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Campbell DR, Sakai AK, Weller SG, Culley TM, Dunbar‐Wallis AK, Andres AM, Wong TG, Dang T, Au B, Ku M, Marcantonio AR, Ngo PJ, Nguyen AA, Tran MH, Tran Q. Genetic potential for changes in breeding systems: Predicted and observed trait changes during artificial selection for male and female allocation in a gynodioecious species. AMERICAN JOURNAL OF BOTANY 2022; 109:1918-1938. [PMID: 36380502 PMCID: PMC9828115 DOI: 10.1002/ajb2.16096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 09/08/2022] [Accepted: 09/08/2022] [Indexed: 06/16/2023]
Abstract
PREMISE Evolution of separate sexes from hermaphroditism often proceeds through gynodioecy, but genetic constraints on this process are poorly understood. Genetic (co-)variances and between-sex genetic correlations were used to predict evolutionary responses of multiple reproductive traits in a sexually dimorphic gynodioecious species, and predictions were compared with observed responses to artificial selection. METHODS Schiedea (Caryophyllaceae) is an endemic Hawaiian lineage with hermaphroditic, gynodioecious, subdioecious, and dioecious species. We measured genetic parameters of Schiedea salicaria and used them to predict evolutionary responses of 18 traits in hermaphrodites and females in response to artificial selection for increased male (stamen) biomass in hermaphrodites or increased female (carpel, capsule) biomass in females. Observed responses over two generations were compared with predictions in replicate lines of treatments and controls. RESULTS In only two generations, both stamen biomass in hermaphrodites and female biomass in females responded markedly to direct selection, supporting a key assumption of models for evolution of dioecy. Other biomass traits, pollen and ovule numbers, and inflorescence characters important in wind pollination evolved indirectly in response to selection on sex allocation. Responses generally followed predictions from multivariate selection models, with some responses unexpectedly large due to increased genetic correlations as selection proceeded. CONCLUSIONS Results illustrate the power of artificial selection and utility of multivariate selection models incorporating sex differences. They further indicate that pollen and ovule numbers and inflorescence architecture could evolve in response to selection on biomass allocation to male versus female function, producing complex changes in plant phenotype as separate sexes evolve.
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Affiliation(s)
- Diane R. Campbell
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Ann K. Sakai
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Stephen G. Weller
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Theresa M. Culley
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
- Department of Biological SciencesUniversity of CincinnatiCincinnatiOH45221USA
| | - Amy K. Dunbar‐Wallis
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
- Department of Ecology and Evolutionary BiologyUniversity of ColoradoBoulderCO80309USA
| | - Allen M. Andres
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Tiffany G. Wong
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Tam Dang
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Bryan Au
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Mickey Ku
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Andrea R. Marcantonio
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Paul J. Ngo
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Andrew A. Nguyen
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
- Department of Gastroenterology and HepatologyKaiser Permanente WashingtonSeattleWA98112USA
| | - My Hanh Tran
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
| | - Quoc‐Phong Tran
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
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Cauret CMS, Mortimer SME, Roberti MC, Ashman TL, Liston A. Chromosome-scale assembly with a phased sex-determining region resolves features of early Z and W chromosome differentiation in a wild octoploid strawberry. G3 (BETHESDA, MD.) 2022; 12:6603112. [PMID: 35666193 PMCID: PMC9339316 DOI: 10.1093/g3journal/jkac139] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/19/2022] [Indexed: 01/07/2023]
Abstract
When sex chromosomes stop recombining, they start to accumulate differences. The sex-limited chromosome (Y or W) especially is expected to degenerate via the loss of nucleotide sequence and the accumulation of repetitive sequences. However, how early signs of degeneration can be detected in a new sex chromosome is still unclear. The sex-determining region of the octoploid strawberries is young, small, and dynamic. Using PacBio HiFi reads, we obtained a chromosome-scale assembly of a female (ZW) Fragaria chiloensis plant carrying the youngest and largest of the known sex-determining region on the W in strawberries. We fully characterized the previously incomplete sex-determining region, confirming its gene content, genomic location, and evolutionary history. Resolution of gaps in the previous characterization of the sex-determining region added 10 kb of sequence including a noncanonical long terminal repeat-retrotransposon; whereas the Z sequence revealed a Harbinger transposable element adjoining the sex-determining region insertion site. Limited genetic differentiation of the sex chromosomes coupled with structural variation may indicate an early stage of W degeneration. The sex chromosomes have a similar percentage of repeats but differ in their repeat distribution. Differences in the pattern of repeats (transposable element polymorphism) apparently precede sex chromosome differentiation, thus potentially contributing to recombination cessation as opposed to being a consequence of it.
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Affiliation(s)
- Caroline M S Cauret
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Sebastian M E Mortimer
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Marcelina C Roberti
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
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Wani IA, Verma S, Ahmad P, El-Serehy HA, Hashim MJ. Reproductive Biology of Rheum webbianum Royle, a Vulnerable Medicinal Herb From Alpines of North-Western Himalaya. FRONTIERS IN PLANT SCIENCE 2022; 13:699645. [PMID: 35251069 PMCID: PMC8891384 DOI: 10.3389/fpls.2022.699645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
Information on reproductive biology and pollination ecology studies of threatened plants are essential to develop strategies for their sustainable utilization and effective conservation. As such, these studies were conducted on Rheum webbianum, a high-value "vulnerable" medicinal herb of the north-western Himalaya. This species presents a unique mode of reproductive behavior through the involvement of different floral events, including the movement of reproductive organs. The plants survive extremely cold conditions through underground perennating rhizomes that sprout into juvenile shoots with the onset of the favorable climatic conditions. The peduncle arises from the axils of the radical leaves, bearing a globular collection of densely arranged hermaphrodite flowers with temporally separated male and female phases; the male phase precedes the female phase (protandry). Anther dehiscence and stigma receptivity is post-anthesis. Anthers dehisce longitudinally along margins, liberating a large mass of spherical and tricolpate pollen with spinulose exine. Pollen viability decreased to < 10% on day 9. Pistil is tristylous, with each style terminating into a fan-shaped stigma lobe. The pollen receptive surface of each stigmatic lobe remains incurved at an angle of 360° and shows upward movement after anthesis, forming a funnel-like structure at an angle of 180° with respect to the ovary. Pollination syndrome is ambophilous. Spontaneous autogamy or geitonogamy to a certain extent is achieved in this species due to the arrangement of flowers in the inflorescence and overlapping of male and female reproductive phases among them. Incurved stigmatic lobes and outward movement of stamens too facilitate outcrossing. Pollen/ovule ratio estimates, results of pollination experiments on breeding behavior, outcrossing, and self-compatibility indices demonstrated that plants are self-compatible and cross-fertile.
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Affiliation(s)
- Ishfaq Ahmad Wani
- Conservation and Molecular Biology Lab, Department of Botany, Baba Ghulam Shah Badshah University, Rajouri, India
| | - Susheel Verma
- Conservation and Molecular Biology Lab, Department of Botany, Baba Ghulam Shah Badshah University, Rajouri, India
| | - Parvaiz Ahmad
- Department of Botany and Microbiology, King Saud University, Riyadh, Saudi Arabia
| | - Hamed A. El-Serehy
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Maha J. Hashim
- Department of Bioscience, University of Nottinghamshire, Nottingham, United Kingdom
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Aonuma W, Kawamoto H, Kazama Y, Ishii K, Abe T, Kawano S. Male/Female Trade-Off in Hermaphroditic Y-Chromosome Deletion Mutants of the Dioecious Plant Silene latifolia. CYTOLOGIA 2021. [DOI: 10.1508/cytologia.86.329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Wataru Aonuma
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo
| | - Hiroki Kawamoto
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo
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McGlothlin JW, Cox RM, Brodie ED. Sex-Specific Selection and the Evolution of Between-Sex Genetic Covariance. J Hered 2020; 110:422-432. [PMID: 31095325 DOI: 10.1093/jhered/esz031] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 05/14/2019] [Indexed: 11/13/2022] Open
Abstract
Because the sexes share a genome, traits expressed in males are usually genetically correlated with the same traits expressed in females. On short timescales, between-sex genetic correlations (rmf) for shared traits may constrain the evolution of sexual dimorphism by preventing males and females from responding independently to sex-specific selection. However, over longer timescales, rmf may evolve, thereby facilitating the evolution of dimorphism. Although it has been suggested that sexually antagonistic selection may reduce rmf, we lack a general theory for the evolution of rmf and its multivariate analog, the between-sex genetic covariance matrix (B). Here, we derive a simple analytical model for the within-generation change in B due to sex-specific directional selection. We present a single-trait example demonstrating that sex-specific directional selection may either increase or decrease between-sex genetic covariance, depending on the relative strength of selection in each sex and on the current value of rmf. Although sexually antagonistic selection can reduce between-sex covariance, it will only do so when selection is much stronger in one sex than in the other. Counterintuitively, sexually antagonistic selection that is equal in strength in the 2 sexes will maintain positive between-sex covariance. Selection acting in the same direction on both sexes is predicted to reduce between-sex covariance in many cases. We illustrate our model numerically using empirical measures of sex-specific selection and between-sex genetic covariance from 2 populations of sexually dimorphic brown anole lizards (Anolis sagrei) and discuss its importance for understanding the resolution of intralocus sexual conflict.
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Affiliation(s)
| | - Robert M Cox
- Department of Biology, University of Virginia, Charlottesville, VA
| | - Edmund D Brodie
- Department of Biology and Mountain Lake Biological Station, University of Virginia, Charlottesville, VA
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Puixeu G, Pickup M, Field DL, Barrett SCH. Variation in sexual dimorphism in a wind-pollinated plant: the influence of geographical context and life-cycle dynamics. THE NEW PHYTOLOGIST 2019; 224:1108-1120. [PMID: 31291691 PMCID: PMC6851585 DOI: 10.1111/nph.16050] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/27/2019] [Indexed: 06/09/2023]
Abstract
Understanding the mechanisms causing phenotypic differences between females and males has long fascinated evolutionary biologists. An extensive literature exists on animal sexual dimorphism but less information is known about sex differences in plants, particularly the extent of geographical variation in sexual dimorphism and its life-cycle dynamics. Here, we investigated patterns of genetically based sexual dimorphism in vegetative and reproductive traits of a wind-pollinated dioecious plant, Rumex hastatulus, across three life-cycle stages using open-pollinated families from 30 populations spanning the geographic range and chromosomal variation (XY and XY1 Y2 ) of the species. The direction and degree of sexual dimorphism was highly variable among populations and life-cycle stages. Sex-specific differences in reproductive function explained a significant amount of temporal change in sexual dimorphism. For several traits, geographical variation in sexual dimorphism was associated with bioclimatic parameters, likely due to the differential responses of the sexes to climate. We found no systematic differences in sexual dimorphism between chromosome races. Sex-specific trait differences in dioecious plants largely result from a balance between sexual and natural selection on resource allocation. Our results indicate that abiotic factors associated with geographical context also play a role in modifying sexual dimorphism during the plant life-cycle.
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Affiliation(s)
- Gemma Puixeu
- Institute of Science and Technology AustriaAm Campus 1Klosterneuburg3400Austria
| | - Melinda Pickup
- Institute of Science and Technology AustriaAm Campus 1Klosterneuburg3400Austria
- Department of Ecology and Evolutionary BiologyUniversity of Toronto25 Willcocks St.TorontoONM5S 3B2Canada
| | - David L. Field
- Department of Ecology and Evolutionary BiologyUniversity of Toronto25 Willcocks St.TorontoONM5S 3B2Canada
- School of ScienceEdith Cowan University270 Joondalup DriveJoondalupWA6027Australia
| | - Spencer C. H. Barrett
- Department of Ecology and Evolutionary BiologyUniversity of Toronto25 Willcocks St.TorontoONM5S 3B2Canada
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Zhang B, Claßen-Bockhoff R. Sex-differential reproduction success and selection on floral traits in gynodioecious Salvia pratensis. BMC PLANT BIOLOGY 2019; 19:375. [PMID: 31455268 PMCID: PMC6712674 DOI: 10.1186/s12870-019-1972-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 08/13/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Gynodioecy, a sexual system with hermaphrodite and female individuals in a population, raises the question how the two sexual morphs are maintained. Salvia pratensis is a gynodioecious species featured by its modified stamens that act as a lever mechanism in pollination. Given sexual dimorphism in floral traits of the species, it is predictable that two sexual morphs differ in their interplay with pollinators and thus in their fitness. In this study, we investigated sex-specific reproduction success and floral adaptation in a population of S. pratensis. RESULTS We found that two sexual morphs in S. pratensis distinctly differed in their floral proportions. Female flowers fitted better to the pollinators than hermaphrodites in terms of touching the stigmas when being probed, and hence were more efficient in pollen deposition. Floral traits overall underwent stronger selection in the population, with stigma position and corolla length subject to disruptive selection mediated by different body-sized bumble bees; some selections on floral traits were significantly different in the strength, even opposite in the direction between two morphs. Flower production tended to be under correlational selection with floral structural traits, implying that a large plant with many flowers did not show an advantage in fitness unless its flower construction mechanically matched the pollinators well. CONCLUSIONS In conclusion, the pollinator-mediated selection likely played an important role in the evolution and maintenance of sexual dimorphism in the gynodioecious S. pratensis; and sex-divergent mechanical interaction with pollinators served as a critical mechanism by which female individuals were maintained in the population with a female advantage in pollen deposition efficiency (i.e. receiving pollen).
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Affiliation(s)
- Bo Zhang
- Key Laboratory of Grassland Ecosystem of Ministry of Education, and Sino-U.S. Centers for Grazingland Ecosystem Sustainability, College of Grassland Science, Gansu Agricultural University, Lanzhou, 730070, China.
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University, 55099, Mainz, Germany.
| | - Regine Claßen-Bockhoff
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University, 55099, Mainz, Germany.
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8
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Sztepanacz JL, Houle D. Cross‐sex genetic covariances limit the evolvability of wing‐shape within and among species of
Drosophila. Evolution 2019; 73:1617-1633. [DOI: 10.1111/evo.13788] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/29/2019] [Indexed: 01/02/2023]
Affiliation(s)
| | - David Houle
- Department of Biology Florida State University Tallahassee Florida 32306
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9
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Sniegula S, Golab MJ, Drobniak SM, Johansson F. The genetic variance but not the genetic covariance of life-history traits changes towards the north in a time-constrained insect. J Evol Biol 2018; 31:853-865. [PMID: 29569290 DOI: 10.1111/jeb.13269] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 03/15/2018] [Accepted: 03/15/2018] [Indexed: 11/30/2022]
Abstract
Seasonal time constraints are usually stronger at higher than lower latitudes and can exert strong selection on life-history traits and the correlations among these traits. To predict the response of life-history traits to environmental change along a latitudinal gradient, information must be obtained about genetic variance in traits and also genetic correlation between traits, that is the genetic variance-covariance matrix, G. Here, we estimated G for key life-history traits in an obligate univoltine damselfly that faces seasonal time constraints. We exposed populations to simulated native temperatures and photoperiods and common garden environmental conditions in a laboratory set-up. Despite differences in genetic variance in these traits between populations (lower variance at northern latitudes), there was no evidence for latitude-specific covariance of the life-history traits. At simulated native conditions, all populations showed strong genetic and phenotypic correlations between traits that shaped growth and development. The variance-covariance matrix changed considerably when populations were exposed to common garden conditions compared with the simulated natural conditions, showing the importance of environmentally induced changes in multivariate genetic structure. Our results highlight the importance of estimating variance-covariance matrixes in environments that mimic selection pressures and not only trait variances or mean trait values in common garden conditions for understanding the trait evolution across populations and environments.
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Affiliation(s)
- Szymon Sniegula
- Department of Ecosystem Conservation, Institute of Nature Conservation, Polish Academy of Sciences, Krakow, Poland
| | - Maria J Golab
- Department of Ecosystem Conservation, Institute of Nature Conservation, Polish Academy of Sciences, Krakow, Poland
| | - Szymon M Drobniak
- Population Ecology Group, Institute of Environmental Sciences, Jagiellonian University, Krakow, Poland
| | - Frank Johansson
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
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10
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Cox RM, Costello RA, Camber BE, McGlothlin JW. Multivariate genetic architecture of the Anolis dewlap reveals both shared and sex-specific features of a sexually dimorphic ornament. J Evol Biol 2017; 30:1262-1275. [PMID: 28370951 DOI: 10.1111/jeb.13080] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/20/2017] [Accepted: 03/03/2017] [Indexed: 01/01/2023]
Abstract
Darwin viewed the ornamentation of females as an indirect consequence of sexual selection on males and the transmission of male phenotypes to females via the 'laws of inheritance'. Although a number of studies have supported this view by demonstrating substantial between-sex genetic covariance for ornament expression, the majority of this work has focused on avian plumage. Moreover, few studies have considered the genetic basis of ornaments from a multivariate perspective, which may be crucial for understanding the evolution of sex differences in general, and of complex ornaments in particular. Here, we provide a multivariate, quantitative-genetic analysis of a sexually dimorphic ornament that has figured prominently in studies of sexual selection: the brightly coloured dewlap of Anolis lizards. Using data from a paternal half-sibling breeding experiment in brown anoles (Anolis sagrei), we show that multiple aspects of dewlap size and colour exhibit significant heritability and a genetic variance-covariance structure (G) that is broadly similar in males (Gm ) and females (Gf ). Whereas sexually monomorphic aspects of the dewlap, such as hue, exhibit significant between-sex genetic correlations (rmf ), sexually dimorphic features, such as area and brightness, exhibit reduced rmf values that do not differ from zero. Using a modified random skewers analysis, we show that the between-sex genetic variance-covariance matrix (B) should not strongly constrain the independent responses of males and females to sexually antagonistic selection. Our microevolutionary analysis is in broad agreement with macroevolutionary perspectives indicating considerable scope for the independent evolution of coloration and ornamentation in males and females.
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Affiliation(s)
- R M Cox
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - R A Costello
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - B E Camber
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - J W McGlothlin
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
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Delahaie B, Charmantier A, Chantepie S, Garant D, Porlier M, Teplitsky C. Conserved G-matrices of morphological and life-history traits among continental and island blue tit populations. Heredity (Edinb) 2017; 119:76-87. [PMID: 28402327 DOI: 10.1038/hdy.2017.15] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 01/25/2017] [Accepted: 01/26/2017] [Indexed: 12/31/2022] Open
Abstract
The genetic variance-covariance matrix (G-matrix) summarizes the genetic architecture of multiple traits. It has a central role in the understanding of phenotypic divergence and the quantification of the evolutionary potential of populations. Laboratory experiments have shown that G-matrices can vary rapidly under divergent selective pressures. However, because of the demanding nature of G-matrix estimation and comparison in wild populations, the extent of its spatial variability remains largely unknown. In this study, we investigate spatial variation in G-matrices for morphological and life-history traits using long-term data sets from one continental and three island populations of blue tit (Cyanistes caeruleus) that have experienced contrasting population history and selective environment. We found no evidence for differences in G-matrices among populations. Interestingly, the phenotypic variance-covariance matrices (P) were divergent across populations, suggesting that using P as a substitute for G may be inadequate. These analyses also provide the first evidence in wild populations for additive genetic variation in the incubation period (that is, the period between last egg laid and hatching) in all four populations. Altogether, our results suggest that G-matrices may be stable across populations inhabiting contrasted environments, therefore challenging the results of previous simulation studies and laboratory experiments.
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Affiliation(s)
- B Delahaie
- Centre d'Ecologie Fonctionnelle et Evolutive, CNRS-UMR5175 CEFE, Montpellier, France
| | - A Charmantier
- Centre d'Ecologie Fonctionnelle et Evolutive, CNRS-UMR5175 CEFE, Montpellier, France
| | - S Chantepie
- Laboratoire d'Écologie Alpine, Université Grenoble Alpes, Unité Mixte de Recherche 5533 CNRS, Grenoble, France
| | - D Garant
- Département de biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - M Porlier
- Département de biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - C Teplitsky
- Centre d'Ecologie Fonctionnelle et Evolutive, CNRS-UMR5175 CEFE, Montpellier, France
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12
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Puentes A, Granath G, Ågren J. Similarity in G matrix structure among natural populations of Arabidopsis lyrata. Evolution 2016; 70:2370-2386. [PMID: 27501272 DOI: 10.1111/evo.13034] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 07/25/2016] [Indexed: 12/31/2022]
Abstract
Understanding the stability of the G matrix in natural populations is fundamental for predicting evolutionary trajectories; yet, the extent of its spatial variation and how this impacts responses to selection remain open questions. With a nested paternal half-sib crossing design and plants grown in a field experiment, we examined differences in the genetic architecture of flowering time, floral display, and plant size among four Scandinavian populations of Arabidopsis lyrata. Using a multivariate Bayesian framework, we compared the size, shape, and orientation of G matrices and assessed their potential to facilitate or constrain trait evolution. Flowering time, floral display and rosette size varied among populations and significant additive genetic variation within populations indicated potential to evolve in response to selection. Yet, some characters, including flowering start and number of flowers, may not evolve independently because of genetic correlations. Using a multivariate framework, we found few differences in the genetic architecture of traits among populations. G matrices varied mostly in size rather than shape or orientation. Differences in multivariate responses to selection predicted from differences in G were small, suggesting overall matrix similarity and shared constraints to trait evolution among populations.
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Affiliation(s)
- Adriana Puentes
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden. .,Department of Ecology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
| | - Gustaf Granath
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.,Department of Ecology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
| | - Jon Ågren
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
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13
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Poissant J, Morrissey MB, Gosler AG, Slate J, Sheldon BC. Multivariate selection and intersexual genetic constraints in a wild bird population. J Evol Biol 2016; 29:2022-2035. [PMID: 27338121 DOI: 10.1111/jeb.12925] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 06/03/2016] [Accepted: 06/22/2016] [Indexed: 01/18/2023]
Abstract
When selection differs between the sexes for traits that are genetically correlated between the sexes, there is potential for the effect of selection in one sex to be altered by indirect selection in the other sex, a situation commonly referred to as intralocus sexual conflict (ISC). While potentially common, ISC has rarely been studied in wild populations. Here, we studied ISC over a set of morphological traits (wing length, tarsus length, bill depth and bill length) in a wild population of great tits (Parus major) from Wytham Woods, UK. Specifically, we quantified the microevolutionary impacts of ISC by combining intra- and intersex additive genetic (co)variances and sex-specific selection estimates in a multivariate framework. Large genetic correlations between homologous male and female traits combined with evidence for sex-specific multivariate survival selection suggested that ISC could play an appreciable role in the evolution of this population. Together, multivariate sex-specific selection and additive genetic (co)variance for the traits considered accounted for additive genetic variance in fitness that was uncorrelated between the sexes (cross-sex genetic correlation = -0.003, 95% CI = -0.83, 0.83). Gender load, defined as the reduction in a population's rate of adaptation due to sex-specific effects, was estimated at 50% (95% CI = 13%, 86%). This study provides novel insights into the evolution of sexual dimorphism in wild populations and illustrates how quantitative genetics and selection analyses can be combined in a multivariate framework to quantify the microevolutionary impacts of ISC.
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Affiliation(s)
- J Poissant
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, UK. .,Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.
| | - M B Morrissey
- School of Biology, University of St Andrews, St Andrews, UK
| | - A G Gosler
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, UK
| | - J Slate
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - B C Sheldon
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, UK
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Staub NL. Age, Sexual Dimorphism, and Growth Rates in the Black Salamander,Aneides flavipunctatus(Plethodontidae). COPEIA 2016. [DOI: 10.1643/cg-14-136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Dioecy (separate male and female individuals) ensures outcrossing and is more prevalent in animals than in plants. Although it is common in bryophytes and gymnosperms, only 5% of angiosperms are dioecious. In dioecious higher plants, flowers borne on male and female individuals are, respectively deficient in functional gynoecium and androecium. Dioecy is inherited via three sex chromosome systems: XX/XY, XX/X0 and WZ/ZZ, such that XX or WZ is female and XY, X0 or ZZ are males. The XX/XY system generates the rarer XX/X0 and WZ/ZZ systems. An autosome pair begets XY chromosomes. A recessive loss-of-androecium mutation (ana) creates X chromosome and a dominant gynoecium-suppressing (GYS) mutation creates Y chromosome. The ana/ANA and gys/GYS loci are in the sex-determining region (SDR) of the XY pair. Accumulation of inversions, deleterious mutations and repeat elements, especially transposons, in the SDR of Y suppresses recombination between X and Y in SDR, making Y labile and increasingly degenerate and heteromorphic from X. Continued recombination between X and Y in their pseudoautosomal region located at the ends of chromosomal arms allows survival of the degenerated Y and of the species. Dioecy is presumably a component of the evolutionary cycle for the origin of new species. Inbred hermaphrodite species assume dioecy. Later they suffer degenerate-Y-led population regression. Cross-hybridization between such extinguishing species and heterologous species, followed by genome duplication of segregants from hybrids, give rise to new species.
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Wyman MJ, Rowe L. Male Bias in Distributions of Additive Genetic, Residual, and Phenotypic Variances of Shared Traits. Am Nat 2014; 184:326-37. [DOI: 10.1086/677310] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Bachtrog D, Mank JE, Peichel CL, Kirkpatrick M, Otto SP, Ashman TL, Hahn MW, Kitano J, Mayrose I, Ming R, Perrin N, Ross L, Valenzuela N, Vamosi JC. Sex determination: why so many ways of doing it? PLoS Biol 2014; 12:e1001899. [PMID: 24983465 PMCID: PMC4077654 DOI: 10.1371/journal.pbio.1001899] [Citation(s) in RCA: 718] [Impact Index Per Article: 71.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining signals is coupled with conserved molecular pathways that trigger male or female development. Conflicting selection on different parts of the genome and on the two sexes may drive many of these transitions, but few systems with rapid turnover of sex determination mechanisms have been rigorously studied. Here we survey our current understanding of how and why sex determination evolves in animals and plants and identify important gaps in our knowledge that present exciting research opportunities to characterize the evolutionary forces and molecular pathways underlying the evolution of sex determination.
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Affiliation(s)
- Doris Bachtrog
- University of California, Berkeley, Department of Integrative Biology, Berkeley, California, United States of America
| | - Judith E. Mank
- University College London, Department of Genetics, Evolution and Environment, London, United Kingdom
| | - Catherine L. Peichel
- Fred Hutchinson Cancer Research Center, Divisions of Human Biology and Basic Sciences, Seattle, Washington, United States of America
| | - Mark Kirkpatrick
- University of Texas, Department of Integrative Biology, Austin, Texas, United States of America
| | - Sarah P. Otto
- University of British Columbia, Department of Zoology, Vancouver, British Columbia, Canada
| | - Tia-Lynn Ashman
- University of Pittsburgh, Department of Biological Sciences, Pittsburgh, Pennsylvania, United States of America
| | - Matthew W. Hahn
- Indiana University, Department of Biology, Bloomington Indiana, United States of America
| | - Jun Kitano
- National Institute of Genetics, Ecological Genetics Laboratory, Mishima, Shizuoka, Japan
| | - Itay Mayrose
- Tel Aviv University, Department of Molecular Biology and Ecology of Plants, Tel Aviv, Israel
| | - Ray Ming
- University of Illinois, Department of Plant Biology, Urbana-Champaign, Illinois, United States of America
| | - Nicolas Perrin
- University of Lausanne, Department of Ecology and Evolution, Lausanne, Switzerland
| | - Laura Ross
- University of Oxford, Department of Zoology, Oxford, United Kingdom
| | - Nicole Valenzuela
- Iowa State University, Department of Ecology, Evolution and Organismal Biology, Ames, Iowa, United States of America
| | - Jana C. Vamosi
- University of Calgary, Department of Biological Sciences, Calgary, Alberta, Canada
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Castric V, Billiard S, Vekemans X. Trait transitions in explicit ecological and genomic contexts: plant mating systems as case studies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 781:7-36. [PMID: 24277293 DOI: 10.1007/978-94-007-7347-9_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Plants are astonishingly diverse in how they reproduce sexually, and the study of plant mating systems provides some of the most compelling cases of parallel and independent evolutionary transitions. In this chapter, we review how the massive amount of genomic data being produced is allowing long-standing predictions from ecological and evolutionary theory to be put to test. After a review of theoretical predictions about the importance of considering the genomic architecture of the mating system, we focus on a set of recent discoveries on how the mating system is controlled in a variety of model and non-model species. In parallel, genomic approaches have revealed the complex interaction between the evolution of genes controlling mating systems and genome evolution, both genome-wide and in the mating system control region. In several cases, major transitions in the mating system can be clearly associated with important ecological changes, hence illuminating an important interplay between ecological and genomic approaches. We also list a number of major unsolved questions that remain for the field, and highlight foreseeable conceptual developments that are likely to play a major role in our understanding of how plant mating systems evolve in Nature.
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Affiliation(s)
- Vincent Castric
- Laboratoire de Génétique et Evolution des Populations Végétales (GEPV), UMR 8198; CNRS, Université Lille 1, Sciences et Technologies, Cité Scientifique, Villeneuve d'Ascq, France,
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Wyman MJ, Stinchcombe JR, Rowe L. A multivariate view of the evolution of sexual dimorphism. J Evol Biol 2014; 26:2070-80. [PMID: 24028470 DOI: 10.1111/jeb.12188] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 04/08/2013] [Accepted: 04/12/2013] [Indexed: 12/31/2022]
Abstract
Sexual differences are often dramatic and widespread across taxa. Their extravagance and ubiquity can be puzzling because the common underlying genome of males and females is expected to impede rather than foster phenotypic divergence. Widespread dimorphism, despite a shared genome, may be more readily explained by considering the multivariate, rather than univariate, framework governing the evolution of sexual dimorphism. In the univariate formulation, differences in genetic variances and a low intersexual genetic correlation (rMF) can facilitate the evolution of sexual dimorphism. However, studies that have analysed sex-specific differences in heritabilities or genetic variances do not always find significant differences. Furthermore, many of the reported estimates of rMF are very high and positive. When monomorphic heritabilities and a high rMF are present together, the evolution of sexual dimorphism on a trait-by-trait basis is severely constrained. By contrast, the multivariate formulation has greater generality and more flexibility. Although the number of multivariate sexual dimorphism studies is low, almost all support sex-specific differences in the G (variance-covariance) matrix; G matrices can differ with respect to size and/or orientation, affecting the response to selection differently between the sexes. Second, whereas positive values of the univariate quantity rMF only hinder positive changes in sexual dimorphism, positive covariances in the intersexual covariance B matrix can either help or hinder. Similarly, the handful of studies reporting B matrices indicate that it is often asymmetric, so that B can affect the evolution of single traits differently between the sexes. Multivariate approaches typically demonstrate that genetic covariances among traits can strongly constrain trait evolution when compared with univariate approaches. By contrast, in the evolution of sexual dimorphism, a multivariate view potentially reveals more opportunities for sexual dimorphism to evolve by considering the effect sex-specific selection has on sex-specific G matrices and an asymmetric B matrix.
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Affiliation(s)
- M J Wyman
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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20
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Sakai AK, Weller SG, Campbell DR, Culley TM, Dunbar-Wallis AK, Andres AM. Measure for measure: comparing morphological and biomass traits for sex allocation in two gynodioecious species. AMERICAN JOURNAL OF BOTANY 2013; 100:1071-1082. [PMID: 23703857 DOI: 10.3732/ajb.1300045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
PREMISE OF THE STUDY Sex allocation models assume male and female traits are measured in a common currency, allocation traits show heritability, and tradeoffs between investment in the two sexual functions occur. The potential for model predictions and genetic parameters to depend on the currency used is not well understood, despite frequent use of measures not in a common currency. • METHODS We analyzed the relationship between common currency (biomass of carpels, seeds, and stamens) measures and morphological measures (numbers of ovules, seeds, and pollen) in Schiedea salicaria (12-13% females) and S. adamantis (39% females), two closely related gynodioecious species. Additionally, we compared heritabilities and genetic correlations for male and female allocation between these two types of measures. • KEY RESULTS Ovule, seed, and pollen number show greater sexual dimorphism in S. adamantis than in S. salicaria. Most but not all morphological traits and analogous biomass traits are highly correlated with a linear relationship. Narrow-sense heritabilities based on the two methods are often similar, but higher for ovule number than carpel mass and lower for anther number than stamen mass in S. adamantis. Neither trait type shows negative genetic correlations between male and female function. • CONCLUSIONS Both trait types show greater sexual dimorphism in S. adamantis, and significant heritabilities suggest that morphological traits will continue to evolve with breeding system changes. Although most relationships between morphological and biomass traits are linear, curvilinear relationships for two traits suggest that caution is warranted if morphological and common currency traits are used interchangeably in fitness gain curves.
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Affiliation(s)
- Ann K Sakai
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
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Govindarajulu R, Liston A, Ashman TL. Sex-determining chromosomes and sexual dimorphism: insights from genetic mapping of sex expression in a natural hybrid Fragaria × ananassa subsp. cuneifolia. Heredity (Edinb) 2013; 110:430-8. [PMID: 23169558 PMCID: PMC3630810 DOI: 10.1038/hdy.2012.96] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 07/23/2012] [Accepted: 08/27/2012] [Indexed: 01/23/2023] Open
Abstract
We studied the natural hybrid (Fragaria × ananassa subsp. cuneifolia) between two sexually dimorphic octoploid strawberry species (Fragaria virginiana and Fragaria chiloensis) to gain insight into the dynamics of sex chromosomes and the genesis of sexual dimorphism. Male sterility is dominant in both the parental species and thus will be inherited maternally, but the chromosome that houses the sex-determining region differs. Thus, we asked whether (1) the cytotypic composition of hybrid populations represents one or both maternal species, (2) the sex-determining chromosome of the hybrid reflects the location of male sterility within the maternal donor species and (3) crosses from the hybrid species show less sexual dimorphism than the parental species. We found that F. × ananassa subsp. cuneifolia populations consisted of both parental cytotypes but one predominated within each population. Genetic linkage mapping of two crosses showed dominance of male sterility similar to the parental species, however, the map location of male sterility reflected the maternal donor in one cross, but not the other. Moreover, female function mapped to a single region in the first cross, but to two regions in the second cross. Aside from components of female function (fruit set and seed set), other traits that have been found to be significantly sexually dimorphic in the pure species were either not dimorphic or were dimorphic in the opposite direction to the parental species. These results suggest that hybrids experience some disruption of dimorphism in secondary sexual traits, as well as novel location and number of quantitative trait locus (QTL) affecting sex function.
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Affiliation(s)
- R Govindarajulu
- Department of Biological Sciences, University
of Pittsburgh, Pittsburgh, PA, USA
| | - A Liston
- Department of Botany and Plant Pathology,
Oregon State University, Corvallis, OR,
USA
| | - T-L Ashman
- Department of Biological Sciences, University
of Pittsburgh, Pittsburgh, PA, USA
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22
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Barrett SCH, Hough J. Sexual dimorphism in flowering plants. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:67-82. [PMID: 23183260 DOI: 10.1093/jxb/ers308] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Among dioecious flowering plants, females and males often differ in a range of morphological, physiological, and life-history traits. This is referred to as sexual dimorphism, and understanding why it occurs is a central question in evolutionary biology. Our review documents a range of sexually dimorphic traits in angiosperm species, discusses their ecological consequences, and details the genetic and evolutionary processes that drive divergence between female and male phenotypes. We consider why sexual dimorphism in plants is generally less well developed than in many animal groups, and also the importance of sexual and natural selection in contributing to differences between the sexes. Many sexually dimorphic characters, including both vegetative and flowering traits, are associated with differences in the costs of reproduction, which are usually greater in females, particularly in longer-lived species. These differences can influence the frequency and distribution of females and males across resource gradients and within heterogeneous environments, causing niche differences and the spatial segregation of the sexes. The interplay between sex-specific adaptation and the breakdown of between-sex genetic correlations allows for the independent evolution of female and male traits, and this is influenced in some species by the presence of sex chromosomes. We conclude by providing suggestions for future work on sexual dimorphism in plants, including investigations of the ecological and genetic basis of intraspecific variation, and genetic mapping and expression studies aimed at understanding the genetic architecture of sexually dimorphic trait variation.
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Affiliation(s)
- Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2.
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Divergence in Defence against Herbivores between Males and Females of Dioecious Plant Species. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:897157. [PMID: 23320247 PMCID: PMC3540699 DOI: 10.1155/2012/897157] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/21/2012] [Accepted: 10/17/2012] [Indexed: 02/04/2023]
Abstract
Defensive traits may evolve differently between sexes in dioecious plant species. Our current understanding of this process hinges on a partial view of the evolution of resistance traits that may result in male-biased herbivory in dioecious populations. Here, we present a critical summary of the current state of the knowledge of herbivory in dioecious species and propose alternative evolutionary scenarios that have been neglected. These scenarios consider the potential evolutionary and functional determinants of sexual dimorphism in patterns of resource allocation to reproduction, growth, and defence. We review the evidence upon which two previous reviews of sex-biased herbivory have concluded that male-biased herbivory is a rule for dioecious species, and we caution readers about a series of shortcomings of many of these studies. Lastly, we propose a minimal standard protocol that should be followed in any studies that intend to elucidate the (co)evolution of interactions between dioecious plants and their herbivores.
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Brock MT, Kover PX, Weinig C. Natural variation in GA1 associates with floral morphology in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2012; 195:58-70. [PMID: 22510148 DOI: 10.1111/j.1469-8137.2012.04145.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
• The genetic architecture of floral traits is evolutionarily important due to the fitness consequences of quantitative variation in floral morphology. Yet, little is known about the genes underlying these traits in natural populations. Using Arabidopsis thaliana, we examine molecular variation at GIBBERELLIC ACID REQUIRING 1 (GA1) and test for associations with floral morphology. • We examined full-length sequence in 32 accessions and describe two haplotypes (comprising four nonsynonymous polymorphisms) in GA1 that segregate at intermediate frequencies. In 133 A. thaliana accessions, we test for genotype-phenotype associations and corroborate these findings in segregating progenies. • The two common GA1 haplotypes were associated with the length of petals, stamens, and to a lesser extent style-stigma length. Associations were confirmed in a segregating progeny developed from 19 accessions. We find analogous results in recombinant inbred lines of the Bayreuth × Shahdara cross, which differ only at one of 4 SNPs, suggesting that this SNP may contribute to the observed association. • Assuming GA1 causally affects floral organ size, it is interesting that adjacent petal and stamen whorls are most strongly affected. This pattern suggests that GA1 could contribute to the greater strength of petal-stamen correlations relative to other floral-length correlations observed in some Brassicaceous species.
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Affiliation(s)
- Marcus T Brock
- Department of Botany, University of Wyoming, Laramie, WY 82071, USA.
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Dufay M, Billard E. How much better are females? The occurrence of female advantage, its proximal causes and its variation within and among gynodioecious species. ANNALS OF BOTANY 2012; 109:505-19. [PMID: 21459860 PMCID: PMC3278283 DOI: 10.1093/aob/mcr062] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 02/10/2011] [Indexed: 05/09/2023]
Abstract
BACKGROUND Gynodioecy is a reproductive system of interest for evolutionary biologists, as it poses the question of how females can be maintained while competing with hermaphrodites that possess both male and female functions. One necessary condition for the maintenance of this polymorphism is the occurrence of a female advantage, i.e. a better seed production or quality by females compared with hermaphrodites. Theoretically, its magnitude can be low when sterility mutations are cytoplasmic, while a 2-fold advantage is needed in the case of nuclear sterility. Such a difference is often thought to be due to reduced inbreeding depression in obligatory outcrossed females. Finally, variation in sex ratio and female advantage occur among populations of some gynodioecious species, though the prevalence of such variation is unknown. SCOPE By reviewing and analysing the data published on 48 gynodioecious species, we examined three important issues about female advantage. (1) Are reduced selfing and inbreeding depression likely to be the major cause of female advantage? (2) What is the magnitude of female advantage and does it fit theoretical predictions? (3) Does the occurrence or the magnitude of female advantage vary among populations within species and why? CONCLUSIONS It was found that a female advantage occurred in 40 species, with a magnitude comprised between 1 and 2 in the majority of cases. In many species, reduced selfing may not be a necessary cause of this advantage. Finally, female advantage varied among populations in some species, but both positive and negative correlations were found with female frequency. The role of reduced selfing in females for the evolution of gynodioecy, as well as the various processes that affect sex ratios and female advantage in populations are discussed.
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Affiliation(s)
- Mathilde Dufay
- Laboratoire GEPV FRE-CNRS 3268, Université des Sciences et Technologies de Lille - Lille 1, Villeneuve d'Ascq Cedex, France.
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Vary LB, Sakai AK, Weller SG. Morphological and functional sex expression in the Malagasy endemic Tina striata (Sapindaceae). AMERICAN JOURNAL OF BOTANY 2011; 98:1040-1048. [PMID: 21613068 DOI: 10.3732/ajb.1000479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
PREMISE OF THE STUDY Knowledge of the functional sex expression of flowers is critical to identify the breeding system and potential for outcrossing in individuals but difficult to determine based solely on floral morphology. Individuals of the Malagasy endemic Tina striata (Sapindaceae) have both morphologically male (staminate) flowers and hermaphroditic (bisexual) flowers, although many Sapindaceae species have only functionally unisexual flowers. Two populations of T. striata were studied to determine the functional sex expression of flowers and their breeding system. METHODS To determine whether morphologically hermaphroditic flowers have only female function, we compared male flowers and morphologically hermaphroditic flowers for (1) floral size, (2) pollen production and morphology, (3) patterns of anther dehiscence, (4) pollen germination, and (5) floral visitation patterns. KEY RESULTS Relative to male flowers, morphologically hermaphroditic flowers had similar pollen grain morphology but smaller androecia and less pollen. Anthers from male flowers dehisced on days 3 and 4 of flowering and then abscised with the male flower. Anthers from hermaphroditic flowers did not dehisce or release pollen and abscised after the fourth day of flowering. Pollen from hermaphroditic flowers was less likely to germinate and produce pollen tubes. Floral visitors were similar for male and hermaphroditic flowers, and no visitation to hermaphroditic flowers was observed after stamen abscission. CONCLUSIONS Morphologically hermaphroditic flowers of T. striata do not have male function and are functionally female; therefore, T. striata has a monoecious breeding system, with possible adaptations to promote outcrossing.
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Affiliation(s)
- Laura B Vary
- Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, California 92697, USA.
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Spigler RB, Ashman TL. Sex ratio and subdioecy in Fragaria virginiana: the roles of plasticity and gene flow examined. THE NEW PHYTOLOGIST 2011; 190:1058-1068. [PMID: 21352233 DOI: 10.1111/j.1469-8137.2011.03657.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Here we examined the roles of sex-differential plasticity (SDP) and gene flow in sex ratio evolution of subdioecious Fragaria virginiana. We assessed whether female frequency varied with resource availability in 17 natural populations and then characterized plasticity and mean investment in allocation to female function at flower and plant levels in the sex morphs in the glasshouse. We estimated patterns of population divergence using five microsatellite markers. We reveal SDP in fruit production substantial enough to translate into a higher equilibrium female frequency at low resources. Thus SDP can account, in part, for the strong negative relationship between female frequency and resources found in the field. Pollen-bearing morphs varied in plasticity across populations, and the degree of plasticity in fruit number was positively correlated with in situ variation in nitrogen (N) availability, suggesting an adaptive component to sex-allocation plasticity. Low neutral genetic differentiation, indicating high gene flow or recent divergence, may contribute to the absence of population differentiation in fruit-setting ability of pollen-bearing morphs despite considerable sex ratio variation. We consider how these processes, in addition to other features of this system, may work in concert to influence sex ratios and to hinder the evolution of dioecy in F. virginiana.
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Affiliation(s)
- Rachel B Spigler
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Ave, Pittsburgh, PA 15260-3929, USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Ave, Pittsburgh, PA 15260-3929, USA
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Cytoplasmic male sterility in Mimulus hybrids has pleiotropic effects on corolla and pistil traits. Heredity (Edinb) 2011; 106:886-93. [PMID: 21245895 DOI: 10.1038/hdy.2010.133] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The mechanisms underlying genetic associations have important consequences for evolutionary outcomes, but distinguishing linkage from pleiotropy is often difficult. Here, we use a fine mapping approach to determine the genetic basis of association between cytonuclear male sterility and other floral traits in Mimulus hybrids. Previous work has shown that male sterility in hybrids between Mimulus guttatus and Mimulus nasutus is due to interactions between a mitochondrial gene from M. guttatus and two tightly linked nuclear restorer alleles on Linkage Group 7, and that male sterility is associated with reduced corolla size. In the present study, we generated a set of nearly isogenic lines segregating for the restorer region and male sterility, but with unique flanking introgressions. Male-sterile flowers had significantly smaller corollas, longer styles and greater stigmatic exsertion than fertile flowers. Because these effects were significant regardless of the genotypic composition of introgressions flanking the restorer region, they suggest that these floral differences are a direct byproduct of the genetic incompatibility causing anther abortion. In addition, we found a non-significant but intriguing trend for male-sterile plants to produce more seeds per flower than fertile siblings after supplemental pollination. Such pleiotropic effects may underlie the corolla dimorphism frequently observed in gynodioecious taxa and may affect selection on cytoplasmic male sterility genes when they initially arise.
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Spigler RB, Lewers KS, Ashman TL. GENETIC ARCHITECTURE OF SEXUAL DIMORPHISM IN A SUBDIOECIOUS PLANT WITH A PROTO-SEX CHROMOSOME. Evolution 2010; 65:1114-26. [DOI: 10.1111/j.1558-5646.2010.01189.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Campbell DR, Weller SG, Sakai AK, Culley TM, Dang PN, Dunbar-Wallis AK. Genetic variation and covariation in floral allocation of two species of Schiedea with contrasting levels of sexual dimorphism. Evolution 2010; 65:757-70. [PMID: 21091465 DOI: 10.1111/j.1558-5646.2010.01172.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The evolution of sexual dimorphism depends in part on the additive genetic variance-covariance matrices within females, within males, and across the sexes. We investigated quantitative genetics of floral biomass allocation in females and hermaphrodites of gynodioecious Schiedea adamantis (Caryophyllaceae). The G-matrices within females (G(f)), within hermaphrodites (G(m)), and between sexes (B) were compared to those for the closely related S. salicaria, which exhibits a lower frequency of females and less-pronounced sexual dimorphism. Additive genetic variation was detected in all measured traits in S. adamantis, with narrow-sense heritability from 0.34-1.0. Female allocation and floral size traits covaried more tightly than did those traits with allocation to stamens. Between-sex genetic correlations were all <1, indicating sex-specific expression of genes. Common principal-components analysis detected differences between G(f) and G(m) , suggesting potential for further independent evolution of the sexes. The two species of Schiedea differed in G(m) and especially so in G(f) , with S. adamantis showing greater genetic variation in capsule mass and tighter genetic covariation between female allocation traits and flower size in females. Despite greater sexual dimorphism in S. adamantis, genetic correlations between the two sexes (standardized elements of B) were similar to correlations between sexes in S. salicaria.
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Affiliation(s)
- Diane R Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697, USA.
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Barker BS, Phillips PC, Arnold SJ. A TEST OF THE CONJECTURE THAT G-MATRICES ARE MORE STABLE THAN B-MATRICES. Evolution 2010; 64:2601-13. [DOI: 10.1111/j.1558-5646.2010.01023.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Charlesworth D, Mank JE. The birds and the bees and the flowers and the trees: lessons from genetic mapping of sex determination in plants and animals. Genetics 2010; 186:9-31. [PMID: 20855574 PMCID: PMC2940314 DOI: 10.1534/genetics.110.117697] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The ability to identify genetic markers in nonmodel systems has allowed geneticists to construct linkage maps for a diversity of species, and the sex-determining locus is often among the first to be mapped. Sex determination is an important area of study in developmental and evolutionary biology, as well as ecology. Its importance for organisms might suggest that sex determination is highly conserved. However, genetic studies have shown that sex determination mechanisms, and the genes involved, are surprisingly labile. We review studies using genetic mapping and phylogenetic inferences, which can help reveal evolutionary pattern within this lability and potentially identify the changes that have occurred among different sex determination systems. We define some of the terminology, particularly where confusion arises in writing about such a diverse range of organisms, and highlight some major differences between plants and animals, and some important similarities. We stress the importance of studying taxa suitable for testing hypotheses, and the need for phylogenetic studies directed to taxa where the patterns of changes can be most reliably inferred, if the ultimate goal of testing hypotheses regarding the selective forces that have led to changes in such an essential trait is to become feasible.
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Affiliation(s)
- Deborah Charlesworth
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, United Kingdom.
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KOVACS JENNIFERL, HOFFMAN ERICA, MARRINER SARAHM, GOODISMAN MICHAELAD. Detecting selection on morphological traits in social insect castes: the case of the social wasp Vespula maculifrons. Biol J Linn Soc Lond 2010. [DOI: 10.1111/j.1095-8312.2010.01495.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Genetic basis of sexual dimorphism in the threespine stickleback Gasterosteus aculeatus. Heredity (Edinb) 2010; 106:218-27. [PMID: 20700139 DOI: 10.1038/hdy.2010.104] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Sexual dimorphism (SD) in morphological, behavioural and physiological features is common, but the genetics of SD in the wild has seldom been studied in detail. We investigated the genetic basis of SD in morphological traits of threespine stickleback (Gasterosteus aculeatus) by conducting a large breeding experiment with fish from an ancestral marine population that acts as a source of morphological variation. We also examined the patterns of SD in a set of 38 wild populations from different habitats to investigate the relationship between the genetic architecture of SD of the marine ancestral population in relation to variation within and among natural populations. The results show that genetic architecture in terms of heritabilities, additive genetic variances and covariances (as well as correlations) is very similar in the two sexes in spite of the fact that many of the traits express significant SD. Furthermore, population differences in threespine stickleback body shape and armour SD appear to have evolved despite constraints imposed by genetic architecture. This implies that constraints for the evolution of SD imposed by strong genetic correlations are not as severe and absolute as commonly thought.
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Dufay M, Pannell JR. THE EFFECT OF POLLEN VERSUS SEED FLOW ON THE MAINTENANCE OF NUCLEAR-CYTOPLASMIC GYNODIOECY. Evolution 2010; 64:772-84. [DOI: 10.1111/j.1558-5646.2009.00847.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Sosenski P, Fornoni J, Molina-Freaner FE, Weller SG, Domínguez CA. Changes in sexual organ reciprocity and phenotypic floral integration during the tristyly-distyly transition in Oxalis alpina. THE NEW PHYTOLOGIST 2010; 185:829-840. [PMID: 19968800 DOI: 10.1111/j.1469-8137.2009.03105.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Although the 6 magnitude and pattern of correlation among floral traits (phenotypic integration) is usually conceived as an adaptation for successful pollination and reproduction, studies on the evolution of plant reproductive systems have generally focused on one or a few characters. If evolutionary transitions between reproductive systems involve morphological floral adjustments, changes in the magnitude and pattern of phenotypic integration of floral traits may be expected. In this study, we focused on the evolutionary dynamics of a complex adaptive trait, the extent of reciprocity (reciprocal placement) among sexual organs in a heterostylous species, and explored the associated changes in phenotypic floral integration during the transition from tristyly to distyly. The extent of reciprocity and both the magnitude and pattern of floral integration were characterized in 12 populations of Oxalis alpina representing the tristyly-distyly gradient. Although the extent of reciprocity increased along the tristyly-distyly transition, the flower size diminished. These adjustments did not affect the magnitude, but did affect the pattern, of floral integration. *Changes in the pattern of floral integration suggested that allometric, functional and pleiotropic relationships among floral traits were affected during this evolutionary transition.
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Affiliation(s)
- Paula Sosenski
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, CP 04510, México Distrito Federal, México
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Wilk JA, Kramer AT, Ashley MV. High variation in clonal vs. sexual reproduction in populations of the wild strawberry, Fragaria virginiana (Rosaceae). ANNALS OF BOTANY 2009; 104:1413-9. [PMID: 19797422 PMCID: PMC2778387 DOI: 10.1093/aob/mcp239] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 06/12/2009] [Accepted: 08/11/2009] [Indexed: 05/21/2023]
Abstract
BACKGROUND AND AIMS Many plants reproduce both clonally and sexually, and the balance between the two modes of reproduction will vary among populations. Clonal reproduction was characterized in three populations of the wild strawberry, Fragaria virginiana, to determine the extent that reproductive mode varied locally between sites. The study sites were fragmented woodlands in Cook County, Illinois, USA. METHODS A total of 95 strawberry ramets were sampled from the three sites via transects. Ramets were mapped and genotyped at five variable microsatellite loci. The variability at these five loci was sufficient to assign plants to clones with high confidence, and the spatial pattern of genets was mapped at each site. KEY RESULTS A total of 27 distinct multilocus genotypes were identified. Of these, 18 genotypes were detected only once, with the remaining nine detected in multiple ramets. The largest clone was identified in 16 ramets. No genets were shared between sites, and each site exhibited markedly different clonal and sexual recruitment patterns, ranging from two non-overlapping and widespread genets to 19 distinct genets. Only one flowering genet was female; the remainder were hermaphrodites. CONCLUSIONS Local population history or fine-scale ecological differences can result in dramatically different reproductive patterns at small spatial scales. This finding may be fairly widespread among clonal plant species, and studies that aim to characterize reproductive modes in species capable of asexual reproduction need to evaluate reproductive modes in multiple populations and sites.
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Affiliation(s)
- John A. Wilk
- Department of Biological Sciences, University of Illinois Chicago, M/C 066, 845 W. Taylor St, Chicago IL 60607, USA
| | - Andrea T. Kramer
- Department of Biological Sciences, University of Illinois Chicago, M/C 066, 845 W. Taylor St, Chicago IL 60607, USA
- Botanic Gardens Conservation International and Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, USA
| | - Mary V. Ashley
- Department of Biological Sciences, University of Illinois Chicago, M/C 066, 845 W. Taylor St, Chicago IL 60607, USA
- For correspondence. E-mail
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McCauley DE, Bailey MF. Recent advances in the study of gynodioecy: the interface of theory and empiricism. ANNALS OF BOTANY 2009; 104:611-20. [PMID: 19515690 PMCID: PMC2729626 DOI: 10.1093/aob/mcp141] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 03/25/2009] [Accepted: 04/29/2009] [Indexed: 05/08/2023]
Abstract
BACKGROUND In this review we report on recent literature concerned with studies of gynodioecy, or the co-occurrence of female and hermaphrodite individuals in natural plant populations. Rather than review this literature in its entirety, our focus is on the interplay between theoretical and empirical approaches to the study of gynodioecy. SCOPE Five areas of active inquiry are considered. These are the cost of restoration, the influence of population structure on spatial sex-ratio variation, the influence of inbreeding on sex expression, the signature of cyto-nuclear coevolution on the mitochondrial genome, and the consequences of mitochondrial paternal leakage. CONCLUSIONS Recent advances in the study of gynodioecy have been made by considering both the ecology of female:hermaphrodite fitness differences and the genetics of sex expression. Indeed theory has guided empiricism and empiricism has guided theory. Future advances will require that some of the methods currently available only for model organisms be applied to a wider range of species.
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Affiliation(s)
- David E McCauley
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.
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Majetic CJ, Raguso RA, Ashman TL. The sweet smell of success: floral scent affects pollinator attraction and seed fitness inHesperis matronalis. Funct Ecol 2009. [DOI: 10.1111/j.1365-2435.2008.01517.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Willmore KE, Roseman CC, Rogers J, Richtsmeier JT, Cheverud JM. Genetic variation in baboon craniofacial sexual dimorphism. Evolution 2009; 63:799-806. [PMID: 19210535 PMCID: PMC2836714 DOI: 10.1111/j.1558-5646.2008.00593.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Sexual dimorphism is a widespread phenomenon and contributes greatly to intraspecies variation. Despite a long history of active research, the genetic basis of dimorphism for complex traits remains unknown. Understanding the sex-specific differences in genetic architecture for cranial traits in a highly dimorphic species could identify possible mechanisms through which selection acts to produce dimorphism. Using distances calculated from three-dimensional landmark data from CT scans of 402 baboon skulls from a known genealogy, we estimated genetic variance parameters in both sexes to determine the presence of gene-by-sex (G x S) interactions and X-linked heritability. We hypothesize that traits exhibiting the greatest degree of sexual dimorphism (facial traits in baboons) will demonstrate either stronger G x S interactions or X-linked effects. We found G x S interactions and X-linked effects for a few measures that span the areas connecting the face to the neurocranium but for no traits restricted to the face. This finding suggests that facial traits will have a limited response to selection for further evolution of dimorphism in this population. We discuss the implications of our results with respect to the origins of cranial sexual dimorphism in this baboon sample, and how the genetic architecture of these traits affects their potential for future evolution.
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Affiliation(s)
- Katherine E Willmore
- Department of Anthropology, Pennsylvania State University, 409 Carpenter Building, University Park, Pennsylvania 16802, USA.
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Cox R, Calsbeek R. Sexually Antagonistic Selection, Sexual Dimorphism, and the Resolution of Intralocus Sexual Conflict. Am Nat 2009; 173:176-87. [DOI: 10.1086/595841] [Citation(s) in RCA: 331] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Penet L, Collin CL, Ashman TL. Florivory increases selfing: an experimental study in the wild strawberry, Fragaria virginiana. PLANT BIOLOGY (STUTTGART, GERMANY) 2009; 11:38-45. [PMID: 19121112 DOI: 10.1111/j.1438-8677.2008.00141.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Florivores are antagonists that damage flowers, and have direct negative effects on flowering and pollination of the attacked plants. While florivory has mainly been studied for its consequences on seed production or siring success, little is known about its impact on mating systems. Damage to flowers can alter pollinator attraction to the plant and may therefore modify patterns of pollen transfer. However, the consequences of damage for mating systems can take two forms: a decrease in flower number reduces opportunities for intra-inflorescence pollen deposition (geitonogamy), which, in turn, may lead to a decrease in selfing; whereas a decrease in floral display may also reduce overall visitation and thus increase the chances of self-pollination via facilitated or autonomous autogamy. We investigated the effects of damage by a bud-clipping weevil (Anthonomus signatus) in Fragaria virginiana in an experimental setting mimicking natural conditions. We found that increased damage led to an increase in selfing, a result consistent with the increased autogamy pathway. We discuss the implications of this finding and evaluate the generality of florivore-mediated mating system expression.
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Affiliation(s)
- L Penet
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
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Spigler RB, Lewers KS, Main DS, Ashman TL. Genetic mapping of sex determination in a wild strawberry, Fragaria virginiana, reveals earliest form of sex chromosome. Heredity (Edinb) 2008; 101:507-17. [PMID: 18797475 DOI: 10.1038/hdy.2008.100] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The evolution of separate sexes (dioecy) from hermaphroditism is one of the major evolutionary transitions in plants, and this transition can be accompanied by the development of sex chromosomes. Studies in species with intermediate sexual systems are providing unprecedented insight into the initial stages of sex chromosome evolution. Here, we describe the genetic mechanism of sex determination in the octoploid, subdioecious wild strawberry, Fragaria virginiana Mill., based on a whole-genome simple sequence repeat (SSR)-based genetic map and on mapping sex determination as two qualitative traits, male and female function. The resultant total map length is 2373 cM and includes 212 markers on 42 linkage groups (mean marker spacing: 14 cM). We estimated that approximately 70 and 90% of the total F. virginiana genetic map resides within 10 and 20 cM of a marker on this map, respectively. Both sex expression traits mapped to the same linkage group, separated by approximately 6 cM, along with two SSR markers. Together, our phenotypic and genetic mapping results support a model of gender determination in subdioecious F. virginiana with at least two linked loci (or gene regions) with major effects. Reconstruction of parental genotypes at these loci reveals that both female and hermaphrodite heterogamety exist in this species. Evidence of recombination between the sex-determining loci, an important hallmark of incipient sex chromosomes, suggest that F. virginiana is an example of the youngest sex chromosome in plants and thus a novel model system for the study of sex chromosome evolution.
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Affiliation(s)
- R B Spigler
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260-3929, USA
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McCauley DE, Olson MS. Do recent findings in plant mitochondrial molecular and population genetics have implications for the study of gynodioecy and cytonuclear conflict? Evolution 2008; 62:1013-25. [PMID: 18315572 DOI: 10.1111/j.1558-5646.2008.00363.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The coexistence of females and hermaphrodites in plant populations, or gynodioecy, is a puzzle recognized by Darwin. Correns identified cytoplasmic inheritance of one component of sex expression, now known as cytoplasmic male sterility (CMS). Lewis established cytonuclear inheritance of gynodioecy as an example of genetic conflict. Although biologists have since developed an understanding of the mechanisms allowing the joint maintenance of CMS and nuclear male fertility restorer genes, puzzles remain concerning the inheritance of sex expression and mechanisms governing the origination of CMS. Much of the theory of gynodioecy rests on the assumption of maternal inheritance of the mitochondrial genome. Here we review recent studies of the genetics of plant mitochondria, and their implications for the evolution and transmission of CMS. New studies of intragenomic recombination provide a plausible origin for the chimeric ORFs that characterize CMS. Moreover, evidence suggests that nonmaternal inheritance of mitochondria may be more common than once believed. These findings may have consequences for the maintenance of cytonuclear polymorphism, mitochondrial recombination, generation of gynomonoecious phenotypes, and interpretation of experimental crosses. Finally we point out that CMS can alter the nature of the cytonuclear conflict that may have originally selected for uniparental inheritance.
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Affiliation(s)
- David E McCauley
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.
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Dorken ME, Mitchard ETA. PHENOTYPIC PLASTICITY OF HERMAPHRODITE SEX ALLOCATION PROMOTES THE EVOLUTION OF SEPARATE SEXES: AN EXPERIMENTAL TEST OF THE SEX-DIFFERENTIAL PLASTICITY HYPOTHESIS USINGSAGITTARIA LATIFOLIA(ALISMATACEAE). Evolution 2008; 62:971-8. [DOI: 10.1111/j.1558-5646.2008.00336.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Chenoweth SF, Rundle HD, Blows MW. Genetic constraints and the evolution of display trait sexual dimorphism by natural and sexual selection. Am Nat 2008; 171:22-34. [PMID: 18171148 DOI: 10.1086/523946] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The evolution of sexual dimorphism involves an interaction between sex-specific selection and a breakdown of genetic constraints that arise because the two sexes share a genome. We examined genetic constraints and the effect of sex-specific selection on a suite of sexually dimorphic display traits in Drosophila serrata. Sexual dimorphism varied among nine natural populations covering a substantial portion of the species range. Quantitative genetic analyses showed that intersexual genetic correlations were high because of autosomal genetic variance but that the inclusion of X-linked effects reduced genetic correlations substantially, indicating that sex linkage may be an important mechanism by which intersexual genetic constraints are reduced in this species. We then explored the potential for both natural and sexual selection to influence these traits, using a 12-generation laboratory experiment in which we altered the opportunities for each process as flies adapted to a novel environment. Sexual dimorphism evolved, with natural selection reducing sexual dimorphism, whereas sexual selection tended to increase it overall. To this extent, our results are consistent with the hypothesis that sexual selection favors evolutionary divergence of the sexes. However, sex-specific responses to natural and sexual selection contrasted with the classic model because sexual selection affected females rather than males.
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Affiliation(s)
- Stephen F Chenoweth
- School of Integrative Biology, University of Queensland, St. Lucia, Queensland 4072, Australia.
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