Riverscape genetics in the endangered Mexican Golden Trout (Oncorhynchus chrysogaster) in Sierra Madre Occidental, Mexico

The combined effect of different threats has caused an accelerated loss of biodiversity in endemic species. Then, it is crucial to quantify potential extinction risks as consequence of global change related with human activities, especially in range restricted species. An example of that situation is represented by the native Mexican trout complex inhabiting the highlands of northwest Mexico and representing the group of salmonids with the southernmost distribution in the world, with the Mexican golden trout (Oncorhynchus chrysogaster) and the coastal nelson trout (O. mykiss nelsoni) as the only described species for this complex.However, as mountaintop species, these salmonids are highly vulnerable to global change effects, mainly by climate change and the introduction of the exotic rainbow trout for aquaculture purposes. The overall aim of this PhD project is to assess the possible relationships between microevolutionary processes of the Mexican golden trout, as well as the spatial structure of their habitat defining extinction risks derived by global change.To address those questions, a riverscape genetics approach was applied at different spatial scales and taxonomic levels including population genetics analyses based on neutral microsatellite markers and Next Generation Sequencing (NGS), G.I.S. (Geographic Information Systems; riverscape characterizations), species distribution modeling and demo-genetic simulations.Initially, population genetics analyses of 11 microsatellite loci revealed a spatial genetic structure for the entire Mexican trout complex as well as genetic introgression for native trout collected in aquaculture farm proximities, these results were corroborated by other using more microsatellite and SNPs markers. Moreover, focusing on O. chrysogaster, species distribution models and demogetic simulations defined riverscape as the main factor driving native population genetic structure, and as a boundary against exotic introgression. Additionally, 9,676 SNP’s were generated by NGS techniques defining a cryptic genetic structure for O. chrysogaster. Finally, landscape genomics approaches revealed a significant influence of riverscape factors on the neutral and adaptive genetic structure of the species.