Larval viability and heterozygote deficiency in populations of marine bivalves: evidence from pair matings of mussels

Mallet, André L.; Ζούρος, Ε.; Gartner-Kepkay, K. E.; Freeman, K. R.; Dickie, L. M.

doi:10.1007/bf00539424

Cited by 88 publications

(63 citation statements)

References 16 publications

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“…Some heterozygote deficiencies have been shown in progenies of controlled mass-matings, suggesting selection against heterozygotes during the larval phase (Adamkewicz et al, 1984;Alvarez et al 1989;Durand et al 1993); however random mating is not certain in this case, and some significant heterozygote excesses also appeared in the same experiments (Alvarez et al, 1989;Durand et al 1993;Hu et al 1993). Pairmating experiments also gave inconsistent results, yielding either heterozygote deficiencies or excesses compared to Mendelian expectations (Mallet et al 1985;Hu et al 1993). As pointed out by Beaumont (1993), larval contamination may be a source of trouble in these experiments.…”

Section: Pgm-93mentioning

confidence: 99%

FINE-GRAINED SPATIAL AND TEMPORAL POPULATION GENETIC STRUCTURE IN THE MARINE BIVALVESPISULA OVALIS

et al. 1997

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Section: Pgm-93mentioning

confidence: 99%

FINE-GRAINED SPATIAL AND TEMPORAL POPULATION GENETIC STRUCTURE IN THE MARINE BIVALVESPISULA OVALIS

et al. 1997

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“…Studies using laboratory reared single families and mass matings of mussels and other bivalves have already provided evidence of direct or indirect selection at a number of enzyme loci (Beaumont eta!., 1983; Adamkewicz et a!., 1984; Hvilsom and Theisen, 1984;Mallet et a!., 1985;Gaffney and Scott, 1984;Mallet et a!., 1986).…”

Section: Introductionmentioning

confidence: 99%

Genetic studies of laboratory reared Mytilus edulis. I. Genotype specific selection in relation to salinity

Beaumont¹,

Beveridge²,

Barnet³

et al. 1988

Heredity

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Significant deviations from the Hardy-Weinberg equilibrium in natural populations of bivalves may be due to a number of factors such as the Wahlund effect, null alleles and selection, and it is often difficult to decide which of these factors is operating. The use of laboratory controlled single crosses and mass matings, where the genotypes of the parents are known, can provide strong evidence for selection when deviations from expected genotype frequencies are observed in the offspring. Several cultures of offspring from a single cross and from a mass mating of the mussel, Mytilus edulis, were reared through the larval stage at either 32 or 25 parts per thousand salinity. At the early post-larval stage salinities were altered for some cultures while others remained unchanged. Samples were taken for electrophoresis as post-larvae and again as juveniles and were scored at the Lap, Pgm, Odh, Hex, Pgk and Gpi loci. Significant deviations from expected frequencies were observed at many loci in the offspring but these deviations did not appear to be related to salinity except at the Lap locus. The allele Lap94 was selected against at low salinity during the post-larval to juvenile stage, but no such selection occurred at low salinity during the larval stage. The data fit Koehn's (1985) model of post-larval selection at the Lap locus in mussels in Long Island Sound, USA, but suggest that there may be ontogenetic variation in fitness at this locus. Results at the Pgm and Gpi loci indicate that these loci are probably acting as markers for other loci on the same chromosome which have a strong effect on fitness. Density dependent factors may have caused some of the non-random mortality amongst offspring which was apparently independent of salinity.

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“…But such differences did not give predictions which fitted the data from B. rostratus (Colgan, 1981). Moreover, Beaumont, Beveridge and Budd (1983) and Mallet et a!. (1985) have demonstrated that heterozygous deficits occur in the progeny of single-pair matings conducted in the laboratory.…”

Section: Introductionmentioning

confidence: 95%

“…The uniformity of genotypic frequencies between sexes disallows the general involvement of sex-linkage (Koehn, Milkman and Mitton, 1976;Garthwaite, 1986). Breeding studies tend to discount the possibility of operation of some process whereby alleles are not expressed in a co-dominant manner in heterozygotes (Beaumont, Beveridge and Budd, 1983;Adamkewicz, Taub and Wall, 1984;Mallet et a!., 1985) although data on F2 and backcross generations are required before this point is proven. Colgan (1984) has shown that selection at loci in linkage disequilibrium is unlikely to cause significant segregation ratio distortions in pedigree analysis.…”

Section: Introductionmentioning

confidence: 99%

Deficits of heterozygotes in relation to selective interactions between loci in the mussels Brachidontes rostratus and Xenostrobus pulex

Colgan

1987

Heredity

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Each marine mussel which has been studied has a polymorphism for leucine aminopeptidase (LAP) loci. In each case, there is a deficit for all, or nearly all, classes of heterozygotes. The consistency of the results suggests that the loci constitute non-transient polymorphisms with heterozygous disadvantage. No satisfactory explanation of this situation has been available. Heterozygous deficits are also often found at other loci in mussels, particularly those encoding aminopeptidase (AP) enzymes. The present work was prompted by the theoretical investigations of Hastings (1982) which revealed the possibility that selective interactions with other loci might enable the maintenance of polymorphisms with marginal underdominance. Non-random associations between genotypes were sought in 10 loci (in four groups of enzymes with related functions) in Brachidonte% rostratus and five loci (in two groups) in Xenostrobus pulex. Five of the 30 pairs of loci displayed significant genotypic associations. However, none of these comprised functionally-related enzymes. It remains possible that epistatic interactions may, in special circumstances, be involved in the maintenance of variation. But the process seems unlikely as a general explanation of genotypic frequencies of the LAP and AP polymorphisms of mussels.

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Larval viability and heterozygote deficiency in populations of marine bivalves: evidence from pair matings of mussels

Cited by 88 publications

References 16 publications

FINE-GRAINED SPATIAL AND TEMPORAL POPULATION GENETIC STRUCTURE IN THE MARINE BIVALVESPISULA OVALIS

FINE-GRAINED SPATIAL AND TEMPORAL POPULATION GENETIC STRUCTURE IN THE MARINE BIVALVESPISULA OVALIS

Genetic studies of laboratory reared Mytilus edulis. I. Genotype specific selection in relation to salinity

Deficits of heterozygotes in relation to selective interactions between loci in the mussels Brachidontes rostratus and Xenostrobus pulex

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