Simon, Alexis; Fraisse, ChristelleIST Austria ; El Ayari, Tahani; Liautard‐Haag, Cathy; Strelkov, Petr; Welch, John J; Bierne, Nicolas
The Mytilus complex of marine mussel species forms a mosaic of hybrid zones, found across temperate regions of the globe. This allows us to study ‘replicated’ instances of secondary contact between closely related species. Previous work on this complex has shown that local introgression is both widespread and highly heterogeneous, and has identified SNPs that are outliers of differentiation between lineages. Here, we developed an ancestry‐informative panel of such SNPs. We then compared their frequencies in newly sampled populations, including samples from within the hybrid zones, and parental populations at different distances from the contact. Results show that close to the hybrid zones, some outlier loci are near to fixation for the heterospecific allele, suggesting enhanced local introgression, or the local sweep of a shared ancestral allele. Conversely, genomic cline analyses, treating local parental populations as the reference, reveal a globally high concordance among loci, albeit with a few signals of asymmetric introgression. Enhanced local introgression at specific loci is consistent with the early transfer of adaptive variants after contact, possibly including asymmetric bi‐stable variants (Dobzhansky‐Muller incompatibilities), or haplotypes loaded with fewer deleterious mutations. Having escaped one barrier, however, these variants can be trapped or delayed at the next barrier, confining the introgression locally. These results shed light on the decay of species barriers during phases of contact.
Journal of Evolutionary Biology
Data used in this work were partly produced through the genotyping and sequencing facilities of ISEM and LabEx CeMEB, an ANR ‘Investissements d'avenir’ program (ANR‐10‐LABX‐04‐01) This project benefited from the Montpellier Bioinformatics Biodiversity platform supported by the LabEx CeMEB. We thank Norah Saarman, Grant Pogson, Célia Gosset and Pierre‐Alexandre Gagnaire for providing samples. This work was funded by a Languedoc‐Roussillon ‘Chercheur(se)s d'Avenir’ grant (Connect7 project). P. Strelkov was supported by the Russian Science Foundation project 19‐74‐20024. This is article 2020‐240 of Institut des Sciences de l'Evolution de Montpellier.
Simon A, Fraisse C, El Ayari T, et al. How do species barriers decay? Concordance and local introgression in mosaic hybrid zones of mussels. Journal of Evolutionary Biology. 2020. doi:10.1111/jeb.13709
Simon, A., Fraisse, C., El Ayari, T., Liautard‐Haag, C., Strelkov, P., Welch, J. J., & Bierne, N. (2020). How do species barriers decay? Concordance and local introgression in mosaic hybrid zones of mussels. Journal of Evolutionary Biology. https://doi.org/10.1111/jeb.13709
Simon, Alexis, Christelle Fraisse, Tahani El Ayari, Cathy Liautard‐Haag, Petr Strelkov, John J Welch, and Nicolas Bierne. “How Do Species Barriers Decay? Concordance and Local Introgression in Mosaic Hybrid Zones of Mussels.” Journal of Evolutionary Biology, 2020. https://doi.org/10.1111/jeb.13709.
A. Simon et al., “How do species barriers decay? Concordance and local introgression in mosaic hybrid zones of mussels,” Journal of Evolutionary Biology, 2020.
Simon A, Fraisse C, El Ayari T, Liautard‐Haag C, Strelkov P, Welch JJ, Bierne N. 2020. How do species barriers decay? Concordance and local introgression in mosaic hybrid zones of mussels. Journal of Evolutionary Biology.
Simon, Alexis, et al. “How Do Species Barriers Decay? Concordance and Local Introgression in Mosaic Hybrid Zones of Mussels.” Journal of Evolutionary Biology, Wiley, 2020, doi:10.1111/jeb.13709.