Fig. 14

Two-dimensional graphs representing the morphology (x axis) and ecology (y axis) of biphasic anuran ontogenies. a Anuran larval morphology and ecology occupy the negative quadrant and are indicated by the orange polygon. Adult morphology and ecology are in the positive quadrant, represented by the green polygon. Both polygons are overlapped by metamorphosis in which there are morphological transformations in the major organ systems affecting breathing, feeding, locomotion and other behaviors, as is observed in Chacophrys pierottii and Ceratophrys spp. Metamorphosis is represented by the region around where the two axes cross. Because of the profound difference between the ecology of most larvae and adults, anurans in the middle of metamorphosis are neither as efficient in locomotion nor feeding as either the larvae or adult life form. Since anurans in transition are typically ineffective in nutritional capture and predator escape, nature selection has acted to shorten the dangerous transformational period of metamorphic climax. This is represented by the relatively small area covered by the polygons where the two axes cross in the figure. b The graph for Lepidobatrachus spp. illustrates the relatively minor ecomorphological differences between larvae and adults compared with most anurans with a biphasic lifestyle (as shown in a). The fast developmental rate and the precocious metamorphic morphologies in Lepidobatrachus tadpoles define a peramorphic larval body plan, suggesting that the free-feeding stage in Lepidobatrachus spp. is equivalent to metamorphic larval stages (between forelimb emergence and complete tail loss) of most anurans [11]. Furthermore, some larval features are conserved during the whole ontogeny (e.g., lateral line system) with adult stages also resembling advanced metamorphic morphologies. Because of the similarity in the life style of the Lepidobatrachus larvae and adult, the typically precarious metamorphic period can be protracted; i.e., this is represented in the figure by not just the greater overlap in adult and larval polygons, but the convergence of those polygons around where the two axes cross, i.e., at metamorphosis