Browsing by Subject "Crocodylus acutus"
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Item Geometric morphometrics of Antillean Crocodiles(2012-08) Weaver, Jeremy; Densmore, Llewellyn D.; Bradley, Robert D.; Strauss, Richard E.Geometric morphometrics commonly have been utilized to explore patterns of variation across a wide range of taxa. We present a geometric morphometric analysis of skull shape morphology for New World crocodilians of the genus Crocodylus, placing emphasis on studying variation within the Greater Antillean region of the Neotropics. It has been suggested that the major factor contributing to the modern diversity of Cuban (C. rhombifer) and American crocodiles (C. acutus) in the Greater Antilles is the result of ancient hybridization. Genetic studies found that mitochondrial DNA haplotypes for C. acutus in the Greater Antilles are actually more closely related to C. rhombifer than other American crocodiles throughout the Neotropics. To infer whether genetic relationships are correlated with morphological relationships, we use geometric morphometrics to assess shape variation and compare skull morphology to a reconstruction of a cytochrome-b gene phylogeny. Analysis of skull shape variation using geometric morphometrics of landmark data reveals three broad groups of New World Crocodylus within the given morphospace. Two of these groups correspond to present day Crocodylus whereas the other corresponds to fossil specimens of C. rhombifer. Within these groups, nearly all sub-groups correspond to our current taxonomic understanding of New World Crocodylus; except for the placement of Greater Antillean C. acutus, which clusters much closer to C. rhombifer. This further supports recent studies of Greater Antillean C. acutus dynamics and their genetic phylogenies, indicating a unique evolutionary history.Item Population structure of the American crocodile (crocodylus acutus) in Coiba Island, Panama, inferred from morphometric measurement and microsatellite markers(2010-12) Garcia, Liza M. M.; Densmore, Llewellyn D.; Bradle, Robert D.; Strauss, Richard E.The purpose of this project was to characterize the genetic and morphological composition of Crocodylus acutus in Coiba Island, Panama, and to infer the population structure derived from the genetic variability between the North and South region of the Island as influenced by geographic barriers and proximity to continental Panama. Multivariate analysis of variance (MANOVA) was performed to analyze the morphometric measurements. The MANOVA for the effect of sample site indicate differences between locations (P = 0.010). Regarding morphometric variables, North and South of Coiba Island overlapped in the discriminant space, but individuals in Mainland were slightly separated from the South of Coiba Island. The analysis of molecular variance (AMOVA) reported a variation among populations of 17.04%, and within populations of 82.96% with an Fst of 0.17 (P < 0.01) implying genetic structure between the populations sampled. The Bayesian analysis based on a clustering method for inferring population structure confirmed the subdivision identifying the maximum likelihood in a K = 3. Geographic barriers influenced the genetic and morphometric variation in the populations of C. acutus in Coiba Island, as confirmed by the presence of three subdivisions, the absence of immigrants and the landscape heterogeneity in the Island. This genetic structure should be considered in conservation programs.