Are the head of hatchling females and males similar? a Geometric morphometry approach

LEIVA, P.; SCARPA, L.; IMHOF, A; SIMONCINI, M.; CIOCAN, H; AMAVET, P; PIÑA, C. I.

Chetumal

Congreso; XXVI Working Meeting Crocodiles Specialist Group - UICN; 2022

Crocodiles Specialist Group - UICN

Studies of crocodilians cephalicregion are relevant in fields of ecology, systematics, evolution andconservation. In addition, these studies have the potential to be applied tosexing of individuals, which would allow sexual discrimination of hatching tobe as effective as they are for adult crocodiles, and could replace currentsexing techniques (surgical examination of gonads and histological cuts). Inthis study we analyzed the cephalic region of Caiman latirostris neonates using geometric morphometry tools, withthe aim of determining if there are morphological differences associated withhatchling sex. We collected 11 clutch and incubated at a constant 32°C (malesand females producing temperature), which would allow us to evaluate if thereis sexual dimorphism in the cephalic region in dorsal view of hatchlings. Weused canonical variate analysis and a principal component analysis for dataanalysis. When analyzing the data from all the clutches together, we found nodifferences between males and females. However, when we analyzed clutches includingthe sites as grouping variable, we registered sexual dimorphism in hatchlings,and also we observed differences on hatchling morphology from different sites. Ourresults suggest that geometric morphometry technique allows, through analysisof dorsal images of cephalic region, a reliable sexing of the hatchlings,without having to sacrifice the animals for the internal gonads inspection orwaiting for the growth of the individuals.