Lakes and ponds as model systems to study parallel evolution

Population genetic theory predicts that effective population size and gene flow can strongly influence the levels and patterns of genetic variability, and thereby also the likelihood, pace and direction of evolutionary transformations. Given that levels and patterns of genetic variability in lakes and ponds often differ from those observed in continuous marine environments, it follows that the dynamics of adaptation and evolution in freshwater habitats are also likely to differ from those in marine habitats. Here, I explore and discuss some ideas relating to the likelihood of parallel phenotypic evolution through similar (parallel) vs. different (convergent) genetic changes with particular focus on freshwater isolates. I will review and discuss the available genetic data with particular focus on freshwater fish populations, and outline possible avenues for future work in which ponds and small lakes could serve as useful model systems to study genetic parallelism and convergence, as well as molecular adaptation in general. Conservation issues related to genetics of isolated pond and lake populations are also addressed.