HOMOZYGOUS VIABILITY AND FERTILITY LOADS IN <i>DROSOPHILA MELANOGASTER </i>

Temin, Rayla Greenberg

doi:10.1093/genetics/53.1.27

Cited by 49 publications

(13 citation statements)

References 22 publications

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“…The qualitative difference observed between male and female fertility loads indicates that this species carries recessive alleles which, when homozygous, cause male sterility, but no equivalent recessives affecting female fertility. That male sterility recessives do not cause sterility in females is not surprising considering the differences in egg and sperm development, matching the sex-specificity of sterility (but not inviability) factors in Drosophila (Chung 1962;Temin 1966;Lindsley & Tokuyasu 1980, p. 273). The real puzzle of these results is twofold: why is the magnitude of the male fertility load so great, and why, by contrast, is the female fertility load negligible?…”

Section: Results and Discussion (A) Separating Viability From Fertility Effectsmentioning

confidence: 91%

“…These results are consistent with our previous interpretation of the pattern of heterosis in this species (Saccheri et al 1996), but also allow the separate quantification of zygote viability load and fertility load. The zygote and embryo viability load (V ) estimated from P and F 1 egg hatching distributions was 1:75^1:29 (95% confidence interval) lethal equivalents per zygote, which is about twice the viability load in Drosophila (when calculated in an equivalent way and assuming that two-thirds of the load affecting egg to adult survival in Drosophila affects viability Male-biased inbreeding depression I. J. Saccheri and others 41 rather than fertility (see Pavan et al 1951;Temin 1966;Saccheri et al 1996)). The fertility load (S ) estimated from P and XP egg hatching distributions, where in XP parents are inbred but their offspring are outcrossed, was 5.47^0.24.…”

Section: Results and Discussion (A) Separating Viability From Fertility Effectsmentioning

confidence: 97%

“…The historical focus of Drosophila (Simmons & Crow 1977) and mammalian (Ralls et al 1988) studies on quantifying viability loads has led to effects on fertility being sidelined. Two notable exceptions are Chung (1962) and Temin (1966), showing that, in D. melanogaster, chromosome II homozygotes causing complete sterility were two to three times as common for males than females. Also, the ratio of partial to complete male sterility loads in Drosophila (0.5) is similar to that in B. anynana (0.45, obtained by excluding the zero class).…”

Section: Results and Discussion (A) Separating Viability From Fertility Effectsmentioning

confidence: 99%

“…Selection in only one sex retards the elimination of deleterious alleles, leading to higher equilibrium allele frequencies compared with an equivalent bi-sexually selected trait. A simple mutation-selection balance model (see Appendix B) suggests that, while sex-limited selection may well favour higher fertility loads in general, it is insufficient, on its own, to account for the magnitude of the male fertility load in B. anynana, or a fertility : viability load ratio of 4 (6.99/1.75)as opposed to an equivalent ratio of 0.5 for D. melanogaster chromosome II (Temin 1966). Certainly in the case of Bicyclus this ratio reflects more than differences in the number of mutable genes affecting fertility versus viability, which Drosophila data suggest is at least three times greater for viability (Lindsley & Lifschytz 1972).…”

Section: Results and Discussion (A) Separating Viability From Fertility Effectsmentioning

confidence: 99%

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Inbreeding uncovers fundamental differences in the genetic load affecting male and female fertility in a butterfly

et al. 2004

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Inbreeding depression is most pronounced for traits closely associated with fitness. The traditional explanation is that natural selection eliminates deleterious mutations with additive or dominant effects more effectively than recessive mutations, leading to directional dominance for traits subject to strong directional selection. Here we report the unexpected finding that, in the butterfly Bicyclus anynana, male sterility contributes disproportionately to inbreeding depression for fitness (complete sterility in about half the sons from brother-sister matings), while female fertility is insensitive to inbreeding. The contrast between the sexes for functionally equivalent traits is inconsistent with standard selection arguments, and suggests that trait-specific developmental properties and cryptic selection play crucial roles in shaping genetic architecture. There is evidence that spermatogenesis is less developmentally stable than oogenesis, though the unusually high male fertility load in B. anynana additionally suggests the operation of complex selection maintaining male sterility recessives. Analysis of the precise causes of inbreeding depression will be needed to generate a model that reliably explains variation in directional dominance and reconciles the gap between observed and expected genetic loads carried by populations. This challenging evolutionary puzzle should stimulate work on the occurrence and causes of sex differences in fertility load.

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Section: Results and Discussion (A) Separating Viability From Fertility Effectsmentioning

confidence: 91%

Section: Results and Discussion (A) Separating Viability From Fertility Effectsmentioning

confidence: 97%

Section: Results and Discussion (A) Separating Viability From Fertility Effectsmentioning

confidence: 99%

Section: Results and Discussion (A) Separating Viability From Fertility Effectsmentioning

confidence: 99%

See 2 more Smart Citations

Inbreeding uncovers fundamental differences in the genetic load affecting male and female fertility in a butterfly

et al. 2004

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“…Among the homozygotes of quasinormal viability, the following percentages of chromosomes induced complete sterility of the females: 10.6% for second, 13.6% for third, and 4.3% for the fourth chromosomes. SWEET and SPIES (1962) found in D. melanogaster 7.9% of the homozygotes for the second and 7.8% for the third chromosomes completely sterile as females; a comparable figure obtained for second chromosomes by TEMIN (1966) is 4.2%. In the present study, only 5.1% (6 out of 118) of second chromosomes of D. pseudoabscura, giving quasinormal or mild semilethal viabilities, proved almost completely sterile, yielding fewer than one individual in the progeny after a six-day period of egg laying.…”

Section: Viability (Percent Wild Type) Fecundity (Eggs In Six Days) Suruiual (Percent Suruiuors From Eggs To Adults) and Fertility (The Pmentioning

confidence: 84%

GENETIC LOADS AFFECTING FERTILITY IN NATURAL POPULATIONS OF DROSOPHILA PSEUDOOBSCURA

Marinković¹

1967

Genetics

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A study of the genetic loads affecting fecundity of females of Drosophila pseudoobscura has recently been reported in this journal ( MARINKOVIC 1967). It has been shown that females homozygous-for second chromosomes derived from natural populations deposit on the average fewer eggs than do females carrying two second chromosomes derived from different wild progenitors. The present report extends the study to the egg-to-adult viability of the progenies of homozygous and heterozygous females, and thus permits estimation of the reduction of the fertility caused by the manifestation of these normally concealed genetic loads. MATERIALS A N D METHODS ' T h e work reported in this article has been carried out under Contract No. AT-(30-1)-3096, U.S. Atomic Energy Commission.

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How much do we know about spontaneous human mutation rates?

Crow

1993

Environ and Mol Mutagen

136

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The much larger number of cell divisions between zygote and sperm than between zygote and egg, the increased age of fathers of children with new dominant mutations, and the greater evolution rate of pseudogenes of the Y chromosome than of those on autosomes all point to a much higher mutation rate in human males than in females, as first pointed out by Haldane [Ann Eugen 13:262-271, 1947] in his classical study of X-linked hemophilia. The age of the father is the main factor determining the human spontaneous mutation rate, and probably the total mutation rate. The total mutation rate in Drosophila males of genes causing minor reduction in viability is at least 0.4 per sperm, and may be considerably higher. The great mutation load implied by a rate of approximately 1 per zygote can be greatly ameliorated by quasi-truncation selection. Corresponding data are not available for the human population. The evolution rate of pseudogenes in primates suggests some 10(2) new mutations per zygote. Presumably the overwhelming majority of these are neutral, but even the approximate fraction is not known. Statistical evidence in Drosophila shows that mutations with minor effects cause about the same heterozygous impairment of fitness as those that are lethal when homozygous. The magnitude of heterozygous effect is such that almost all mutant genes are eliminated as heterozygotes before ever becoming homozygous. Although quantitative data in the human species are lacking, anecdotal information supports the conclusion that partial dominance is the rule here as well. This suggests that if the human mutation rate were increased or decreased, the effects would be spread over a period of 50-100 generations.

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HOMOZYGOUS VIABILITY AND FERTILITY LOADS IN DROSOPHILA MELANOGASTER

Cited by 49 publications

References 22 publications

Inbreeding uncovers fundamental differences in the genetic load affecting male and female fertility in a butterfly

Inbreeding uncovers fundamental differences in the genetic load affecting male and female fertility in a butterfly

GENETIC LOADS AFFECTING FERTILITY IN NATURAL POPULATIONS OF DROSOPHILA PSEUDOOBSCURA

How much do we know about spontaneous human mutation rates?

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