Rotifers: excellent subjects for the study of macro- and microevolutionary change

Rotifers, both as individuals and as a phylogenetic group, are particularly worthwhile subjects for the study of evolution. Over the past decade molecular and experimental work on rotifers has facilitated major progress in three lines of evolutionary research. First, we continue to reveal the phylogentic relationships within the taxon Rotifera and its placement within the tree of life. Second, we have gained a better understanding of how macroevolutionary transitions occur and how evolutionary strategies can be maintained over millions of years. In the case of rotifers, we are challenged to explain the evolution of obligate asexuality (in the bdelloids) as mode of reproduction and how speciation occurs in the absence of sex. Recent research with bdelloid rotifers has identified novel mechanisms such as horizontal gene transfer and resistance to radiation as factors potentially affecting macroevolutionary change. Third, we are finding that microevolutionary change can be sufficiently rapid to interact with ecological dynamics. Rotifers can be easily cultured, reproduce quickly, and occur at high levels of clonal, genetic diversity in nature. These features make them excellent eukaryotic model systems for the study of eco-evolutionary dynamics.