A quantitative genetic test of adaptive decoupling across metamorphosis for locomotor and life-history traits in the pacific tree frog, Hyla regilla.

Metamorphosis is assumed to be beneficial because it can break developmental links between traits in the different phases of a complex life-cycle and thereby allow larval and adult phases to adapt independently. I tested the prediction that correlations between the larval and adult phases are smaller than within stages. I estimated phenotypic and additive genetic variances and correlations for tadpole swimming speed, frog jump distance, body size, and larval period in a single population of the Pacific tree frog, Hyla regilla. These traits are known or reasonably assumed to be important for survival in this and other anuran species from temporary ponds. Only the three size variables were affected by sire identity. Heritabilities for locomotor performance, larval period, and size-independent performance were low (0.00-0.23) and not significant. Body size measurements showed somewhat higher and statistically significant heritabilities (0.24-0.34). Most traits were phenotypically correlated. On average, phenotypic correlations were larger between phases than within phases (0.41 vs. 0.28). Genetic correlations involving body-size traits were positive and large, and average within- and between-phase genetic correlation coefficients were identical (0.81). These results do not support the adaptive decoupling hypothesis, and they indicate that a paucity of additive genetic variation is a likely constraint on the evolution of traits measured for this population.