Patterns of Population Structure and Historical Dispersal in Squaloid Sharks: A Species-Level Approach using Molecular Markers
Squaloids (Order Squaliformes) are a highle diverse group of mostly deepwater habitats (> 200 m). Many species are regularly caught in commercial fisheries worldwide but their low productivity and correspondingly low intrinsic rebound potentials make them particularly vulnerable to population dep...
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| Format: | Text |
| Language: | English |
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W&M ScholarWorks
2012
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| Online Access: | https://scholarworks.wm.edu/etd/1539616812 https://doi.org/10.25773/v5-z41e-2z41 https://scholarworks.wm.edu/context/etd/article/2379/viewcontent/3492314.pdf |
| Summary: | Squaloids (Order Squaliformes) are a highle diverse group of mostly deepwater habitats (> 200 m). Many species are regularly caught in commercial fisheries worldwide but their low productivity and correspondingly low intrinsic rebound potentials make them particularly vulnerable to population depletion and overexploitation. of special concern to fisheries management and conservation efforts are the spiny dogfish Squalus acanthias, the leafscale gulper shark Centrophorus squamosus and the Portuguese dogfish Centroscymnus coelolepis. These taxa have recently been declared overfished in several parts of each species' distribution but management efforts have been made to recover the "stocks" without a good understanding of the species' population structure and the level of connectivity among populations. as such, the goal of this dissertation is to elucidate the intraspecific patterns of population structure of each species, for future inclusion in fisheries management efforts, and to infer the patterns of historical dispersal of the three species of squaloid sharks. to this end, I have developed a suite of highly polymorphic molecular markers (including nuclear microsatellites and nucleotide sequences of mitochondrial DNA gene regions) and have collected tissues samples from throughout each species geographic range. The genetic population structure of S. acanthias was characterized by high genetic divergence across the equatorial Pacific, and by comparatively higher genetic homogeneity among the sample collections from the South Pacific and Atlantic oceans. Nevertheless, small but significant genetic differentiation was detected by both nuclear and mitochondrial markers among spiny dogfish collections from either side of the equatorial Atlantic. Genetic differentiation in the spiny dogfish occurred across low latitude regions characterized by warm-temperate and tropical waters, suggesting that such regions may act as effective barriers to gene flow among populations. Regarding C. coelolepis and C. squamosus, the ... |
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