Morphological diversity of the American crocodile (Crocodylus acutus) in the Yucatán Peninsula

Abstract

Recent evidence suggests that morphological divergence of the American crocodile (Crocodylus acutus) occurred in Greater Antilles under conditions of prolonged isolation and hybridization with the Cuban crocodile (C. rhombifer). We investigated morphological diversity in C. acutus in the coastal zone of the Yucatan Peninsula, where isolation and hybridization have also been reported. We compared the relationships among various morphological traits between insular and coastal populations. Our results suggest morphological diversity in the region, which is possibly related to population isolation and mechanical constraints imposed by differences in diet. A broad-snouted morphotype appears typical of island populations. Hybridization could also cause morphological variation, but its importance in this case remains to be confirmed. Sexual dimorphism of the American crocodile in the region appears to be less pronounced than for other crocodilians. We also provide population-specific size estimation models for two populations (Banco Chinchorro and Cozumel) to improve future monitoring.