Genetic constraints at the metamorphic boundary: Morphological development in the wood frog, Rana sylvatica

Organisms with complex life-cycles often experience very different environments in different phases of their life. Genes expressed in more than one phase could potentially create a conflict or constraint on evolutionary change if the pattern of selection on those genes were different in the different phases. The potential importance of this type of constraint across metamorphosis in frogs was assessed by measuring the genetic correlation between several morphological traits in both larval and juvenile Ran~l sylcatica. Genetic correlations within a stage tended to be moderately high and significant whereas correlations across stages were low and not significant. Errors on the genetic parameters make it impossible to prove that there are no genetic constraints across metamorphosis in this population of frogs, but the results are consistent with the hypothesis that gene expression and developmental regulation are partitioned separately before and after metamorphosis.