Microsatellite variation and population genetic structure of the red throat emperor on the Great Barrier Reef

Authors

  • L. Van Herwerden,

    Corresponding author
    1. Australian Institute of Marine Science, PMB No 3, Townsville, Queensland 4810, Australia,
    2. Department of Marine Biology, James Cook University, Townsville, Queensland 4811, Australia,
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  • J. Benzie,

    Corresponding author
    1. Centre for Marine and Coastal Studies, University of New South Wales, Sydney, New South Wales 2052, Australia,
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  • C. Davies

    1. CRC Reef/Department of Tropical Environmental Studies and Geography, James Cook University, Townsville, Queensland 4811, Australia and
    2. National Oceans Office, GPO Box 2139, Hobart, Tasmania 7001, Australia
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†Author to whom correspondence should be addressed. Tel.: +61 7 4781 5678; fax: +61 7 4781 5285; email: lynne.vanherwerden@jcu.edu.au

Abstract

Analysis (using three analytical approaches) of eight microsatellite markers from six locations in three geographic regions of the Great Barrier Reef (GBR), including populations that differed in demographic characteristics, showed no evidence of genetic stock structure in the red throat emperor Lethrinus miniatus. Measures of inter-population differentiation were non-significant (P ≥ 0·67). Using a Bayesian clustering approach, ‘admixture’ was detected (mean alpha values >1) with allele frequencies for each of the locations sampled being correlated equally with allele frequencies from all locations sampled. The number of populations (K) identified was one, based on the estimates of the probability of the data at various K values (K = 1, 2, 3, … 6). Additionally, alpha values did not stabilize to relatively constant values in any of the Bayesian analyses performed, indicating that there was no real genetic structure between locations. Analysis of genetic variation as detected by analysis of molecular variance (AMOVA) indicated that almost all of the variance in the data (99·74%, P ≤ 0·023) was within populations, rather than among populations (0·15%, P ≤ 0·176) or amongst regions sampled (0·10%, P ≤ 0·247) on the GBR. Fst statistics identified four individual loci having statistically significant differentiation among populations, but these were only related to one out of 12 pair-wise comparisons where populations differed demographically. Given these results (albeit using neutral markers), together with the capacity of adults and larvae to be mobile between reefs on the inter-connected GBR, it is considered unlikely that L. miniatus populations exist as distinct genetic stocks in the GBR. It is therefore not possible, using neutral markers, to reject the null hypothesis that the fishery be managed as a single panmictic stock.

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