PLEURODELES WALTL AND PLEURODELES POIRETI - CORRELATIONS BETWEEN THEIR IBERIC OR NORTH-AFRICAN ORIGIN AND GENE-B OR GENE-BETA OF PEPTIDASE-1, A SEX-LINKED ENZYME

In Pleurodeles waltl and Pleurodeles poireti, one of the two genes enc oding the peptidase-1, the gene pep-1 beta or its allele pep-1B are lo cated on the chromosomes W and Z respectively. The gene pep-1A is eith er linked to chromosome Z in P. waltl or to chromosome W in P. poireti . From our results concerning sex reversals by heat treatment and from study of the two species in the wild, we propose that the gene pep-1 beta has all African origin, as have P. poireti and some P. waltl, and on the other hand, that its allele pep-1B has an european origin. P. waltl and P. poireti could provide from a reciprocal exchange between the sex chromosomes Z arid W which could have occured in north africa before the pliocene age. So, before the formation of the Gibraltar str ait, some P. waltl could have colonized the north of Africa from what will become iberic peninsula. Because of its isolation, the gene pep-1 B could have evolved to give the allele pep-1 beta.