Abstract
Hybridization dynamics between co‐occurring species in environments where human‐mediated changes take place are important to quantify for furthering our understanding of human impacts on species evolution and for informing management. The allis shad Alosa alosa (Linnaeus, 1758) and twaite shad Alosa fallax (Lacépède, 1803), two clupeids sister species, have been severely impacted by human activities across Europe. The shrinkage of A. alosa distribution range along with the decline of the remaining populations' abundance threatens its persistence. The main objective was to evaluate the extent of hybridization and introgression between those interacting species. We developed a set of 77 species‐specific SNP loci that allowed a better resolution than morphological traits as they enabled the detection of hybrids up to the third generation. Variable rates of contemporary hybridization and introgression patterns were detected in 12 studied sites across the French Atlantic coast. Mitochondrial markers revealed a cyto‐nuclear discordance almost invariably involving A. alosa individuals with an A. fallax mitochondrial DNA and provided evidence of historical asymmetric introgression. Overall, contemporary and historical introgression revealed by nuclear and mitochondrial markers strongly suggests that a transfer of genes occurs from A. fallax toward A. alosa genome since at least four generations. Moreover, the outcomes of introgression greatly depend on the catchments where local processes are thought to occur. Undoubtedly, interspecific interaction and gene flow should not be overlooked when considering the management of those species.
Highlights
Hybridization among wild taxa is a natural process that occurs in at least 25% of plant and 10% of animal species (Mallet, 2005)
Several studies have explored the extent of hybridization be‐ tween A. alosa and A. fallax in Morocco (Sabatié, 1993), France and Portugal (Alexandrino et al, 2006; Boisneau, Mennesson‐Boisneau, & Guyomard, 1992), Ireland (Coscia, Rountree, King, Roche, & Mariani, 2010), and England (Jolly, Maitland, & Genner, 2011), using molecular markers and the count of gill rakers
The addition of mitochondrial mark‐ ers revealed a cyto‐nuclear discordance almost invariably involving A. alosa individuals with an A. fallax mitochondrial DNA suggesting that mitochondrial introgression is highly asymmetric
Summary
Hybridization among wild taxa is a natural process that occurs in at least 25% of plant and 10% of animal species (Mallet, 2005). Several studies have explored the extent of hybridization be‐ tween A. alosa and A. fallax in Morocco (Sabatié, 1993), France and Portugal (Alexandrino et al, 2006; Boisneau, Mennesson‐Boisneau, & Guyomard, 1992), Ireland (Coscia, Rountree, King, Roche, & Mariani, 2010), and England (Jolly, Maitland, & Genner, 2011), using molecular markers (allozyme, microsatellite, and mitochondrial markers) and the count of gill rakers These studies revealed the presence of hybrids across the distribution range and the exchange of genetic material between both species, but gaps of knowledge are remaining. Variation in hybridization outcomes across time and geographical scales helped refining our understanding of species reproductive barriers, the consequences of introgression and their implication in a conservation and man‐ agement context
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
