Refuge areas and suture zones in the Pyrenean and Cantabrian regions: geographic variation of the female MPI sex-linked alleles among oviparous populations of the lizard Lacerta (Zootoca) vivipara

The viviparous lizard Lacerta (Zootoca) vivipara exhibits several alleles o f the mannose-6-phosphate isomerase (MPI) enzyme that are carried exclusive ly on the female W sex-chromosome. Previous studies showed that both the ov iparous and viviparous Forms of L. (Zootoca) vivipara have these female sex -linked alleles. We document the existence of geographic variation of these alleles among the oviparous populations of southwestern France and northwe stern Spain. Two oviparous sub-groups were identified: all females from the eastern and central Pyrenees and most Females from Aquitaine and from the northern slope of the western Pyrenees exhibited the fast migrating alleles MPI110 Or MPI120 whereas all females from the Cantabric mountains, Spanish Basque country, and from the south slope of the western Pyrenees exhibited the slow migrating allele MPI90. Populations with both fast and slow migra ting alleles occurred at some stations in the upper Ossau valley (western P yrenees) and also at a lowland station of south Aquitaine. The hypothesis t hat several oviparous forms could have retreated to different places of the Pyreneo-Iberian refugia during the Quaternary glaciations could explain th e conservation or the evolution of the polymorphism of the MPI alleles, and that is consistent with the phylogeographic scenario previously proposed t o account for the reproductive and cytogenetical variation observed in this species.