Touria Benazzou

Hybridation naturelle entre deux espèces sympatriques de souris Mus musculus domesticus L. et Mus spretus Lataste

Using protein loci and DNA markers, we show by a multilocus genetic analysis that certain populations of the two sympatric mouse species Mus musculus domesticus and Mus spretus show clear signs of partial introgression. Given the sterility of F1 males and the known partial genetic incompatibilities between the genomes of the two species, our finding does not invalidate the biological species complex, but allows to think that very limited genetic exchanges remain possible even long after the divergence of taxa. This may have some consequences on the dynamics of certain kinds of invasive or advantageous DNAs like transposable elements or pathogen resistance genes.

Phylogeography of the North African dipodil (Rodentia: Muridae) based on cytochrome-b sequences

Abstract The present study aims to depict the overall pattern of the history of the North African dipodil, Gerbillus campestris, in the northern Sahara. More specifically we document whether or not Pleistocene refugia, the Sahara desert, and the Moulouya River structure patterns of diversity in this species. The phylogenetic relationships among populations were determined by analyses of the cytochrome-b gene in 100 specimens collected in 5 countries (Morocco, Algeria, Tunisia, Mali, and Niger) and 27 localities. Our study highlights a complex phylogeographic pattern for G. campestris in North Africa, with 9 phylogenetic lineages differing by up to 2.5% of sequence divergence. Most of these lineages are allopatric, except in Morocco where 2 lineages are overlapping in the south. These genetic lineages probably arose during the successive cycles of cooling and warming climatic conditions that characterized the end of the Pleistocene, caused by the combined effects of habitat changes and marine transgressions. The divergence between Saharan and Moroccan populations occurred during a period of aridification at the end of the Pleistocene. The Moulouya and the Bou Regreg rivers also seem to be major biogeographical barriers to gene flow in this species.

Genetic differentiation of European anchovy (Engraulis encrasicolus) along the Moroccan coast reveals a phylogeographic break around the 25th parallel North

ABSTRACT Seven microsatellite markers were used to investigate the population structure of the offshore ecotype of the European anchovy (Engraulis encrasicolus) by comparing 12 marine samples collected off the Moroccan coast with an inshore sample taken as a reference for the lagoonal ecotype. F-statistics, correspondence analysis and Bayesian assignment all concurred to cluster the European anchovy in this region into three groups: (i) one reference lagoonal sample, (ii) samples north of the 25°N latitude and (iii) samples south of it. Moreover, the Bayesian cluster analysis pointed toward the existence of an admixture between the group north of 25°N and the lagoonal ecotype, while this was not detectable with the group south of 25°N. Differential introgression between the two ecotypes could be one of the plausible explanations for the observed genetic structure and reveals the possible existence of a phylogeographic break around the 25th parallel North. Our study illustrates the fact that, for those species that encompass several incompletely isolated ecotypes, the level of gene flow among them may vary in space and serve as a tool for stock identification. This information may be useful to improve fishery management of this important harvested species along the Moroccan coast.