Table 2. Mean estimates of the component of reproductive isolating barriers (RIi ) and estimated divergence time (Mya) of closely related species pairs in Daphnia . We omitted articles that only examine hybrid success, as these studies do not have a direct comparison with parental species. Estimates ofRIi for each species pair were obtained from data sources and were calculated based on methods from Sobel and Chen (2014). Sequence divergence estimates were based on Colbourne and Hebert 19961, Taylor et al. 19962, and Schwenk et al 20003.