Influence of Climatic Variables on Corporal Attributes of Adult Female Caiman and Their Relationship with Reproductive Success

Abstract

Studies on crocodilians indicate that energy investment in reproduction is conditioned by prey availability, which is in turn affected by rainfall. Therefore, environmental variables may affect individual body condition (BC) and physiological condition (PC). We evaluated the influence of climatic factors on the BC and PC of wild reproductive female Caiman latirostris and their performance in different seasons. We found no relationship between female BC and climatic variables, which indicates that only females that have managed to overcome a minimum required BC can reproduce and suggests that the minimum BC is not fixed. Females with higher BC produced nests with greater hatching success, proving that if there is a minimum energy threshold that triggers reproduction; once the threshold is surpassed the excess energy may be invested in quality of progeny. We observed that as rainfall increases in river headwaters in March-April, clutch size decreases, indicating that in years with lower rainfall, only larger females may reproduce. Regarding PC, muscle fatty acid (FA) indicated C18:2 has a strong association with minimum temperatures in September, suggesting that temperatures of the first warm months determine the availability of food. Also, variation in plasma FA are associated with precipitation in October and December, showing that precipitation influences diet and PC. We conclude that rainfall and minimum ambient temperatures modulate the reproduction of C. latirostris and the dynamics of the population as a whole. Also, BC is a useful indicator for evaluating reproductive performance and PC is a useful indicator to evaluate nutritional status of populations.