Heritability of sexual proportion in experimental sex-ratio populations of Drosophila mediopunctata

Varandas, Flavia Roque; Sampaio, Michelle Cristina; Carvalho, Antonio Bernardo

doi:10.1038/hdy.1997.128

Cited by 25 publications

(15 citation statements)

References 27 publications

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“…Second, sex-ratio has a much greater effect on the rest of genome precisely because it affects the sex ratio, and thus, the transmission rates of different genomic compartments. In addition to favoring modifiers that reduce any fitness cost, sex-ratio favors modifiers that render the sex ratio more equal, as mandated by Fisher's principle [52]. The evolutionary cycle of distorter and suppressor could go on indefinitely as long as new sex-ratio mutations unaffected by existing suppressors can occur.…”

Section: Discussionmentioning

confidence: 99%

A sex-ratio Meiotic Drive System in Drosophila simulans. I: An Autosomal Suppressor

et al. 2007

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Sex ratio distortion (sex-ratio for short) has been reported in numerous species such as Drosophila, where distortion can readily be detected in experimental crosses, but the molecular mechanisms remain elusive. Here we characterize an autosomal sex-ratio suppressor from D. simulans that we designate as not much yang (nmy, polytene chromosome position 87F3). Nmy suppresses an X-linked sex-ratio distorter, contains a pair of near-perfect inverted repeats of 345 bp, and evidently originated through retrotransposition from the distorter itself. The suppression is likely mediated by sequence homology between the suppressor and distorter. The strength of sex-ratio is greatly enhanced by lower temperature. This temperature sensitivity was used to assign the sex-ratio etiology to the maturation process of the Y-bearing sperm, a hypothesis corroborated by both light microscope observations and ultrastructural studies. It has long been suggested that an X-linked sex-ratio distorter can evolve by exploiting loopholes in the meiotic machinery for its own transmission advantage, which may be offset by other changes in the genome that control the selfish distorter. Data obtained in this study help to understand this evolutionary mechanism in molecular detail and provide insight regarding its evolutionary impact on genomic architecture and speciation.

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Section: Discussionmentioning

confidence: 99%

A sex-ratio Meiotic Drive System in Drosophila simulans. I: An Autosomal Suppressor

et al. 2007

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“…meiotic drive. Such sex ratio distorters are known to spread rapidly in outcrossing populations and to invoke strong autosomal counter‐selection (Hurst et al 1996; Varandas et al 1997; Carvalho et al 1998; Blows et al 1999). If drive suppressors do not evolve, sex ratio distorters will frequently become fixed, i.e.…”

Section: Potential Parental Control Mechanisms At Meiosismentioning

confidence: 99%

Why Parental Sex Ratio Manipulation is Rare in Higher Vertebrates (Invited Article)

Krackow

2002

Ethology

112

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The debate over adaptive parental sex ratio adjustment in higher vertebrates appears neither to be resolvable by the current approach, nor does it necessarily make sense. It rests on the a priori supposition of parental manipulation, which is questioned here from first principle. It is considered an unlikely biological hypothesis if we extend our perspective to gametic and offspring optimal strategies, and to the potential mechanisms existing in the avian and mammalian reproductive systems. Evenness of primary sex ratios is expected to be optimal from the gametic point of view and is supposed here to be the more likely evolutionary outcome. Also, manipulations by sex‐selective offspring mortality is argued to be unlikely as usually the benefits will be surpassed by the costs incurred. Furthermore, parents can adjust behavioural and energetic investment patterns to their offspring sex (ratio), thereby minimizing any costs of sex ratio control inability. Slight biases in offspring sex ratios are then viewed as resulting from physiological limitations ultimately relating to sex differences in embryonic development. Contrary to recent attempts to understand higher vertebrate sex ratio variation by further refinement of functional models (of parental optima) and data analysis, Bayesian logic precludes those approaches to gain useful new insights. To prove the basic assumption of parental manipulation, apart from defining gametic and offspring optima, the emphasis should lie on identifying control mechanisms by experimental verification.

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“…Data for other species are scarce or absent but the persistence of SR polymorphisms in natural populations strongly suggests that SR chromosomes are also deleterious in these cases. For example, the frequency of SR in a natural population of D. mediopunctata did not change in 10 years (1987: 13.2% 1997: 14.0%; Varandas et al. , 1997 ; A.…”

Section: Introductionmentioning

confidence: 99%

Are Drosophila SR drive chromosomes always balanced?

Carvalho

Vaz

1999

Heredity

Self Cite

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SR chromosomes are the best-known case of sex chromosome meiotic drive. These X chromosomes cause the production of female-biased progenies in several Drosophila species. Due to their meiotic drive advantage, they are expected to spread and become ®xed, resulting in population extinction due to the lack of males. However, this apparently does not occur: SR chromosomes are maintained in balanced polymorphisms, resulting from the equilibrium between their meiotic drive advantage and deleterious ®tness e ects. In this paper we review the current explanations for their deleterious e ects and we argue that it is highly improbable that all newly emerged SR are su ciently deleterious to avoid ®xation. Unbalanced SR almost certainly arise and go unnoticed because of three possible outcomes: (i) ®xation followed by extinction of the population or species; (ii) ®xation followed by the emergence and ®xation of drive suppressors, restoring the normal 1:1 sexual proportion; or (iii) transformation into balanced SR due to partial suppression. If these outcomes really occur, then extant cases of sex-chromosome meiotic drive such as SR, causing small deviations on the population sexual proportion, are only the tip of the iceberg and strong sexual proportion shifts (possibly followed by extinction) are a more common feature of species evolution than is usually assumed.

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Heritability of sexual proportion in experimental sex-ratio populations of Drosophila mediopunctata

Cited by 25 publications

References 27 publications

A sex-ratio Meiotic Drive System in Drosophila simulans. I: An Autosomal Suppressor

A sex-ratio Meiotic Drive System in Drosophila simulans. I: An Autosomal Suppressor

Why Parental Sex Ratio Manipulation is Rare in Higher Vertebrates (Invited Article)

Are Drosophila SR drive chromosomes always balanced?

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