Influence of climatic variables on corporal attributes of Caiman latirostris females and their relationship with reproduction

P LEIVA; C I. PIÑA; M SIMONCINI ; LÁBAQUE M. C.

Congreso; 25th Working Meeting of Crocodile Specialist Group; Argentina; 2018

Although the reproductive ecology of C. latirostris has been studied in several aspects, it is still unknown the influences of climatic variables on female?s conditions and their reproduction. Studies in reptiles recorded that energy invested in reproduction is conditioned by the availability of preys, which is affected by local and regional rainfall. The aim of this study is to evaluate influence of rainfall and temperature over corporal attributes of C. latirostris females (body and physiological condition) and their reproductive performance (clutch size and hatching success [hatchlings/number of eggs]) from wild populations in Santa Fe Province. Body condition was calculated by the Scaled Mass Index (SMI), physiological condition was characterized by fatty acid profiles (FA) in plasma and muscle of reproductive female. Through principal component analysis was evaluated the effect of climatic variables (temperature, local rainfall, and rainfall in the headwaters of the rivers prior to oviposition) on the female?s corporal attributes and reproductive performance. No relationship was found between female?s body condition and climatic variables; this could indicate that only females that have managed to overcome the minimum required body condition can reproduce. Although for the moment it is unknown what are the causes that would allow a female to reproduce and it is possible that this threshold is flexible. A relationship was found between female body condition and hatching success of their nests, females with better body condition have greater hatching success. Is possible that there is a minimum energy threshold to reproduce, but once the threshold is overtaken, the excess energy could be invested to improve progeny quality. In addition, it was observed a negative association between clutch size and rainfall in the headwaters of rivers in March-April. According to the relationship between body size, clutch size and energy cost of reproduction, it is possible that in years with lower rainfall, only larger females would reproduce. Respect to the physiological condition, muscle FA showed that essential fatty acids such as linoleic (C18:2) has a strong association with minimum temperatures of September, which shows that temperatures of first warm months (spring), determines the availability of food items that are in relation to values of essential fatty acids (EFA). Also, muscle FA (C18:1, C18:2, C22:6 and total polyunsaturated) showed association with hatching success, which in turn are indirectly related to a higher body condition. In plasma EFA and total polyunsaturated was associated with rainfalls in headwaters of rivers in December, showing that precipitation would affect plasma FA through diet. Our results suggest that body condition allows to evaluate reproductive performance of the species; and females physiological condition is affected by precipitation and temperature.