Variation in parental investment and relative clutch mass of the spiny-tail iguana, Ctenosaura pectinata (Squamata: Iguanidae) in central México

Resumen

We measured the length, width, volume, and weight of 871 freshly laid eggs of 28 clutches of Ctenosaura
pectinata. The iguanas were obtained from a tropical dry forest area in central Mexico. The relative clutch mass was
related positively to the average egg weight but not to average egg volume. Unlike what usually occurs in lizards,
where the body length strongly predicts egg production, in C. pectinata clutch size and egg size were not correlated
with female weight or snout-vent length. Observed differences revealed variation in the weight-size of the egg within an
individual clutch. Therefore, there is not an optimization of the egg in the studied population of Ctenosaura, as usually
occurs in small lizards. This variation associated with reproduction takes place in the middle of the dry season, and
may be interpreted as an adaptation to facilitate the adjustment of different phenotypes in environments with extreme
drought.