Mexican black spiny-tailed iguana Ctenosaura pectinata (squamata:iguanidae): Female reproductive traits and hatchling phenotypic variability in a harvested population

We show life history information on the Mexican Black Spiny-Tailed Iguana, Ctenosaura Pectinata. The biometrics data were used to estimate: size at maturity; relative clutch mass (RCM); period of incubation; mean number of hatchlings; mean clutch size; clutch mass; mean egg mass per clutch (MEM); mean hatchling mass (MHM); mean hatchling size per clutch; and expenditure per progeny (EPP). With these data, we found that: Females' minimum height at maturity was attained at 24.0 cm, and egg production was significantly related to body size. Furthermore, the hatchling mass is more variable than the hatchling size, and EPP decreases with female length.

Methods
We determined clutch size from two sources: 1) Iguanas killed by hunters during the breeding season, and 2) clutches incubated in the individual cages during the hatching season. We measured the size (SVL, cm) and weight (g) of hatchlings after the incubation period. In addition, we counted the number of eggs per clutch and count the number of eggshells, non-hatched eggs, and dead hatchling Iguanas. For every hatchling, we recorded the date of birth, mass (g), SVL (cm), total size (cm), and particular morphological traits, such as body color and physical malformations.

We calculate reproductive effort indirectly in terms of the relative clutch mass using the ratio between clutch mass and body mass. We also estimated the reproductive effort per hatchling through the expenditure per progeny index, which uses the percentage between average egg or hatchling mass and female mass. Thus, we obtained mean egg mass, mean hatchling mass, and expenditure per progeny.