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MORPHOLOGICAL VARIATION IN HATCHLING AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) FROM THREE FLORIDA LAKES
Milnes, M., A. R. Woodward, AND L. Guillette Jr. MORPHOLOGICAL VARIATION IN HATCHLING AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) FROM THREE FLORIDA LAKES. JOURNAL OF HERPETOLOGY 35(2):264-271, (2001).
Morphological variation of 508 hatchling alligators from three lakes in north central Florida (Lakes Woodruff, Apopka, and Orange) was analyzed using multivariate statistics. Morphological variation was found among clutches as well as among lakes. Principal components analysis was used to determine the proportion of the variation attributable to shape as opposed to size. Shape accounted for 42% and 36% of the variation among
individuals and clutches, respectively. Linear discriminant analysis with cross-validation was performed to determine whether the clutch from which an individual came or the lake from which a clutch came could be predicted. Success of predicting clutch membership varied from 67% for Lake Apopka to 74% for Orange Lake. The lake from which a clutch was obtained could be predicted with a success rate of 49%. The optimal subset of measurement variables, obtained from stepwise discriminant analysis, was used to illustrate the morphological variation among clutches and lakes in a scatterplot of the first two canonical variables. Assuming factors such as genetics, nutrition, age, size, and stress affect hatchling morphology, one would suspect hatchlings from the same clutch to be more similar than hatchlings from different clutches. Likewise, we suggest that a lake effect could be the result of intrapopulational similarity of environmental factors, such as food and resource availability, nutrient levels, contaminant levels, and parental lineage (genetics). We hypothesize that demographic and environmental influence on the maternal contribution to the embryonic environment, rather than genetic influence, is responsible for the observed pattern of morphological variation.