P3.202 Friday, Jan. 6 Contrasting influence of spatial and ecological factors on genetic diversity and morphological differentiation of two freshwater invertebrate species GOUIN, N*; BERTIN, A; BORQUEZ, J; SAMPERTEGUI, S; RUIZ, V; FIGUEROA, R; CEAZA, La Serena, Chile; Universidad de La Serena, Chile; Universidad de Concepción, Chile; Universidad de Concepción, Chile; Universidad de Concepción, Chile; Centro EULA, Concepción, Chile email@example.com
Population differentiation results from the combination of evolutionary, ecological and stochastic processes. While lotic organisms are usually distributed along environmental gradients, they may show species-specific responses to the environment depending on their ecological requirements. Here, we investigate the effects of spatial and ecological processes on genetic diversity (mitochondrial DNA; COI gene) and morphological differentiation among populations of two freshwater invertebrates, Chilina dombeyana (CD) and Aquarius chilensis (AC), in a Chilean watershed. Both species show interpopulation genetic and morphological differentiation (p<0.001), with a higher genetic structure in CD (FSC=0.39) than in AC (FSC=0.17). Isolation by distance was detected for both morphological and genetic data in CD, but not in AC. In both species, morphological variation was influenced mainly by habitat and water characteristics. While significant correlations between nucleotide diversity and indices of water and riparian habitat quality were detected in both species, the direction and magnitude of the correlations were different between them (r=-0.40 and -0.41, respectively, for CD and r=0.51 and 0.66, respectively, in AC). These results suggest that these two species are influenced by different environmental factors and that AC may be more sensitive to local water quality. Consistent with this view, we also found that sites where AC shows the highest levels of genetic diversity also harbor higher macroinvertebrate diversity. Future studies are necessary to elucidate the ecological mechanisms underlying these observations.