Influence of Climatic Variables on Corporal Attributes of Caiman latirostris Females and their Relationship with Reproduction

PML LEIVA; CI PIÑA,; MS SIMONCINI ; MC LABAQUE

Santa Fe

Congreso; XXV Working Meeting CSG-UICN; 2018

CSG-UICN

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 theirreproduction. Studies in reptiles recorded that energy invested in reproduction isconditioned 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 corporalattributes of C. latirostris females (body and physiological condition) and theirreproductive performance (clutch size and hatching success [hatchlings/number ofeggs]) from wild populations in Santa Fe Province. Body condition was calculated bythe Scaled Mass Index (SMI), physiological condition was characterized by fatty acidprofiles (FA) in plasma and muscle of reproductive female. Through principalcomponent analysis was evaluated the effect of climatic variables (temperature, localrainfall, and rainfall in the headwaters of the rivers prior to oviposition) on the female?scorporal attributes and reproductive performance. No relationship was found betweenfemale?s body condition and climatic variables; this could indicate that only femalesthat 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 femaleto reproduce and it is possible that this threshold is flexible. A relationship was foundbetween female body condition and hatching success of their nests, females with betterbody condition have greater hatching success. Is possible that there is a minimumenergy threshold to reproduce, but once the threshold is overtaken, the excess energycould be invested to improve progeny quality. In addition, it was observed a negativeassociation 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 ofreproduction, it is possible that in years with lower rainfall, only larger females wouldreproduce. Respect to the physiological condition, muscle FA showed that essentialfatty acids such as linoleic (C18:2) has a strong association with minimum temperaturesof September, which shows that temperatures of first warm months (spring), determinesthe 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 associationwith hatching success, which in turn are indirectly related to a higher body condition. Inplasma EFA and total polyunsaturated was associated with rainfalls in headwaters ofrivers in December, showing that precipitation would affect plasma FA through diet.Our results suggest that body condition allows to evaluate reproductive performance ofthe species; and females physiological condition is affected by precipitation andtemperature.