"The interaction between overdominant heterosis and hybrid incompatibilities"Ayala-Lopez, JulioJulio A. Ayala-Lopez*1,2, Stephan Peischl1,3, Claudia Bank1,2 * Lead author, PhD student in the Theoretical Ecology and Evolution group, University of Bern. 1Institute of Ecology and Evolution, University of Bern, Switzerland 2Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland 3Interfaculty Bioinformatics Unit, University of Bern, Switzerland Hybridization between genetically diverging populations is common. A long-standing question is whether speciation can occur despite hybridization or because of hybridization. Models of hybrid incompatibilities predict that speciation can occur in the presence of gene flow and strong selection against hybrids. The outcome is also influenced by parental contributions and linkage architecture. On the other hand, empirical work has shown that heterosis can counteract the effect of incompatibilities, hindering the speciation process. Theoretical models that consider both the positive and negative effects of hybridization in fitness remain elusive. To address this question, we develop a model to study how Dobzhansky-Muller incompatibilities (DMIs) interact with overdominant mutations in a two-locus model with gene flow. We find that the strength of overdominance relative to incompatibilities determines the genetics of the hybrid population in the long term. We show that the prevalence of hybrids in the long term is increased in the presence of heterosis, even when DMIs lead to a fitness loss in later-generation hybrids. Our work demonstrates how hybrid populations may suffer from genomic conflict caused by the interplay of heterosis and hybrid incompatibilities. |
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