Behavioral and Morphological Adaptations by Galapagos Land Iguanas (Conolophus subcristatus) to Water and Energy Requirements of Eggs and Neonates

We examine the importance of both the hydric environment ofnaturally incubating reptilian eggs and the energetic needsof hatchlings via an investigation of reproduction in Galapagosland iguanas (Conolophus subcristatus). Hatching success ofegg clutches and the size of subsequent hatchlings are bothpositively correlated with the water potential of natural nests,as predicted from previous laboratory experiments. Water potentialsrepresenting optimal incubation environments are available foronly a brief period in nature, and depend upon the same seasonalrainfall as does food abundance for the emerging hatchlings.The temporal placement of the reproductive season of Conolophussubcristatus balances these conflicting needs for water by eggsand energy by hatchlings. Oviposition occurs slightly beforesuitable water potentials are reached and hatchling emergenceoccurs after the peak in food abundance. Morphological adaptations by Conolophus subcristatus to theirprecarious reproductive phenology include greater amounts ofalbumen in their eggs, and greater energy reserves in emergenthatchlings than most other lizard species. These adaptationslessen the severity of an arid environment where water becomesavailable for periods too short to allow both oviposition andhatching to be temporally placed in an optimal manner.