Authors
Shawn R. Narum
Steve Boe
Paul Moran
Matt Powell
Report Reference
#Transactions
of the American Fisheries Society
135:979-986, 2006
Publication Date
2006
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Small-scale Genetic Structure
and Variation in Steelhead of the Grande Ronde River, Oregon, USA
Abstract |
| Patterns
of genetic variation in summer-run steelhead Oncorhynchus mykiss
from the Grande Ronde River, Oregon, were evaluated with 20 microsatellite
loci to determine the level of fine-scale genetic structure and influences
from hatchery-reared stocks. Included were temporal collections of
three wild populations (Lookingglass Creek, Catherine Creek, and the
upper Grande Ronde River) and one hatchery population (Wallowa Hatchery).
Average gene diversity was moderate to high in all collections (range=
0.794–0.815). Genetic variance among sample locations was greater
than that of temporal collections within sites, as pairwise exact
tests within populations were not significant except for Lookingglass
Creek (P = 0.00005). Structure among the four populations was evident
from pairwise tests, which yielded 23 significant results from 28
comparisons (adjusted critical value = 0.0018), but Catherine Creek
collections were not significantly different from Wallowa Hatchery
collections. None of the eight collections had a significant probability
of differing from mutation drift equilibrium (e.g., recent bottleneck)
under the two-phased mutation model (P = 0.060–0.985) when analyzed
with BOTTLENECK software. Additionally, the ratios of allele number
to allele range (M values ) for the eight collections (0.773–0.819)
were not within the range that suggests a recent decrease in effective
population size (M < 0.68 implies a probable bottleneck). Results
from this study suggest the existence of gene flow between steelhead
from Catherine Creek and Wallowa Hatchery, but no evidence for low
diversity or recent bottleneck events was detected in any of the four
populations. This study provides several pieces of evidence to suggest
that steelhead in the Grande Ronde River should be a conservation
priority as a source of genetic diversity for the Snake River basin. |
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