Fig. 4. Temperature compensation of resting heart rate (RHR; beats min^–1). t, M. trossulus; g, M. galloprovincialis; e, M. edulis. Symbols connected by solid lines are observed RHR values averaged across salinity treatments. Symbols connected by broken lines are observed RHRs at 14°C and expected RHRs at 21°C, using the species-specific Q₁₀ estimate and assuming no physiological compensation. If there was complete temperature compensation, there would be no difference between the observed values for 14°C- and 21°C-acclimated animals (symbols connected by a horizontal line; not shown). However, the observed RHR at 21°C is lower than expected for all species, indicating partial compensation with acclimation temperature.