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De Lisle SP. Understanding the evolution of ecological sex differences: Integrating character displacement and the Darwin-Bateman paradigm. Evol Lett 2019. [DOI: 10.1002/evl3.134] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Stephen P. De Lisle
- Evolutionary Ecology Unit, Department of Biology; Lund University; Lund 22362 Sweden
- Current address: Department of Ecology & Evolutionary Biology, University of Connecticut; Storrs Connecticut 06269
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52
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Svensson EI, Goedert D, Gómez-Llano MA, Spagopoulou F, Nava-Bolaños A, Booksmythe I. Sex differences in local adaptation: what can we learn from reciprocal transplant experiments? Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0420. [PMID: 30150219 DOI: 10.1098/rstb.2017.0420] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2018] [Indexed: 12/13/2022] Open
Abstract
Local adaptation is of fundamental interest to evolutionary biologists. Traditionally, local adaptation has been studied using reciprocal transplant experiments to quantify fitness differences between residents and immigrants in pairwise transplants between study populations. Previous studies have detected local adaptation in some cases, but others have shown lack of adaptation or even maladaptation. Recently, the importance of different fitness components, such as survival and fecundity, to local adaptation have been emphasized. Here, we address another neglected aspect in studies of local adaptation: sex differences. Given the ubiquity of sexual dimorphism in life histories and phenotypic traits, this neglect is surprising, but may be partly explained by differences in research traditions and terminology in the fields of local adaptation and sexual selection. Studies that investigate differences in mating success between resident and immigrants across populations tend to be framed in terms of reproductive and behavioural isolation, rather than local adaptation. We briefly review the published literature that bridges these areas and suggest that reciprocal transplant experiments could benefit from quantifying both male and female fitness components. Such a more integrative research approach could clarify the role of sex differences in the evolution of local adaptations.This article is part of the theme issue 'Linking local adaptation with the evolution of sex differences'.
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Affiliation(s)
| | - Debora Goedert
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | | | - Foteini Spagopoulou
- Animal Ecology, Department of Ecology and Evolution, Uppsala University, 752 36 Uppsala, Sweden
| | - Angela Nava-Bolaños
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Apdo. Postal 70-275, Ciudad Universitaria, 04510 Ciudad de México, México.,Secretaría de Educación Abierta y Continua, Facultad de Ciencias, Universidad Nacional Autónoma de México, Avenida Universidad 3000, C.U., 04510 Ciudad de México, México
| | - Isobel Booksmythe
- School of Biological Sciences, Monash University, 3800 Victoria, Australia
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53
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Connallon T, Débarre F, Li XY. Linking local adaptation with the evolution of sex differences. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0414. [PMID: 30150215 DOI: 10.1098/rstb.2017.0414] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2018] [Indexed: 01/21/2023] Open
Abstract
Many conspicuous forms of evolutionary diversity occur within species. Two prominent examples include evolutionary divergence between populations differentially adapted to their local environments (local adaptation), and divergence between females and males in response to sex differences in selection (sexual dimorphism sensu lato). These two forms of diversity have inspired vibrant research programmes, yet these fields have largely developed in isolation from one another. Nevertheless, conceptual parallels between these research traditions are striking. Opportunities for local adaptation strike a balance between local selection, which promotes divergence, and gene flow-via dispersal and interbreeding between populations-which constrains it. Sex differences are similarly constrained by fundamental features of inheritance that mimic gene flow. Offspring of each sex inherit genes from same-sex and opposite-sex parents, leading to gene flow between each differentially selected half of the population, and raising the question of how sex differences arise and are maintained. This special issue synthesizes and extends emerging research at the interface between the research traditions of local adaptation and sex differences. Each field can promote understanding of the other, and interactions between local adaptation and sex differences can generate new empirical predictions about the evolutionary consequences of selection that varies across space, time, and between the sexes.This article is part of the theme issue 'Linking local adaptation with the evolution of sex differences'.
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Affiliation(s)
- Tim Connallon
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Florence Débarre
- CNRS, UMR 7241 Centre Interdisciplinaire de Recherche en Biologie (CIRB), Collège de France, Paris, France
| | - Xiang-Yi Li
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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54
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Muralidhar P. Mating preferences of selfish sex chromosomes. Nature 2019; 570:376-379. [PMID: 31168095 DOI: 10.1038/s41586-019-1271-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/08/2019] [Indexed: 11/09/2022]
Abstract
The evolution of female mating preferences for harmful male traits is a central paradox of sexual selection1-9. Two dominant explanations for this paradox8,10 are Fisher's runaway process, which is based on genetic correlations between preference and trait1,3,4, and Zahavi's handicap principle, in which the trait is an honest costly signal of male quality2,6,8,11. However, both of these explanations require the exogenous initial spread of female preferences before harmful male traits can evolve1-4,6,8,11. Here I present a mechanism for the evolution of female mating preferences for harmful male traits that is based on the selfish evolutionary interests of sex chromosomes. I demonstrate that female-biased genetic elements-such as the W and X sex chromosomes-will evolve mating preferences for males who display traits that reduce their fitness and/or that of their male offspring, but increase fitness in female offspring. In particular, W-linked preferences can cause nearly lethal male traits to sweep to fixation. Sex-linked preferences can drive the evolution of traits such as ornamental handicaps and male parental care, and can explain variation in ornamentation and behaviour across taxa with divergent sex-determining mechanisms.
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Affiliation(s)
- Pavitra Muralidhar
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA. .,Program for Evolutionary Dynamics, Harvard University, Cambridge, MA, USA.
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55
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Wright AE, Rogers TF, Fumagalli M, Cooney CR, Mank JE. Phenotypic sexual dimorphism is associated with genomic signatures of resolved sexual conflict. Mol Ecol 2019; 28:2860-2871. [PMID: 31038811 PMCID: PMC6618015 DOI: 10.1111/mec.15115] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 04/08/2019] [Accepted: 04/22/2019] [Indexed: 12/12/2022]
Abstract
Intralocus sexual conflict, where an allele benefits one sex at the expense of the other, has an important role in shaping genetic diversity of populations through balancing selection. However, the potential for mating systems to exert balancing selection through sexual conflict on the genome remains unclear. Furthermore, the nature and potential for resolution of sexual conflict across the genome has been hotly debated. To address this, we analysed de novo transcriptomes from six avian species, chosen to reflect the full range of sexual dimorphism and mating systems. Our analyses combine expression and population genomic statistics across reproductive and somatic tissue, with measures of sperm competition and promiscuity. Our results reveal that balancing selection is weakest in the gonad, consistent with the resolution of sexual conflict and evolutionary theory that phenotypic sex differences are associated with lower levels of ongoing conflict. We also demonstrate a clear link between variation in sexual conflict and levels of genetic variation across phylogenetic space in a comparative framework. Our observations suggest that this conflict is short-lived, and is resolved via the decoupling of male and female gene expression patterns, with important implications for the role of sexual selection in adaptive potential and role of dimorphism in facilitating sex-specific fitness optima.
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Affiliation(s)
- Alison E. Wright
- Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
| | - Thea F. Rogers
- Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
| | | | | | - Judith E. Mank
- Department of Genetics, Evolution and EnvironmentUniversity College LondonLondonUK
- Department of Organismal BiologyUppsala UniversityUppsalaSweden
- Department of ZoologyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
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56
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Ågren JA, Munasinghe M, Clark AG. Sexual conflict through mother's curse and father's curse. Theor Popul Biol 2019; 129:9-17. [PMID: 31054851 DOI: 10.1016/j.tpb.2018.12.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 11/15/2018] [Accepted: 12/27/2018] [Indexed: 12/31/2022]
Abstract
In contrast with autosomes, lineages of sex chromosomes reside for different amounts of time in males and females, and this transmission asymmetry makes them hotspots for sexual conflict. Similarly, the maternal inheritance of the mitochondrial genome (mtDNA) means that mutations that are beneficial in females can spread in a population even if they are deleterious in males, a form of sexual conflict known as Mother's Curse. While both Mother's Curse and sex chromosome induced sexual conflict have been well studied on their own, the interaction between mitochondrial genes and genes on sex chromosomes is poorly understood. Here, we use analytical models and computer simulations to perform a comprehensive examination of how transmission asymmetries of nuclear, mitochondrial, and sex chromosome-linked genes may both cause and resolve sexual conflicts. For example, the accumulation of male-biased Mother's Curse mtDNA mutations will lead to selection in males for compensatory nuclear modifier loci that alleviate the effect. We show how the Y chromosome, being strictly paternally transmitted provides a particularly safe harbor for such modifiers. This analytical framework also allows us to discover a novel kind of sexual conflict, by which Y chromosome-autosome epistasis may result in the spread of male beneficial but female deleterious mutations in a population. We christen this phenomenon Father's Curse. Extending this analytical framework to ZW sex chromosome systems, where males are the heterogametic sex, we also show how W-autosome epistasis can lead to a novel kind of nuclear Mother's Curse. Overall, this study provides a comprehensive framework to understand how genetic transmission asymmetries may both cause and resolve sexual conflicts.
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Affiliation(s)
- J Arvid Ågren
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14583, USA
| | - Manisha Munasinghe
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14583, USA; Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, 14853, USA.
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57
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Baral S, Arumugam G, Deshmukh R, Kunte K. Genetic architecture and sex-specific selection govern modular, male-biased evolution of doublesex. SCIENCE ADVANCES 2019; 5:eaau3753. [PMID: 31086812 PMCID: PMC6506240 DOI: 10.1126/sciadv.aau3753] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 03/29/2019] [Indexed: 06/09/2023]
Abstract
doublesex regulates early embryonic sex differentiation in holometabolous insects, along with the development of species-, sex-, and morph-specific adaptations during pupal stages. How does a highly conserved gene with a critical developmental role also remain functionally dynamic enough to gain ecologically important adaptations that are divergent in sister species? We analyzed patterns of exon-level molecular evolution and protein structural homology of doublesex from 145 species of four insect orders representing 350 million years of divergence. This analysis revealed that evolution of doublesex was governed by a modular architecture: Functional domains and female-specific regions were highly conserved, whereas male-specific sequences and protein structures evolved up to thousand-fold faster, with sites under pervasive and/or episodic positive selection. This pattern of sex bias was reversed in Hymenoptera. Thus, highly conserved yet dynamic master regulators such as doublesex may partition specific conserved and novel functions in different genic modules at deep evolutionary time scales.
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58
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Toups MA, Rodrigues N, Perrin N, Kirkpatrick M. A reciprocal translocation radically reshapes sex-linked inheritance in the common frog. Mol Ecol 2019; 28:1877-1889. [PMID: 30576024 DOI: 10.1111/mec.14990] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 12/04/2018] [Accepted: 12/04/2018] [Indexed: 12/22/2022]
Abstract
X and Y chromosomes can diverge when rearrangements block recombination between them. Here we present the first genomic view of a reciprocal translocation that causes two physically unconnected pairs of chromosomes to be coinherited as sex chromosomes. In a population of the common frog (Rana temporaria), both pairs of X and Y chromosomes show extensive sequence differentiation, but not degeneration of the Y chromosomes. A new method based on gene trees shows both chromosomes are sex-linked. Furthermore, the gene trees from the two Y chromosomes have identical topologies, showing they have been coinherited since the reciprocal translocation occurred. Reciprocal translocations can thus reshape sex linkage on a much greater scale compared with inversions, the type of rearrangement that is much better known in sex chromosome evolution, and they can greatly amplify the power of sexually antagonistic selection to drive genomic rearrangement. Two more populations show evidence of other rearrangements, suggesting that this species has unprecedented structural polymorphism in its sex chromosomes.
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Affiliation(s)
- Melissa A Toups
- Department of Integrative Biology, University of Texas, Austin, Texas.,Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Rodrigues
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Perrin
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Mark Kirkpatrick
- Department of Integrative Biology, University of Texas, Austin, Texas
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59
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Ruzicka F, Hill MS, Pennell TM, Flis I, Ingleby FC, Mott R, Fowler K, Morrow EH, Reuter M. Genome-wide sexually antagonistic variants reveal long-standing constraints on sexual dimorphism in fruit flies. PLoS Biol 2019; 17:e3000244. [PMID: 31022179 PMCID: PMC6504117 DOI: 10.1371/journal.pbio.3000244] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 05/07/2019] [Accepted: 04/09/2019] [Indexed: 01/02/2023] Open
Abstract
The evolution of sexual dimorphism is constrained by a shared genome, leading to ‘sexual antagonism’, in which different alleles at given loci are favoured by selection in males and females. Despite its wide taxonomic incidence, we know little about the identity, genomic location, and evolutionary dynamics of antagonistic genetic variants. To address these deficits, we use sex-specific fitness data from 202 fully sequenced hemiclonal Drosophila melanogaster fly lines to perform a genome-wide association study (GWAS) of sexual antagonism. We identify approximately 230 chromosomal clusters of candidate antagonistic single nucleotide polymorphisms (SNPs). In contradiction to classic theory, we find no clear evidence that the X chromosome is a hot spot for sexually antagonistic variation. Characterising antagonistic SNPs functionally, we find a large excess of missense variants but little enrichment in terms of gene function. We also assess the evolutionary persistence of antagonistic variants by examining extant polymorphism in wild D. melanogaster populations and closely related species. Remarkably, antagonistic variants are associated with multiple signatures of balancing selection across the D. melanogaster distribution range and in their sister species D. simulans, indicating widespread and evolutionarily persistent (about 1 million years) genomic constraints on the evolution of sexual dimorphism. Based on our results, we propose that antagonistic variation accumulates because of constraints on the resolution of sexual conflict over protein coding sequences, thus contributing to the long-term maintenance of heritable fitness variation. This study characterises antagonistic loci across the genome of the fruit fly Drosophila melanogaster, finding them to be preferentially associated with variation in coding sequences and to be selectively maintained across worldwide populations of D. melanogaster, and even its sister species D. simulans.
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Affiliation(s)
- Filip Ruzicka
- Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Mark S. Hill
- Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- Department of Ecology and Evolutionary Biology, The University of Michigan, Ann Arbor, Michigan, United States of America
| | - Tanya M. Pennell
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
- College of Life and Environmental Sciences, University of Exeter, Penryn, United Kingdom
| | - Ilona Flis
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
- The Pirbright Institute, Pirbright, Surrey, United Kingdom
| | - Fiona C. Ingleby
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Richard Mott
- Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- UCL Genetics Institute, University College London, London, United Kingdom
| | - Kevin Fowler
- Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Edward H. Morrow
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
- * E-mail: (MR); (EHM)
| | - Max Reuter
- Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- * E-mail: (MR); (EHM)
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60
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Connallon T, Sharma S, Olito C. Evolutionary Consequences of Sex-Specific Selection in Variable Environments: Four Simple Models Reveal Diverse Evolutionary Outcomes. Am Nat 2019; 193:93-105. [DOI: 10.1086/700720] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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61
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Grieshop K, Arnqvist G. Sex-specific dominance reversal of genetic variation for fitness. PLoS Biol 2018; 16:e2006810. [PMID: 30533008 PMCID: PMC6303075 DOI: 10.1371/journal.pbio.2006810] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 12/21/2018] [Accepted: 11/27/2018] [Indexed: 11/18/2022] Open
Abstract
The maintenance of genetic variance in fitness represents one of the most longstanding enigmas in evolutionary biology. Sexually antagonistic (SA) selection may contribute substantially to maintaining genetic variance in fitness by maintaining alternative alleles with opposite fitness effects in the two sexes. This is especially likely if such SA loci exhibit sex-specific dominance reversal (SSDR)-wherein the allele that benefits a given sex is also dominant in that sex-which would generate balancing selection and maintain stable SA polymorphisms for fitness. However, direct empirical tests of SSDR for fitness are currently lacking. Here, we performed a full diallel cross among isogenic strains derived from a natural population of the seed beetle Callosobruchus maculatus that is known to exhibit SA genetic variance in fitness. We measured sex-specific competitive lifetime reproductive success (i.e., fitness) in >500 sex-by-genotype F1 combinations and found that segregating genetic variation in fitness exhibited pronounced contributions from dominance variance and sex-specific dominance variance. A closer inspection of the nature of dominance variance revealed that the fixed allelic variation captured within each strain tended to be dominant in one sex but recessive in the other, revealing genome-wide SSDR for SA polymorphisms underlying fitness. Our findings suggest that SA balancing selection could play an underappreciated role in maintaining fitness variance in natural populations.
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Affiliation(s)
- Karl Grieshop
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala, Sweden
- * E-mail:
| | - Göran Arnqvist
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala, Sweden
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62
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Nogueira VB, Imparato DO, de Souza SJ, de Sousa MBC. Sex-biased gene expression in the frontal cortex of common marmosets (Callithrix jacchus) and potential behavioral correlates. Brain Behav 2018; 8:e01148. [PMID: 30378298 PMCID: PMC6305938 DOI: 10.1002/brb3.1148] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 09/27/2018] [Accepted: 09/30/2018] [Indexed: 12/14/2022] Open
Abstract
INTRODUCTION The common marmoset (Callithrix jacchus), a small New World monkey, has been widely used as a biological model in neuroscience to elucidate neural circuits involved in cognition and to understand brain dysfunction in neuropsychiatric disorders. In this regard, the availability of gene expression data derived from next-generation sequencing (NGS) technologies represents an opportunity for a molecular contextualization. Sexual dimorphism account for differences in diseases prevalence and prognosis. Here, we explore sex differences on frontal cortex of gene expression in common marmoset's adults. METHODS Gene expression profiles in six different tissues (cerebellum, frontal cortex, liver, heart, and kidney) were analyzed in male and female marmosets. To emphasize the translational value of this species for behavioral studies, we focused on sex-biased gene expression from the frontal cortex of male and female in common marmosets and compared to humans (Homo sapiens). RESULTS In this study, we found that frontal cortex genes whose expression is male-biased are conserved between marmosets and humans and enriched with "house-keeping" functions. On the other hand, female-biased genes are more related to neural plasticity functions involved in remodeling of synaptic circuits, stress cascades, and visual behavior. Additionally, we developed and made available an application-the CajaDB-to provide a friendly interface for genomic, expression, and alternative splicing data of marmosets together with a series of functionalities that allow the exploration of these data. CajaDB is available at cajadb.neuro.ufrn.br. CONCLUSION The data point to differences in gene expression of male and female common marmosets in all tissues analyzed. In frontal cortex, female-biased expression in synaptic plasticity, stress, and visual processing might be linked to biological and behavioral mechanisms of this sex. Due to the limited sample size, the data here analyzed are for exploratory purposes.
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Affiliation(s)
- Viviane Brito Nogueira
- Health Sciences Graduate Program, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Danilo Oliveira Imparato
- Bioinformatics Multidisciplinary Environment, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Sandro José de Souza
- Brain Institute, Bioinformatics Multidisciplinary Environment, Federal University of Rio Grande do Norte, Natal, Brazil
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63
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Dean R, Hammer C, Higham V, Dowling DK. Masculinization of gene expression is associated with male quality in Drosophila melanogaster. Evolution 2018; 72:2736-2748. [PMID: 30382578 DOI: 10.1111/evo.13618] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 12/19/2022]
Abstract
The signature of sexual selection has been revealed through the study of differences in patterns of genome-wide gene expression, both between the sexes and between alternative reproductive morphs within a single sex. What remains unclear, however, is whether differences in gene expression patterns between individuals of a given sex consistently map to variation in individual quality. Such a pattern, particularly if found in males, would provide unambiguous evidence that the phenotypic response to sexual selection is shaped through sex-specific alterations to the transcriptome. To redress this knowledge gap, we explored whether patterns of sex-biased gene expression are associated with variation in male reproductive quality in Drosophila melanogaster. We measured two male reproductive phenotypes, and their association with sex-biased gene expression, across a selection of inbred lines from the Drosophila Genetic Reference Panel. Genotypes with higher expression of male-biased genes produced males exhibiting shorter latencies to copulation, and higher capacity to inseminate females. Conversely, female-biased genes tended to show negative associations with these male reproductive traits across genotypes. We uncovered similar patterns, by reanalyzing a published dataset from a second D. melanogaster population. Our results reveal the footprint of sexual selection in masculinising the male transcriptome.
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Affiliation(s)
- Rebecca Dean
- School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia.,Department of Genetics, Evolution and Environment, University College London, WC1E 6BT, United Kingdom
| | - Camille Hammer
- School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia
| | - Vanessa Higham
- School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia
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64
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Lynch R, Wasielewski H, Cronk L. Sexual conflict and the Trivers-Willard hypothesis: Females prefer daughters and males prefer sons. Sci Rep 2018; 8:15463. [PMID: 30337613 PMCID: PMC6193998 DOI: 10.1038/s41598-018-33650-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 10/01/2018] [Indexed: 11/21/2022] Open
Abstract
Because parental care is expected to depend on the fitness returns generated by each unit of investment, it should be sensitive to both offspring condition and parental ability to invest. The Trivers-Willard Hypothesis (TWH) predicts that parents who are in good condition will bias investment towards sons, while parents who are in poor condition will bias investment towards daughters because high-quality sons are expected to out-reproduce high quality daughters, while low-quality daughters are expected to out-reproduce low quality sons. We report results from an online experiment testing the Trivers-Willard effect by measuring implicit and explicit psychological preferences and behaviorally implied preferences for sons or daughters both as a function of their social and economic status and in the aftermath of a priming task designed to make participants feel wealthy or poor. We find only limited support for predictions derived from the TWH and instead find that women have strong preferences for girls and men have preferences for boys.
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Affiliation(s)
- Robert Lynch
- Department of Biology, University of Turku, Vesilinnantie 5, Turku, FIN-20014, Finland.
| | - Helen Wasielewski
- Department of Psychology, Arizona State University, 950S. McAllister Ave, Tempe, AZ, 85287, USA
| | - Lee Cronk
- Department of Anthropology, Rutgers University, 131 George Street, New Brunswick, NJ, 08901, USA
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65
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Dutoit L, Mugal CF, Bolívar P, Wang M, Nadachowska-Brzyska K, Smeds L, Yazdi HP, Gustafsson L, Ellegren H. Sex-biased gene expression, sexual antagonism and levels of genetic diversity in the collared flycatcher (Ficedula albicollis) genome. Mol Ecol 2018; 27:3572-3581. [DOI: 10.1111/mec.14789] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 03/28/2018] [Accepted: 04/02/2018] [Indexed: 12/30/2022]
Affiliation(s)
- Ludovic Dutoit
- Department of Evolutionary Biology; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
| | - Carina F. Mugal
- Department of Evolutionary Biology; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
| | - Paulina Bolívar
- Department of Evolutionary Biology; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
| | - Mi Wang
- Department of Evolutionary Biology; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
| | | | - Linnéa Smeds
- Department of Evolutionary Biology; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
| | - Homa P. Yazdi
- Department of Evolutionary Biology; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
| | - Lars Gustafsson
- Department of Animal Ecology; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
| | - Hans Ellegren
- Department of Evolutionary Biology; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
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67
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Abstract
As an immediate consequence of sexual reproduction, biphasic life cycles with alternating diploid and haploid phases are a common characteristic of sexually reproducing eukaryotes. Much of our focus in evolutionary biology has been directed toward dynamics in diploid or haploid populations, but we rarely consider selection occurring during both phases when studying evolutionary processes. One of the reasons for this apparent omission is the fact that many flowering plants and metazoans are predominantly diploid with a very short haploid gametic phase. While this gametic phase may be short, it can play a crucial role in fundamental processes including the rate of adaptation, the load of mutation, and the evolution of features such as recombination. In addition, if selection acts in different directions between the two phases, a genetic conflict will occur, impacting the maintenance of genetic variation. Here we provide an overview of theoretical and empirical studies investigating the importance of selection at the haploid gametic phase in predominantly diploid organisms and discuss future directions to improve our understanding of the underlying dynamics and the general implications of haploid selection.
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68
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Charlesworth D. Evolution of recombination rates between sex chromosomes. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0456. [PMID: 29109220 DOI: 10.1098/rstb.2016.0456] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2017] [Indexed: 11/12/2022] Open
Abstract
In species with genetic sex-determination, the chromosomes carrying the sex-determining genes have often evolved non-recombining regions and subsequently evolved the full set of characteristics denoted by the term 'sex chromosomes'. These include size differences, creating chromosomal heteromorphism, and loss of gene functions from one member of the chromosome pair. Such characteristics and changes have been widely reviewed, and underlie molecular genetic approaches that can detect sex chromosome regions. This review deals mainly with the evolution of new non-recombining regions, focusing on how certain evolutionary situations select for suppressed recombination (rather than the proximate mechanisms causing suppressed recombination between sex chromosomes). Particularly important is the likely involvement of sexually antagonistic polymorphisms in genome regions closely linked to sex-determining loci. These may be responsible for the evolutionary strata of sex chromosomes that have repeatedly formed by recombination suppression evolving across large genome regions. More studies of recently evolved non-recombining sex-determining regions should help to test this hypothesis empirically, and may provide evidence about whether other situations can sometimes lead to sex-linked regions evolving. Similarities with other non-recombining genome regions are discussed briefly, to illustrate common features of the different cases, though no general properties apply to all of them.This article is part of the themed issue 'Evolutionary causes and consequences of recombination rate variation in sexual organisms'.
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Affiliation(s)
- Deborah Charlesworth
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratory, University of Edinburgh, King's Buildings, Edinburgh EH9 3FL, UK
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69
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Immonen E, Hämäläinen A, Schuett W, Tarka M. Evolution of sex-specific pace-of-life syndromes: genetic architecture and physiological mechanisms. Behav Ecol Sociobiol 2018; 72:60. [PMID: 29576676 PMCID: PMC5856903 DOI: 10.1007/s00265-018-2462-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 11/13/2017] [Accepted: 02/07/2018] [Indexed: 11/16/2022]
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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Affiliation(s)
- Elina Immonen
- Department of Ecology and Genetics, Evolutionary Biology Centre (EBC), Uppsala University, Norbyvägen 18 D, SE-75 236 Uppsala, Sweden
| | - Anni Hämäläinen
- Department of Biological Sciences, University of Alberta, Edmonton, T6G 2E9 Canada
| | - Wiebke Schuett
- Zoological Institute, University of Hamburg, Martin-Luther-King Platz 3, 20146 Hamburg, Germany
| | - Maja Tarka
- Center for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology (NTNU), Høgskoleringen 5, 7491 Trondheim, Norway
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70
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Wright AE, Fumagalli M, Cooney CR, Bloch NI, Vieira FG, Buechel SD, Kolm N, Mank JE. Male-biased gene expression resolves sexual conflict through the evolution of sex-specific genetic architecture. Evol Lett 2018; 2:52-61. [PMID: 30283664 PMCID: PMC6089503 DOI: 10.1002/evl3.39] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/04/2018] [Accepted: 01/09/2018] [Indexed: 12/20/2022] Open
Abstract
Many genes are subject to contradictory selection pressures in males and females, and balancing selection resulting from sexual conflict has the potential to substantially increase standing genetic diversity in populations and thereby act as an important force in adaptation. However, the underlying causes of sexual conflict, and the potential for resolution, remains hotly debated. Using transcriptome‐resequencing data from male and female guppies, we use a novel approach, combining patterns of genetic diversity and intersexual divergence in allele frequency, to distinguish the different scenarios that give rise to sexual conflict, and how this conflict may be resolved through regulatory evolution. We show that reproductive fitness is the main source of sexual conflict, and this is resolved via the evolution of male‐biased expression. Furthermore, resolution of sexual conflict produces significant differences in genetic architecture between males and females, which in turn lead to specific alleles influencing sex‐specific viability. Together, our findings suggest an important role for sexual conflict in shaping broad patterns of genome diversity, and show that regulatory evolution is a rapid and efficient route to the resolution of conflict.
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Affiliation(s)
- Alison E Wright
- Department of Animal and Plant Sciences University of Sheffield Sheffield United Kingdom
| | - Matteo Fumagalli
- Department of Life Sciences, Silwood Park Campus Imperial College London London United Kingdom
| | - Christopher R Cooney
- Department of Animal and Plant Sciences University of Sheffield Sheffield United Kingdom
| | - Natasha I Bloch
- Department of Genetics, Evolution and Environment University College London London United Kingdom
| | - Filipe G Vieira
- Centre for GeoGenetics, Natural History Museum of Denmark University of Copenhagen Copenhagen Denmark
| | | | - Niclas Kolm
- Department of Zoology Stockholm University Stockholm Sweden
| | - Judith E Mank
- Department of Genetics, Evolution and Environment University College London London United Kingdom.,Department of Organismal Biology Uppsala University Uppsala Sweden
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71
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Fontaine A, Filipovic I, Fansiri T, Hoffmann AA, Cheng C, Kirkpatrick M, Rašic G, Lambrechts L. Extensive Genetic Differentiation between Homomorphic Sex Chromosomes in the Mosquito Vector, Aedes aegypti. Genome Biol Evol 2018; 9:2322-2335. [PMID: 28945882 PMCID: PMC5737474 DOI: 10.1093/gbe/evx171] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2017] [Indexed: 12/25/2022] Open
Abstract
Mechanisms and evolutionary dynamics of sex-determination systems are of particular interest in insect vectors of human pathogens like mosquitoes because novel control strategies aim to convert pathogen-transmitting females into nonbiting males, or rely on accurate sexing for the release of sterile males. In Aedes aegypti, the main vector of dengue and Zika viruses, sex determination is governed by a dominant male-determining locus, previously thought to reside within a small, nonrecombining, sex-determining region (SDR) of an otherwise homomorphic sex chromosome. Here, we provide evidence that sex chromosomes in Ae. aegypti are genetically differentiated between males and females over a region much larger than the SDR. Our linkage mapping intercrosses failed to detect recombination between X and Y chromosomes over a 123-Mbp region (40% of their physical length) containing the SDR. This region of reduced male recombination overlapped with a smaller 63-Mbp region (20% of the physical length of the sex chromosomes) displaying high male–female genetic differentiation in unrelated wild populations from Brazil and Australia and in a reference laboratory strain originating from Africa. In addition, the sex-differentiated genomic region was associated with a significant excess of male-to-female heterozygosity and contained a small cluster of loci consistent with Y-specific null alleles. We demonstrate that genetic differentiation between sex chromosomes is sufficient to assign individuals to their correct sex with high accuracy. We also show how data on allele frequency differences between sexes can be used to estimate linkage disequilibrium between loci and the sex-determining locus. Our discovery of large-scale genetic differentiation between sex chromosomes in Ae. aegypti lays a new foundation for mapping and population genomic studies, as well as for mosquito control strategies targeting the sex-determination pathway.
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Affiliation(s)
- Albin Fontaine
- Department of Genomes and Genetics, Insect-Virus Interactions Group, Institut Pasteur, Paris, France.,Département des Maladies Infectieuses, Unité de Parasitologie et Entomologie, Institut de Recherche Biomédicale des Armées, Marseille, France.,Centre National de la Recherche Scientifique, URA 3012, Paris, France.,Aix Marseille Université, UM63, CNRS 7278, IRD 198, INSERM 1095, AP-HM, IHU-Méditerranée Infection, France
| | - Igor Filipovic
- Pest and Environmental Adaptation Research Group, School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Victoria, Australia
| | - Thanyalak Fansiri
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Ary A Hoffmann
- Pest and Environmental Adaptation Research Group, School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Victoria, Australia
| | - Changde Cheng
- Department of Integrative Biology, University of Texas, Austin
| | | | - Gordana Rašic
- Pest and Environmental Adaptation Research Group, School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Victoria, Australia
| | - Louis Lambrechts
- Department of Genomes and Genetics, Insect-Virus Interactions Group, Institut Pasteur, Paris, France.,Centre National de la Recherche Scientifique, URA 3012, Paris, France
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72
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Connallon T, Hall MD. Genetic constraints on adaptation: a theoretical primer for the genomics era. Ann N Y Acad Sci 2018; 1422:65-87. [PMID: 29363779 DOI: 10.1111/nyas.13536] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/20/2017] [Accepted: 09/28/2017] [Indexed: 12/14/2022]
Abstract
Genetic constraints are features of inheritance systems that slow or prohibit adaptation. Several population genetic mechanisms of constraint have received sustained attention within the field since they were first articulated in the early 20th century. This attention is now reflected in a rich, and still growing, theoretical literature on the genetic limits to adaptive change. In turn, empirical research on constraints has seen a rapid expansion over the last two decades in response to changing interests of evolutionary biologists, along with new technologies, expanding data sets, and creative analytical approaches that blend mathematical modeling with genomics. Indeed, one of the most notable and exciting features of recent progress in genetic constraints is the close connection between theoretical and empirical research. In this review, we discuss five major population genetic contexts of genetic constraint: genetic dominance, pleiotropy, fitness trade-offs between types of individuals of a population, sign epistasis, and genetic linkage between loci. For each, we outline historical antecedents of the theory, specific contexts where constraints manifest, and their quantitative consequences for adaptation. From each of these theoretical foundations, we discuss recent empirical approaches for identifying and characterizing genetic constraints, each grounded and motivated by this theory, and outline promising areas for future work.
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Affiliation(s)
- Tim Connallon
- School of Biological Sciences, and Centre for Geometric Biology, Monash University, Clayton, Victoria, Australia
| | - Matthew D Hall
- School of Biological Sciences, and Centre for Geometric Biology, Monash University, Clayton, Victoria, Australia
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73
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Campbell CL, Dickson LB, Lozano-Fuentes S, Juneja P, Jiggins FM, Black WC. Alternative patterns of sex chromosome differentiation in Aedes aegypti (L). BMC Genomics 2017; 18:943. [PMID: 29202694 PMCID: PMC5716240 DOI: 10.1186/s12864-017-4348-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 11/23/2017] [Indexed: 12/16/2022] Open
Abstract
Background Some populations of West African Aedes aegypti, the dengue and zika vector, are reproductively incompatible; our earlier study showed that divergence and rearrangements of genes on chromosome 1, which bears the sex locus (M), may be involved. We also previously described a proposed cryptic subspecies SenAae (PK10, Senegal) that had many more high inter-sex FST genes on chromosome 1 than did Ae.aegypti aegypti (Aaa, Pai Lom, Thailand). The current work more thoroughly explores the significance of those findings. Results Intersex standardized variance (FST) of single nucleotide polymorphisms (SNPs) was characterized from genomic exome capture libraries of both sexes in representative natural populations of Aaa and SenAae. Our goal was to identify SNPs that varied in frequency between males and females, and most were expected to occur on chromosome 1. Use of the assembled AaegL4 reference alleviated the previous problem of unmapped genes. Because the M locus gene nix was not captured and not present in AaegL4, the male-determining locus, per se, was not explored. Sex-associated genes were those with FST values ≥ 0.100 and/or with increased expected heterozygosity (Hexp, one-sided T-test, p < 0.05) in males. There were 85 genes common to both collections with high inter-sex FST values; all genes but one were located on chromosome 1. Aaa showed the expected cluster of high inter-sex FST genes proximal to the M locus, whereas SenAae had inter-sex FST genes along the length of chromosome 1. In addition, the Aaa M-locus proximal region showed increased Hexp levels in males, whereas SenAae did not. In SenAae, chromosomal rearrangements and subsequent suppressed recombination may have accelerated X-Y differentiation. Conclusions The evidence presented here is consistent with differential evolution of proto-Y chromosomes in Aaa and SenAae. Electronic supplementary material The online version of this article (doi: 10.1186/s12864-017-4348-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Corey L Campbell
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA.
| | - Laura B Dickson
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
| | - Saul Lozano-Fuentes
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
| | - Punita Juneja
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - William C Black
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
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74
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Kasimatis KR, Nelson TC, Phillips PC. Genomic Signatures of Sexual Conflict. J Hered 2017; 108:780-790. [PMID: 29036624 PMCID: PMC5892400 DOI: 10.1093/jhered/esx080] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Accepted: 09/18/2017] [Indexed: 02/06/2023] Open
Abstract
Sexual conflict is a specific class of intergenomic conflict that describes the reciprocal sex-specific fitness costs generated by antagonistic reproductive interactions. The potential for sexual conflict is an inherent property of having a shared genome between the sexes and, therefore, is an extreme form of an environment-dependent fitness effect. In this way, many of the predictions from environment-dependent selection can be used to formulate expected patterns of genome evolution under sexual conflict. However, the pleiotropic and transmission constraints inherent to having alleles move across sex-specific backgrounds from generation to generation further modulate the anticipated signatures of selection. We outline methods for detecting candidate sexual conflict loci both across and within populations. Additionally, we consider the ability of genome scans to identify sexually antagonistic loci by modeling allele frequency changes within males and females due to a single generation of selection. In particular, we highlight the need to integrate genotype, phenotype, and functional information to truly distinguish sexual conflict from other forms of sexual differentiation.
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Affiliation(s)
- Katja R Kasimatis
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Thomas C Nelson
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
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75
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76
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Rice MA, Hobbs LE, Wallace KJ, Ophir AG. Cryptic sexual dimorphism in spatial memory and hippocampal oxytocin receptors in prairie voles (Microtus ochrogaster). Horm Behav 2017; 95:94-102. [PMID: 28818500 PMCID: PMC5623076 DOI: 10.1016/j.yhbeh.2017.08.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 08/07/2017] [Accepted: 08/12/2017] [Indexed: 02/07/2023]
Abstract
Sex differences are well documented and are conventionally associated with intense sex-specific selection. For example, spatial memory is frequently better in males, presumably due to males' tendency to navigate large spaces to find mates. Alternatively, monogamy (in which sex-specific selection is relatively relaxed) should diminish or eliminate differences in spatial ability and the mechanisms associated with this behavior. Nevertheless, phenotypic differences between monogamous males and females persist, sometimes cryptically. We hypothesize that sex-specific cognitive demands are present in monogamous species that will influence neural and behavioral phenotypes. The effects of these demands should be observable in spatial learning performance and neural structures associated with spatial learning and memory. We analyzed spatial memory performance, hippocampal volume and cell density, and hippocampal oxytocin receptor (OTR) expression in the socially monogamous prairie vole. Compared to females, males performed better in a spatial memory and spatial learning test. Although we found no sex difference in hippocampal volume or cell density, male OTR density was significantly lower than females, suggesting that performance may be regulated by sub-cellular mechanisms within the hippocampus that are less obvious than classic neuroanatomical features. Our results suggest an expanded role for oxytocin beyond facilitating social interactions, which may function in part to integrate social and spatial information.
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Affiliation(s)
- Marissa A Rice
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA; Department of Integrative Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Lauren E Hobbs
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Kelly J Wallace
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA
| | - Alexander G Ophir
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA; Department of Integrative Biology, Oklahoma State University, Stillwater, OK 74078, USA.
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77
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Differential evolutionary patterns and expression levels between sex-specific and somatic tissue-specific genes in peanut. Sci Rep 2017; 7:9016. [PMID: 28827710 PMCID: PMC5566475 DOI: 10.1038/s41598-017-09905-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/01/2017] [Indexed: 11/08/2022] Open
Abstract
The patterns of evolution and expression of tissue-specific genes are poorly understood beyond sex-specific genes. Accordingly, we identified 3,191 tissue-specific genes and 38,745 common genes using 22 RNA-seq datasets from cultivated peanut. The expression levels of tissue-specific genes were significantly lower than those of common genes. Further, the expression levels of sex-specific genes were significantly higher than those of somatic tissue-specific genes. Among sex-specific genes, the expression levels of gynoecium-specific genes were significantly higher than those of androecium-specific genes. Function-specific genes were lacking among tissue-specific genes, and tissue-specific gene annotations overlapped among different tissues. Duplicate gene pairs were classified as homogeneous pairs expressed within the same tissue or heterogeneous pairs expressed in different tissues. Heterogeneous gene pairs evolved more rapidly than homogeneous gene pairs. In addition, somatic tissue-specific genes evolved faster than sex-specific genes. Molecular signatures of selection indicated that somatic tissue-specific genes have mainly experienced relaxed selection, while sex-specific genes have been under stronger selective constraint. Somatic tissue-specific genes had higher codon usage bias than sex-specific genes. These contrasting patterns between somatic tissue-specific and sex-specific genes provide new insights into the basic biology and evolution of peanut, an important crop.
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78
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Schulenburg H, Félix MA. The Natural Biotic Environment of Caenorhabditis elegans. Genetics 2017; 206:55-86. [PMID: 28476862 PMCID: PMC5419493 DOI: 10.1534/genetics.116.195511] [Citation(s) in RCA: 249] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/28/2017] [Indexed: 01/05/2023] Open
Abstract
Organisms evolve in response to their natural environment. Consideration of natural ecological parameters are thus of key importance for our understanding of an organism's biology. Curiously, the natural ecology of the model species Caenorhabditis elegans has long been neglected, even though this nematode has become one of the most intensively studied models in biological research. This lack of interest changed ∼10 yr ago. Since then, an increasing number of studies have focused on the nematode's natural ecology. Yet many unknowns still remain. Here, we provide an overview of the currently available information on the natural environment of C. elegans We focus on the biotic environment, which is usually less predictable and thus can create high selective constraints that are likely to have had a strong impact on C. elegans evolution. This nematode is particularly abundant in microbe-rich environments, especially rotting plant matter such as decomposing fruits and stems. In this environment, it is part of a complex interaction network, which is particularly shaped by a species-rich microbial community. These microbes can be food, part of a beneficial gut microbiome, parasites and pathogens, and possibly competitors. C. elegans is additionally confronted with predators; it interacts with vector organisms that facilitate dispersal to new habitats, and also with competitors for similar food environments, including competitors from congeneric and also the same species. Full appreciation of this nematode's biology warrants further exploration of its natural environment and subsequent integration of this information into the well-established laboratory-based research approaches.
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Affiliation(s)
- Hinrich Schulenburg
- Zoological Institute, Christian-Albrechts Universitaet zu Kiel, 24098 Kiel, Germany
| | - Marie-Anne Félix
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, École Normale Supérieure, L'université de Recherche Paris Sciences et Lettres, 75005, France
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79
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Pulit SL, Karaderi T, Lindgren CM. Sexual dimorphisms in genetic loci linked to body fat distribution. Biosci Rep 2017; 37:BSR20160184. [PMID: 28073971 PMCID: PMC5291139 DOI: 10.1042/bsr20160184] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 01/07/2017] [Accepted: 01/10/2017] [Indexed: 01/02/2023] Open
Abstract
Obesity is a chronic condition associated with increased morbidity and mortality and is a risk factor for a number of other diseases including type 2 diabetes and cardiovascular disease. Obesity confers an enormous, costly burden on both individuals and public health more broadly. Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes. Body fat distribution is distinct from overall obesity in measurement, but studies of body fat distribution can yield insights into the risk factors for and causes of overall obesity. Sexual dimorphism in body fat distribution is present throughout life. Though sexual dimorphism is subtle in early stages of life, it is attenuated in puberty and during menopause. This phenomenon could be, at least in part, due to the influence of sex hormones on the trait. Findings from recent large genome-wide association studies (GWAS) for various measures of body fat distribution (including waist-to-hip ratio, hip or waist circumference, trunk fat percentage and the ratio of android and gynoid fat percentage) emphasize the strong sexual dimorphism in the genetic regulation of fat distribution traits. Importantly, sexual dimorphism is not observed for overall obesity (as assessed by body mass index or total fat percentage). Notably, the genetic loci associated with body fat distribution, which show sexual dimorphism, are located near genes that are expressed in adipose tissues and/or adipose cells. Considering the epidemiological and genetic evidence, sexual dimorphism is a prominent feature of body fat distribution. Research that specifically focuses on sexual dimorphism in fat distribution can provide novel insights into human physiology and into the development of obesity and its comorbidities, as well as yield biological clues that will aid in the improvement of disease prevention and treatment.
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Affiliation(s)
- Sara L Pulit
- Department of Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tugce Karaderi
- Department of Biological Sciences, Faculty of Arts and Sciences, Eastern Mediterranean University, Famagusta, Cyprus
| | - Cecilia M Lindgren
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, U.K.
- Wellcome Trust Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, U.K
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80
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Guirao-Rico S, Sánchez-Gracia A, Charlesworth D. Sequence diversity patterns suggesting balancing selection in partially sex-linked genes of the plant Silene latifolia are not generated by demographic history or gene flow. Mol Ecol 2017; 26:1357-1370. [PMID: 28035715 DOI: 10.1111/mec.13969] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 12/02/2016] [Accepted: 12/12/2016] [Indexed: 01/16/2023]
Abstract
DNA sequence diversity in genes in the partially sex-linked pseudoautosomal region (PAR) of the sex chromosomes of the plant Silene latifolia is higher than expected from within-species diversity of other genes. This could be the footprint of sexually antagonistic (SA) alleles that are maintained by balancing selection in a PAR gene (or genes) and affect polymorphism in linked genome regions. SA selection is predicted to occur during sex chromosome evolution, but it is important to test whether the unexpectedly high sequence polymorphism could be explained without it, purely by the combined effects of partial linkage with the sex-determining region and the population's demographic history, including possible introgression from Silene dioica. To test this, we applied approximate Bayesian computation-based model choice to autosomal sequence diversity data, to find the most plausible scenario for the recent history of S. latifolia and then to estimate the posterior density of the most relevant parameters. We then used these densities to simulate variation to be expected at PAR genes. We conclude that an excess of variants at high frequencies at PAR genes should arise in S. latifolia populations only for genes with strong associations with fully sex-linked genes, which requires closer linkage with the fully sex-linked region than that estimated for the PAR genes where apparent deviations from neutrality were observed. These results support the need to invoke selection to explain the S. latifolia PAR gene diversity, and encourage further work to test the possibility of balancing selection due to sexual antagonism.
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Affiliation(s)
- Sara Guirao-Rico
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JN, UK
| | - Alejandro Sánchez-Gracia
- Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat, Universitat de Barcelona, Av. Diagonal 643, Barcelona, 08028, Spain
| | - Deborah Charlesworth
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JN, UK
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