Dispersal and many other factors affect population genetic structure. In central Chile, rivers are characterised by strong currents and transverse mountain chains, which impose physical barriers to the populations that inhabit them. The objective of the present study was to study the population genetic structure of two widespread species of aquatic insects, the caddisfly Smicridea annulicornis and the mayfly Andesiops torrens, in three isolated rivers, Choapa, Maipo and Maule. The analysis of population structure, using both mtDNA (cytochrome C oxidase subunit 1, COI) and nuclear markers (amplified fragment length polymorphism, AFLP), considered samples from within and among rivers. In S. annulicornis, we found differentiation within and among rivers, indicating a low dispersal among the study area. Populations of A. torrens shared haplotypes in all three rivers and no differences were found among rivers, indicating that this species probably has more dispersal potential than does S. annulicornis; however, significant differences were observed within rivers. Our results indicate that the transverse mountain chains are not a barrier for A. torrens, which can disperse among rivers. Within rivers, the population structure suggests that these species are probably adapted to avoid drift because of the torrential character of these Chilean rivers.
Population genetic structure of sexual and parthenogenetic damselflies inferred from mitochondrial and nuclear markers