Lj. English et al., Allozyme variation in three generations of selection for whole weight in Sydney rock oysters (Saccostrea glomerata), AQUACULTURE, 193(3-4), 2001, pp. 213-225
Genetic variability in second and third generations of a selective breeding
line of Sydney rock oysters (Saccostrea glomerata) was compared with one a
nother and a control group. using 14 allozyme loci, All groups showed a sim
ilar and high degree of genetic variability. Overall, the percentage of pol
ymorphic loci (P < 0.99 criterion) was 66.7%, the mean observed land expect
ed) heterozygosity (+/- S.D.) was 0.222 +/- 0.087 (0.223 +/- 0.087), and th
e mean number of alleles per locus (+/- S.D.) was 2.5 +/- 0.6, While select
ion for increased whole weight does not appear to have significantly dimini
shed genetic variation of the two generations of the selected breeding line
relative to the controls, there were some significant allele frequency dif
ferences among groups (n = 100 per group). Unexpectedly, the allele frequen
cies from the third-generation sample was more similar to those of the cont
rol sample than the second-generation sample, due to sampling error in the
latter samples, This was reflected in estimated effective population number
s of 41.4 +/- 14.0 for the second-generation line and 383.8 +/- 249 for the
third-generation lines, when compared to the control group, and 7.5 +/- 2
for the third generation when compared to the second generation. Numbers of
alleles remaining in all eases were similar to numbers expected if allele
loss occurred through genetic drift or sampling variation only. (C) 2001 El
sevier Science B.V. All rights reserved.