Zoological Studies

Vol. 49 No. 3, 2010

Effects of Incubation and Rearing Temperatures on Caiman latirostris Growth

María Virginia Parachú Marcó1,2,*, Carlos Ignacio Piña1,2,3, Melina Simoncini1,2, and Larriera Alejandro1,4

1Proyecto Yacaré Laboratorio de Zoología Aplicada: Anexo Vertebrados (FHUC - UNL/MASPyMA), A. del Valle 8700, (PC3000) Santa Fe, Argentina.  E-mail:yacare@arnet.com.ar
2CIC y TTP - CONICET, Dr. Matteri y España, (PC3105) Diamante, Entre Ríos, Argentina
3Facultad de Ciencias y Tecnología, Universidad Autónoma de Entre Ríos (UAdER), and Facultad de Ciencias de la Alimentación, Universidad Nacional de Entre Ríos (UNER), Entre Ríos, Argentina
4Facultad de Humanidades y Ciencias, Universidad Nacional del Litoral.  Secretaría de Estado de Medio Ambiente y Desarrollo Sustentable de la Provincia de Santa Fe, Aristóbulo del Valle 8700 - (PC3000), Santa Fe, Argentina

María Virginia Parachú Marcó, Carlos Ignacio Piña, Melina Simoncini, and Larriera Alejandro (2010) Different studies found that incubation temperature has an influence on the size of Caiman latirostris hatchlings and determines their gonadal sex.  Experimental manipulations revealed that the effects of temperature on growth are independent of sex.  Ambient temperature after hatching is also an influential factor: juvenile caiman had lower growth at a cool (29°C) vs. a warm temperature (33°C) independent of incubation temperatures.  Two-month-old caiman were raised at 2 different temperatures (29 and 33°C) for 100 d.  These animals were subjected to different incubation treatments: 29, 31 (females), 33 (males), and 33°C with 17β-estradiol (females).  No differences were found in growth based on incubation temperature or sex.  Our data indicate that the evolutionary advantage of a temperature-dependent sex determination, if it exists, is not bound to differential growth between the sexes nor to incubation temperature, at least in the 1st stages of life before hatchlings reach their 1st winter.  Temperatures during the development and grow-out phases have direct effects on the size of the broad-snouted caiman.

Key words: Broad-snouted caiman, Development, Temperature-sex determination, Estradiol

*Correspondence: E-mail:virginiapara2@yahoo.com.ar