Genetic and Morphometric Variability in Caiman latirostris (Broad-Snouted Caiman), Reptilia, Alligatoridae

Abstract

Caiman latirostris (broad-snouted caiman) is a crocodilian species from Argentina subject of management plans. The goal of this study was estimating the distribution of genetic variability using RAPD markers and quantitative traits in wild populations of C. latirostris from Santa Fe province, Argentina. We sampled animals from four populations to obtain DNA and morphometric measurements. Eight RAPD primers were used and PCR products were analyzed on 4% polyacrylamide gels stained with silver nitrate. Eleven allometric measurements were obtained in animals within 48 hr after birth. We were able to reveal a relatively high number of variable markers in the studied populations. Our estimates of polymorphism and heterozygosity are higher than recorded values in other crocodilians using isozymes, the studied populations showed low levels of gene flow and some population subdivision. The study of quantitative traits conducted by nested analysis of variance and principal component analysis indicated higher levels of variance among nests within populations than among populations. We found that some head measurements have the highest contribution to morphological differences among populations; this fact could support the role of these traits in reproductive or feeding behavior. Estimated genetic differentiation value (FST) among populations was higher than quantitative trait differentiation value (QST), suggesting a higher contribution of neutral than adaptive loci to the genetic differentiation among populations. Quantitative traits are probably more related with fitness and the differentiation among populations remained relatively lower. The high heritability estimated for some traits indicates great potential to improve them in management plans.