A number of minor errors were published in J. Exp. Biol.218, 1410-1418.

The corrected sections are reproduced below, with changes highlighted in bold. These changes do not affect the conclusions of the paper.

RESULTS

Metabolic substrates: respiratory quotient

Mean respiratory quotient (RQ=CO2/O2, where CO2 is the rate of CO2 production and O2 is the rate of O2 consumption) across treatments and size classes was 0.743. Mean RQ of the mating males (median=0.71) was significantly lower than that of the courting males (median=0.76) [Kruskal–Wallis test, K1=24.091 (where the subscript 1 indicates d.f.), P<0.001]. A non-parametric test was used because these data failed a normality test (Shapiro–Wilk, P<0.05). This difference in RQ between courting and mating males was driven by small courting males having a significantly higher RQ than small mating males (Kruskal–Wallis test, K3=31.394, P<0.001; multiple comparisons using Dunn's method; Fig. 5). This suggests that small, mating males were using different metabolic substrates after mating from those used by the small, courting males.

DISCUSSION

Size-dependent strategies of ejaculate expenditure

The shift in RQ, seen only in small males (Fig. 5), provides support for the hypothesis that smaller males are investing in plug production, as a shift in the substrates used in metabolism could be due to shunting resources to plug production from muscular activity (i.e. mate searching and courtship).

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