| 1. |
- Arnqvist, Göran, et al.
(författare)
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Genome size correlates with reproductive fitness in seed beetles
- 2015
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 282:1815
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Tidskriftsartikel (refereegranskat)abstract
- The ultimate cause of genome size (GS) evolution in eukaryotes remains a major and unresolved puzzle in evolutionary biology. Large-scale comparative studies have failed to find consistent correlations between GS and organismal properties, resulting in the 'C-value paradox'. Current hypotheses for the evolution of GS are based either on the balance between mutational events and drift or on natural selection acting upon standing genetic variation in GS. It is, however, currently very difficult to evaluate the role of selection because within-species studies that relate variation in life-history traits to variation in GS are very rare. Here, we report phylogenetic comparative analyses of GS evolution in seed beetles at two distinct taxonomic scales, which combines replicated estimation of GS with experimental assays of life-history traits and reproductive fitness. GS showed rapid and bidirectional evolution across species, but did not show correlated evolution with any of several indices of the relative importance of genetic drift. Within a single species, GS varied by 4-5% across populations and showed positive correlated evolution with independent estimates of male and female reproductive fitness. Collectively, the phylogenetic pattern of GS diversification across and within species in conjunction with the pattern of correlated evolution between GS and fitness provide novel support for the tenet that natural selection plays a key role in shaping GS evolution.
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| 2. |
- Arnqvist, Göran, Professor, 1961-, et al.
(författare)
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The pace-of-life : A sex-specific link between metabolic rate and life history in bean beetles
- 2017
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 31:12, s. 2299-2309
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Tidskriftsartikel (refereegranskat)abstract
- Metabolic rate (MR) is a key functional trait simply because metabolism converts resources into population growth rate. Yet, our empirical understanding of the sources of within species variation in MR, as well as of its life history and ecological correlates, is rather limited. Here, we assess whether MR lies at the root of a syndrome of correlated rate-dependent life-history traits in an insect.Selection for early (E) or late (L) age-at-reproduction for >160 generations in the bean beetle Acanthoscelides obtectus has produced beetles that differ markedly in juvenile development, body size, fecundity schedules, ageing and life span. Here, we use micro-respirometry to test whether this has been associated with the evolution of age- and sex-specific metabolic phenotypes.We find that mass-specific MR is 18% higher in E lines compared to L lines and that MR decreases more rapidly with chronological, but not biological, age in E lines. Males, under sexual selection to “live-fast-die-young”, show 50% higher MR than females and MR decreased more rapidly with age in males.Our results are consistent with a central role for MR for the divergence in “pace-of-life” seen in these beetles, supporting the view that MR lies at the root of ecologically relevant life-history trait variation within species.
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| 3. |
- Bayram, Helen L., et al.
(författare)
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Identification of novel ejaculate proteins in a seed beetle and division of labour across male accessory reproductive glands
- 2019
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Ingår i: Insect biochemistry and molecular biology. - : Pergamon. - 0965-1748 .- 1879-0240. ; 104, s. 50-57
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Tidskriftsartikel (refereegranskat)abstract
- The male ejaculate contains a multitude of seminal fluid proteins (SFPs), many of which are key reproductive molecules, as well as sperm. However, the identification of SFPs is notoriously difficult and a detailed understanding of this complex phenotype has only been achieved in a few model species. We employed a recently developed proteomic method involving whole-organism stable isotope labelling coupled with proteomic and transcriptomic analyses to characterize ejaculate proteins in the seed beetle Callosobruchus maculatus. We identified 317 proteins that were transferred to females at mating, and a great majority of these showed signals of secretion and were highly male-biased in expression in the abdomen. These male-derived proteins were enriched with proteins involved in general metabolic and catabolic processes but also with proteolytic enzymes and proteins involved in protection against oxidative stress. Thirty-seven proteins showed significant homology with SFPs previously identified in other insects. However, no less than 92 C. maculatus ejaculate proteins were entirely novel, receiving no significant blast hits and lacking homologs in extant data bases, consistent with a rapid and divergent evolution of SFPs. We used 3D micro-tomography in conjunction with proteomic methods to identify 5 distinct pairs of male accessory reproductive glands and to show that certain ejaculate proteins were only recovered in certain male glands. Finally, we provide a tentative list of 231 candidate female-derived reproductive proteins, some of which are likely important in ejaculate processing and/or sperm storage.
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| 4. |
- Bayram, Helen L., et al.
(författare)
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Novel seminal fluid proteins in the seed beetle Callosobruchus maculatus identified by a proteomic and transcriptomic approach
- 2017
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Ingår i: Insect molecular biology (Print). - : Wiley. - 0962-1075 .- 1365-2583. ; 26:1, s. 58-73
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Tidskriftsartikel (refereegranskat)abstract
- The seed beetle Callosobruchus maculatus is a significant agricultural pest and increasingly studied model of sexual conflict. Males possess genital spines that increase the transfer of seminal fluid proteins (SFPs) into the female body. As SFPs alter female behaviour and physiology, they are likely to modulate reproduction and sexual conflict in this species. Here, we identified SFPs using proteomics combined with a de novo transcriptome. A prior 2D-sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis identified male accessory gland protein spots that were probably transferred to the female at mating. Proteomic analysis of these spots identified 98 proteins, a majority of which were also present within ejaculates collected from females. Standard annotation workflows revealed common functional groups for SFPs, including proteases and metabolic proteins. Transcriptomic analysis found 84 transcripts differentially expressed between the sexes. Notably, genes encoding 15 proteins were highly expressed in male abdomens and only negligibly expressed within females. Most of these sequences corresponded to 'unknown' proteins (nine of 15) and may represent rapidly evolving SFPs novel to seed beetles. Our combined analyses highlight 44 proteins for which there is strong evidence that they are SFPs. These results can inform further investigation, to better understand the molecular mechanisms of sexual conflict in seed beetles.
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| 5. |
- Dordevic, Mirko, et al.
(författare)
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Sex-specific mitonuclear epistasis and the evolution of mitochondrial bioenergetics, ageing, and life history in seed beetles
- 2017
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Ingår i: Evolution. - : WILEY. - 0014-3820 .- 1558-5646. ; 71:2, s. 274-288
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Tidskriftsartikel (refereegranskat)abstract
- The role of mitochondrial DNA for the evolution of life-history traits remains debated. We examined mitonuclear effects on the activity of the multisubunit complex of the electron transport chain (ETC) involved in oxidative phosphorylation (OXPHOS) across lines of the seed beetle Acanthoscelides obtectus selected for a short (E) or a long (L) life for more than >160 generations. We constructed and phenotyped mitonuclear introgression lines, which allowed us to assess the independent effects of the evolutionary history of the nuclear and the mitochondrial genome. The nuclear genome was responsible for the largest share of divergence seen in ageing. However, the mitochondrial genome also had sizeable effects, which were sex-specific and expressed primarily as epistatic interactions with the nuclear genome. The effects of mitonuclear disruption were largely consistent with mitonuclear coadaptation. Variation in ETC activity explained a large proportion of variance in ageing and life-history traits and this multivariate relationship differed somewhat between the sexes. In conclusion, mitonuclear epistasis has played an important role in the laboratory evolution of ETC complex activity, ageing, and life histories and these are closely associated. The mitonuclear architecture of evolved differences in life-history traits and mitochondrial bioenergetics was sex-specific.
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| 6. |
- Hämäläinen, Anni, et al.
(författare)
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Evolution of sex-specific pace-of-life syndromes : causes and consequences
- 2018
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 72:3
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Forskningsöversikt (refereegranskat)abstract
- Males and females commonly differ in their life history optima and, consequently, in the optimal expression of life history, behavioral and physiological traits involved in pace-of-life syndromes (POLS). Sex differences in mean trait expression typically result if males and females exhibit different fitness optima along the same pace-of-life continuum, but the syndrome structure may also differ for the sexes. Due to sex-specific selective pressures imposed by reproductive roles and breeding strategies, the sexes may come to differ in the strength of correlation among traits, or different traits may covary in males and females. Ignorance of these selective forces operating between and within the sexes may lead to flawed conclusions about POLS manifestation in the species, and stand in the way of understanding the evolution, maintenance, and variability of POLS. We outline ways in which natural and sexual selection influence sex-specific trait evolution, and describe potential ultimate mechanisms underlying sex-specific POLS. We make predictions on how reproductive roles and the underlying sexual conflict lead to sex-specific trait covariances. These predictions lead us to conclude that sexual dimorphism in POLS is expected to be highly prevalent, allow us to assess possible consequences for POLS evolution, and provide guidelines for future studies.
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| 7. |
- Immonen, Elina, et al.
(författare)
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Complex mitonuclear interactions and metabolic costs of mating in male seed beetles
- 2016
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 29:2, s. 360-370
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Tidskriftsartikel (refereegranskat)abstract
- The lack of evolutionary response to selection on mitochondrial genes through males predicts the evolution of nuclear genetic influence on male-specific mitochondrial function, for example by gene duplication and evolution of sex-specific expression of paralogs involved in metabolic pathways. Intergenomic epistasis may therefore be a prevalent feature of the genetic architecture of male-specific organismal function. Here, we assess the role of mitonuclear genetic variation for male metabolic phenotypes [metabolic rate and respiratory quotient (RQ)] associated with ejaculate renewal, in the seed beetle Callosobruchus maculatus, by assaying lines with crossed combinations of distinct mitochondrial haplotypes and nuclear lineages. We found a significant increase in metabolic rate following mating relative to virgin males. Moreover, processes associated with ejaculate renewal showed variation in metabolic rate that was affected by mitonuclear interactions. Mitochondrial haplotype influenced mating-related changes in RQ, but this pattern varied over time. Mitonuclear genotype and the energy spent during ejaculate production affected the weight of the ejaculate, but the strength of this effect varied across mitochondrial haplotypes showing that the genetic architecture of male-specific reproductive function is complex. Our findings unveil hitherto underappreciated metabolic costs of mating and ejaculate renewal, and provide the first empirical demonstration of mitonuclear epistasis on male reproductive metabolic processes.
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| 8. |
- Immonen, Elina, et al.
(författare)
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Direct and indirect genetic effects of sex-specific mitonuclear epistasis on reproductive ageing
- 2016
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 116:3, s. 338-347
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondria are involved in ageing and their function requires coordinated action of both mitochondrial and nuclear genes. Epistasis between the two genomes can influence lifespan but whether this also holds for reproductive senescence is unclear. Maternal inheritance of mitochondria predicts sex differences in the efficacy of selection on mitonuclear genotypes that should result in differences between females and males in mitochondrial genetic effects. Mitonuclear genotype of a focal individual may also indirectly affect trait expression in the mating partner. We tested these predictions in the seed beetle Callosobruchus maculatus, using introgression lines harbouring distinct mitonuclear genotypes. Our results reveal both direct and indirect sexspecific effects of mitonuclear epistasis on reproductive ageing. Females harbouring coadapted mitonuclear genotypes showed higher lifetime fecundity due to slower senescence relative to novel mitonuclear combinations. We found no evidence for mitonuclear coadaptation in males. Mitonuclear epistasis not only affected age-specific ejaculate weight, but also influenced male age-dependent indirect effects on traits expressed by their female partners (fecundity, egg size, longevity). These results demonstrate important consequences of sex-specific mitonuclear epistasis for both mating partners, consistent with a role for mitonuclear genetic constraints upon sex-specific adaptive evolution.
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| 9. |
- Immonen, Elina, et al.
(författare)
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Evolution of sex-specific pace-of-life syndromes : genetic architecture and physiological mechanisms
- 2018
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 72:3
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Forskningsöversikt (refereegranskat)abstract
- Sex differences in life history, physiology, and behavior are nearly ubiquitous across taxa, owing to sex-specific selection that arises from different reproductive strategies of the sexes. The pace-of-life syndrome (POLS) hypothesis predicts that most variation in such traits among individuals, populations, and species falls along a slow-fast pace-of-life continuum. As a result of their different reproductive roles and environment, the sexes also commonly differ in pace-of-life, with important consequences for the evolution of POLS. Here, we outline mechanisms for how males and females can evolve differences in POLS traits and in how such traits can covary differently despite constraints resulting from a shared genome. We review the current knowledge of the genetic basis of POLS traits and suggest candidate genes and pathways for future studies. Pleiotropic effects may govern many of the genetic correlations, but little is still known about the mechanisms involved in trade-offs between current and future reproduction and their integration with behavioral variation. We highlight the importance of metabolic and hormonal pathways in mediating sex differences in POLS traits; however, there is still a shortage of studies that test for sex specificity in molecular effects and their evolutionary causes. Considering whether and how sexual dimorphism evolves in POLS traits provides a more holistic framework to understand how behavioral variation is integrated with life histories and physiology, and we call for studies that focus on examining the sex-specific genetic architecture of this integration.
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| 10. |
- Immonen, Elina, et al.
(författare)
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Mating Changes Sexually Dimorphic Gene Expression in the Seed Beetle Callosobruchus maculatus
- 2017
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653 .- 1759-6653. ; 9:3, s. 677-699
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Tidskriftsartikel (refereegranskat)abstract
- Sexually dimorphic phenotypes arise largely from sex-specific gene expression, which hasmainly been characterized in sexually naive adults. However, we expect sexual dimorphism in transcription to be dynamic and dependent on factors such as reproductive status. Mating induces many behavioral and physiological changes distinct to each sex and is therefore expected to activate regulatory changes in many sex-biased genes. Here, we first characterized sexual dimorphism in gene expression in Callosobruchus maculatus seed beetles. We then examined how females and males respond to mating and how it affects sex-biased expression, both in sex-limited (abdomen) and sex-shared (head and thorax) tissues. Mating responses were largely sex-specific and, as expected, females showed more genes responding compared with males (similar to 2,000 vs. similar to 300 genes in the abdomen, similar to 500 vs. similar to 400 in the head and thorax, respectively). Of the sex-biased genes present in virgins, 16%(1,041 genes) in the abdomen and 17%(243 genes) in the head and thorax altered their relative expression between the sexes as a result of mating. Sex-bias status changed in 2% of the genes in the abdomen and 4% in the head and thorax following mating. Mating responses involved de-feminization of females and, to a lesser extent, de-masculinization of males relative to their virgin state: mating decreased rather than increased dimorphic expression of sex-biased genes. The fact that regulatory changes of both types of sex-biased genes occurred in both sexes suggests that male-and female-specific selection is not restricted to male-and female-biased genes, respectively, as is sometimes assumed.
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