Multiple Mating and the "Sex-Ratio" Trait in Drosophila pseudoobscura

Evolution ◽  
1981 ◽  
Vol 35 (2) ◽  
pp. 275 ◽  
Author(s):  
Andrew Beckenbach
Keyword(s):  
Sex Ratio ◽  
Multiple Mating ◽  
Drosophila Pseudoobscura

scholarly journals VIRILITY DEFICIENCY AND THE SEX-RATIO TRAIT IN DROSOPHILA PSEUDOOBSCURA. II. MULTIPLE MATING AND OVERALL VIRILITY SELECTION

Genetics ◽  
1983 ◽  
Vol 105 (3) ◽  
pp. 663-679
Author(s):  
Chung-I Wu
Keyword(s):  
Theoretical Model ◽  
Sex Ratio ◽  
Multiple Mating ◽  
The Other ◽  
Drosophila Pseudoobscura ◽  
Relative Importance ◽  
Fitness Components ◽  
Female Remating

ABSTRACT Previous studies on fitness components of Drosophila have shown the over-whelming importance of virility selection. In this study, virility selection is further partitioned into two components—one with respect to virgin females and the other with respect to nonvirgin females. The relative importance of the two components to the overall virility selection depends on the remating tendency of females which is investigated here. A theoretical model is then proposed to estimate virility selection under the condition of frequent female remating. The model is tested experimentally. When this model is applied to the Sex-Ratio system of D. pseudoobscura, Sex-Ratio males are found to suffer substantial virility reduction. The significance of this finding to the Sex-Ratio problem is discussed.

Multiple Mating and Female Fitness in Drosophila pseudoobscura

Evolution ◽  
1983 ◽  
Vol 37 (4) ◽  
pp. 714 ◽  
Author(s):  
Monte E. Turner ◽  
Wyatt W. Anderson
Keyword(s):  
Multiple Mating ◽  
Drosophila Pseudoobscura ◽  
Female Fitness

scholarly journals Evolution of male strategies with sex-ratio–dependent pay-offs: connecting pair bonds with grandmothering

2017 ◽  
Vol 372 (1729) ◽  
pp. 20170041 ◽  
Author(s):  
Sara L. Loo ◽  
Kristen Hawkes ◽  
Peter S. Kim
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Human Evolution ◽  
Paternal Care ◽  
Multiple Mating ◽  
Sex Ratios ◽  
Mate Guarding ◽  
Equation Model ◽  
Pair Bonding ◽  
Pair Bonds

Men's provisioning of mates and offspring has been central to ideas about human evolution because paternal provisioning is absent in our closest evolutionary cousins, the great apes, and is widely assumed to result in pair bonding, which distinguishes us from them. Yet mathematical modelling has shown that paternal care does not readily spread in populations where competition for multiple mates is the common male strategy. Here we add to models that point to the mating sex ratio as an explanation for pairing as pay-offs to mate guarding rise with a male-biased sex ratio. This is of interest for human evolution because our grandmothering life history shifts the mating sex ratio from female- to male-biased. Using a difference equation model, we explore the relative pay-offs for three competing male strategies (dependant care, multiple mating, mate guarding) in response to changing adult sex ratios. When fertile females are abundant, multiple mating prevails. As they become scarce, mate guarding triumphs. The threshold for this shift depends on guarding efficiency. Combined with mating sex ratios of hunter–gatherer and chimpanzee populations, these results strengthen the hypothesis that the evolution of our grandmothering life history propelled the shift to pair bonding in the human lineage. This article is part of the themed issue ‘Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies’.

scholarly journals Sex ratios in natural populations of Drosophila pseudoobscura from Mexico

Genetika ◽  
2012 ◽  
Vol 44 (3) ◽  
pp. 491-498 ◽  
Author(s):  
Victor Salceda ◽  
Carolina Arceo-Maldonado
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Natural Populations ◽  
Diploid Species ◽  
Drosophila Pseudoobscura ◽  
Adult Offspring ◽  
Equal Proportion ◽  
X Chromosomes ◽  
The Individual ◽  
Number Of Males

Most species show an equal proportion of individuals of both sexes. In diploid species sex ratio is determined by a genic balance between sex chromosomes. In Drosophila sex is determined by the ratio of X- chromosomes versus autosomes and in some species of the genus it is related to the presence of an inversion in the sex chromosome. The present work analyses the sex ratio in 27 natural populations of Drosophila pseudoobscura that inhabit Mexico. Female flies captured in nature were counted and their sex ratio calculated and been called generation P, then cultured individualy, allowed to leave adult offspring which was quantified in order to get its sex ratio and designated generation F1. sex ratio was calculated using the expression: number of males times 100 divided by the number of females proposed by Darwin (1871). The sex ratio of each population was taken using the average of all the individual counts from each sample. The values found varied among different generations and populations, so for generation P their values varieded 37.4 to 190.4 and in generation F1 from 31.3 up to 96.4 males for each 100 females. According to their geographical distribution four North to South transects were arranged and in them means varied from 60.8 to 81.7 males for each 100 females. All this means that in Mexican population are more females than males, exceptionally more males than females.

EVIDENCE FOR EXTENSIVE GENETIC DIFFERENTIATION BETWEEN THE SEX-RATIO AND THE STANDARD ARRANGEMENT OF DROSOPHILA PSEUDOOBSCURA AND D. PERSIMILIS AND IDENTIFICATION OF HYBRID STERILITY FACTORS

Genetics ◽  
1983 ◽  
Vol 105 (1) ◽  
pp. 71-86
Author(s):  
Chung-I Wu ◽  
Andrew T Beckenbach
Keyword(s):  
Sex Ratio ◽  
Genetic Differentiation ◽  
Genetic Background ◽  
Hybrid Sterility ◽  
Strong Support ◽  
Meiotic Drive ◽  
Complete Loss ◽  
Drosophila Pseudoobscura ◽  
Drosophila Persimilis ◽  
Standard Arrangement

ABSTRACT This study deals with sex-ratio genes tightly linked within the Sex-Ratio inversion. By taking advantage of the fact that the Sex-Ratio chromosome of Drosophila persimilis [SR(B)] is homosequential to the Standard chromosome of D. pseudoobscura [ST(A)], we carried out two reciprocal introgression experiments. Individual segments of SR(B) or ST(A) were introgressed into the genome of D. pseudoobscura or D. persimilis, respectively. Males possessing a hybrid SR(B)-ST(A) X chromosome and a genetic background derived from either of the two species were tested for fertility and sex-ratio expression.—It was found that, in terms of the meiotic drive genes, the Sex-Ratio chromosome differs extensively from the Standard chromosome. Because recombinations of these genes result in a complete loss of sex-ratio expression, this finding lends strong support to the hypothesis of gene coadaptation. Coadaptation, in this context, is the advantage of being transmitted preferentially. In light of this finding, the evolution of the sex-ratio system in these two sibling species is discussed.—Introgression experiments also yielded information about hybrid sterility. With reciprocal introgression, sterility interactions were found to be "asymmetric." The asymmetry is fully expected from the viewpoint of evolution of postmating reproductive isolation.

No evidence of mate discrimination against males carrying a sex ratio distorter in Drosophila pseudoobscura

2011 ◽  
Vol 66 (4) ◽  
pp. 561-568 ◽  
Author(s):  
T. A. R. Price ◽  
Z. Lewis ◽  
D. T. Smith ◽  
G. D. D. Hurst ◽  
N. Wedell
Keyword(s):  
Sex Ratio ◽  
Drosophila Pseudoobscura

"Sex Ratio" in Drosophila pseudoobscura: Spermiogenic Failure

Science ◽  
1970 ◽  
Vol 169 (3948) ◽  
pp. 888-889 ◽  
Author(s):  
D. Policansky ◽  
J. Ellison
Keyword(s):  
Sex Ratio ◽  
Drosophila Pseudoobscura
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