Influence of incubation conditions on hatching success, embryo development and hatchling phenotype of common chameleon (Chamaeleo chamaeleon) eggs

Abstract

Chameleons lay flexible-shelled eggs that are affected by environmental characteristics during incubation. We incubated eggs of six clutches under four treatments using two different constant temperatures (25 and 29°C) and water potentials (- 150 kPa and -600 kPa). Eggs gained mass in all treatments, especially under the wetter and warmer conditions. Temperature, not water potential, affected hatching rate, which was 100% under 25°C and 64% under 29°C. Development time was considered as the period during which eggs were incubated under both constant temperatures and differed between treatments, from an average length of 98.8 days in the wettest and warmest media to 144.2 days in the driest and coldest one. Differences in hatchling phenotype were mostly explained by clutch identity, although it was also affected by incubation treatments, with bigger and heavier hatchlings in colder treatments. Incubation conditions did not affect hatchling growth nor survival rates, but survivors were differentiated by their higher increase in egg mass during incubation. © Koninklijke Brill NV, Leiden, 2003.