A Comparison of the Relative Fitness of Genotypes Segregating for the t<sup>w2</sup>Allele in Laboratory Stock and Its Possible Effect on Gene Frequency in Mouse Populations

Johnston, Phyllis G.; Brown, G. H.

doi:10.1086/282577

Cited by 31 publications

(21 citation statements)

References 5 publications

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“…Since the present study shows outbreeding is common, systematic inbreeding is an unlikely explanation. Few data exist to support either lower transmission frequencies or selection against heterozygotes (Martin and Andrewartha, 1962;Johnston and Brown, 1969).…”

Section: Discussionmentioning

confidence: 99%

Gene Flow in House Mice: Introduction of a New Allele Into Free‐living Populations

Baker

1981

Evolution

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Section: Discussionmentioning

confidence: 99%

Gene Flow in House Mice: Introduction of a New Allele Into Free‐living Populations

Baker

1981

Evolution

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“…In addition, it is unlikely that the fitness of tit females is sufficiently high to result in a substantial increase in the frequency of heterozygotes in wild populations. Indeed, fertility of t w2 /t w2 females is considerably lower than that of either +/+ or +/t females (Johnston and Brown, 1969), Thus, selection possibly is nearly as intense against individuals homozygous for semilethal haplotypes as against individuals homozygous for lethal hapJotypes. If this is the case, the lower transmission ratio of males carrying semilethal haplotypes would be expected to produce lower frequencies of t-carrying individuals in populations with semilethal than in populations with lethal alleles.…”

Section: Resljl Ts and Discljssionmentioning

confidence: 97%

“…The debate over factors controlling the frequency of t-haplotypes in natural populations has arisen because theoretical models incorporating selection against homozygotes counteracted by transmission-ratio distortion yield predicted equilibrium frequencies of t-carrying individuals substantially higher than those actually observed (Bruck, 1957; I?,u.nn and Levene, 1961; Lewontin, 1968). Hypotheses proposed to account for the lower thun.expected frequency of t-haplotypes have included inbreeding (Petras, 1967), genetic drift (Le·wontin· andDunn, 1960), interdemic selection (Lewontin, 1962), heterozygote disadvantage (Drickamer and Lenington, 1987;Egid and Lenington, 1985;Johnston and Brown, 1969;Lenington, 1983;Lenington and Egid, 1985; Levine et aI., 1980;Meyers, 1973) and lowered transmission ratio of t-haplotypes in natural matings as compared with laboratory test crosses (Lenington, 1986; Levin et aI., 1969).Recently, we began to explore in detail the possibility of differences in fitness between + I + and +It mice. We found that both male and female mice can discriminate +1+ from +It individuals of the opposite sex on the basis of odor alone and select odors of + I + animals Lenington, 1983;Lenington and Egid, 1985).…”

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confidence: 99%

Distribution of T-Haplotypes in Natural Populations of Wild House Mice

Lenington

Franks

Williams

1988

Journal of Mammalogy

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ABSTRAcr.-Data obtained from published studies and from mice trapped for use in our laboratory were analyzed to determine the relationship between frequency of t-haplotypes in wild house mice (Mus musculus) and other variables such as sex, age at capture, and kind of t-haplotype found in the population. In addition, the frequency of t-alleles in populations from which mice had been sampled repeatedly was examined to determine whether, within populations, frequency of t-haplotypes tends to change over time. Populations in which semilethal haplotypes predominated had higher frequencies of heterozygous animals than populations in which the predominant haplotype was a lethaL Furthermore, frequencies of t-haplotypes were higher in males than in females. However, no difference in frequency of t-alleles was found between mice trapped as juveniles and individuals of the same sex trapped as adults. Furthermore, only one of 14 populations from which mice were trapped repeatedly showed evidence of a change in frequency of heterozygotes over time. The relevance of these data for potential processes controlling the frequency of t-haplotypes in wild populations is discussed.Considerable debate (Lacy, 1978) has existed over factors controlling the frequency of alleles at the T-locus in wild house mice (Mus musculus). About 25% of wild house mice are heterozygous (+ It) for a variable recessive allele and the remainder usually are homozygous (+ I +) for the wild-type allele (Bennett, 1978). All recessive t-alleles (or t-haplotypes) are deleterious when homozygous. Some alleles (designated "semilethal") produce some viable homozygotes but cause sterility in homozygous males. Others ("lethal alleles") cause death in all homozygous embryos. These lethal haplotypes can be classified further by complementation testing into 16 groups (Klein et aI., 1984) of which two (t wi and t wS ) are common in North American wild house mice (Bennett, 1978).The principal factor maintaining these deleterious alleles in wild populations is transmissionratio distortion in heterozygous males that may transmit their t-haplotype to as many as 95-100% of their progeny. The debate over factors controlling the frequency of t-haplotypes in natural populations has arisen because theoretical models incorporating selection against homozygotes counteracted by transmission-ratio distortion yield predicted equilibrium frequencies of t-carrying individuals substantially higher than those actually observed (Bruck, 1957; I?,u.nn and Levene, 1961; Lewontin, 1968). Hypotheses proposed to account for the lower thun.expected frequency of t-haplotypes have included inbreeding (Petras, 1967), genetic drift (Le·wontin· andDunn, 1960), interdemic selection (Lewontin, 1962), heterozygote disadvantage (Drickamer and Lenington, 1987;Egid and Lenington, 1985;Johnston and Brown, 1969;Lenington, 1983;Lenington and Egid, 1985; Levine et aI., 1980;Meyers, 1973) and lowered transmission ratio of t-haplotypes in natural matings as compared with laboratory test crosses (Lenington, 19...

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“…For a variety of reasons, the distorter alleles have additional negative fitness effects in heterozygous condition (e.g., Johnston and Brown 1969;Ardlie and Silver 1996a;Ardlie 1998 and references therein). This is especially so for heterozygous males.…”

Section: Male Fertilitymentioning

confidence: 99%

EVOLUTION AT THE MOUSE t COMPLEX: WHY IS THE t HAPLOTYPE PRESERVED AS AN INTEGRAL UNIT?

Boven¹,

Weissing

2000

Evolution

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Segregation distorters are selfish genetic elements that bias Mendelian segregation in their favor. All well-known segregation distortion systems consist of one or more "distorter" loci that act upon a "responder" locus. At the t complex of the house mouse, segregation distortion is brought about by the harmful effect of t alleles at a number of distorter loci on the wild-type variant of the responder locus. The responder and distorter alleles are closely linked by a number of inversions, thus forming a coherent t haplotype. It has been conjectured that the close integration of the various components into a "complete" t haplotype has been crucial for the evolutionary success of these selfish genetic elements. By means of a population genetical metapopulation model, we show that this intuition may be unfounded. In fact, under most circumstances an "insensitive" t haplotype retaining only the responder did invade and reach a high frequency, despite the fact that this haplotype has a strong segregation disadvantage. For certain population structures, the complete t haplotype was even competitively excluded by partial t haplotypes with lower segregation ratios. Moreover, t haplotypes carrying one or more recessive lethals only prevailed over their nonlethal counterparts if the product of local population size and migration rate (Nm) was not much smaller or larger than one. These phenomena occurred for rather realistic fitness, segregation, and recombination values. It is therefore quite puzzling that partial t haplotypes are absent from natural house mousepopulations, and that t haplotypes carrying recessive lethals prevail over nonlethal t haplotypes.

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A Comparison of the Relative Fitness of Genotypes Segregating for the t^w2Allele in Laboratory Stock and Its Possible Effect on Gene Frequency in Mouse Populations

Cited by 31 publications

References 5 publications

Gene Flow in House Mice: Introduction of a New Allele Into Free‐living Populations

Gene Flow in House Mice: Introduction of a New Allele Into Free‐living Populations

Distribution of T-Haplotypes in Natural Populations of Wild House Mice

EVOLUTION AT THE MOUSE t COMPLEX: WHY IS THE t HAPLOTYPE PRESERVED AS AN INTEGRAL UNIT?

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A Comparison of the Relative Fitness of Genotypes Segregating for the tw2Allele in Laboratory Stock and Its Possible Effect on Gene Frequency in Mouse Populations

Cited by 31 publications

References 5 publications

Gene Flow in House Mice: Introduction of a New Allele Into Free‐living Populations

Gene Flow in House Mice: Introduction of a New Allele Into Free‐living Populations

Distribution of T-Haplotypes in Natural Populations of Wild House Mice

EVOLUTION AT THE MOUSE t COMPLEX: WHY IS THE t HAPLOTYPE PRESERVED AS AN INTEGRAL UNIT?

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A Comparison of the Relative Fitness of Genotypes Segregating for the t^w2Allele in Laboratory Stock and Its Possible Effect on Gene Frequency in Mouse Populations