| 1. |
- Iinatti Brengdahl, Martin, 1990-, et al.
(författare)
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Age-specific effects of deletions: Implications for ageing theories
- 2022
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Annan publikationabstract
- Evolution of ageing requires mutations with late-life deleterious effects. Classic theories assume these mutations either have neutral (Mutation Accumulation) or beneficial (Antagonistic Pleiotropy) effects early in life, but it is also possible that they start out as mildly harmful and gradually become more deleterious with age. Despite a wealth of studies on the genetics of ageing, we still have a poor understanding of how common mutations with age-specific effects are and what ageing theory they support. To advance our knowledge on this topic we measure a set of genomic deletions for their heterozygous effects on juvenile performance, fecundity at three ages, and adult survival. Most deletions have age-specific effects, and these are commonly harmful late in life. Many of the deletions assayed here would thus contribute to ageing if present in a population. Taking only age-specific fecundity into account, some deletions support Antagonistic Pleiotropy, but the majority of them better fit a scenario where their negative effects on fecundity become progressively worse with age. Most deletions have a negative effect on juvenile performance, a fact which strengthens the conclusion that deletions primarily contribute to ageing through negative effects that amplify with age.
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| 2. |
- Iinatti Brengdahl, Martin, et al.
(författare)
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Age-specific effects of deletions: implications for aging theories
- 2023
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Ingår i: Evolution. - : OXFORD UNIV PRESS. - 0014-3820 .- 1558-5646. ; 77:1, s. 254-263
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of aging requires mutations with late-life deleterious effects. Classic theories assume these mutations either have neutral (mutation accumulation) or beneficial (antagonistic pleiotropy) effects early in life, but it is also possible that they start out as mildly harmful and gradually become more deleterious with age. Despite a wealth of studies on the genetics of aging, we still have a poor understanding of how common mutations with age-specific effects are and what aging theory they support. To advance our knowledge on this topic, we measure a set of genomic deletions for their heterozygous effects on juvenile performance, fecundity at 3 ages, and adult survival. Most deletions have age-specific effects, and these are commonly harmful late in life. Many of the deletions assayed here would thus contribute to aging if present in a population. Taking only age-specific fecundity into account, some deletions support antagonistic pleiotropy, but the majority of them better fit a scenario where their negative effects on fecundity become progressively worse with age. Most deletions have a negative effect on juvenile performance, a fact that strengthens the conclusion that deletions primarily contribute to aging through negative effects that amplify with age.
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| 3. |
- Malacrino, Antonino, et al.
(författare)
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Ageing desexualizes the Drosophila brain transcriptome
- 2022
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - London : The Royal Society Publishing. - 0962-8452 .- 1471-2954. ; 289:1980
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Tidskriftsartikel (refereegranskat)abstract
- General evolutionary theory predicts that individuals in low condition should invest less in sexual traits compared to individuals in high condition. Whether this positive association between condition and investment also holds between young (high condition) and senesced (low condition) individuals is however less clear, since elevated investment into reproduction may be beneficial when individuals approach the end of their life. To address how investment into sexual traits changes with age, we study genes with sex-biased expression in the brain, the tissue from which sexual behaviours are directed. Across two distinct populations of Drosophila melanogaster, we find that old brains display fewer sex-biased genes, and that expression of both male-biased and female-biased genes converges towards a sexually intermediate phenotype owing to changes in both sexes with age. We further find that sex-biased genes in general show heightened age-dependent expression in comparison to unbiased genes and that age-related changes in the sexual brain transcriptome are commonly larger in males than females. Our results hence show that ageing causes a desexualization of the fruit fly brain transcriptome and that this change mirrors the general prediction that low condition individuals should invest less in sexual phenotypes.
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| 4. |
- Mital, Avani, et al.
(författare)
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Shorter effective lifespan in laboratory populations of D. melanogaster might reduce sexual selection
- 2022
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer. - 0340-5443 .- 1432-0762. ; 76:4
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Tidskriftsartikel (refereegranskat)abstract
- The role of sexual selection in mediating levels of sexual conflict has been demonstrated in many experimental evolution studies on Drosophila spp. where competition among males for mating was the target of selection. Sexual selection has also been shown to affect the evolution of life-histories. However, the influence of divergent life-histories on reproductive strategies and, therefore, sexual selection and possibly sexual conflict has been less well studied. We examined D. melanogaster populations selected for a short development time and early age at reproduction for changes in reproductive behavior and traits that are proxies of sexual selection. We report a large reduction in reproductive competition experienced by the males of these populations, compared to ancestral populations that are not consciously selected for rapid development or early reproduction, potentially leading to reduced sexual selection. We show that rapidly developing and early reproducing populations have very low levels of mating in their lifetime (females are more or less monandrous), low courtship levels, shorter copulation duration, and longer time from eclosion to first mating, compared to the controls. These results are discussed in the context of the previously demonstrated reduction of inter-locus sexual conflict in these populations. We show that life-history strategies might have a large and significant impact on sexual selection, with each influencing the other and contributing to the complexities of adaptation. Significance statement Sexual conflict, often manifested as an arms-race between males and females trying to enhance their own reproductive success at some cost to the other, is of great evolutionary interest because it can maintain genetic variation in populations, prevent the independent optimization of male and female traits, and also promote speciation. Sexual selection, or variation in mating success, is well known to affect levels of sexual conflict. However, it is not so clear whether, and how, the regular evolution of life-histories also affects sexual selection. Here, we show that life-history evolution in fruit fly populations selected for traits not directly related to sexual conflict might, nevertheless, mediate the possible evolution of altered sexual conflict levels through effects on sexual selection. Populations that evolved to develop to adulthood fast, and reproduce relatively early in life, are shown to potentially experience less sexual selection, which can explain the low sexual conflict levels earlier observed in them.
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| 5. |
- Naresh, Vinesh Shenoi, et al.
(författare)
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On aging and age-specific effects of spontaneous mutations
- 2023
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Ingår i: Evolution. - : Oxford University Press. - 0014-3820 .- 1558-5646. ; 77:8, s. 1780-1790
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Tidskriftsartikel (refereegranskat)abstract
- Evolutionary theory assumes that mutations that cause aging either have beneficial early-life effects that gradually become deleterious with advancing age (antagonistic pleiotropy [AP]) or that they only have deleterious effects at old age (mutation accumulation [MA]). Mechanistically, aging is predicted to result from damage accumulating in the soma. While this scenario is compatible with AP, it is not immediately obvious how damage would accumulate under MA. In a modified version of the MA theory, it has been suggested that mutations with weakly deleterious effects at young age can also contribute to aging, if they generate damage that gradually accumulates with age. Mutations with increasing deleterious effects have recently gained support from theoretical work and studies of large-effect mutations. Here we address if spontaneous mutations also have negative effects that increase with age. We accumulate mutations with early-life effects in Drosophila melanogaster across 27 generations and compare their relative effects on fecundity early and late in life. Our mutation accumulation lines on average have substantially lower early-life fecundity compared to controls. These effects were further maintained throughout life, but they did not increase with age. Our results suggest that most spontaneous mutations do not contribute to damage accumulation and aging.
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| 6. |
- Shenoi, Vinesh, et al.
(författare)
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On ageing and age-specific effects of spontaneous mutations
- 2023
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Annan publikationabstract
- Evolutionary theories of ageing assume causal mutations either have beneficial early-life effects which gradually become deleterious with advancing age (antagonistic pleiotropy: AP) or mutations that only have deleterious effects at old age (mutation accumulation: MA). Mechanistically, ageing is predicted to result from damage accumulating in the soma. While this scenario is compatible with AP, it is not immediately obvious how damage would accumulate under MA. In a modified version of the MA theory, it has been suggested that mutations with weakly deleterious effects at young age can also contribute to ageing, if they generate damage that gradually accumulates with age. Mutations with increasing deleterious effects have recently gained support from theoretical work and studies of large-effect mutations. Here we address if spontaneous mutations also have negative effects that increase with age. We accumulate mutations with early-life effects in Drosophila melanogaster across 27 generations and compare their relative effects on fecundity early and late in life. Our mutation accumulation lines on average have substantially lower early-life fecundity compared to controls. These effects were further maintained throughout life, but they did not increase with age. Our results thus suggest that most spontaneous mutations do not contribute to damage accumulation and ageing.
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