Contrasting evolutionary responses in two co-distributed species of<i>Galaxias</i>(Pisces, Galaxiidae) in a river from the glaciated range in Southern Chile

Life-history traits are among the most important factors affecting population abundance and genetic diversity of species. Here, we analysed the genetic patterns of twoGalaxiasspecies with different life-history traits to investigate how these biological differences impacted their evolution in the Valdivia River basin, Southern Chile. We analysed mitochondrial DNA (mtDNA) sequences from 225 individuals ofGalaxias maculatusand 136 ofG. plateito compare patterns of genetic diversity, structure and demographic growth across the basin.Galaxias maculatuspresented higher genetic diversity and higher genetic structure thanG. platei. Demographic analyses showedG. maculatuskept a higher population size over time, with a signal of demographic expansion in the last 250 kyr. WhereasGalaxias platei, exhibited lower, but constant population size over time. Furthermore, haplotype networks revealed higher lineage diversity inG. maculatuswith a tendency to occupy different areas of the basin. Coalescent simulations ruled out that genetic differences between species could be explained by stochastic processes (genetic drift), suggesting species-specific biological differences as responsible for the observed genetic differences. We discuss how differences in life-history traits and past glaciations interact to shape the evolutionary history of the twoGalaxiasspecies.

Kimelfe