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1.	Abbott, Jessica, et al. (författare) Epigenetics and Sex-Specific Fitness : An Experimental Test Using Male-Limited Evolution in Drosophila melanogaster 2013 Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:7, s. e70493- Tidskriftsartikel (refereegranskat)abstract When males and females have different fitness optima for the same trait but share loci, intralocus sexual conflict is likely to occur. Epigenetic mechanisms such as genomic imprinting (in which expression is altered according to parent-of-origin) and sex-specific maternal effects have been suggested as ways by which this conflict can be resolved. However these ideas have not yet been empirically tested. We designed an experimental evolution protocol in Drosophila melanogaster that enabled us to look for epigenetic effects on the X-chromosome-a hotspot for sexually antagonistic loci. We used special compound-X females to enforce father-to-son transmission of the X-chromosome for many generations, and compared fitness and gene expression levels between Control males, males with a Control X-chromosome that had undergone one generation of father-son transmission, and males with an X-chromosome that had undergone many generations of father-son transmission. Fitness differences were dramatic, with experimentally-evolved males approximately 20% greater than controls, and with males inheriting a non-evolved X from their father about 20% lower than controls. These data are consistent with both strong intralocus sexual conflict and misimprinting of the X-chromosome under paternal inheritance. However, expression differences suggested that reduced fitness under paternal X inheritance was largely due to deleterious maternal effects. Our data confirm the sexually-antagonistic nature of Drosophila's X-chromosome and suggest that the response to male-limited X-chromosome evolution entails compensatory evolution for maternal effects, and perhaps modification of other epigenetic effects via coevolution of the sex chromosomes.
2.	Abbott, Jessica K., et al. (författare) Obtaining snapshots of genetic variation using hemiclonal analysis 2011 Ingår i: Trends in Ecology & Evolution. - : Elsevier BV. - 0169-5347 .- 1872-8383. ; 26:7, s. 359-368 Forskningsöversikt (refereegranskat)abstract Hemiclones are naturally occurring or artificially produced individuals that share a single specific genetic haplotype. Natural hemiclones are produced via hybridization between two closely related species, whereas hemiclonal analysis in Drosophila is carried out in the laboratory via crosses with artificially created 'clone-generator' females with a specific genetic make-up. Hemiclonal analysis in Drosophila has been applied successfully to date to obtain measures of standing genetic variation for numerous traits. Here, we review the current hemiclonal literature and suggest future directions for hemiclonal research, including its application in molecular and genomic studies, and the adaptation of natural hemiclonal systems to carry out Drosophila-type studies of standing genetic variation.
3.	Abbott, Jessica K., et al. (författare) The microevolutionary response to male-limited X-chromosome evolution in Drosophila melanogaster reflects macroevolutionary patterns 2020 Ingår i: Journal of Evolutionary Biology. - : Wiley-Blackwell. - 1010-061X .- 1420-9101. ; 33:6, s. 738-750 Tidskriftsartikel (refereegranskat)abstract Due to its hemizygous inheritance and role in sex determination, the X-chromosome is expected to play an important role in the evolution of sexual dimorphism and to be enriched for sexually antagonistic genetic variation. By forcing the X-chromosome to only be expressed in males over >40 generations, we changed the selection pressures on the X to become similar to those experienced by the Y. This releases the X from any constraints arising from selection in females and should lead to specialization for male fitness, which could occur either via direct effects of X-linked loci or trans-regulation of autosomal loci by the X. We found evidence of masculinization via up-regulation of male-benefit sexually antagonistic genes and down-regulation of X-linked female-benefit genes. Potential artefacts of the experimental evolution protocol are discussed and cannot be wholly discounted, leading to several caveats. Interestingly, we could detect evidence of microevolutionary changes consistent with previously documented macroevolutionary patterns, such as changes in expression consistent with previously established patterns of sexual dimorphism, an increase in the expression of metabolic genes related to mito-nuclear conflict and evidence that dosage compensation effects can be rapidly altered. These results confirm the importance of the X in the evolution of sexual dimorphism and as a source for sexually antagonistic genetic variation and demonstrate that experimental evolution can be a fruitful method for testing theories of sex chromosome evolution.
4.	Adl, Sina M., et al. (författare) Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes 2019 Ingår i: Journal of Eukaryotic Microbiology. - : WILEY. - 1066-5234 .- 1550-7408. ; 66:1, s. 4-119 Tidskriftsartikel (refereegranskat)abstract This revision of the classification of eukaryotes follows that of Adl et al., 2012 [J. Euk. Microbiol. 59(5)] and retains an emphasis on protists. Changes since have improved the resolution of many nodes in phylogenetic analyses. For some clades even families are being clearly resolved. As we had predicted, environmental sampling in the intervening years has massively increased the genetic information at hand. Consequently, we have discovered novel clades, exciting new genera and uncovered a massive species level diversity beyond the morphological species descriptions. Several clades known from environmental samples only have now found their home. Sampling soils, deeper marine waters and the deep sea will continue to fill us with surprises. The main changes in this revision are the confirmation that eukaryotes form at least two domains, the loss of monophyly in the Excavata, robust support for the Haptista and Cryptista. We provide suggested primer sets for DNA sequences from environmental samples that are effective for each clade. We have provided a guide to trophic functional guilds in an appendix, to facilitate the interpretation of environmental samples, and a standardized taxonomic guide for East Asian users.
5.	Bailey, Richard I., et al. (författare) Female Drosophila melanogaster Gene Expression and Mate Choice : The X Chromosome Harbours Candidate Genes Underlying Sexual Isolation 2011 Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:2, s. e17358- Tidskriftsartikel (refereegranskat)abstract Background: The evolution of female choice mechanisms favouring males of their own kind is considered a crucial step during the early stages of speciation. However, although the genomics of mate choice may influence both the likelihood and speed of speciation, the identity and location of genes underlying assortative mating remain largely unknown. Methods and Findings: We used mate choice experiments and gene expression analysis of female Drosophila melanogaster to examine three key components influencing speciation. We show that the 1,498 genes in Zimbabwean female D. melanogaster whose expression levels differ when mating with more (Zimbabwean) versus less (Cosmopolitan strain) preferred males include many with high expression in the central nervous system and ovaries, are disproportionately X-linked and form a number of clusters with low recombination distance. Significant involvement of the brain and ovaries is consistent with the action of a combination of pre- and postcopulatory female choice mechanisms, while sex linkage and clustering of genes lead to high potential evolutionary rate and sheltering against the homogenizing effects of gene exchange between populations. Conclusion: Taken together our results imply favourable genomic conditions for the evolution of reproductive isolation through mate choice in Zimbabwean D. melanogaster and suggest that mate choice may, in general, act as an even more important engine of speciation than previously realized.
6.	Camus, M. Florencia, et al. (författare) Single Nucleotides in the mtDNA Sequence Modify Mitochondrial Molecular Function and Are Associated with Sex-Specific Effects on Fertility and Aging 2015 Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 25:20, s. 2717-2722 Tidskriftsartikel (refereegranskat)abstract Mitochondria underpin energy conversion in eukaryotes. Their small genomes have been the subject of increasing attention, and there is evidence that mitochondrial genetic variation can affect evolutionary trajectories and shape the expression of life-history traits considered to be key human health indicators [1, 2]. However, it is not understood how genetic variation across a diminutive genome, which in most species harbors only about a dozen protein-coding genes, can exert broad-scale effects on the organisnnal phenotype [2, 3]. Such effects are particularly puzzling given that the mitochondrial genes involved are under strong evolutionary constraint and that mitochondrial gene expression is highly conserved across diverse taxa [4]. We used replicated genetic lines in the fruit fly, Drosophila melanogaster, each characterized by a distinct and naturally occurring mitochondrial haplotype placed alongside an isogenic nuclear background. We demonstrate that sequence variation within the mitochondria! DNA (mtDNA) affects both the copy number of mitochondrial genomes and patterns of gene expression across key mitochondrial protein-coding genes. In several cases, haplotype-mediated patterns of gene expression were gene-specific, even for genes from within the same transcriptional units. This invokes post-transcriptional processing of RNA in the regulation of mitochondrial genetic effects on organismal phenotypes. Notably, the haplotype-mediated effects on gene expression could be traced backward to the level of individual nucleotides and forward to sex-specific effects on fertility and longevity. Our study thus elucidates how small-scale sequence changes in the mitochondrial genome can achieve broad-scale regulation of health-related phenotypes and even contribute to sex-related differences in longevity.
7.	Collet, Julie M., et al. (författare) Rapid evolution of the intersexual genetic correlation for fitness in Drosophila melanogaster 2016 Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 70:4, s. 781-795 Tidskriftsartikel (refereegranskat)abstract Sexual antagonism (SA) arises when male and female phenotypes are under opposing selection, yet genetically correlated. Until resolved, antagonism limits evolution toward optimal sex-specific phenotypes. Despite its importance for sex-specific adaptation and existing theory, the dynamics of SA resolution are not well understood empirically. Here, we present data from Drosophila melanogaster, compatible with a resolution of SA. We compared two independent replicates of the LHM population in which SA had previously been described. Both had been maintained under identical, controlled conditions, and separated for around 200 generations. Although heritabilities of male and female fitness were similar, the intersexual genetic correlation differed significantly, being negative in one replicate (indicating SA) but close to zero in the other. Using population sequencing, we show that phenotypic differences were associated with population divergence in allele frequencies at nonrandom loci across the genome. Large frequency changes were more prevalent in the population without SA and were enriched at loci mapping to genes previously shown to have sexually antagonistic relationships between expression and fitness. Our data suggest that rapid evolution toward SA resolution has occurred in one of the populations and open avenues toward studying the genetics of SA and its resolution.
8.	Davies, Natasha, et al. (författare) Evidence for stronger sexual selection in males than in females using an adapted method of Bateman's classic study of Drosophila melanogaster 2023 Ingår i: Evolution. - : Oxford University Press. - 0014-3820 .- 1558-5646. ; 77:11, s. 2420-2430 Tidskriftsartikel (refereegranskat)abstract Bateman's principles, originally a test of Darwin's theoretical ideas, have since become fundamental to sexual selection theory and vital to contextualizing the role of anisogamy in sex differences of precopulatory sexual selection. Despite this, Bateman's principles have received substantial criticism, and researchers have highlighted both statistical and methodological errors, suggesting that Bateman's original experiment contains too much sampling bias for there to be any evidence of sexual selection. This study uses Bateman's original method as a template, accounting for two fundamental flaws in his original experiments, (a) viability effects and (b) a lack of mating behavior observation. Experimental populations of Drosophila melanogaster consisted of wild-type focal individuals and nonfocal individuals established by backcrossing the brown eye (bw-) eye-color marker-thereby avoiding viability effects. Mating assays included direct observation of mating behavior and total number of offspring, to obtain measures of mating success, reproductive success, and standardized variance measures based on Bateman's principles. The results provide observational support for Bateman's principles, particularly that (a) males had significantly more variation in number of mates compared with females and (b) males had significantly more individual variation in total number of offspring. We also find a significantly steeper Bateman gradient for males compared to females, suggesting that sexual selection is operating more intensely in males. However, female remating was limited, providing the opportunity for future study to further explore female reproductive success in correlation with higher levels of remating.
9.	Gilks, William P, et al. (författare) Sex differences in disease genetics: evidence, evolution, and detection. 2014 Ingår i: Trends in Genetics. - : Elsevier BV. - 1362-4555 .- 0168-9525. ; 30:10, s. 453-463 Forskningsöversikt (refereegranskat)abstract Understanding the genetic architecture of disease is an enormous challenge, and should be guided by evolutionary principles. Recent studies in evolutionary genetics show that sexual selection can have a profound influence on the genetic architecture of complex traits. Here, we summarise data from heritability studies and genome-wide association studies (GWASs) showing that common genetic variation influences many diseases and medically relevant traits in a sex-dependent manner. In addition, we discuss how the discovery of sex-dependent effects in population samples is improved by joint interaction analysis (rather than separate-sex), as well as by recently developed software. Finally, we argue that although genetic variation that has sex-dependent effects on disease risk could be maintained by mutation-selection balance and genetic drift, recent evidence indicates that intra-locus sexual conflict could be a powerful influence on complex trait architecture, and maintain sex-dependent disease risk alleles in a population because they are beneficial to the opposite sex.
10.	Harper, Jon Alexander, et al. (författare) Systematic review reveals multiple sexually antagonistic polymorphisms affecting human disease and complex traits 2021 Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 75:12, s. 3087-3097 Tidskriftsartikel (refereegranskat)abstract An evolutionary model for sex differences in disease risk posits that alleles conferring higher risk in one sex may be protective in the other. These sexually antagonistic (SA) alleles are predicted to be maintained at frequencies higher than expected under purifying selection against unconditionally deleterious alleles, but there are apparently no examples in humans. Discipline-specific terminology, rather than a genuine lack of such alleles, could explain this disparity. We undertook a two-stage review of evidence for SA polymorphisms in humans using search terms from (i) evolutionary biology and (ii) biomedicine. Although the first stage returned no eligible studies, the second revealed 51 genes with sex-opposite effects; 22 increased disease risk or severity in one sex but protected the other. Those with net positive effects occurred at higher frequencies. None were referred to as SA. Our review reveals significant communication barriers to fields as a result of discipline-specific terminology.
11.	Harper, Jon Alexander, et al. (författare) Systematic review reveals sexually antagonistic knockouts in model organisms 2022 Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 12:12 Forskningsöversikt (refereegranskat)abstract Sexual antagonism is thought to be an important selective force in multiple evolutionary processes, but very few examples of the genes involved are known. Such a deficit of loci could partially be explained by the lack of overlap in terminology between scientific disciplines. Following a similar review in humans, we searched systematically for studies that described genes with sexually antagonistic or sex-opposite effects in any taxa, using terms designed to capture alternative descriptions of sexual antagonism. Despite drawing on a potentially very large pool of studies we found only eight articles, which between them described seven candidate variants, five of these were gene knockouts. In every case, the variants had net negative effects on the focal trait. One locus was independently validated between studies, but in comparison to previous data on variants in humans and the fruit-fly, the studies generally suffered from small sample sizes, with concomitant high variance. Our review highlights the radically different effects that gene deletions can have on males and females, where the beneficial effects seen in one sex may facilitate the evolution of gene loss. We searched systematically for genetic variants with sexually antagonistic or sex-opposite effects in any taxa. Of 2116 articles, we found seven candidate variants, five of which were gene knockouts. Our review highlights the radically different effects that gene deletions can have on males and females, where the beneficial effects seen in one sex may facilitate the evolution of gene loss.
12.	Innocenti, Paolo, et al. (författare) A joint index for the intensity of sex-specific selection 2010 Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 64:9, s. 2775-2778 Tidskriftsartikel (refereegranskat)abstract A growing body of experimental and field data shows that selective pressures often differ between males and females. Surprisingly, to date, little attempt has been made to formalize a metric expressing the relative behavior of directional selection in the two sexes. We propose an index that describes the extent to which concordant or antagonistic selection is operating between the sexes for a given trait. This joint index could prove especially useful for the study of intralocus sexual conflict and the evolution of sexual dimorphism, providing a common scale to directly compare different traits within or among taxonomic levels, and allowing an assessment on how common sexually antagonistic selection might be in extant populations.
13.	Innocenti, Paolo, et al. (författare) Experimental Evidence Supports a Sex-Specific Selective Sieve in Mitochondrial Genome Evolution 2011 Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 332:6031, s. 845-848 Tidskriftsartikel (refereegranskat)abstract Mitochondria are maternally transmitted; hence, their genome can only make a direct and adaptive response to selection through females, whereas males represent an evolutionary dead end. In theory, this creates a sex-specific selective sieve, enabling deleterious mutations to accumulate in mitochondrial genomes if they exert male-specific effects. We tested this hypothesis, expressing five mitochondrial variants alongside a standard nuclear genome in Drosophila melanogaster, and found striking sexual asymmetry in patterns of nuclear gene expression. Mitochondrial polymorphism had few effects on nuclear gene expression in females but major effects in males, modifying nearly 10% of transcripts. These were mostly male-biased in expression, with enrichment hotspots in the testes and accessory glands. Our results suggest an evolutionary mechanism that results in mitochondrial genomes harboring male-specific mutation loads.
14.	Innocenti, Paolo, et al. (författare) Female responses to experimental removal of sexual selection components in Drosophila melanogaster 2014 Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 14, s. 239- Tidskriftsartikel (refereegranskat)abstract Background: Despite the common assumption that multiple mating should in general be favored in males, but not in females, to date there is no consensus on the general impact of multiple mating on female fitness. Notably, very little is known about the genetic and physiological features underlying the female response to sexual selection pressures. By combining an experimental evolution approach with genomic techniques, we investigated the effects of single and multiple matings on female fecundity and gene expression. We experimentally manipulated the opportunity for mating in replicate populations of Drosophila melanogaster by removing components of sexual selection, with the aim of testing differences in short term post-mating effects of females evolved under different mating strategies. Results: We show that monogamous females suffer decreased fecundity, a decrease that was partially recovered by experimentally reversing the selection pressure back to the ancestral state. The post-mating gene expression profiles of monogamous females differ significantly from promiscuous females, involving 9% of the genes tested (approximately 6% of total genes in D. melanogaster). These transcripts are active in several tissues, mainly ovaries, neural tissues and midgut, and are involved in metabolic processes, reproduction and signaling pathways. Conclusions: Our results demonstrate how the female post-mating response can evolve under different mating systems, and provide novel insights into the genes targeted by sexual selection in females, by identifying a list of candidate genes responsible for the decrease in female fecundity in the absence of promiscuity.
15.	Innocenti, Paolo, et al. (författare) The Sexually Antagonistic Genes of Drosophila melanogaster 2010 Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 8:3, s. e1000335- Tidskriftsartikel (refereegranskat)abstract When selective pressures differ between males and females, the genes experiencing these conflicting evolutionary forces are said to be sexually antagonistic. Although the phenotypic effect of these genes has been documented in both wild and laboratory populations, their identity, number, and location remains unknown. Here, by combining data on sex-specific fitness and genome-wide transcript abundance in a quantitative genetic framework, we identified a group of candidate genes experiencing sexually antagonistic selection in the adult, which correspond to 8% of Drosophila melanogaster genes. As predicted, the X chromosome is enriched for these genes, but surprisingly they represent only a small proportion of the total number of sex-biased transcripts, indicating that the latter is a poor predictor of sexual antagonism. Furthermore, the majority of genes whose expression profiles showed a significant relationship with either male or female adult fitness are also sexually antagonistic. These results provide a first insight into the genetic basis of intralocus sexual conflict and indicate that genetic variation for fitness is dominated and maintained by sexual antagonism, potentially neutralizing any indirect genetic benefits of sexual selection.
16.	Kuijper, Bram, et al. (författare) Direct observation of female mating frequency using time-lapse photography 2009 Ingår i: Fly. - 1933-6934. ; 3:2, s. 118-120 Tidskriftsartikel (refereegranskat)abstract One basic condition of postmating sexual selection is that females mate more than once before fertilizing their ova. Knowledge of the frequency and extent of multiple mating in a given population or species is therefore important in order to fully understand the potential for sexual selection, in the form of sperm competition, sexual conflict and cryptic female choice. Surprisingly, there are only a handful of studies that have attempted to estimate the frequency of multiple mating in insects (including Drosophila) and none have made direct observations over extended periods of time. Here we use time-lapse photography to directly score matings in isolated pairs of D. melanogaster and show that multiple mating in the laboratory occurs at a high frequency but at comparable rates with wild caught females. We also find that the interval to remating rises approximately additively with each mating, indicating either an increase in female resistance or male reluctance to remate. These results suggest that the opportunity for postmating sexual selection in laboratory and natural environments are not dramatically different and that there may be a causal link between the rise in female mating resistance and the concomitant rise in the cost of mating. The method is easily executed and could be adapted to other insect models.
17.	Lund-Hansen, Katrine K., et al. (författare) Feminization of complex traits in Drosophila melanogaster via female-limited X chromosome evolution 2020 Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:12, s. 2703-2713 Tidskriftsartikel (refereegranskat)abstract A handful of studies have investigated sexually antagonistic constraints on achieving sex-specific fitness optima, although exclusively through male-genome-limited evolution experiments. In this article, we established a female-limited X chromosome evolution experiment, where we used an X chromosome balancer to enforce the inheritance of the X through the matriline, thus removing exposure to male selective constraints. This approach eliminates the effects of sexually antagonistic selection on the X chromosome, permitting evolution toward a single sex-specific optimum. After multiple generations of selection, we found strong evidence that body size and development time had moved toward a female-specific optimum, whereas reproductive fitness and locomotion activity remained unchanged. The changes in body size and development time are consistent with previous results, and suggest that the X chromosome is enriched for sexually antagonistic genetic variation controlling these particular traits. The lack of change in reproductive fitness and locomotion activity could be due to a number of mutually nonexclusive explanations, including a lack of sexually antagonistic variance on the X chromosome for those traits or confounding effects of the use of the balancer chromosome. This study is the first to employ female-genome-limited selection and adds to the understanding of the complexity of sexually antagonistic genetic variation.
18.	Lund-Hansen, Katrine K., et al. (författare) Sexually antagonistic coevolution between the sex chromosomes of Drosophila melanogaster 2021 Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National academy of Science. - 0027-8424 .- 1091-6490. ; 118:8 Tidskriftsartikel (refereegranskat)abstract Antagonistic interactions between the sexes are important drivers of evolutionary divergence. Interlocus sexual conflict is generally described as a conflict between alleles at two interacting loci whose identity and genomic location are arbitrary, but with opposite fitness effects in each sex. We build on previous theory by suggesting that when loci under interlocus sexual conflict are located on the sex chromosomes it can lead to cycles of antagonistic coevolution between them and therefore between the sexes. We tested this hypothesis by performing experimental crosses using Drosophila melanogaster where we reciprocally exchanged the sex chromosomes between five allopatric wild-type populations in a round-robin design. Disrupting putatively coevolved sex chromosome pairs resulted in increased male reproductive success in 16 of 20 experimental populations (10 of which were individually significant), but also resulted in lower offspring egg-to-adult viability that affected both male and female fitness. After 25 generations of experimental evolution these sexually antagonistic fitness effects appeared to be resolved. To formalize our hypothesis, we developed population genetic models of antagonistic coevolution using fitness expressions based on our empirical results. Our model predictions support the conclusion that antagonistic coevolution between the sex chromosomes is plausible under the fitness effects observed in our experiments. Together, our results lend both empirical and theoretical support to the idea that cycles of antagonistic coevolution can occur between sex chromosomes and illustrate how this process, in combination with autosomal coadaptation, may drive genetic and phenotypic divergence between populations.
19.	Morrow, Edward H., et al. (författare) Female postmating immune responses, immune system evolution and immunogenic males 2012 Ingår i: Biological Reviews. - 1464-7931 .- 1469-185X. ; 87:3, s. 631-638 Forskningsöversikt (refereegranskat)abstract Females in many taxa experience postmating activation of their immune system, independently of any genital trauma or pathogenic attack arising from male-female genital contact. This response has always been interpreted as a product of natural selection as it either prepares the female immune system for antigens arising from an implanted embryo (in the case of placental mammals), or is a pre-emptive strike against infection or injury acquired during mating. While the first hypothesis has empirical support, the second is not entirely satisfactory. Recently, studies that have experimentally dissected the postmating responses of Drosophila melanogaster females point to a different explanation: male reproductive peptides/proteins that have evolved in response to postmating male-male competition are directly responsible for activating particular elements of the female immune system. Thus, in a broad sense, males may be said to be immunogenic to females. Here, we discuss a possible direct role of sexual selection/sexual conflict in immune system evolution, in contrast to indirect trade-offs with other life-history traits, presenting the available evidence from a range of taxa and proposing ways in which the competing hypotheses could be tested. The major implication of this review is that immune system evolution is not only a product of natural selection but also that sexual selection and potentially sexual conflict enforces a direct selective pressure. This is a significant shift, and will compel researchers studying immune system evolution and ecological immunity to look beyond the forces generated by parasites and pathogens to those generated by the male ejaculate.
20.	Reinius, Björn, et al. (författare) Abundance of female-biased and paucity of male-biased somatically expressed genes on the mouse X-chromosome. 2012 Ingår i: BMC genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 13 Tidskriftsartikel (refereegranskat)abstract ABSTRACT: Background: Empirical evaluations of sexually dimorphic expression of genes on the mammalian X-chromosome are needed to understand the evolutionary forces and the gene-regulatory mechanisms controlling this chromosome. We performed a large-scale sex-bias expression analysis of genes on the X-chromosome in six different somatic tissues from mouse. Results: Our results show that the mouse X-chromosome is enriched with female-biased genes and depleted of male-biased genes. This suggests that feminisation as well as de-masculinisation of the X-chromosome has occurred in terms of gene expression in non-reproductive tissues. Several mechanisms may be responsible for the control of female-biased expression on chromosome X, and escape from X-inactivation is a main candidate. We confirmed escape in case of Tmem29 using RNA-FISH analysis. In addition, we identified novel female-biased non-coding transcripts located in the same female-biased cluster as the well-known coding X-inactivation escapee Kdm5c, likely transcribed from the transition-region between active and silenced domains. We also found that previously known escapees only partially explained the overrepresentation of female-biased X-genes, particularly for tissue-specific female-biased genes. Therefore, the gene set we have identified contains tissue-specific escapees and/or genes controlled by other sexually skewed regulatory mechanisms. Analysis of gene age showed that evolutionarily old X-genes (>100 myr, preceding the radiation of placental mammals) are more frequently female-biased than younger genes. Conclusion: Altogether, our results have implications for understanding both gene regulation and gene evolution of mammalian X-chromosomes, and suggest that the final result in terms of the X-gene composition (masculinisation versus feminisation) is a compromise between different evolutionary forces acting on reproductive and somatic tissues.
21.	Rode, Nicolas O., et al. (författare) An examination of genetic variation and selection on condition in Drosophila melanogaster males 2009 Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 131:2, s. 167-177 Tidskriftsartikel (refereegranskat)abstract According to the genic capture hypothesis, the maintenance of additive genetic variation in fitness-related traits is due to both condition-dependence of these traits and high genetic variation for condition. Evidence supporting this latter assumption is scarce. In this study, we investigated, using hemiclonal analysis, standing genetic variation for condition and relative adult fitness in male Drosophila melanogaster (Meigen) (Diptera: Drosophilidae). The absolute fat and the relative fat content were used as indices of body condition and were measured along with adult relative fitness from males reared in high or low larval densities. The results did not demonstrate genetic variation for condition or adult relative fitness. However, the larval density encountered during development had a strong and significant effect on all traits. Surprisingly, although not significant, negative selection gradients acting on absolute fat and relative fat content were also found in both treatments. These findings challenge one of the main assumptions of the genic capture hypothesis and the use of fat content as an ideal index of condition.
22.	Roth, Steffen, et al. (författare) The evolution of female-biased genital diversity in bedbugs (Cimicidae) 2024 Ingår i: Evolution. - : Oxford University Press. - 0014-3820 .- 1558-5646. ; 78:2, s. 329-341 Tidskriftsartikel (refereegranskat)abstract Rapid genitalia evolution is believed to be mainly driven by sexual selection. Recently, noncopulatory genital functions have been suggested to exert stronger selection pressure on female genitalia than copulatory functions. In bedbugs (Cimicidae), the impact of the copulatory function can be isolated from the noncopulatory impact. Unlike in other taxa, female copulatory organs have no function in egg-laying or waste-product expulsion. Males perform traumatic mating by piercing the female integument, thereby imposing antagonistic selection on females and suspending selection to morphologically match female genitalia. We found the location of the copulatory organ evolved rapidly, changing twice between dorsal and ventral sides, and several times along the anteroposterior and the left-right axes. Male genital length and shape varied much less, did not appear to follow the positional changes seen in females, and showed no evidence for coevolution. Female genitalia position evolved 1.5 times faster than male genital length and shape and showed little neutral or geographic signals. Instead, we propose that nonmorphological male traits, such as mating behavior, may drive female genitalia morphology in this taxon. Models of genitalia evolution may benefit from considering morphological genital responses to nonmorphological stimuli, such as male mating behavior or copulatory position.
23.	Winkler, Lennart, et al. (författare) Stronger net selection on males across animals 2021 Ingår i: eLIFE. - : eLIFE SCIENCES PUBL LTD. - 2050-084X. ; 10 Tidskriftsartikel (refereegranskat)abstract Sexual selection is considered the major driver for the evolution of sex differences. However, the eco-evolutionary dynamics of sexual selection and their role for a population's adaptive potential to respond to environmental change have only recently been explored. Theory predicts that sexual selection promotes adaptation at a low demographic cost only if sexual selection is aligned with natural selection and if net selection is stronger on males compared to females. We used a comparative approach to show that net selection is indeed stronger in males and provide preliminary support that this sex bias is associated with sexual selection. Given that both sexes share the vast majority of their genes, our findings corroborate the notion that the genome is often confronted with a more stressful environment when expressed in males. Collectively, our study supports one of the long-standing key assumptions required for sexual selection to bolster adaptation, and sexual selection may therefore enable some species to track environmental change more efficiently.

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