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Marine Biology

, Volume 137, Issue 5–6, pp 1059–1066 | Cite as

No apparent genetic basis to demographic differences in scarid fishes across continental shelf of the Great Barrier Reef

  • C. L. Dudgeon
  • N. Gust
  • D. Blair

Abstract

 Two species of parrot fish, Scarus frenatus and Chlorurus sordidus, are known to exhibit demographic and life-history differences across the continental shelf of the northern Great Barrier Reef (GBR). DNA sequences from the mitochondrial (mt) control region were analysed to determine whether there were genetic differences between the populations from the mid- and outer-shelf reefs. Analysis of molecular variance (AMOVA) indicated high levels of gene exchange for both species at a local scale between reefs on mid- and outer continental shelf positions (20 km apart) and at a broader scale along the length of the GBR province (>1000 km apart). There was no evidence to suggest that local differences in scarid life-history characteristics on the northern GBR have a genetic basis. Rather it appears more likely that phenotypically plastic responses to prevailing social and environmental conditions explain differences in the life-history characteristics of both taxa. However, analysis of genetic variation and historical demography revealed striking differences between the two species. S. frenatus haplotypes differed from one another at relatively few nucleotide sites (mean = 3.30), and the pairwise mismatch distribution suggested this species has undergone a population expansion within the limit of the resolution of the marker. C. sordidus haplotypes, however, differed from one another at a number of sites (mean = 7.67). Mismatch distribution analysis suggested that the population size of this species has remained at equilibrium over time. These patterns could also reflect differences in the metapopulation sizes or generation times between taxa. Some of the implications for fisheries management are discussed.

Keywords

Continental Shelf Great Barrier Reef Fishery Management Population Expansion Historical Demography 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • C. L. Dudgeon
    • 1
  • N. Gust
    • 2
  • D. Blair
    • 1
  1. 1.School of Zoology and Tropical Ecology, James Cook University, Townsville, Queensland 4811, Australia Fax: 0081 74 725 1570 e-mail: Christine.Dudgeon@jcu.edu.auAU
  2. 2.School of Marine Biology and Aquaculture, James Cook University, Townsville, Queensland 4811, AustraliaAU

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