Frequency histograms of egg development across mating pair combinations. Histograms showing the frequency distributions of the proportion of eggs that did not develop (upper row), and the proportion of partially developed eggs (lower row), across each mating pair combination (by column left to right; BC, BB and CC). For BC mating pairs, more than half the clutches had a majority of undeveloped eggs (a). The remaining clutches varied in the proportion of undeveloped eggs and eggs beginning embryogenesis (b). Of these clutches showing signs of development, there was a bimodal distribution of either a majority of eggs partially developing (c), or eggs developing normally (d), rather than a normal distribution of development success. BB clutches rarely consisted of undeveloped eggs (e) or partially developed eggs (f). Instead, clutches had a majority of eggs that developed normally (g). The majority of CC clutches consisted of at least some undeveloped eggs (h). Of the eggs beginning embryogenesis, almost all developed normally (i).