Genetic Structure of Atlantic Sturgeon Populations Based on Mitochondrial DNA Control Region Sequences

Abstract

The Atlantic sturgeon Acipenser oxyrinchus oxyrinchus has a latitudinally broad distribution along the east coast of North America, with extant populations occurring from the Saint Lawrence River to rivers in southern Georgia. This species once supported intensive caviar-based fisheries that resulted in overharvest and sharply reduced population abundances; presently, directed commercial fishing for Atlantic sturgeon is banned in U.S. waters. We sequenced a 203base-pair section of the mitochondrial DNA (mtDNA) control region of 322 Atlantic sturgeon specimens from 11 river systems across their range to elucidate their stock structure. We found a pronounced latitudinal cline in the number of composite mtDNA haplotypes and in haplotypic diversity, which increased from north to south, from previously glaciated and subsequently recolonized systems to the portion of their range unglaciated during the Pleistocene. The observed number of haplotypes per population ranged from 1 haplotype in each of the two northernmost population samples to 17 in the sample from the Savannah River. Haplotypic diversity ranged from 0.0 to 0.90. The greater genetic diversity within and among southern populations is likely a product of the persistence of these populations through the Pleistocene and to the faster mutation rates associated with their shorter generation times. Of 39 composite mtDNA haplotypes found, 64% were unique to particular populations. Monomorphism of the two Canadian populations suggested a strong founder effect. Three haplotypes unique to northern populations were probably the result of base substitutions that occurred within the past 10,000 years. In contrast with an earlier study, we found stock structure among southern populations and evidence of at least seven genetic stocks across this subspecies' range.

Stock Origins of Subadult and Adult Atlantic Sturgeon, Acipenser oxyrinchus, in a Non-natal Estuary, Long Island Sound

“…Assignment accuracies to individual populations were lower, with a mean value of 84.5 %. Lowest accuracies (56-81.6 %) were to those populations within the Southeastern DPS, consistent with earlier mtDNA (Wirgin et al 2000;Grunwald et al 2008) and microsatellite (King et al 2001, unpublished data) studies comparing these and other populations within that area.…”

Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

“…The loss of any population within a DPS will result in (1) a long-term gap in the range of the DPS that is unlikely to be recolonized, (2) loss of reproducing individuals, (3) loss of genetic biodiversity, (4) potential loss of unique haplotypes, (5) potential loss of adaptive traits, (6) reduction in total number, and 7) potential for loss of population source of recruits. The loss of a population will negatively impact the persistence and viability of the DPS as a whole, as fewer than two individuals per generation spawn outside their natal rivers (King et al 2001;Waldman et al 2002;Wirgin et al 2000). The persistence of individual populations, and in turn the DPS, depends on successful spawning and rearing within the freshwater habitat, the immigration into marine habitats to grow, and then the return of adults to natal rivers to spawn.…”

Heteroplasmy and length variation in the tRNApro-Dloop regions of three sturgeon species (A. stellatus, A. gueldenstaedtii and H. huso) from the Turkish coast of the Black Sea

“…Kb was determined as 0.203 in A. stellatus, and the highest value was as 0.285 in H. huso (Table 3). Note: n = sample size, f(3-4) = frequency of the 3-4 size class sturgeon species, all of which are Eurasian species in the Black Sea [3][4][5]18,25]. However, there are no molecular or morphometric analysis based studies previously conducted on sturgeon fish in Turkey.…”