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Genetic structure of avian populations — allozymes revisited


  • P.-A. Crochet

    Corresponding author
    1. Centre d’Ecologie Fonctionnelle et Evolutive, CNRS 1919 route de Mende, F-34293 Montpellier cedex 5, France; Laboratoire Génome, Populations, Interactions, CNRS UPR 9060 — Université de Montpellier 2, Place E. Bataillon, 34095 Montpellier cedex 5 France; Station Biologique de la Tour du Valat, Le Sambuc, 13200 Arles, France.
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Pierre-André Crochet. Present address: Department of Animal Ecology, EBC, Norbyvägen 18D, 752 36 Uppsala, Sweden. Fax: +46 18 471 6484; E-mail:


Selection on allozymes has sometimes been advanced as one explanation for the low levels of population differentiation detected in avian populations by the use of enzymatic markers. Comparisons of the amount of population subdivision (estimated by FST values or analogous indices) measured by enzymatic and mitochondrial DNA (mtDNA) markers in birds were seen as evidence for this because mtDNA typically produces a more structured picture of population subdivisions. In fact, when taking into account the smaller effective population size of mtDNA, nuclear and mitochondrial markers give concordant results. Some discrepancies still exist, but I suggest that some might originate from different amounts of nuclear vs. mitochondrial gene flow due to partial reproductive isolation. Variable number of tandem repeat (VNTR) loci do not provide a dramatically different picture of population structures in birds compared to allozymes. Although more tests are needed, such as comparing the amount of genetic structure detected in the same populations with allozymes and microsatellites, the low levels of population subdivision measured with allozymes in birds seem to reflect historical and demographic processes and would not appear to result from any peculiarities of bird enzymatic loci.