Land snails are important organisms to understand biogeographical changes in different regions. Their low dispersion ability produces a particular population structure that resembles historical patterns of genetic diversity. I compared genetic patterns in two different species: Bostryx scalariformis (Orthalicidae) from the coast of Peru and Systrophia helicycloides (Scolodontidae) from the western Amazonian basin. Both species presented a high mutation rate in their mitochondrial genome and also a high intraspecific divergence.
B. scalariformis shows two different lineages which correspond to its different morphotypes. El Niño Southern Oscillation ant the coastal desert could have played a key role in the modeling of the genetic structure in this land snail. On the other hand, S. helicycloides shows lineages with widely distributed and also restricted haplotypes. The actual genetic structure in S. helicycloides seems to be influenced by historical geoclimatic changes, like the rise of the Andes or Pleistocene refuges that both may have produced lineage differentiation. In this case, actual river dynamics could be influential on the distribution of the genetic diversity.

According to Romero, the populations of Bostryx are influenced by the El Nino cycles and their influence on the expanding and contracting ‘lomas’ vegetation islands in the coastal desert. On the contrary, the Systrophia populations seem to have been mixed under the influence of the river dynamics in the Madre de Dios region.

Tags: Bostryx, Scolodontidae, Peru, presentation, varia