Fig. 3

Air- breathing is correlated with cell death in R. pirica limbs. a, b Quantification of LysoTracker–positive cells in ID3, or ID4 of the hindlimbs of early stage 36 R. pirica, reared overnight in a container without a net or with a net (a) or for 3 days in a tank without or with a tube covered with a net (b). Each symbol represents an individual specimen. Mean + SEM. Two–tailed unpaired t–test. ∗p < 0.05. c Schematic illustrating the life history and limb development strategies of various amphibians. X. laevis and C. pyrrhogaster have aquatic tadpoles and no interdigital cell death [1, 17], while amniotes exhibit extensive interdigital cell death. Here we show that R. pirica has aquatic tadpoles, and exhibits interdigital cell death. The cell death observed in R. pirica tadpoles has been experimentally correlated to their frequent air–breathing behavior. Illustrations are modified after [17]