Temporal stability and spatial divergence of mitochondrial DNA haplotype frequencies in red drum (Sciaenops ocellatus) from coastal regions of the western Atlantic Ocean and Gulf of Mexico
Jr. Gold et al., Temporal stability and spatial divergence of mitochondrial DNA haplotype frequencies in red drum (Sciaenops ocellatus) from coastal regions of the western Atlantic Ocean and Gulf of Mexico, MARINE BIOL, 133(4), 1999, pp. 593-602
Restriction-site variation in mitochondrial (mt) DNA was assayed among 1675
red drum (Sciaenops ocellatus Linnaeus) sampled from 20 localities along t
he southeastern coast of the USA (western Atlantic) and the Gulf of Mexico
(Gulf). Up to four consecutive year-classes (cohorts) were sampled at most
localities. Nucleotide-sequence divergence among 170 mtDNA haplotypes ident
ified ranged tin percentage) from 0.184 to 1.913, with a mean (+/-SD) of 0.
887 +/- 0.300. Comparisons of mtDNA haplotype frequencies across year-class
es within localities were non-significant, indicating temporal stability of
breeding components within localities. Significant heterogeneity in mtDNA
haplotype frequencies was found across all localities, between (pooled) sam
ples from the western Atlantic and the Gulf, and among geographically space
d, regional groupings in the Gulf. Genetic divergence between subpopulation
s of red drum in the western Atlantic and Gulf follows a pattern exhibited
in other marine fishes, and probably stems from physical (historical enviro
nmental heterogeneity, absence of suitable habitat, and current patterns) a
nd, perhaps, behavioral factors. Genetic differences among red drum in the
Gulf appear to be due largely to an isolation-by-distance effect that is at
tributable to behavioral factors. The latter may include female philopatry
to natal bays or estuaries, limited offshore (coastwise) movement of female
s relative to their natal bay or estuary, or both. Genetic divergence among
red drum in the Gulf occurs despite high gene flow (estimated as the numbe
r of genetic effective migrants in an island mode). Conservation and manage
ment of red drum should be based on the premise that strategies for a given
bay or estuary will impact geographically proximal bays or estuaries more
than distal ones. Trajectories of correlograms in spatial autocorrelation a
nalysis suggest a geographic neighborhood size, relative to genetic migrati
on of red drum from a bay or estuary, of roughly 500 to 600 km.