Data from: A field test of a model for the stability of androdioecy in the freshwater shrimp, Eulimnadia texana

The evolution of hermaphroditism from dioecy is a poorly studied transition. Androdioecy (the coexistence of males and hermaphrodites) has been suggested as an intermediate step in this evolutionary transition, or could be a stable reproductive mode. Freshwater crustaceans in the genus Eulimnadia have reproduced via androdioecy for 24+ million years, and thus are excellent organisms to test for the stability of androdioecy. Two related models that allow for the stable maintenance of males and hermaphrodites rely on the counterbalancing of three life history parameters. We tested these models in the field over three field seasons and compared the results to previous estimates of these three parameters. Male and hermaphroditic ratios within years were not well predicted using either the original model or an updated version of this model. Using parameter estimates of the previous year to predict the next year's sex ratios revealed a much better fit to the original version of the model. The applicability of these models to the stable maintenance of androdioecy is discussed.