Deviation from Hardy–Weinberg equilibrium, and temporal instability in allele frequencies at microsatellite loci in a local population of Atlantic cod
Abstract A total of 1455 spawning cod, sampled from a local spawning area in Trondheimsfjord (Norway) between 1985 and 2002, was screened at the microsatellite loci Gmo132 and Gmo2. Samples from 15 spawning years comprising 29 consecutive cohorts were analysed. At the Gmo132 locus, but not at Gmo2,...
| Published in: | ICES Journal of Marine Science |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Oxford University Press (OUP)
2005
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1016/j.icesjms.2005.05.009 http://academic.oup.com/icesjms/article-pdf/62/8/1588/29123986/62-8-1588.pdf |
| Summary: | Abstract A total of 1455 spawning cod, sampled from a local spawning area in Trondheimsfjord (Norway) between 1985 and 2002, was screened at the microsatellite loci Gmo132 and Gmo2. Samples from 15 spawning years comprising 29 consecutive cohorts were analysed. At the Gmo132 locus, but not at Gmo2, allele frequencies varied significantly among sampling years as well as cohorts, corresponding to FST-values of 0.004 and 0.006, respectively. Both loci showed examples of significant deviations from Hardy–Weinberg expectation within sampling years as well as cohorts, manifested as deficiencies of heterozygotes. Combining the p-values from the single tests (Fisher's method) revealed an overall significant p-value for deviation from the Hardy–Weinberg expectations at Gmo132 but not at Gmo2. Trend tests showed significant HW deficiencies at both loci for annual samples but not for cohorts. Possible reasons for the deficiencies were discussed; inter alia the existence of null alleles, or a form of pseudo Wahlund effect due to a patchy distribution of habitats for settling O-group cod in the Trondheimsfjord. It was noted that there might be a relationship between the relatively high temporal within-population variability of allele frequencies at Gmo132 and the fact that among microsatellite loci studied so far, Gmo132 is the one that usually shows the highest genetic differentiation geographically in cod. |
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