Fig. 2.

Total cumulative UV-B exposure estimates for all R. cascadae (Upper; 107,352 embryos) and A. macrodactylum (Lower; 4,519 embryos) embryos surveyed across 22 breeding sites for each species. Thresholds for both panels correspond to cumulative exposures received in field experiments that had no effect on embryonic survival (Lower) and that resulted in a significant reduction in survival (Upper). For R. cascadae, 5.7% of all embryos received UV-B exceeding the lower threshold, and none received UV-B exceeding the upper threshold; for A. macrodactylum, these values were 11.2% and 1.1%, respectively. Ten embryos of A. macrodactylum had an estimated UV-B exposure exceeding the range of the x-axis; these are denoted by (10) just beyond the x-axis.