Kinetic performance across a temperature gradient of 3 Idh -1 alleles in the cricket Allonemobius socius. Enzyme efficiency (A) was measured as the increase in reaction velocity with increasing substrate concentration (see Methods). Km (B) and Vmax (C) were calculated using standard Michaelis-Menten methods. Means ± SE are given (n = 3 individuals per genotype). Individual ANOVA's were used to test for differences between genotypes at each temperature and significant differences indicated (*P < 0.1, **P < 0.05, ***P < 0.01).