Molecular assessment of the genetic integrity,distinctiveness and phylogeographic context of the Saltwater crocodile (<Emphasis Type="Italic">Crocodylus porosus</Emphasis>) on Palau |
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Authors: | M A Russello P Brazaitis J Gratten G J Watkins-Colwell A Caccone |
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Institution: | (1) Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA;(2) Peabody Museum of Natural History, Yale University, New Haven, CT, USA;(3) Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, UK;(4) Yale Institute for Biospheric Studies, Yale University, New Haven, CT, USA;(5) Unit of Biology and Physical Geography, University of British Columbia Okanagan, 3333 University Way, Kelowna, BC, Canada, V1V 1V7 |
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Abstract: | The saltwater crocodile (Crocodylus porosus) is the largest and most broadly distributed crocodilian species, and thus is of special conservation and economic interest.
Similar to other parts of its range throughout the Indo-Pacific, C. porosus distributed in the Republic of Palau have experienced a severe population decline over the past century primarily due to
commercial hunting and eradication campaigns. In addition, several thousand crocodiles of undocumented species and origin
were imported into Palau during the 1930’s for commercial farming purposes, potentially polluting the gene pool of the endemic
saltwater crocodiles. Analysis of 39 individuals collected throughout the Republic of Palau revealed a single mitochondrial
DNA control region haplotype shared by populations sampled in Sulawesi, Borneo and Australia. The mtDNA results, in combination
with microsatellite genotypic data at six loci, detected no evidence for inter-specific hybridization between endemic Palauan
C. porosus and potentially introduced Crocodylus species. There was no evidence for a genetic bottleneck in the Palauan population, however an excess of rare alleles was
identified, indirectly suggesting a recent history of admixture potentially linked to introductions of non-native C. porosus. Following from these findings, Palauan C. porosus should be included in the single ESU previously established for all saltwater crocodiles given the recovery of a fixed, but
geographically widespread haplotype. Although Palauan C. porosus exhibited significant genetic differentiation relative to all other sampled populations, it’s delineation as a distinct management
unit is precluded at the present time by evidence that the genetic integrity of the population may have been compromised by
the introduction of non-native saltwater crocodiles. |
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Keywords: | Saltwater crocodile Microsatellite Mitochondrial DNA control region Population bottleneck Management unit |
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