Allozymes and fitness: Evolution of a problem

Eanes, Walter F.

doi:10.1016/0169-5347(87)90098-x

Cited by 36 publications

(18 citation statements)

References 23 publications

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“…Alternatively, selection acting multiplicatively on individual loci would require homozygote viabilities ranging from 0.60 to 0.90 to produce the genotypic distributions observed in November. These viability differentials would have caused the selective mortality of over half the population between September and November and are orders of magnitude larger than those inferred to exist at typical allozyme loci (Eanes, 1987). Therefore, a direct test of the selective-mortality hypothesis seemed necessary.…”

Section: Discussionmentioning

confidence: 99%

ENZYME HETEROZYGOSITY, GROWTH RATE, AND VIABILITY IN MYTILUS EDULIS : ANOTHER LOOK

Gaffney

1990

Evolution

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Section: Discussionmentioning

confidence: 99%

ENZYME HETEROZYGOSITY, GROWTH RATE, AND VIABILITY IN MYTILUS EDULIS : ANOTHER LOOK

Gaffney

1990

Evolution

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“…High levels of structural polymorphism have been documented in diverse species and evidence for high levels of regulatory polymorphism is also now accumulating, although the molecular bases of the latter have seldom been determined (but see Strand & McDonald, 1989;Laurie et al, 1992 for notable exceptions). Despite exhaustive effort, little unambiguous evidence for an adaptive role for structural polymorphism has thus far accumulated (Eanes, 1987;Aquadro, 1992 for reviews) and this has fuelled speculation that the regulatory variation may be of greater adaptive significance (Singh & Choudhary, 1989;Dickinson, 1991). However, direct experimental tests *Correspondence of the adaptive significance of regulatory variation are still few.…”

Section: Introductionmentioning

confidence: 99%

Causes and consequences of esterase 6 enzyme activity variation in pre-adult Drosophila melanogaster

et al. 1994

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We report heritable threefold differences in both larval and pupal esterase 6 activity among 17 isoallelic lines of D. melanogasrer extracted from a natural population. The activity differences in the two stages are only weakly correlated with each other or with previously determined values for esterase 6 activity in adults of these lines. The pre-adult activity variation is also unrelated to polymorphisms among the lines for six esterase 6 allozymes and six restriction sites in a region encompassing the esterase 6 coding DNA and the first kbp of 5' flanking DNA. However, two insertions, of 8.0 and 6.8 kbp, located about 1.4 kbp 5' of the esterase 6 coding region are associated with low activity in larvae and, to a lesser extent, in pupae, albeit not in adults. Restriction mapping reveals similarity between the 8.0 kbp insert and the 7.4 kbp retrotransposon 17.6. The differences in larval activity among lines are positively correlated with fitness as assessed from assays of pre-adult viability and development time but no significant associations between pupal esterase 6 activity and these measures are detected. Some effects of esterase 6 allozyme differences are also found for viability and development time but these effects could be explained by linkage disequilibrium between the 8.0 kbp insert and the EST6-9 allozyme.

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“…Thus, the controversy between selectionists and neutralists remains largely unresolved (2)(3)(4)(5). Statistical surveys suggest that some part of the allozyme variation cannot be due to random genetic drift (6)(7)(8)(9)(10).…”

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confidence: 99%

Strong natural selection causes microscale allozyme variation in a marine snail.

Johannesson¹,

Johannesson²,

Lundgren³

1995

Proc. Natl. Acad. Sci. U.S.A.

133

111

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Natural selection is one of the most fundamental processes in biology. However, there is still a controversy over the importance of selection in microevolution of molecular traits. Despite the general lack ofdata most authors hold the view that selection on molecular characters may be important, but at lower rates than selection on most phenotypic traits. Here we present evidence that natural selection may contribute substantially to molecular variation on a scale of meters only. In populations of the marine snail Littorina saxatilis living on exposed rocky shores, steep microclines in allele frequencies between splash and surf zone groups are present in the enzyme aspartate aminotransferase (allozyme locus Aat; EC. 2.6.1.1). We followed one population over 7 years, including a period of strong natural perturbation. The surf zone part of the population dominated by the allele atwl' was suddenly eliminated by a bloom of a toxin-producing microflagellate. Downshore migration of splash zone snails with predominantlyAat120 alleles resulted in a drastic increase in surf zone frequency of Aat 20, from 0.4 to 0.8 over 2 years. Over the next four to six generations, however, the frequency of Aat120 returned to the original value. We estimated the coefficient of selection ofAat120 in the surfzone to be about 0.4. Earlier studies show similar or even sharperAat clines in other countries. Thus, we conclude that microclinal selection is an important evolutionary force in this system.

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Allozymes and fitness: Evolution of a problem

Cited by 36 publications

References 23 publications

ENZYME HETEROZYGOSITY, GROWTH RATE, AND VIABILITY IN MYTILUS EDULIS : ANOTHER LOOK

ENZYME HETEROZYGOSITY, GROWTH RATE, AND VIABILITY IN MYTILUS EDULIS : ANOTHER LOOK

Causes and consequences of esterase 6 enzyme activity variation in pre-adult Drosophila melanogaster

Strong natural selection causes microscale allozyme variation in a marine snail.

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