A comparative study of the development of motor patterns associated with prey capture by leopard frogs of the Rana pipiens complex (Anura: Ranidae)

The motor patterns involved with prey capture were studied in three species of leopard frogs. Data were obtained from adult Rana pipiens and Rana blairi and from juvenile Rana sphenocephala. R. pipiens and R. blairi.

Adult R. pipiens and R. blairi both displayed highly stereotyped, accurate prey catching sequences. Preliminary studies of young of the year postmetamorphic R. pipiens suggested, however, that these motor patterns are not consistently stereotyped at the time of metamorphosis. Interspecific analyses were designed to determine whether the differences between juveniles and adults were due to an ontogenetic modification .of behavior or if there was evidence for interstage selection against frogs with inefficient feeding behaviors. Additionally, the analysis addressed the question of species specific variation within a closely related group of leopard frogs.

Results suggest that several aspects of these motor patterns do indeed change during the first month following metamorphosis. These changes include latency of behavioral onset, time to completion of a feeding trial, and the efficiency of prey capture as determined by a prey catching index (PCI). Survivorship of iii laboratory populations was 100% for R. pipiens and R. blairi but was reduced to 80% for R. sphenocephala. Among juvenile animals, R. pipiens and R. blairi were more similar to each other than either was to R. sphenocephala in terms of both ontogenetic effects and stage specific mortality. This pattern is coincident with the independently established phylogenetic relatedness of the group.