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Philosophical Transactions of the Royal... Oct 2016We review the phenomenon of condition-dependent sex-where individuals' condition affects the likelihood that they will reproduce sexually rather than asexually. In... (Review)
Review
We review the phenomenon of condition-dependent sex-where individuals' condition affects the likelihood that they will reproduce sexually rather than asexually. In recent years, condition-dependent sex has been studied both theoretically and empirically. Empirical results in microbes, fungi and plants support the theoretical prediction that negative condition-dependent sex, in which individuals in poor condition are more likely to reproduce sexually, can be evolutionarily advantageous under a wide range of settings. Here, we review the evidence for condition-dependent sex and its potential implications for the long-term survival and adaptability of populations. We conclude by asking why condition-dependent sex is not more commonly observed, and by considering generalizations of condition-dependent sex that might apply even for obligate sexuals.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
Topics: Biological Evolution; Reproduction; Selection, Genetic; Sex
PubMed: 27619702
DOI: 10.1098/rstb.2015.0539 -
Philosophical Transactions of the Royal... Oct 2018While gene flow can reduce the potential for local adaptation, hybridization may conversely provide genetic variation that increases the potential for local adaptation.... (Review)
Review
While gene flow can reduce the potential for local adaptation, hybridization may conversely provide genetic variation that increases the potential for local adaptation. Hybridization may also affect adaptation through altering sexual dimorphism and sexual conflict, but this remains largely unstudied. Here, we discuss how hybridization may affect sexual dimorphism and conflict due to differential effects of hybridization on males and females, and then how this, in turn, may affect local adaptation. First, in species with heterochromatic sexes, the lower viability of the heterogametic sex in hybrids could shift the balance in sexual conflict. Second, sex-specific inheritance of the mitochondrial genome in hybrids may lead to cytonuclear mismatches, for example, in the form of 'mother's curse', with potential consequences for sex ratio and sex-specific expression. Third, sex-biased introgression and recombination may lead to sex-specific consequences of hybridization. Fourth, transgressive segregation of sexually antagonistic alleles could increase sexual dimorphism in hybrid populations. Sexual dimorphism can reduce sexual conflict and enhance intersexual niche partitioning, increasing the fitness of hybrids. Adaptive introgression of alleles reducing sexual conflict or enhancing intersexual niche partitioning may facilitate local adaptation, and could favour the colonization of novel habitats. We review these consequences of hybridization on sex differences and local adaptation, and discuss how their prevalence and importance could be tested empirically.This article is part of the theme issue 'Linking local adaptation with the evolution of sex differences'.
Topics: Acclimatization; Adaptation, Physiological; Alleles; Animals; Conflict, Psychological; DNA, Mitochondrial; Female; Gene Flow; Genome, Mitochondrial; Genomics; Hybridization, Genetic; Male; Sex; Sex Characteristics; Sexual Behavior
PubMed: 30150218
DOI: 10.1098/rstb.2017.0419 -
Journal of Lipid Research Sep 1968The evidence for intraspecies chemical communication in insects is reviewed, with emphasis on those studies where known organic compounds have been implicated. These... (Review)
Review
The evidence for intraspecies chemical communication in insects is reviewed, with emphasis on those studies where known organic compounds have been implicated. These signal-carrying chemicals are known as pheromones. There are two distinct types of pheromones, releasers and primers. Releaser pheromones initiate immediate behavioral responses in insects upon reception, while primer pheromones cause physiological changes in an animal that ultimately result in a behavior response. Chemically identified releaser pheromones are of three basic types: those which cause sexual attraction, alarm behavior, and recruitment. Sex pheromones release the entire repertoire of sexual behavior. Thus a male insect may be attracted to and attempt to copulate with an inanimate object that has sex pheromone on it. It appears that most insects are rather sensitive and selective for the sex pheromone of their species. Insects show far less sensitivity and chemospecificity for alarm pheromones. Alarm selectivity is based more on volatility than on unique structural features. Recruiting pheromones are used primarily in marking trails to food sources. Terrestrial insects lay continuous odor trails, whereas bees and other airborne insects apply the substances at discrete intervals. It appears that a complex pheromone system is used by the queen bee in the control of worker behavior. One well-established component of this system is a fatty acid, 9-ketodecenoic acid, produced by the queen and distributed among the workers. This compound prevents the development of ovaries in the workers and inhibits their queen-rearing activities. In addition, the same compound is used by virgin queen bees as a sex attractant.
Topics: Alcohols; Animal Communication; Animals; Ants; Bees; Bombyx; Chemical Phenomena; Chemistry; Coleoptera; Female; Insecta; Keto Acids; Male; Pheromones; Sex; Species Specificity; Terpenes
PubMed: 4882034
DOI: No ID Found -
Current Biology : CB Apr 2014
Topics: Recombination, Genetic; Reproduction; Sex; Species Specificity
PubMed: 24735848
DOI: 10.1016/j.cub.2014.01.060 -
Philosophical Transactions of the Royal... Oct 2016Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features... (Review)
Review
Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often 'weird' features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
Topics: Biological Evolution; Eukaryota; Meiosis; Recombination, Genetic; Sex
PubMed: 27619705
DOI: 10.1098/rstb.2016.0001 -
Journal of the American Medical... Jan 2022
Topics: Gender Identity; Health Status; Humans; Medical Informatics; Sex
PubMed: 35024858
DOI: 10.1093/jamia/ocab287 -
MBio Nov 2017Both sex (i.e., biological construct of male and female) and gender (i.e., social construct of masculine and feminine) impact the pathogenesis of diseases, including...
Both sex (i.e., biological construct of male and female) and gender (i.e., social construct of masculine and feminine) impact the pathogenesis of diseases, including those caused by microbial infections. Following the 2015 NIH policy for consideration of sex as a biological variable in preclinical research, in 2018, authors of papers published in primary-research American Society for Microbiology (ASM) journals will be asked to report the sex of the research subjects and animals and of materials derived directly from them. To address the need for sex reporting in ASM journals, we systematically reviewed 2,928 primary-research articles published in six primary-research ASM journals (, , , , , and ) in 2016. Approximately 37% of animal studies and 9% of primary cell culture papers published in 2016 would have been affected by the new sex-reporting policy. For animal studies (i.e., studies with any nonhuman vertebrate hosts), most published papers either did not report the sex of the animals or used only female animals, and a minority used only males or both sexes. For published studies using primary cells from diverse animal species (i.e., humans and nonhuman vertebrates), almost all studies failed to report the sex of donors from which the cells were isolated. We believe that reporting the sex of animals and even of the donors of derived cells could improve the rigor and reproducibility of research conducted in microbiology and immunology and published in ASM journals.
Topics: Animals; Humans; Peer Review, Research; Reproducibility of Results; Sex
PubMed: 29138308
DOI: 10.1128/mBio.01868-17 -
Philosophical Transactions of the Royal... Oct 2016Fungi are a diverse group of organisms with a huge variation in reproductive strategy. While almost all species can reproduce sexually, many reproduce asexually most of... (Review)
Review
Fungi are a diverse group of organisms with a huge variation in reproductive strategy. While almost all species can reproduce sexually, many reproduce asexually most of the time. When sexual reproduction does occur, large variation exists in the amount of in- and out-breeding. While budding yeast is expected to outcross only once every 10 000 generations, other fungi are obligate outcrossers with well-mixed panmictic populations. In this review, we give an overview of the costs and benefits of sexual and asexual reproduction in fungi, and the mechanisms that evolved in fungi to reduce the costs of either mode. The proximate molecular mechanisms potentiating outcrossing and meiosis appear to be present in nearly all fungi, making them of little use for predicting outcrossing rates, but also suggesting the absence of true ancient asexual lineages. We review how population genetic methods can be used to estimate the frequency of sex in fungi and provide empirical data that support a mixed mode of reproduction in many species with rare to frequent sex in between rounds of mitotic reproduction. Finally, we highlight how these estimates might be affected by the fungus-specific mechanisms that evolved to reduce the costs of sexual and asexual reproduction.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
Topics: Biological Evolution; Fungi; Reproduction; Reproduction, Asexual; Sex
PubMed: 27619703
DOI: 10.1098/rstb.2015.0540 -
Philosophical Transactions of the Royal... Oct 2016Isogamy is a reproductive system where all gametes are morphologically similar, especially in terms of size. Its importance goes beyond specific cases: to this day... (Review)
Review
Isogamy is a reproductive system where all gametes are morphologically similar, especially in terms of size. Its importance goes beyond specific cases: to this day non-anisogamous systems are common outside of multicellular animals and plants, they can be found in all eukaryotic super-groups, and anisogamous organisms appear to have isogamous ancestors. Furthermore, because maleness is synonymous with the production of small gametes, an explanation for the initial origin of males and females is synonymous with understanding the transition from isogamy to anisogamy. As we show here, this transition may also be crucial for understanding why sex itself remains common even in taxa with high costs of male production (the twofold cost of sex). The transition to anisogamy implies the origin of male and female sexes, kickstarts the subsequent evolution of sex roles, and has a major impact on the costliness of sexual reproduction. Finally, we combine some of the consequences of isogamy and anisogamy in a thought experiment on the maintenance of sexual reproduction. We ask what happens if there is a less than twofold benefit to sex (not an unlikely scenario as large short-term benefits have proved difficult to find), and argue that this could lead to a situation where lineages that evolve anisogamy-and thus the highest costs of sex-end up being associated with constraints that make invasion by asexual reproduction unlikely (the 'anisogamy gateway' hypothesis).This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
Topics: Biological Evolution; Eukaryota; Germ Cells; Reproduction; Sex
PubMed: 27619696
DOI: 10.1098/rstb.2015.0532 -
BMJ (Clinical Research Ed.) Oct 1989
Review
Topics: Aged; Aged, 80 and over; Decision Making; Female; Humans; Male; Sex; Sexual Behavior
PubMed: 2508943
DOI: 10.1136/bmj.299.6705.934