1
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Mitchell C, Wylde Z, Del Castillo E, Rapkin J, House CM, Hunt J. Beauty or function? The opposing effects of natural and sexual selection on cuticular hydrocarbons in male black field crickets. J Evol Biol 2023; 36:1266-1281. [PMID: 37534753 DOI: 10.1111/jeb.14198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 04/21/2023] [Accepted: 05/10/2023] [Indexed: 08/04/2023]
Abstract
Although many theoretical models of male sexual trait evolution assume that sexual selection is countered by natural selection, direct empirical tests of this assumption are relatively uncommon. Cuticular hydrocarbons (CHCs) are known to play an important role not only in restricting evaporative water loss but also in sexual signalling in most terrestrial arthropods. Insects adjusting their CHC layer for optimal desiccation resistance is often thought to come at the expense of successful sexual attraction, suggesting that natural and sexual selection are in opposition for this trait. In this study, we sampled the CHCs of male black field crickets (Teleogryllus commodus) using solid-phase microextraction and then either measured their evaporative water loss or mating success. We then used multivariate selection analysis to quantify the strength and form of natural and sexual selection targeting male CHCs. Both natural and sexual selection imposed significant linear and stabilizing selection on male CHCs, although for very different combinations. Natural selection largely favoured an increase in the total abundance of CHCs, especially those with a longer chain length. In contrast, mating success peaked at a lower total abundance of CHCs and declined as CHC abundance increased. However, mating success did improve with an increase in a number of specific CHC components that also increased evaporative water loss. Importantly, this resulted in the combination of male CHCs favoured by natural selection and sexual selection being strongly opposing. Our findings suggest that the balance between natural and sexual selection is likely to play an important role in the evolution of male CHCs in T. commodus and may help explain why CHCs are so divergent across populations and species.
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Affiliation(s)
- Christopher Mitchell
- Centre for Ecology & Conservation, School of Biosciences, University of Exeter, Cornwall Campus, Penryn, UK
| | - Zachariah Wylde
- School of Science, Western Sydney University, Hawkesbury Campus, Penrith, New South Wales, Australia
| | - Enrique Del Castillo
- Department of Industrial & Manufacturing Engineering and Department of Statistics, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - James Rapkin
- Centre for Ecology & Conservation, School of Biosciences, University of Exeter, Cornwall Campus, Penryn, UK
| | - Clarissa M House
- School of Science, Western Sydney University, Hawkesbury Campus, Penrith, New South Wales, Australia
| | - John Hunt
- Centre for Ecology & Conservation, School of Biosciences, University of Exeter, Cornwall Campus, Penryn, UK
- School of Science, Western Sydney University, Hawkesbury Campus, Penrith, New South Wales, Australia
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2
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Madaj A, Durka W, Michalski SG. Two common, often coexisting grassland plant species differ in their evolutionary potential in response to experimental drought. Ecol Evol 2023; 13:e10430. [PMID: 37664507 PMCID: PMC10469005 DOI: 10.1002/ece3.10430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 09/05/2023] Open
Abstract
For terrestrial plant communities, the increase in frequency and intensity of drought events is considered as one of the most severe consequences of climate change. While single-species studies demonstrate that drought can lead to relatively rapid adaptive genetic changes, the evolutionary potential and constraints to selection need to be assessed in comparative approaches to draw more general conclusions. In a greenhouse experiment, we compare the phenotypic response and evolutionary potential of two co-occurring grassland plant species, Bromus erectus and Trifolium pratense, in two environments differing in water availability. We quantified variation in functional traits and reproductive fitness in response to drought and compared multivariate genetic variance-covariance matrices and predicted evolutionary responses between species. Species showed different drought adaptation strategies, reflected in both their species-specific phenotypic plasticity and predicted responses to selection indicating contrasting evolutionary potential under drought. In T. pratense we found evidence for stronger genetic constraints under drought compared to more favourable conditions, and for some traits plastic and predicted evolutionary responses to drought had opposing directions, likely limiting the potential for adaptive change. Our study contributes to a more detailed understanding of the evolutionary potential of species with different adaptive strategies in response to climate change and may help to inform future scenarios for semi-natural grassland ecosystems.
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Affiliation(s)
- Anna‐Maria Madaj
- Department of Community EcologyHelmholtz‐Centre for Environmental Research – UFZHalle (Saale)Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
- Institute of BiologyLeipzig UniversityLeipzigGermany
| | - Walter Durka
- Department of Community EcologyHelmholtz‐Centre for Environmental Research – UFZHalle (Saale)Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
| | - Stefan G. Michalski
- Department of Community EcologyHelmholtz‐Centre for Environmental Research – UFZHalle (Saale)Germany
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3
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Watanabe J. Statistics of eigenvalue dispersion indices: Quantifying the magnitude of phenotypic integration. Evolution 2021; 76:4-28. [PMID: 34679186 DOI: 10.1111/evo.14382] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/13/2021] [Accepted: 09/20/2021] [Indexed: 01/28/2023]
Abstract
Analysis of trait covariation plays a pivotal role in the study of phenotypic evolution. The magnitude of covariation is often quantified with statistics based on dispersion of eigenvalues of a covariance or correlation matrix-eigenvalue dispersion indices. This study clarifies the statistical justifications of these statistics and elaborates on their sampling properties. The relative eigenvalue variance of a covariance matrix is known in the statistical literature a test statistic for sphericity, and thus is an appropriate measure of eccentricity of variation. The same of a correlation matrix is equal to the average squared correlation, which has a straightforward interpretation as a measure of integration. Here, expressions for the mean and variance of these statistics are analytically derived under multivariate normality, clarifying the effects of sample size N, number of variables p, and parameters on sampling bias and error. Simulations confirm that approximations involved are reasonably accurate with a moderate sample size (N ≥ 16-64). Importantly, sampling properties of these indices are not adversely affected by a high p:N ratio, promising their utility in high-dimensional phenotypic analyses. They can furthermore be applied to shape variables and phylogenetically structured data with appropriate modifications.
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Affiliation(s)
- Junya Watanabe
- Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
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4
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Oh KP, Shaw KL. Axes of multivariate sexual signal divergence among incipient species: Concordance with selection, genetic variation and phenotypic plasticity. J Evol Biol 2021; 35:109-123. [PMID: 34668602 DOI: 10.1111/jeb.13951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 10/11/2021] [Indexed: 11/30/2022]
Abstract
Sexual signalling traits are often observed to diverge rapidly among populations, thereby playing a potentially key early role in the evolution of reproductive isolation. While often assumed to reflect divergent sexual selection among populations, patterns of sexual trait diversification might sometimes be biased along axes of standing additive genetic variation and covariation among trait components. Additionally, theory predicts that environmentally induced phenotypic variation might facilitate rapid trait evolution, suggesting that patterns of divergence between populations should mirror phenotypic plasticity within populations. Here, we evaluate the concordance between observed axes of multivariate sexual trait divergence and predicted divergence based on (1) interpopulation variation in sexual selection, (2) additive genetic variances and (3) temperature-related phenotypic plasticity in male courtship song among geographically isolated populations of the Hawaiian swordtail cricket, Laupala cerasina, which exhibit sexual isolation due acoustic signalling traits. The major axis of multivariate divergence, dmax , accounted for 76% of variation among population male song trait means and was moderately correlated with interpopulation differences in directional sexual selection based on female preferences. However, the majority of additive genetic variance was largely oriented away from the direction of divergence, suggesting that standing genetic variation may not play a dominant role in the patterning of signal divergence. In contrast, the axis of phenotypic plasticity strongly mirrored patterns of interpopulation phenotypic divergence, which is consistent with a role for temperature-related plasticity in facilitating instead of inhibiting male song evolution and sexual isolation in these incipient species. We propose potential mechanisms by which sexual selection might interact with phenotypic plasticity to facilitate the rapid acoustic diversification observed in this species and clade.
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Affiliation(s)
- Kevin P Oh
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
| | - Kerry L Shaw
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
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5
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Wittman TN, Robinson CD, McGlothlin JW, Cox RM. Hormonal pleiotropy structures genetic covariance. Evol Lett 2021; 5:397-407. [PMID: 34367664 PMCID: PMC8327939 DOI: 10.1002/evl3.240] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 05/03/2021] [Accepted: 05/17/2021] [Indexed: 11/08/2022] Open
Abstract
Quantitative genetic theory proposes that phenotypic evolution is shaped by G, the matrix of genetic variances and covariances among traits. In species with separate sexes, the evolution of sexual dimorphism is also shaped by B, the matrix of between‐sex genetic variances and covariances. Despite considerable focus on estimating these matrices, their underlying biological mechanisms are largely speculative. We experimentally tested the hypothesis that G and B are structured by hormonal pleiotropy, which occurs when one hormone influences multiple phenotypes. Using juvenile brown anole lizards (Anolis sagrei) bred in a paternal half‐sibling design, we elevated the steroid hormone testosterone with slow‐release implants while administering empty implants to siblings as a control. We quantified the effects of this manipulation on the genetic architecture of a suite of sexually dimorphic traits, including body size (males are larger than females) and the area, hue, saturation, and brightness of the dewlap (a colorful ornament that is larger in males than in females). Testosterone masculinized females by increasing body size and dewlap area, hue, and saturation, while reducing dewlap brightness. Control females and males differed significantly in G, but treatment of females with testosterone rendered G statistically indistinguishable from males. Whereas B was characterized by low between‐sex genetic correlations when estimated between control females and males, these same correlations increased significantly when estimated between testosterone females and either control or testosterone males. The full G matrix (including B) for testosterone females and either control or testosterone males was significantly less permissive of sexually dimorphic evolution than was G estimated between control females and males, suggesting that natural sex differences in testosterone help decouple genetic variance between the sexes. Our results confirm that hormonal pleiotropy structures genetic covariance, implying that hormones play an important yet overlooked role in mediating evolutionary responses to selection.
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Affiliation(s)
- Tyler N Wittman
- Department of Biology University of Virginia Charlottesville Virginia 22904
| | | | - Joel W McGlothlin
- Department of Biological Sciences Virginia Tech Blacksburg Virginia 24061
| | - Robert M Cox
- Department of Biology University of Virginia Charlottesville Virginia 22904
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6
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Cruz FB, Moreno Azocar DL, Vanhooydonck B, Schulte JA, Abdala CS, Herrel A. Drivers and patterns of bite force evolution in liolaemid lizards. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Phenotypic variation is the result of selection on traits that are relevant in a given ecological context. Phylogenetic history, genetic drift, and any developmental or structural constraints may, however, limit variation in trait expression. It has been proposed that organismal performance traits take up a pivotal role in driving variation in morphology due to their central role in survival and reproductive success. However, how strong the links are between morphology and performance, and how the strength of this relationship impacts the rate of evolution of form and function need to be studied across a wider variety of systems to better understand the origin and evolution of biodiversity. Here we used data on the jaw system (muscle architecture and head dimensions) of liolaemid lizards to investigate the drivers of in vivo bite force variation and test for differences in evolutionary rates in morphology and performance. Our results show high rates of evolution for performance traits compared to morphological traits such as external head dimensions. Many-to-one mapping of morphology to performance, that is the possibility that different anatomical trait combinations lead to similar levels of performance, appears to be common in the jaw system of these lizards. Finally, traits showing greater mechanical sensitivity (muscle cross-sectional areas) showed higher rates of evolution compared to traits involved in other functions and that are probably subject to trade-offs (e.g. head width).
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Affiliation(s)
- Félix B Cruz
- Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA) CONICET-UNCOMA, Quintral, Bariloche, Argentina
| | - Débora Lina Moreno Azocar
- Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA) CONICET-UNCOMA, Quintral, Bariloche, Argentina
| | - Bieke Vanhooydonck
- Department of Biology, University of Antwerp, Universiteitsplein 1, Antwerpen,Belgium
| | - James A Schulte
- Division of Amphibians and Reptiles, National Museum of Natural History, Washington, DC, USA
| | - Cristian S Abdala
- Unidad Ejecutora Lillo (UEL)- CONICET and Facultad de Cs. Naturales e IML, UNT. Miguel Lillo, Tucumán, Argentina
| | - Anthony Herrel
- Department of Biology, University of Antwerp, Universiteitsplein 1, Antwerpen,Belgium
- UMR 7179 CNRS/MNHN, Département Adaptations du Vivant, Bâtiment d’Anatomie Comparée, Paris, France
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7
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Contingency and determinism in the evolution of bird song sound frequency. Sci Rep 2021; 11:11600. [PMID: 34078943 PMCID: PMC8172888 DOI: 10.1038/s41598-021-90775-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 05/11/2021] [Indexed: 11/08/2022] Open
Abstract
Sexual signals are archetypes of contingent evolution: hyper-diverse across species, often evolving fast and in unpredictable directions. It is unclear to which extent their evolutionary unpredictability weakens deterministic evolution, or takes place bounded by deterministic patterns of trait evolution. We compared the evolution of sound frequency in sexual signals (advertisement songs) and non-sexual social signals (calls) across > 500 genera of the crown songbird families. Contrary to the acoustic adaptation hypothesis, we found no evidence that forest species used lower sound frequencies in songs or calls. Consistent with contingent evolution in song, we found lower phylogenetic signal for the sound frequency of songs than calls, which suggests faster and less predictable evolution, and found unpredictable direction of evolution in lineages with longer songs, which presumably experience stronger sexual selection on song. Nonetheless, the most important deterministic pattern of sound frequency evolution—its negative association with body size—was stronger in songs than calls. This can be explained by songs being longer-range signals than most calls, and thus using sound frequencies that animals of a given size produce best at high amplitude. Results indicate that sexual selection can increase aspects of evolutionary contingency while strengthening, rather than weakening, deterministic patterns of evolution.
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8
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Styga JM, Welsh DP. Spawning substrate shift associated with the evolution of a female sexual characteristic in a family of fishes. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Because ‘primary’ sexual characteristics (i.e. those directly associated with reproduction) can be extremely variable, evolve quickly, and can be impacted by both natural and sexual selection, they are often considered excellent model systems in which to study evolution. Here, we explore the evolution of the anal sheath, a trait hypothesized to facilitate the release and proper placement of eggs on the spawning substrate, and its relationship to spawning habitat and maximum body size in a family of fish (Fundulidae). In addition to using phylogenetically informed statistics to determine the role of preferred spawning habitat and maximum body size on the evolution of anal sheath length, we reconstruct the evolutionary history of the anal sheath and preferred spawning habitat. We then test for significant phylogenetic signal and evolutionary rate shifts in the size of the anal sheath and the preferred spawning habitat. Our results indicate that preferred spawning habitat, and not maximum body length, significantly influences anal sheath size, which is associated with a significant phylogenetic signal, and an evolutionary rate similar to that of preferred spawning substrate. We discuss these results in terms of potential evolutionary mechanisms driving anal sheath length.
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Affiliation(s)
| | - Daniel P Welsh
- Fitchburg State University, Department of Biology and Chemistry, Fitchburg, MA, USA
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9
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House CM, Lewis Z, Sharma MD, Hodgson DJ, Hunt J, Wedell N, Hosken DJ. Sexual selection on the genital lobes of male Drosophila simulans. Evolution 2021; 75:501-514. [PMID: 33386741 DOI: 10.1111/evo.14158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 12/03/2020] [Accepted: 12/11/2020] [Indexed: 12/01/2022]
Abstract
Sexual selection is thought to be responsible for the rapid divergent evolution of male genitalia with several studies detecting multivariate sexual selection on genital form. However, in most cases, selection is only estimated during a single episode of selection, which provides an incomplete view of net selection on genital traits. Here, we estimate the strength and form of multivariate selection on the genitalia arch of Drosophila simulans when mating occurs in the absence of a competitor and during sperm competition, in both sperm defence and offense roles (i.e., when mating first and last). We found that the strength of sexual selection on the genital arch was strongest during noncompetitive mating and weakest during sperm offense. However, the direction of selection was similar across selection episodes with no evidence for antagonistic selection. Overall, selection was not particularly strong despite genitals clearly evolving rapidly in this species.
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Affiliation(s)
- Clarissa M House
- School of Science, Western Sydney University, Richmond, NSW, Australia
| | - Zenobia Lewis
- School of Life Sciences, University of Liverpool, Liverpool, UK
| | - Manmohan D Sharma
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
| | - David J Hodgson
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
| | - John Hunt
- School of Science, Western Sydney University, Richmond, NSW, Australia.,Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
| | - Nina Wedell
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
| | - David J Hosken
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
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10
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Pesevski M, Dworkin I. Genetic and environmental canalization are not associated among altitudinally varying populations of Drosophila melanogaster. Evolution 2020; 74:1755-1771. [PMID: 32562566 DOI: 10.1111/evo.14039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 05/19/2020] [Accepted: 05/30/2020] [Indexed: 01/23/2023]
Abstract
Organisms are exposed to environmental and mutational effects influencing both mean and variance of phenotypes. Potentially deleterious effects arising from this variation can be reduced by the evolution of buffering (canalizing) mechanisms, ultimately reducing phenotypic variability. There has been interest regarding the conditions enabling the evolution of canalization. Under some models, the circumstances under which genetic canalization evolves are limited despite apparent empirical evidence for it. It has been argued that genetic canalization evolves as a correlated response to environmental canalization (congruence model). Yet, empirical evidence has not consistently supported predictions of a correlation between genetic and environmental canalization. In a recent study, a population of Drosophila adapted to high altitude showed evidence of genetic decanalization relative to those from low altitudes. Using strains derived from these populations, we tested if they varied for multiple aspects of environmental canalization We observed the expected differences in wing size, shape, cell (trichome) density and mutational defects between high- and low-altitude populations. However, we observed little evidence for a relationship between measures of environmental canalization with population or with defect frequency. Our results do not support the predicted association between genetic and environmental canalization.
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Affiliation(s)
- Maria Pesevski
- Department of Biology, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - Ian Dworkin
- Department of Biology, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
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11
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Wylde Z, Bonduriansky R. Condition dependence of phenotypic integration and the evolvability of genitalic traits in a neriid fly. Biol Lett 2020; 16:20200124. [PMID: 32453964 DOI: 10.1098/rsbl.2020.0124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The spectacular diversity of insect male genitalia, and their relative insensitivity to the environment, have long puzzled evolutionary biologists and taxonomists. We asked whether the unusual evolvability of male genitalia could be associated with low morphological integration of genitalic traits, by comparison with male somatic traits and female traits. We also asked whether this pattern was robust to variation in resource availability during development, which affects adult condition. To address these questions, we manipulated larval diet quality in a split-brood design and compared levels of integration of male and female genitalic and somatic traits in the neriid fly, Telostylinus angusticollis. We found that male genitalic traits were substantially less integrated than male somatic traits, and less integrated than female genitalic traits. Female genitalic traits were also less integrated than female somatic traits, but the difference was less pronounced than in males. However, integration of male genitalic traits was negatively condition-dependent, with high-condition males exhibiting lower trait integration than low-condition males. Finally, genitalic traits exhibited lower larval diet × family interactions than somatic traits. These results could help explain the unusually high evolvability of male genitalic traits in insects.
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Affiliation(s)
- Zachariah Wylde
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Russell Bonduriansky
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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12
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Castro JPL, Yancoskie MN, Marchini M, Belohlavy S, Hiramatsu L, Kučka M, Beluch WH, Naumann R, Skuplik I, Cobb J, Barton NH, Rolian C, Chan YF. An integrative genomic analysis of the Longshanks selection experiment for longer limbs in mice. eLife 2019; 8:e42014. [PMID: 31169497 PMCID: PMC6606024 DOI: 10.7554/elife.42014] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 05/19/2019] [Indexed: 12/30/2022] Open
Abstract
Evolutionary studies are often limited by missing data that are critical to understanding the history of selection. Selection experiments, which reproduce rapid evolution under controlled conditions, are excellent tools to study how genomes evolve under selection. Here we present a genomic dissection of the Longshanks selection experiment, in which mice were selectively bred over 20 generations for longer tibiae relative to body mass, resulting in 13% longer tibiae in two replicates. We synthesized evolutionary theory, genome sequences and molecular genetics to understand the selection response and found that it involved both polygenic adaptation and discrete loci of major effect, with the strongest loci tending to be selected in parallel between replicates. We show that selection may favor de-repression of bone growth through inactivating two limb enhancers of an inhibitor, Nkx3-2. Our integrative genomic analyses thus show that it is possible to connect individual base-pair changes to the overall selection response.
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Affiliation(s)
- João PL Castro
- Friedrich Miescher Laboratory of the Max Planck SocietyTübingenGermany
| | | | | | | | - Layla Hiramatsu
- Friedrich Miescher Laboratory of the Max Planck SocietyTübingenGermany
| | - Marek Kučka
- Friedrich Miescher Laboratory of the Max Planck SocietyTübingenGermany
| | - William H Beluch
- Friedrich Miescher Laboratory of the Max Planck SocietyTübingenGermany
| | - Ronald Naumann
- Max Planck Institute for Molecular Cell Biology and GeneticsDresdenGermany
| | | | | | - Nicholas H Barton
- Institute of Science and Technology (IST) AustriaKlosterneuburgAustria
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13
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Ruan Y, Zhu D, Lu J. Social adaptation and adaptation pressure among the "drifting elderly" in China: A qualitative study in Shanghai. Int J Health Plann Manage 2019; 34:e1149-e1165. [PMID: 30734968 DOI: 10.1002/hpm.2750] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 01/14/2019] [Accepted: 01/15/2019] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE In China, a population of "drifting elderly" that is mainly composed of older parents who migrate for nonemployment reasons has emerged and developed rapidly. The need to understand their social adaptation after migration is well recognized but neglected, so we explored this in the current study. METHODS A qualitative study using a grounded theory approach was undertaken involving 53 elderly interprovincial migrants in five districts of Shanghai from July 2016 to May 2018. This involved in-depth interviews with participants. Adaptation of the drifting elderly and their motivations for migrating were studied, and differences in daily life when compared with before migrating, difficulties encountered after migrating, and social-adaptation pressure were analyzed. RESULTS The drifting elderly had poor adaptation regarding self-identity, daily activities, and social context. The adaptation process regarding daily life, social relationships, and obtaining social support was difficult. They experienced both proximate adaptation pressure (induced by providing and/or obtaining social support) and evolutionary adaptation pressure (induced by mismatch and/or constraints). CONCLUSION The social adaptation of the drifting elderly was affected by differences in daily life when compared with before migrating, and adaptation pressure was caused by both proximate and evolutionary factors. The decision to migrate was the result of a rational principle of maintaining the intergenerational support structure, and it was influenced by the evolutionary advantage related to maintaining this structure. Strengthening social support for the drifting elderly is necessary to promote their adaptation.
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Affiliation(s)
- Yuhui Ruan
- School of Public Health, Fudan University, Shanghai, China
| | - Demi Zhu
- School of International and Public Affairs, Shanghai Jiao Tong University, Shanghai, China
| | - Jun Lu
- School of Public Health, Fudan University, Shanghai, China.,China Research Center on Disability Issues, Fudan University, Shanghai, China
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14
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Baab KL. Evolvability and craniofacial diversification in genus
Homo. Evolution 2018; 72:2781-2791. [DOI: 10.1111/evo.13637] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 10/20/2018] [Indexed: 12/31/2022]
Affiliation(s)
- Karen L. Baab
- Department of Anatomical Sciences Midwestern University Glendale Arizona 85308
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15
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Reichert MS, Höbel G. Phenotypic integration and the evolution of signal repertoires: A case study of treefrog acoustic communication. Ecol Evol 2018; 8:3410-3429. [PMID: 29607035 PMCID: PMC5869261 DOI: 10.1002/ece3.3927] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/15/2018] [Accepted: 01/23/2018] [Indexed: 11/09/2022] Open
Abstract
Animal signals are inherently complex phenotypes with many interacting parts combining to elicit responses from receivers. The pattern of interrelationships between signal components reflects the extent to which each component is expressed, and responds to selection, either in concert with or independently of others. Furthermore, many species have complex repertoires consisting of multiple signal types used in different contexts, and common morphological and physiological constraints may result in interrelationships extending across the multiple signals in species' repertoires. The evolutionary significance of interrelationships between signal traits can be explored within the framework of phenotypic integration, which offers a suite of quantitative techniques to characterize complex phenotypes. In particular, these techniques allow for the assessment of modularity and integration, which describe, respectively, the extent to which sets of traits covary either independently or jointly. Although signal and repertoire complexity are thought to be major drivers of diversification and social evolution, few studies have explicitly measured the phenotypic integration of signals to investigate the evolution of diverse communication systems. We applied methods from phenotypic integration studies to quantify integration in the two primary vocalization types (advertisement and aggressive calls) in the treefrogs Hyla versicolor, Hyla cinerea, and Dendropsophus ebraccatus. We recorded male calls and calculated standardized phenotypic variance-covariance (P) matrices for characteristics within and across call types. We found significant integration across call types, but the strength of integration varied by species and corresponded with the acoustic similarity of the call types within each species. H. versicolor had the most modular advertisement and aggressive calls and the least acoustically similar call types. Additionally, P was robust to changing social competition levels in H. versicolor. Our findings suggest new directions in animal communication research in which the complex relationships among the traits of multiple signals are a key consideration for understanding signal evolution.
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Affiliation(s)
- Michael S. Reichert
- School of Biological, Earth and Environmental SciencesUniversity College CorkCorkIreland
| | - Gerlinde Höbel
- Department of Biological SciencesUniversity of Wisconsin‐MilwaukeeMilwaukeeWIUSA
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16
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Penna A, Melo D, Bernardi S, Oyarzabal MI, Marroig G. The evolution of phenotypic integration: How directional selection reshapes covariation in mice. Evolution 2017; 71:2370-2380. [PMID: 28685813 PMCID: PMC5655774 DOI: 10.1111/evo.13304] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 06/10/2017] [Indexed: 02/03/2023]
Abstract
Variation is the basis for evolution, and understanding how variation can evolve is a central question in biology. In complex phenotypes, covariation plays an even more important role, as genetic associations between traits can bias and alter evolutionary change. Covariation can be shaped by complex interactions between loci, and this genetic architecture can also change during evolution. In this article, we analyzed mouse lines experimentally selected for changes in size to address the question of how multivariate covariation changes under directional selection, as well as to identify the consequences of these changes to evolution. Selected lines showed a clear restructuring of covariation in their cranium and, instead of depleting their size variation, these lines increased their magnitude of integration and the proportion of variation associated with the direction of selection. This result is compatible with recent theoretical works on the evolution of covariation that take the complexities of genetic architecture into account. This result also contradicts the traditional view of the effects of selection on available covariation and suggests a much more complex view of how populations respond to selection.
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Affiliation(s)
- Anna Penna
- Laboratório de Evolução de Mamíferos, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil
| | - Diogo Melo
- Laboratório de Evolução de Mamíferos, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil
| | - Sandra Bernardi
- Cátedra de Histología y Embriología Básica. Facultad de Ciencias Veterinarias, Universidad Nacional de Rosario, Argentina
| | - Maria Inés Oyarzabal
- Cátedra de Producción de Bovinos para Carne, Facultad de Ciencias Veterinarias y Consejo de Investigaciones, Universidad Nacional de Rosario, Argentina
| | - Gabriel Marroig
- Laboratório de Evolução de Mamíferos, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil
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17
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Sztepanacz JL, Blows MW. Accounting for Sampling Error in Genetic Eigenvalues Using Random Matrix Theory. Genetics 2017; 206:1271-1284. [PMID: 28476865 PMCID: PMC5500129 DOI: 10.1534/genetics.116.198606] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 04/17/2017] [Indexed: 11/18/2022] Open
Abstract
The distribution of genetic variance in multivariate phenotypes is characterized by the empirical spectral distribution of the eigenvalues of the genetic covariance matrix. Empirical estimates of genetic eigenvalues from random effects linear models are known to be overdispersed by sampling error, where large eigenvalues are biased upward, and small eigenvalues are biased downward. The overdispersion of the leading eigenvalues of sample covariance matrices have been demonstrated to conform to the Tracy-Widom (TW) distribution. Here we show that genetic eigenvalues estimated using restricted maximum likelihood (REML) in a multivariate random effects model with an unconstrained genetic covariance structure will also conform to the TW distribution after empirical scaling and centering. However, where estimation procedures using either REML or MCMC impose boundary constraints, the resulting genetic eigenvalues tend not be TW distributed. We show how using confidence intervals from sampling distributions of genetic eigenvalues without reference to the TW distribution is insufficient protection against mistaking sampling error as genetic variance, particularly when eigenvalues are small. By scaling such sampling distributions to the appropriate TW distribution, the critical value of the TW statistic can be used to determine if the magnitude of a genetic eigenvalue exceeds the sampling error for each eigenvalue in the spectral distribution of a given genetic covariance matrix.
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Affiliation(s)
- Jacqueline L Sztepanacz
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia 4072
| | - Mark W Blows
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia 4072
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18
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Hughes KA, Leips J. Pleiotropy, constraint, and modularity in the evolution of life histories: insights from genomic analyses. Ann N Y Acad Sci 2017; 1389:76-91. [PMID: 27936291 PMCID: PMC5318229 DOI: 10.1111/nyas.13256] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/10/2016] [Accepted: 08/22/2016] [Indexed: 12/20/2022]
Abstract
Multicellular organisms display an enormous range of life history (LH) strategies and present an evolutionary conundrum; despite strong natural selection, LH traits are characterized by high levels of genetic variation. To understand the evolution of life histories and maintenance of this variation, the specific phenotypic effects of segregating alleles and the genetic networks in which they act need to be elucidated. In particular, the extent to which LH evolution is constrained by the pleiotropy of alleles contributing to LH variation is generally unknown. Here, we review recent empirical results that shed light on this question, with an emphasis on studies employing genomic analyses. While genome-scale analyses are increasingly practical and affordable, they face limitations of genetic resolution and statistical power. We describe new research approaches that we believe can produce new insights and evaluate their promise and applicability to different kinds of organisms. Two approaches seem particularly promising: experiments that manipulate selection in multiple dimensions and measure phenotypic and genomic response and analytical approaches that take into account genome-wide associations between markers and phenotypes, rather than applying a traditional marker-by-marker approach.
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Affiliation(s)
- Kimberly A. Hughes
- Department of Biological Science, Florida State University, Tallahassee, Florida
| | - Jeff Leips
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, Maryland
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19
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Maraqa MS, Griffin R, Sharma MD, Wilson AJ, Hunt J, Hosken DJ, House CM. Constrained evolution of the sex comb in Drosophila simulans. J Evol Biol 2016; 30:388-400. [PMID: 27859860 PMCID: PMC5324616 DOI: 10.1111/jeb.13015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 11/03/2016] [Accepted: 11/07/2016] [Indexed: 11/30/2022]
Abstract
Male fitness is dependent on sexual traits that influence mate acquisition (precopulatory sexual selection) and paternity (post-copulatory sexual selection), and although many studies have documented the form of selection in one or the other of these arenas, fewer have done it for both. Nonetheless, it appears that the dominant form of sexual selection is directional, although theoretically, populations should converge on peaks in the fitness surface, where selection is stabilizing. Many factors, however, can prevent populations from reaching adaptive peaks. Genetic constraints can be important if they prevent the development of highest fitness phenotypes, as can the direction of selection if it reverses across episodes of selection. In this study, we examine the evidence that these processes influence the evolution of the multivariate sex comb morphology of male Drosophila simulans. To do this, we conduct a quantitative genetic study together with a multivariate selection analysis to infer how the genetic architecture and selection interact. We find abundant genetic variance and covariance in elements of the sex comb. However, there was little evidence for directional selection in either arena. Significant nonlinear selection was detected prior to copulation when males were mated to nonvirgin females, and post-copulation during sperm offence (again with males mated to nonvirgins). Thus, contrary to our predictions, the evolution of the D. simulans sex comb is limited neither by genetic constraints nor by antagonistic selection between pre- and post-copulatory arenas, but nonlinear selection on the multivariate phenotype may prevent sex combs from evolving to reach some fitness maximizing optima.
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Affiliation(s)
- M S Maraqa
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
| | - R Griffin
- Department of Biology, University of Turku, Turun Yliopisto, Finland
| | - M D Sharma
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
| | - A J Wilson
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
| | - J Hunt
- School of Science and Health, Western Sydney University, Penrith, NSW, Australia
| | - D J Hosken
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall, UK
| | - C M House
- School of Science and Health, Western Sydney University, Penrith, NSW, Australia
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20
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Abstract
The strikingly high incidence of obstructed labor due to the disproportion of fetal size and the mother's pelvic dimensions has puzzled evolutionary scientists for decades. Here we propose that these high rates are a direct consequence of the distinct characteristics of human obstetric selection. Neonatal size relative to the birth-relevant maternal dimensions is highly variable and positively associated with reproductive success until it reaches a critical value, beyond which natural delivery becomes impossible. As a consequence, the symmetric phenotype distribution cannot match the highly asymmetric, cliff-edged fitness distribution well: The optimal phenotype distribution that maximizes population mean fitness entails a fraction of individuals falling beyond the "fitness edge" (i.e., those with fetopelvic disproportion). Using a simple mathematical model, we show that weak directional selection for a large neonate, a narrow pelvic canal, or both is sufficient to account for the considerable incidence of fetopelvic disproportion. Based on this model, we predict that the regular use of Caesarean sections throughout the last decades has led to an evolutionary increase of fetopelvic disproportion rates by 10 to 20%.
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21
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Simon MN, Machado FA, Marroig G. High evolutionary constraints limited adaptive responses to past climate changes in toad skulls. Proc Biol Sci 2016; 283:20161783. [PMID: 27798306 PMCID: PMC5095385 DOI: 10.1098/rspb.2016.1783] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/29/2016] [Indexed: 12/27/2022] Open
Abstract
Interactions among traits that build a complex structure may be represented as genetic covariation and correlation. Genetic correlations may act as constraints, deflecting the evolutionary response from the direction of natural selection. We investigated the relative importance of drift, selection, and constraints in driving skull divergence in a group of related toad species. The distributional range of these species encompasses very distinct habitats with important climatic differences and the species are primarily distinguished by differences in their skulls. Some parts of the toad skull, such as the snout, may have functional relevance in reproductive ecology, detecting water cues. Thus, we hypothesized that the species skull divergence was driven by natural selection associated with climatic variation. However, given that all species present high correlations among skull traits, our second prediction was of high constraints deflecting the response to selection. We first extracted the main morphological direction that is expected to be subjected to selection by using within- and between-species covariance matrices. We then used evolutionary regressions to investigate whether divergence along this direction is explained by climatic variation between species. We also used quantitative genetics models to test for a role of random drift versus natural selection in skull divergence and to reconstruct selection gradients along species phylogeny. Climatic variables explained high proportions of between-species variation in the most selected axis. However, most evolutionary responses were not in the direction of selection, but aligned with the direction of allometric size, the dimension of highest phenotypic variance in the ancestral population. We conclude that toad species have responded to selection related to climate in their skulls, yet high evolutionary constraints dominated species divergence and may limit species responses to future climate change.
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Affiliation(s)
- Monique Nouailhetas Simon
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277, Cidade Universitária, 05508-090, São Paulo, SP, Brazil
| | - Fabio Andrade Machado
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277, Cidade Universitária, 05508-090, São Paulo, SP, Brazil
| | - Gabriel Marroig
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277, Cidade Universitária, 05508-090, São Paulo, SP, Brazil
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22
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Haber A, Dworkin I. Disintegrating the fly: A mutational perspective on phenotypic integration and covariation. Evolution 2016; 71:66-80. [PMID: 27778314 DOI: 10.1111/evo.13100] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 10/06/2016] [Accepted: 10/11/2016] [Indexed: 01/23/2023]
Abstract
The structure of environmentally induced phenotypic covariation can influence the effective strength and magnitude of natural selection. Yet our understanding of the factors that contribute to and influence the evolutionary lability of such covariation is poor. Most studies have either examined environmental variation without accounting for covariation, or examined phenotypic and genetic covariation without distinguishing the environmental component. In this study, we examined the effect of mutational perturbations on different properties of environmental covariation, as well as mean shape. We use strains of Drosophila melanogaster bearing well-characterized mutations known to influence wing shape, as well as naturally derived strains, all reared under carefully controlled conditions and with the same genetic background. We find that mean shape changes more freely than the covariance structure, and that different properties of the covariance matrix change independently from each other. The perturbations affect matrix orientation more than they affect matrix eccentricity or total variance. Yet, mutational effects on matrix orientation do not cluster according to the developmental pathway that they target. These results suggest that it might be useful to consider a more general concept of "decanalization," involving all aspects of variation and covariation.
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Affiliation(s)
- Annat Haber
- BEACON Center for the study of Evolution in Action, Michigan State University, East Lansing, Michigan, 48824.,Department of Zoology, Tel Aviv University, Tel Aviv, Israel
| | - Ian Dworkin
- BEACON Center for the study of Evolution in Action, Michigan State University, East Lansing, Michigan, 48824.,Department of Integrative Biology, Michigan State University, East Lansing, Michigan, 48824.,Department of Biology, McMaster University, Hamilton, Ontario, Canada
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23
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Wood CW, Brodie ED. Environmental effects on the structure of the G-matrix. Evolution 2016; 69:2927-40. [PMID: 26462609 DOI: 10.1111/evo.12795] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 07/31/2015] [Accepted: 09/22/2015] [Indexed: 12/29/2022]
Abstract
Genetic correlations between traits determine the multivariate response to selection in the short term, and thereby play a causal role in evolutionary change. Although individual studies have documented environmentally induced changes in genetic correlations, the nature and extent of environmental effects on multivariate genetic architecture across species and environments remain largely uncharacterized. We reviewed the literature for estimates of the genetic variance-covariance (G) matrix in multiple environments, and compared differences in G between environments to the divergence in G between conspecific populations (measured in a common garden). We found that the predicted evolutionary trajectory differed as strongly between environments as it did between populations. Between-environment differences in the underlying structure of G (total genetic variance and the relative magnitude and orientation of genetic correlations) were equal to or greater than between-population differences. Neither environmental novelty, nor the difference in mean phenotype predicted these differences in G. Our results suggest that environmental effects on multivariate genetic architecture may be comparable to the divergence that accumulates over dozens or hundreds of generations between populations. We outline avenues of future research to address the limitations of existing data and characterize the extent to which lability in genetic correlations shapes evolution in changing environments.
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Affiliation(s)
- Corlett W Wood
- Mountain Lake Biological Station, and Department of Biology, University of Virginia, Charlottesville, Virginia, 22904.
| | - Edmund D Brodie
- Mountain Lake Biological Station, and Department of Biology, University of Virginia, Charlottesville, Virginia, 22904
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24
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Brookfield JFY. Why are estimates of the strength and direction of natural selection from wild populations not congruent with observed rates of phenotypic change? Bioessays 2016; 38:927-34. [PMID: 27401716 DOI: 10.1002/bies.201600017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Observing adaptive evolution is difficult. In the fossil record, phenotypic evolution happens much more slowly than in artificial selection experiments or in experimental evolution. Yet measures of selection on phenotypic traits, with high heritabilities, suggest that phenotypic evolution should also be rapid in the wild, and this discrepancy often remains even after accounting for correlations between different traits (i.e. making predictions using the multivariate version of the breeder's equation). Are fitness correlations with quantitative traits adequate measures of selection in the wild? We should instead view fitnesses as average properties of genotypes, while acknowledging that they can be environment-dependent. Populations will tend to remain at fitness equilibria, once these are attained, and phenotypes will then be stable. Thus, studying the causes of adaptive change at a genotypic rather than phenotypic level may reveal that, typically, it is occurring too slowly to be easily observed.
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Affiliation(s)
- John F Y Brookfield
- School of Life Sciences, University of Nottingham, University Park, Nottingham, UK
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25
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Prokop ZM, Drobniak SM. Genetic variation in male attractiveness: It is time to see the forest for the trees. Evolution 2016; 70:913-21. [PMID: 26940698 DOI: 10.1111/evo.12898] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 02/15/2016] [Indexed: 01/19/2023]
Abstract
Female choice based on multiple male traits, rather than on any single one, has been reported in many species and may well be a rule rather than an exception. However, the implications this has for selection acting on choosiness itself remain underappreciated. We argue that this constitutes one of the important impediments to our understanding of the evolution of mate choice. We discuss this issue primarily in the context of the Fisherian model of sexual selection. We review theory and empirical data, showing how the crucial parameter of the model-genetic variation in male attractiveness-can be estimated when attractiveness is a function of multiple traits. Based on the reviewed theory, we show how relying on individual male traits, instead of overall attractiveness, can produce biased estimates of Fisherian benefits of female choice. This bias can be substantial, especially when many traits contribute to male attractiveness. We discuss a number of methodological issues that, we hope, will stimulate future studies and help resolving the long-standing mystery of mate choice.
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Affiliation(s)
- Zofia M Prokop
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland.
| | - Szymon M Drobniak
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland.,Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, CH, 8057, Zurich, Switzerland
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26
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Brieuc MSO, Ono K, Drinan DP, Naish KA. Integration of Random Forest with population-based outlier analyses provides insight on the genomic basis and evolution of run timing in Chinook salmon (Oncorhynchus tshawytscha). Mol Ecol 2015; 24:2729-46. [PMID: 25913096 DOI: 10.1111/mec.13211] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Revised: 04/15/2015] [Accepted: 04/21/2015] [Indexed: 01/11/2023]
Abstract
Anadromous Chinook salmon populations vary in the period of river entry at the initiation of adult freshwater migration, facilitating optimal arrival at natal spawning. Run timing is a polygenic trait that shows evidence of rapid parallel evolution in some lineages, signifying a key role for this phenotype in the ecological divergence between populations. Studying the genetic basis of local adaptation in quantitative traits is often impractical in wild populations. Therefore, we used a novel approach, Random Forest, to detect markers linked to run timing across 14 populations from contrasting environments in the Columbia River and Puget Sound, USA. The approach permits detection of loci of small effect on the phenotype. Divergence between populations at these loci was then examined using both principle component analysis and FST outlier analyses, to determine whether shared genetic changes resulted in similar phenotypes across different lineages. Sequencing of 9107 RAD markers in 414 individuals identified 33 predictor loci explaining 79.2% of trait variance. Discriminant analysis of principal components of the predictors revealed both shared and unique evolutionary pathways in the trait across different lineages, characterized by minor allele frequency changes. However, genome mapping of predictor loci also identified positional overlap with two genomic outlier regions, consistent with selection on loci of large effect. Therefore, the results suggest selective sweeps on few loci and minor changes in loci that were detected by this study. Use of a polygenic framework has provided initial insight into how divergence in a trait has occurred in the wild.
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Affiliation(s)
- Marine S O Brieuc
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, 98195-5020, USA
| | - Kotaro Ono
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, 98195-5020, USA
| | - Daniel P Drinan
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, 98195-5020, USA
| | - Kerry A Naish
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, 98195-5020, USA
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27
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Blows MW, Allen SL, Collet JM, Chenoweth SF, McGuigan K. The Phenome-Wide Distribution of Genetic Variance. Am Nat 2015; 186:15-30. [DOI: 10.1086/681645] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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28
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Porto A, Sebastião H, Pavan SE, VandeBerg JL, Marroig G, Cheverud JM. Rate of evolutionary change in cranial morphology of the marsupial genus Monodelphis is constrained by the availability of additive genetic variation. J Evol Biol 2015; 28:973-85. [PMID: 25818173 DOI: 10.1111/jeb.12628] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/18/2015] [Accepted: 03/20/2015] [Indexed: 01/09/2023]
Abstract
We tested the hypothesis that the rate of marsupial cranial evolution is dependent on the distribution of genetic variation in multivariate space. To do so, we carried out a genetic analysis of cranial morphological variation in laboratory strains of Monodelphis domestica and used estimates of genetic covariation to analyse the morphological diversification of the Monodelphis brevicaudata species group. We found that within-species genetic variation is concentrated in only a few axes of the morphospace and that this strong genetic covariation influenced the rate of morphological diversification of the brevicaudata group, with between-species divergence occurring fastest when occurring along the genetic line of least resistance. Accounting for the geometric distribution of genetic variation also increased our ability to detect the selective regimen underlying species diversification, with several instances of selection only being detected when genetic covariances were taken into account. Therefore, this work directly links patterns of genetic covariation among traits to macroevolutionary patterns of morphological divergence. Our findings also suggest that the limited distribution of Monodelphis species in morphospace is the result of a complex interplay between the limited dimensionality of available genetic variation and strong stabilizing selection along two major axes of genetic variation.
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Affiliation(s)
- A Porto
- Department of Biology, Washington University in St Louis, St Louis, MO, USA
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29
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Gvoždík L. Mismatch Between Ectotherm Thermal Preferenda and Optima for Swimming: A Test of the Evolutionary Pace Hypothesis. Evol Biol 2015. [DOI: 10.1007/s11692-015-9305-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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30
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Blows MW, McGuigan K. The distribution of genetic variance across phenotypic space and the response to selection. Mol Ecol 2014; 24:2056-72. [DOI: 10.1111/mec.13023] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/20/2014] [Accepted: 11/25/2014] [Indexed: 01/31/2023]
Affiliation(s)
- Mark W. Blows
- School of Biological Sciences; University of Queensland; St Lucia Qld 4072 Australia
| | - Katrina McGuigan
- School of Biological Sciences; University of Queensland; St Lucia Qld 4072 Australia
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31
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Armbruster WS, Pélabon C, Bolstad GH, Hansen TF. Integrated phenotypes: understanding trait covariation in plants and animals. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130245. [PMID: 25002693 PMCID: PMC4084533 DOI: 10.1098/rstb.2013.0245] [Citation(s) in RCA: 169] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Integration and modularity refer to the patterns and processes of trait interaction and independence. Both terms have complex histories with respect to both conceptualization and quantification, resulting in a plethora of integration indices in use. We review briefly the divergent definitions, uses and measures of integration and modularity and make conceptual links to allometry. We also discuss how integration and modularity might evolve. Although integration is generally thought to be generated and maintained by correlational selection, theoretical considerations suggest the relationship is not straightforward. We caution here against uncontrolled comparisons of indices across studies. In the absence of controls for trait number, dimensionality, homology, development and function, it is difficult, or even impossible, to compare integration indices across organisms or traits. We suggest that care be invested in relating measurement to underlying theory or hypotheses, and that summative, theory-free descriptors of integration generally be avoided. The papers that follow in this Theme Issue illustrate the diversity of approaches to studying integration and modularity, highlighting strengths and pitfalls that await researchers investigating integration in plants and animals.
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Affiliation(s)
- W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO12DY, UK Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Christophe Pélabon
- Center for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Geir H Bolstad
- Center for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Thomas F Hansen
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, PO Box 1066, 0316 Oslo, Norway
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