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Alavioon, Ghazal
Publications (6 of 6) Show all publications
Alavioon, G., Garcia, A. C., LeChatelier, M., Maklakov, A. A. & Immler, S. (2019). Selection for longer lived sperm within ejaculate reduces reproductive ageing in offspring. EVOLUTION LETTERS, 3(2), 198-206
Open this publication in new window or tab >>Selection for longer lived sperm within ejaculate reduces reproductive ageing in offspring
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2019 (English)In: EVOLUTION LETTERS, ISSN 2056-3744, Vol. 3, no 2, p. 198-206Article in journal (Refereed) Published
Abstract [en]

Males produce numerous sperm in a single ejaculate that greatly outnumber their potential egg targets. Recent studies found that phenotypic and genotypic variation among sperm in a single ejaculate of a male affects the fitness and performance of the resulting offspring. Specifically, within-ejaculate sperm selection for sperm longevity increased the performance of the resulting offspring in several key life-history traits in early life. Because increased early-life reproductive performance often correlates with rapid ageing, it is possible that within-ejaculate sperm selection increases early-life fitness at the cost of accelerated senescence. Alternatively, within-ejaculate sperm selection could improve offspring quality throughout the life cycle, including reduced age-specific deterioration. We tested the two alternative hypotheses in an experimental setup using zebrafish Danio rerio. We found that within-ejaculate sperm selection for sperm longevity reduced age-specific deterioration of fecundity and offspring survival but had no effect on fertilization success in males. Remarkably, we found an opposing effect of within-ejaculate sperm selection on female fecundity, where selection for sperm longevity resulted in increased early-life performance followed by a slow decline, while females sired by unselected sperm started low but increased their fecundity with age. Intriguingly, within-ejaculate sperm selection also reduced the age-specific decline in fertilization success in females, suggesting that selection for sperm longevity improves at least some aspects of female reproductive ageing. These results demonstrate that within-ejaculate variation in sperm phenotype contributes to individual variation in animal life histories in the two sexes and may have important implications for assisted fertilization programs in livestock and humans.

Keywords
Ageing, reproductive success, sperm selection, sperm competition, senescence
National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-382654 (URN)10.1002/evl3.101 (DOI)000463987900008 ()
Funder
EU, European Research Council, HapSelA 336633Knut and Alice Wallenberg Foundation
Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-04-29Bibliographically approved
Alavioon, G. (2018). Haploid selection in animals: Exploring the fitness consequences and underlying mechanisms. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Haploid selection in animals: Exploring the fitness consequences and underlying mechanisms
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A consequence of sexual reproduction in eukaryotes is the evolution of a biphasic life cycle with alternating diploid and haploid gametic phases. While our focus in evolutionary biology is on selection during the diploid phase, we know relatively little about selection occurring during the haploid gametic stage. This is particularly true in predominantly diploid animals, where gene expression and hence selection have long been thought to be absent in haploid cells like gametes and particularly sperm. During my PhD, I tested the idea of selection during the haploid gametic phase using zebrafish Danio rario as a study species. I combined a large-scale selection experiment over three generations with fitness assays and next-generation sequencing to assess the importance of haploid selection. We measured offspring fitness in all three generations.  In addition, we compared gene expression in brain and testes of F1 and F3 adult male from each treatment by RNA sequencing. We found that offspring sired by longer-lived sperm showed higher survival rate and higher early- and late-life reproductive fitness compared to offspring sired by shorter-lived sperm. We also found differentially expressed genes between the two treatments with functions in metabolic and developmental pathways. These findings suggest that the observed fitness differences to be caused by small expression changes in many basic genes. We also tested for a genetic underpinning of the selected sperm phenotypes and identified allelic differences across the entire genome. Finally, we investigated the additive genetic component and parental effect of different sperm phenotypes. We found generally low additive genetic variation and high parental effects on sperm performance traits. In conclusion, this thesis provides evidence that the phenotypic variation among intact fertile sperm within an ejaculate affects offspring fitness throughout life and provides a clear link between sperm phenotype and offspring fitness and between sperm phenotype and sperm genotype.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 41
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1681
Keywords
sperm, evolution, haploid selection, reproductive aging, fitness
National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-350192 (URN)978-91-513-0358-1 (ISBN)
Public defence
2018-09-14, Lindahlsalen, Norbyvagen 18d, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2018-08-24 Created: 2018-05-07 Last updated: 2018-09-06
Alavioon, G., Hotzy, C., Nakhro, K., Rudolf, S., Scofield, D., Zajitschek, S., . . . Immler, S. (2017). Haploid selection within a single ejaculate increases offspring fitness. Proceedings of the National Academy of Sciences of the United States of America (30), 8053-8058
Open this publication in new window or tab >>Haploid selection within a single ejaculate increases offspring fitness
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2017 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, no 30, p. 8053-8058Article in journal (Refereed) Published
Abstract [en]

An inescapable consequence of sex in eukaryotes is the evolution of a biphasic life cycle with alternating diploid and haploid phases. The occurrence of selection during the haploid phase can have far-reaching consequences for fundamental evolutionary processes including the rate of adaptation, the extent of inbreeding depression, and the load of deleterious mutations, as well as for applied research into fertilization technology. Although haploid selection is well established in plants, current dogma assumes that in animals, intact fertile sperm within a single ejaculate are equivalent at siring viable offspring. Using the zebrafish Danio rerio, we show that selection on phenotypic variation among intact fertile sperm within an ejaculate affects offspring fitness. Longer-lived sperm sired embryos with increased survival and a reduced number of apoptotic cells, and adult male offspring exhibited higher fitness. The effect on embryo viability was carried over into the second generation without further selection and was equally strong in both sexes. Sperm pools selected by motile phenotypes differed genetically at numerous sites throughout the genome. Our findings clearly link within-ejaculate variation in sperm phenotype to offspring fitness and sperm genotype in a vertebrate and have major implications for adaptive evolution.

National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-320335 (URN)10.1073/pnas.1705601114 (DOI)000406189900080 ()28698378 (PubMedID)
Funder
Swedish Research CouncilEU, European Research Council
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2018-05-07Bibliographically approved
Lind, M. I., Berg, E. C., Alavioon, G. & Maklakov, A. A. (2015). Evolution of differential maternal age effects on male and female offspring development and longevity. Functional Ecology, 29(1), 104-110
Open this publication in new window or tab >>Evolution of differential maternal age effects on male and female offspring development and longevity
2015 (English)In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 29, no 1, p. 104-110Article in journal (Refereed) Published
Abstract [en]

Maternal age effects on life-history traits, including longevity, are widespread and can be seen as a manifestation of ageing. However, little is known about how maternal life span may influence the maternal age effect. At a given chronological age, a long-lived parent may be at a younger biological age than a short-lived parent and thus has a less severe parental age effect. However, earlier work using experimentally evolved short- and long-lived lines did not support this hypothesis. We scored developmental time and longevity of 14995 individual seed beetles, Callosobruchus maculatus derived from replicate short-lived and long-lived lines created via artificial selection on male life span. Offspring from older mothers had shorter life span, which is consistent with most of the literature. We found support for the hypothesis that detrimental maternal age effects evolve to be weaker under selection for long life span. However, this finding was only apparent in males, suggesting that maternal age affects male and female offspring differently. These results suggest that sex-dependent parental age effects should be incorporated in the studies of longevity and ageing evolution and that selection on one sex can cause evolution of parental age effects in the other sex.

Keywords
ageing, Callosobruchus maculatus, eclosion success, sex-specific response
National Category
Evolutionary Biology Zoology
Identifiers
urn:nbn:se:uu:diva-246667 (URN)10.1111/1365-2435.12308 (DOI)000348562600013 ()
Available from: 2015-03-18 Created: 2015-03-09 Last updated: 2017-12-04Bibliographically approved
Immler, S., Hotzy, C., Alavioon, G., Petersson, E. & Arnqvist, G. (2014). Sperm variation within a single ejaculate affects offspring development in Atlantic salmon. Biology Letters, 10(2), 20131040
Open this publication in new window or tab >>Sperm variation within a single ejaculate affects offspring development in Atlantic salmon
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2014 (English)In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 10, no 2, p. 20131040-Article in journal (Refereed) Published
Abstract [en]

It is generally believed that variation in sperm phenotype within a single ejaculate has no consequences for offspring performance, because sperm phenotypes are thought not to reflect sperm genotypes. We show that variation in individual sperm function within an ejaculate affects the performance of the resulting offspring in the Atlantic salmon Salmo salar. We experimentally manipulated the time between sperm activation and fertilization in order to select for sperm cohorts differing in longevity within single ejaculates of wild caught male salmon. We found that within-ejaculate variation in sperm longevity significantly affected offspring development and hence time until hatching. Whether these effects have a genetic or epigenetic basis needs to be further evaluated. However, our results provide experimental evidence for transgenerational effects of individual sperm function.

Keywords
gamete selection, epigenetics, haploid selection, sperm competition, fish
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-222203 (URN)10.1098/rsbl.2013.1040 (DOI)000332378300009 ()
Available from: 2014-04-09 Created: 2014-04-08 Last updated: 2017-12-05Bibliographically approved
Silva, W. T. A., Jolly, C., Alavioon, G., Kiehl, B. & Immler, S.Social environment of fathers affects gene expression patterns in early offspring.
Open this publication in new window or tab >>Social environment of fathers affects gene expression patterns in early offspring
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(English)Manuscript (preprint) (Other academic)
National Category
Developmental Biology Genetics Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-359417 (URN)
Available from: 2018-09-01 Created: 2018-09-01 Last updated: 2018-09-05
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