Genetic Assessment

More research highlights from the past year....

2) Genetic assessment of restoration aquaculture practices

Olympia oyster seed produced from wild broodstock in our restoration hatchery from two different years (2010 and 2011) were compared.  Wild broodstock were collected from five locations in in the south subbasin of Puget Sound in both 2010 and 2011. Each year, approximately 500 broodstock were randomly assigned to each of 20 breeding groups.  In 2010, the larvae produced by each breeding group were collected and reared separately as a seed group (n=20). In 2011, the larvae produced on a given day  from all breeding groups were reared separately as a seed group (n=20).  A tissue subsample from 10 individuals from each seed group was taken in 2013 and stored in 70% EtOH. From 10 randomly selected seed groups from each year, DNA was extracted from each sampled individual following standard protocols, and each individual was genotyped at 7 microsatellite loci.  Raw genotype data, binned into length classes using TANDEM (Matschiner & Salzburger, 2009), were used to calculate pairwise relatedness using the maximum likelihood estimator of Queller and Goodnight (1989) as implemented in GenALEx (Peakall and Smouse 2006, 2012).  Mean pairwise relatedness values within each seed group ranged from 0.07-0.28 (2010) and 0.09-0.33 (2011) (Fig. 3, open circles).   Mean pairwie relatedness among 100 pairs over all seed groups (100 bootstrap replicates) did not differ significantly from zero for 2010 or 2011 (P<0.05; Fig. , solid circles).  This result suggests that the partial matrix breeding design as implemented incorporates sufficient genetic diversity to obviate undo relatedness, assuming equal contribution from each breeding group.  Future work will broaden comparisons to include the restoration seed, commercially produced seed, and wild groups. We will conduct allele count rarefaction (HP-Rare, Kalinowski 2005), apply the more powerful groupwise maximum likelihood relatedness estimator of Jones & Wang (2009), and test for shifts in allele frequency among groups.

Fig. 3. Mean pairwise relatedness values for offspring from ten breeding groups of Olympia oysters, Ostrea lurida, in 2010 and 2011 (open circles) and from pairs randomly sampled from each year (closed circles).

Fig. 3. Mean pairwise relatedness values for offspring from ten breeding groups of Olympia oysters, Ostrea lurida, in 2010 and 2011 (open circles) and from pairs randomly sampled from each year (closed circles).