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Genetic diversity and population structure of Amazonian crocodilians

Published online by Cambridge University Press:  19 August 2004

Izeni P. Farias
Affiliation:
Universidade Federal do Amazonas, Departamento de Biologia, ICB, 69077-000 Manaus, AM, Brazil
Ronis Da Silveira
Affiliation:
Universidade Federal do Pará, Departamento de Biologia, CCB, 66075-110 Belém, PA, Brazil
Benoit de Thoisy
Affiliation:
Association Kwata, B.P. 672, F-97335 Cayenne Cedex, French Guiana
Luis A. Monjeló
Affiliation:
Universidade Federal do Amazonas, Departamento de Biologia, ICB, 69077-000 Manaus, AM, Brazil
John Thorbjarnarson
Affiliation:
Wildlife Conservation Society, Gainesville, FL 32605, USA
Tomas Hrbek
Affiliation:
Washington University School of Medicine, Department of Anatomy and Neurobiology, St. Louis, MO 63110, USA
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Abstract

We used the mitochondrial cytochrome b gene to study the population genetic structure of Melanosuchus niger (Brazil: Negro and Purus Rivers, Lake Janauacá; French Guiana: Kaw River swamps), and Caiman crocodilus (Brazil: Purus River, Lake Janauacá; French Guiana: Kaw River swamps). We found 10 haplotypes in M. niger and 9 haplotypes in C. crocodilus. Nested clade analysis indicated that isolation-by-distance was an important population dynamic in M. niger, but was unable to differentiate between isolation-by-distance, historical fragmentation or range expansion in C. crocodilus. Fu's Fs statistic supported the hypothesis of a demographic expansion in one out of four and two out of three sampled localities of M. niger and C. crocodilus, respectively. Populations of M. niger in central Amazonia also appeared to show differentiation that was correlated with water type. These results are compatible with the life-style of these two crocodilians; C. crocodilus is a habitat generalist and appears to disperse rapidly to newly available habitats, while M. niger is a more sedentary habitat specialist. Both species appear to be recovering from unregulated over-harvesting, however, their responses are life-history and, potentially, ecologically-dependent.

Type
Research Article
Copyright
2004 The Zoological Society of London

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