Genetic Assessment of Lake Sturgeon Population Structure in the Laurentian Great Lakes

Abstract

Many populations of lake sturgeon Acipenser fulvescens have decreased in size throughout the Great Lakes basin. To implement management strategies such as stocking, it is important to understand the genetic structure of lake sturgeon spawning populations. Lake sturgeon from 27 spawning locations (25 from the Great Lakes basin and 2 from the Hudson Bay drainage) were analyzed using 12 microsatellite loci. Population structure was detected at different spatial scales. At the largest scale, consistent genetic breaks were observed among three clusters of spawning populations: (1) Hudson Bay–northern Lake Superior, (2) southern Lake Superior, and (3) the rest of the Great Lakes. These clusters were identified using a Bayesian approach that does not define the populations a priori. Within each of the three clusters, sublevels of genetic structure were detected. These sublevel clusters accounted for 8.82% of the genetic variation (P < 0.000), while differences among populations within the clusters accounted for 3.72% of the genetic variation (P < 0.000). At the smallest scale, significant genetic differentiation was detected between most sampled locations through pairwise genetic differentiation index (FST) tests and pairwise contingency tests. Lake sturgeon showed greater genetic differentiation in Lake Superior than elsewhere, which could be due to the lake's bathymetry. The lower genetic resolution observed elsewhere in the Great Lakes could be due to more recent colonization events. The results can be used to delineate management units and to select appropriate donor populations for supplementation or reintroductions.

Evaluating the genetic consequences of river fragmentation in lake sturgeon (Acipenser fulvescens Rafinesque, 1817) populations

“…Habitat degradation and fragmentation by dams continues to decrease their abundance and impede restoration efforts (Schueller and Hayes, 2011) by altering spawning behavior and reducing recruitment (Auer, 1996b;Haxton and Findlay, 2008). Despite significant declines in abundance, neither this study nor others (DeHaan et al, 2006;Drauch and Rhodes, 2007;Welsh et al, 2008;McDermid et al, 2011;Wozney et al, 2011) have observed significant decreases in genetic variability or evidence of inbreeding within populations of Lake Sturgeon. It is believed that the sturgeon are buffered from expected losses of genetic diversity because of their longevity and overlapping generations.…”

Validation of 12 species-specific, tetrasomic microsatellite loci from the Russian sturgeon, Acipenser gueldenstaedtii, for genetic broodstock management

“…The magnitude of genetic population differentiation strongly depends on the population status (wild or farmed) as well as the geographical scale of sampling (i.e., a stronger differentiation can be expected if the whole distribution range is covered compared to sampling within a single river, lake, or sea basin). Therefore, a comparison with available population genetic studies on lake sturgeon (McQuown et al 2003;Welsh et al 2008;Wozney et al 2011) and Siberian sturgeon (Barmintseva and Mugue 2017) would be suspect and was not attempted.…”

The effect of multiple spawning events on cohort genetic diversity of lake sturgeon (Acipenser fulvescens) in the Kaministiquia River

“…Extracted DNA was then analyzed at 12 disomic microsatellite loci (AfuG9, AfuG56, AfuG63, AfuG74, AfuG112, AfuG160, AfuG195, AfuG204, Aox27, Afu68, Afu68b, Spl120; Welsh and May 2006). Details on the protocol and variability of the loci are described in Welsh et al (2008). Genotypes from the 2005 samples were visualized using a BioRad BaseStation with an internal 400 ROX size standard.…”

“…The lowest allele frequency used was 0.02, and 95 % parametric confidence intervals were calculated. The effective population size (N e ) of the adult population in the Kaministiquia River (n=85; data published in Welsh et al 2008) was also computed to see whether N b in the larval cohorts reflects the overall N e in the population.…”

“…Unlike most other populations in the Great Lakes, the individuals in this population may be year-round river residents (Friday and Chase 2005). High genetic differentiation from other Great Lakes spawning populations suggests that few migrants enter the river for spawning (Welsh et al 2008). Spawning takes place just downstream of Kakabeka Falls, a 39 m waterfall located approximately 47 km from the confluence of Lake Superior.…”