perspective. It is out of the scope to summarize here the vast applications of molecular markers in population genetics. Rather than making a catalogue of methods used with different markers, we will attempt to use a comparative approach in order to outline their properties as regards to the three major applications in population genetics: diversity, differentiation and gene flow.
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