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Alternate Title

Isolation-by-Distance Gene Flow Among Vermilion Snapper (Rhomboplites aurorubens Cuvier, 1829

Abstract

Using 12 microsatellite DNA markers, spatial patterns in genetic variation were investigated for 618 specimens of vermilion snapper (Rhomboplites aurorubens). Specimens were obtained from nine collection areas within coastal U.S. waters of the southeastern Atlantic and Gulf of Mexico. Allelic counts ranged from 3 to 29; sample gene diversities ranged from 0.08 to 0.941. Departures from Hardy-Weinberg expectations were observed at one locus in two samples. In both cases, heterozygote deficiencies accounted for the significant test result. Because sample FIs values were also significantly positive for this locus, it was excluded from further analysis. In tests for allele frequency heterogeneity, no differences were observed between any sample pair at any locus or over all loci. For some analyses, collection areas were partitioned into four regional groups (Atlantic, eastern gulf, northern gulf, and western gulf). Small but statistically significant allele frequencies differences were observed between the Atlantic group and the northern, eastern, and western gulf groups. However, fixation-index, AMOVA, and Bayesian analyses were consistent with a null hypothesis that all specimens belonged to a single, panmictic population. Significant patterns of isolation-by-distance gene flow emerged from the Mantel testing and spatial autocorrelation analyses (SAC), both within the gulf and over the tested Atlantic-gulf range. In the overall SAC analysis, the mean r-intercept value, which reflects the maximum scale of genetically effective dispersal, was 1,085 km. From these results, it may be inferred that the population dynamics of vermilion snapper in the western Gulf will be independent of those in the eastern Gulf.

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