NEONATOLOGY OF REPTILES

Abstract

Neonatal reptiles are here defined as an age class of young eureptilian amniotes (excluding birds) that express attributes most influenced by the pre-paritive development environ- ment (oviduct, egg, and egg nest) and by the demands of parition and first dispersal. Neonatal character states are typically transformed, reduced, or eliminated during the first 10% of their pre- reproductive development. Traditionally, neonates have not been distinguished from juvenile rep- tiles. As a result the neonatology of reptiles has rarely been addressed in past literature. Recent studies reveal a complex array of developmental scenarios involving character state transformations, heterochrony, unique character states in morphology, behavior, physiology, nutrition, dispersion and health. Unique morphological features (such as egg teeth) and limited skeletal ossification charac- terize many neonates. Distinguishing behaviors include "reversal" movements, utilization of bright color patterns, and startling movements with both serving as anti-predation mechanisms. Prolonged association with protective parents, group migration, unique agonistic behavior, and tendencies to- ward rapid dispersion characterize the neonates of individual species. Neonatal physiological attri- butes include: a special availability to inoculation by symbiont fermenting anaerobes in herbivores, rapid conforming responses to their external environments in thermal and hydric exchanges, and in the case of some turtles, extraordinary capacities for supercooling (8.9 C). Post-paritive lecithotrophy (nutrition from residual yolk) sustain both the overwintering of nestlings and the dispersion of non- feeding young for as long as several months. Resistance to infections (such as mycoplasmas) from their maternal parents, combine with nutritive reserves of residual yolk and a common tendency for rapid dispersion to make neonates attractive candidates for augmentation and translocation programs. Coupled with the practical advantages of maintaining and manipulating small animals in a laboratory environment, these qualities distinguish neonates as particularly useful models for ex- perimentally evaluating the relative apportionment of reproductive resources into greater numbers of offspring or into improved quality/survivorship of individual offspring.