Résumé
Examples of massive mitochondrial introgressions combined with no or very limited nuclear introgressions (i.e. mito-nuclear discordance) are accumulating, stimulating the development of various hypotheses to explain this pattern. On the one hand, selective hypotheses propose a selective advantage of the introgressing mitochondrial variants, or counter-selection of the nuclear genome; On the other hand, neutral hypotheses invoke sex-biased processes and/or drift and/or spatial invasions. The neutral hypotheses however are mostly verbal and have not been quantitatively evaluated. Here we reassess all these hypotheses using simulations under a wide range of demographic and genetic scenarios.