Climate change may lead to higher nest temperatures, which may increase embryo development rate, but reduce hatchling size and growth. Larger body size permits better performance, making growth an important fitness trait. In ectotherms, growth is affected by temperature and food quality. To segregate the effects of incubation temperature vs. alimentation on the growth of the Mexican black spiny tailed iguana Ctenosaura pectinata, we incubated eggs at 29 and 32ºC, and hatchlings were kept at 30ºC and fed either high- or low-quality food for one year, recording body size and mass every two weeks. Iguanas incubated at 29ºC grew faster than those incubated at 32ºC. However, food quality had a stronger effect on growth than incubation temperature; iguanas fed with high-quality food reached larger body sizes. Growth models suggested that differences in growth between incubation temperatures and food types remain throughout their lives. We found that incubation temperature had long-lasting effects on an ectotherm and higher incubation temperatures may lead to reduced growth and maturation at later age. However, food may transcend the effect of increased incubation temperature and thus good alimentation may mitigate climate change effects on growth.

Twelve gravid Mexican black spiny tailed iguana, Ctenosaura pectinata, females were maintained in captivity until oviposition.

40 eggs were incubated at a stable 29ºC and 40 eggs at 32ºC.

Hatchlings were individually housed and maintained at 28-32°C (mean = 30°C).

Day light was provided from 8:00 to 18:00h.

20 iguanas from each incubation temperature, 50% males and 50% females, were fed with either low-quality food (poultry food; Engordina 5D, Purina México) or high-quality food (rabbit food; Conejina, Purina México).

Every two weeks for one year, we measured snout vent length (SVL) and body mass. For SVL we used a digital caliper (Absolute Digimatic Mitutoyo Caliper Model CD-6” C, Mitutoyo Corporation; ± 0.01 mm); and for body mass an analytical balance (Sartorius, BL 610, Sartorius AG Göttingen, Germany; ± 0.01 g). 

Data on growth in hatchling iguanas incubated at 29 or 32ºC and fed low or high-quality food. Data includes measures of snout vent length and body mass of the iguanas every two weeks over one year.