1
|
Wilson AE, Siddiqui A, Dworkin I. Spatial heterogeneity in resources alters selective dynamics in Drosophila melanogaster. Evolution 2021; 75:1792-1804. [PMID: 33963761 DOI: 10.1111/evo.14262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 04/13/2021] [Accepted: 04/23/2021] [Indexed: 11/26/2022]
Abstract
Environmental features can alter the behaviors and phenotypes of organisms, influencing the dynamics of natural and sexual selection. Experimental environmental manipulation, particularly when conducted in experiments where the dynamics of the purging of deleterious alleles are compared, has demonstrated both direct and indirect effects on the strength and direction of selection. However, many of these studies are conducted with fairly simplistic environments, where it is not always clear how or why particular forms of spatial heterogeneity influence behavior or selection. Using Drosophila melanogaster, we tested three different spatial environments designed to determine if spatial constraint of critical resources influences the efficiency of natural and sexual selection. We conducted two allele purging experiments to (1) assess effects of these spatial treatments on selective dynamics of six recessive mutations, and (2) determine how these dynamics changed when sexual selection was relaxed and spatial area reduced for two of the mutants. Allele purging dynamics depended on spatial environment, however the patterns of purging rates between the environments differed across distinct deleterious mutations. We also tested two of the mutant alleles, and demonstrate sexual selection increased the purging rate.
Collapse
Affiliation(s)
- Audrey E Wilson
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Ali Siddiqui
- Department of Health Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Ian Dworkin
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| |
Collapse
|
2
|
Brengdahl MI, Kimber CM, Elias P, Thompson J, Friberg U. Deleterious mutations show increasing negative effects with age in Drosophila melanogaster. BMC Biol 2020; 18:128. [PMID: 32993647 PMCID: PMC7526172 DOI: 10.1186/s12915-020-00858-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 08/28/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND In order for aging to evolve in response to a declining strength of selection with age, a genetic architecture that allows for mutations with age-specific effects on organismal performance is required. Our understanding of how selective effects of individual mutations are distributed across ages is however poor. Established evolutionary theories assume that mutations causing aging have negative late-life effects, coupled to either positive or neutral effects early in life. New theory now suggests evolution of aging may also result from deleterious mutations with increasing negative effects with age, a possibility that has not yet been empirically explored. RESULTS To directly test how the effects of deleterious mutations are distributed across ages, we separately measure age-specific effects on fecundity for each of 20 mutations in Drosophila melanogaster. We find that deleterious mutations in general have a negative effect that increases with age and that the rate of increase depends on how deleterious a mutation is early in life. CONCLUSIONS Our findings suggest that aging does not exclusively depend on genetic variants assumed by the established evolutionary theories of aging. Instead, aging can result from deleterious mutations with negative effects that amplify with age. If increasing negative effect with age is a general property of deleterious mutations, the proportion of mutations with the capacity to contribute towards aging may be considerably larger than previously believed.
Collapse
Affiliation(s)
| | | | - Phoebe Elias
- IFM Biology, Linköping University, Linköping, Sweden
| | | | - Urban Friberg
- IFM Biology, Linköping University, Linköping, Sweden.
| |
Collapse
|
3
|
Sexual Selection Does Not Increase the Rate of Compensatory Adaptation to a Mutation Influencing a Secondary Sexual Trait in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2020; 10:1541-1551. [PMID: 32122961 PMCID: PMC7202011 DOI: 10.1534/g3.119.400934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Theoretical work predicts that sexual selection can enhance natural selection, increasing the rate of adaptation to new environments and helping purge harmful mutations. While some experiments support these predictions, remarkably little work has addressed the role of sexual selection on compensatory adaptation—populations’ ability to compensate for the costs of deleterious alleles that are already present. We tested whether sexual selection, as well as the degree of standing genetic variation, affect the rate of compensatory evolution via phenotypic suppression in experimental populations of Drosophila melanogaster. These populations were fixed for a spontaneous mutation causing mild abnormalities in the male sex comb, a structure important for mating success. We fine-mapped this mutation to an ∼85 kb region on the X chromosome containing three candidate genes, showed that the mutation is deleterious, and that its phenotypic expression and penetrance vary by genetic background. We then performed experimental evolution, including a treatment where opportunity for mate choice was limited by experimentally enforced monogamy. Although evolved populations did show some phenotypic suppression of the morphological abnormalities in the sex comb, the amount of suppression did not depend on the opportunity for sexual selection. Sexual selection, therefore, may not always enhance natural selection; instead, the interaction between these two forces may depend on additional factors.
Collapse
|
4
|
Sharp NP, Whitlock MC. No evidence of positive assortative mating for genetic quality in fruit flies. Proc Biol Sci 2019; 286:20191474. [PMID: 31575372 DOI: 10.1098/rspb.2019.1474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
In sexual populations, the effectiveness of selection will depend on how gametes combine with respect to genetic quality. If gametes with deleterious alleles are likely to combine with one another, deleterious genetic variation can be more easily purged by selection. Assortative mating, where there is a positive correlation between parents in a phenotype of interest such as body size, is often observed in nature, but does not necessarily reveal how gametes ultimately combine with respect to genetic quality itself. We manipulated genetic quality in fruit fly populations using an inbreeding scheme designed to provide an unbiased measure of mating patterns. While inbred flies had substantially reduced reproductive success, their gametes did not combine with those of other inbred flies more often than expected by chance, indicating a lack of positive assortative mating. Instead, we detected a negative correlation in genetic quality between parents, i.e. disassortative mating, which diminished with age. This pattern is expected to reduce the genetic variance for fitness, diminishing the effectiveness of selection. We discuss how mechanisms of sexual selection could produce a pattern of disassortative mating. Our study highlights that sexual selection has the potential to either increase or decrease genetic load.
Collapse
Affiliation(s)
- Nathaniel P Sharp
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.,Department of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Michael C Whitlock
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| |
Collapse
|
5
|
Castillo DM, Moyle LC. Conspecific sperm precedence is reinforced, but postcopulatory sexual selection weakened, in sympatric populations of Drosophila. Proc Biol Sci 2019; 286:20182535. [PMID: 30900533 PMCID: PMC6452082 DOI: 10.1098/rspb.2018.2535] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/06/2019] [Indexed: 12/21/2022] Open
Abstract
Sexual selection can accelerate speciation by driving the evolution of reproductive isolation, but forces driving speciation could also reciprocally feedback on sexual selection. This might be particularly important in the context of 'reinforcement', where selection acts directly to increase prezygotic barriers to reduce the cost of heterospecific matings. Using assays of sperm competition within and between two sister species, we show a signature of reinforcement where these species interact: populations of Drosophila pseudoobscura that co-occur with sister species D. persimilis have an elevated ability to outcompete heterospecific sperm, consistent with selection for increased postcopulatory isolation. We also find these D. pseudoobscura populations have decreased sperm competitive ability against conspecifics, reducing the opportunity for sexual selection within these populations. Our findings demonstrate that direct selection to increase reproductive isolation against other species can compromise the efficacy of sexual selection within species, a collateral effect of reproductive traits responding to heterospecific interactions.
Collapse
Affiliation(s)
- Dean M. Castillo
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
- Department of Molecular Biology and Genetics, Cornell University, 526 Campus Road, Ithaca, NY 14853, USA
| | - Leonie C. Moyle
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
| |
Collapse
|
6
|
Noël E, Fruitet E, Lelaurin D, Bonel N, Ségard A, Sarda V, Jarne P, David P. Sexual selection and inbreeding: Two efficient ways to limit the accumulation of deleterious mutations. Evol Lett 2018; 3:80-92. [PMID: 30788144 PMCID: PMC6369961 DOI: 10.1002/evl3.93] [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: 10/11/2018] [Accepted: 11/14/2018] [Indexed: 12/12/2022] Open
Abstract
Theory and empirical data showed that two processes can boost selection against deleterious mutations, thus facilitating the purging of the mutation load: inbreeding, by exposing recessive deleterious alleles to selection in homozygous form, and sexual selection, by enhancing the relative reproductive success of males with small mutation loads. These processes tend to be mutually exclusive because sexual selection is reduced under mating systems that promote inbreeding, such as self‐fertilization in hermaphrodites. We estimated the relative efficiency of inbreeding and sexual selection at purging the genetic load, using 50 generations of experimental evolution, in a hermaphroditic snail (Physa acuta). To this end, we generated lines that were exposed to various intensities of inbreeding, sexual selection (on the male function), and nonsexual selection (on the female function). We measured how these regimes affected the mutation load, quantified through the survival of outcrossed and selfed juveniles. We found that juvenile survival strongly decreased in outbred lines with reduced male selection, but not when female selection was relaxed, showing that male‐specific sexual selection does purge deleterious mutations. However, in lines exposed to inbreeding, where sexual selection was also relaxed, survival did not decrease, and even increased for self‐fertilized juveniles, showing that purging through inbreeding can compensate for the absence of sexual selection. Our results point to the further question of whether a mixed strategy combining the advantages of both mechanisms of genetic purging could be evolutionary stable.
Collapse
Affiliation(s)
- Elsa Noël
- UMR AGAP (CIRAD-INRA-Montpellier SupAgro) 2 Place Pierre Viala 34060 Montpellier Cedex 1 France.,Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Elise Fruitet
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France.,Department of Entomology Max Planck Institute for Chemical Ecology, Hans Knöll Strasse 8 Jena 07745 Germany.,IBED University of Amsterdam Science Park 904, 1098 XH Amsterdam The Netherlands
| | - Dennyss Lelaurin
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Nicolas Bonel
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France.,Universidad Nacional del Sur B8000ICN Bahía Blanca Argentina
| | - Adeline Ségard
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Violette Sarda
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Philippe Jarne
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Patrice David
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| |
Collapse
|
7
|
Berger D, Martinossi-Allibert I, Grieshop K, Lind MI, Maklakov AA, Arnqvist G. Intralocus Sexual Conflict and the Tragedy of the Commons in Seed Beetles. Am Nat 2016; 188:E98-E112. [DOI: 10.1086/687963] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
8
|
Grieshop K, Stångberg J, Martinossi-Allibert I, Arnqvist G, Berger D. Strong sexual selection in males against a mutation load that reduces offspring production in seed beetles. J Evol Biol 2016; 29:1201-10. [DOI: 10.1111/jeb.12862] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 01/15/2023]
Affiliation(s)
- K. Grieshop
- Department of Ecology and Genetics; Animal Ecology; Uppsala University; Uppsala Sweden
| | - J. Stångberg
- Department of Ecology and Genetics; Animal Ecology; Uppsala University; Uppsala Sweden
| | | | - G. Arnqvist
- Department of Ecology and Genetics; Animal Ecology; Uppsala University; Uppsala Sweden
| | - D. Berger
- Department of Ecology and Genetics; Animal Ecology; Uppsala University; Uppsala Sweden
| |
Collapse
|
9
|
Collet JM, Blows MW, McGuigan K. Transcriptome-wide effects of sexual selection on the fate of new mutations. Evolution 2015; 69:2905-16. [DOI: 10.1111/evo.12778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/03/2015] [Accepted: 09/08/2015] [Indexed: 12/20/2022]
Affiliation(s)
- Julie M. Collet
- School of Biological Sciences; The University of Queensland; Queensland 4072 Australia
| | - Mark W. Blows
- School of Biological Sciences; The University of Queensland; Queensland 4072 Australia
| | - Katrina McGuigan
- School of Biological Sciences; The University of Queensland; Queensland 4072 Australia
| |
Collapse
|
10
|
Chenoweth SF, Appleton NC, Allen SL, Rundle HD. Genomic Evidence that Sexual Selection Impedes Adaptation to a Novel Environment. Curr Biol 2015; 25:1860-6. [PMID: 26119752 DOI: 10.1016/j.cub.2015.05.034] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 04/01/2015] [Accepted: 05/15/2015] [Indexed: 01/01/2023]
Abstract
Sexual selection is widely appreciated for generating remarkable phenotypic diversity, but its contribution to adaptation and the purging of deleterious mutations is unresolved. To provide insight into the impact of sexual selection on naturally segregating polymorphisms across the genome, we previously evolved 12 populations of Drosophila serrata in a novel environment employing a factorial manipulation of the opportunities for natural and sexual selection. Here, we genotype more than 1,400 SNPs in the evolved populations and reveal that sexual selection affected many of the same genomic regions as natural selection, aligning with it as often as opposing it. Intriguingly, more than half of the 80 SNPs showing treatment effects revealed an interaction between natural and sexual selection. For these SNPs, while sexual selection alone often caused a change in allele frequency in the same direction as natural selection alone, when natural and sexual selection occurred together, changes in allele frequency were greatly reduced or even reversed. This suggests an antagonism between natural and sexual selection arising from male-induced harm to females. Behavioral experiments showed that males preferentially courted and mated with high-fitness females, and that the harm associated with this increased male attention eliminated the female fitness advantage. During our experiment, females carrying otherwise adaptive alleles may therefore have disproportionally suffered male-induced harm due to their increased sexual attractiveness. These results suggest that a class of otherwise adaptive mutations may not contribute to adaptation when mating systems involve sexual conflict and male mate preferences.
Collapse
Affiliation(s)
- Stephen F Chenoweth
- School of Biological Sciences, University of Queensland, St. Lucia, Brisbane 4072, Australia.
| | - Nicholas C Appleton
- School of Biological Sciences, University of Queensland, St. Lucia, Brisbane 4072, Australia
| | - Scott L Allen
- School of Biological Sciences, University of Queensland, St. Lucia, Brisbane 4072, Australia
| | - Howard D Rundle
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| |
Collapse
|
11
|
The effect of parasites on sex differences in selection. Heredity (Edinb) 2015; 114:367-72. [PMID: 25649503 DOI: 10.1038/hdy.2014.110] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 10/26/2014] [Accepted: 10/27/2014] [Indexed: 11/08/2022] Open
Abstract
The life history strategies of males and females are often divergent, creating the potential for sex differences in selection. Deleterious mutations may be subject to stronger selection in males, owing to sexual selection, which can improve the mean fitness of females and reduce mutation load in sexual populations. However, sex differences in selection might also maintain sexually antagonistic genetic variation, creating a sexual conflict load. The overall impact of separate sexes on fitness is unclear, but the net effect is likely to be positive when there is a large sex difference in selection against deleterious mutations. Parasites can also have sex-specific effects on fitness, and there is evidence that parasites can intensify the fitness consequences of deleterious mutations. Using lines that accumulated mutations for over 60 generations, we studied the effect of the pathogenic bacterium Pseudomonas aeruginosa on sex differences in selection in the fruit fly Drosophila melanogaster. Pseudomonas infection increased the sex difference in selection, but may also have weakened the intersexual correlation for fitness. Our results suggest that parasites may increase the benefits of sexual selection.
Collapse
|
12
|
White AJ, Rundle HD. Territory defense as a condition-dependent component of male reproductive success inDrosophila serrata. Evolution 2015; 69:407-18. [DOI: 10.1111/evo.12580] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 11/14/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Alison J. White
- Department of Biology, University of Ottawa; 30 Marie Curie Private; Ottawa Ontario K1N 6N5 Canada
| | - Howard D. Rundle
- Department of Biology, University of Ottawa; 30 Marie Curie Private; Ottawa Ontario K1N 6N5 Canada
| |
Collapse
|
13
|
Cabral LG, Holland B. Courtship song does not increase the rate of adaptation to a thermally stressful environment in a Drosophila melanogaster laboratory population. PLoS One 2014; 9:e111148. [PMID: 25365209 PMCID: PMC4218839 DOI: 10.1371/journal.pone.0111148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 09/29/2014] [Indexed: 11/18/2022] Open
Abstract
Courtship song in D. melanogaster contributes substantially to male mating success through female selection. We used experimental evolution to test whether this display trait is maintained through adaptive female selection because it indicates heritable male quality for thermal stress tolerance. We used non-displaying, outbred populations of D. melanogaster (nub1) mutants and measured their rate of adaptation to a new, thermally stressful environment, relative to wild-type control populations that retained courtship song. This design retains sexually selected conflict in both treatments. Thermal stress should select across genomes for newly beneficial alleles, increasing the available genetic and phenotypic variation and, therefore, the magnitude of female benefit derived from courtship song. Following introduction to the thermally stressful environment, net reproductive rate decreased 50% over four generations, and then increased 19% over the following 16 generations. There were no differences between the treatments. Possible explanations for these results are discussed.
Collapse
Affiliation(s)
- Larry G. Cabral
- Department of Biological Sciences, California State University, Sacramento, California, United States of America
| | - Brett Holland
- Department of Biological Sciences, California State University, Sacramento, California, United States of America
| |
Collapse
|
14
|
Trojan Genes and Transparent Genomes: Sexual Selection, Regulatory Evolution and the Real Hopeful Monsters. Evol Biol 2014. [DOI: 10.1007/s11692-014-9276-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
|
15
|
Almbro M, Simmons LW. SEXUAL SELECTION CAN REMOVE AN EXPERIMENTALLY INDUCED MUTATION LOAD. Evolution 2013; 68:295-300. [DOI: 10.1111/evo.12238] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 08/07/2013] [Indexed: 01/26/2023]
Affiliation(s)
- Maria Almbro
- Centre for Evolutionary Biology; School of Animal Biology (M092); The University of Western Australia; Crawley 6009 Australia
| | - Leigh W. Simmons
- Centre for Evolutionary Biology; School of Animal Biology (M092); The University of Western Australia; Crawley 6009 Australia
| |
Collapse
|
16
|
Zikovitz AE, Agrawal AF. The condition dependency of fitness in males and females: the fitness consequences of juvenile diet assessed in environments differing in key adult resources. Evolution 2013; 67:2849-60. [PMID: 24094338 DOI: 10.1111/evo.12170] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 05/03/2013] [Indexed: 11/29/2022]
Abstract
Variation in environmental or genetic quality leads to phenotypic variation in condition, but how much variation in fitness is created by this variation in condition? Using Drosophila melanogaster, we manipulated condition via alternative larval diets and then tested several key factors predicted to influence how much variation in fitness results from differences in condition. Specifically, we were interested in whether male and female fitness are affected equally by condition and whether the strength of selection on condition depends on the abundance of key resources limiting the reproductive output of each sex. We measured selection on condition in alternative assay contexts that varied in the abundance of adult food (a key resource for females) or in the abundance of females (a key resource for males). Overall, selection tended to be stronger on males than females. However, selection on males was weakened when the abundance of their key resource (females) was elevated. Increasing the abundance of the key resource for females (live yeast) elevated their reproductive output as expected but did not change the strength of selection in this sex. Instead, this manipulation increased selection on males, suggesting that this environmental factor indirectly affects selection on males via their interaction with females.
Collapse
Affiliation(s)
- Andrea E Zikovitz
- Department of Ecology & Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada
| | | |
Collapse
|
17
|
Does your gene need a background check? How genetic background impacts the analysis of mutations, genes, and evolution. Trends Genet 2013; 29:358-66. [PMID: 23453263 DOI: 10.1016/j.tig.2013.01.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 01/09/2013] [Accepted: 01/25/2013] [Indexed: 11/23/2022]
Abstract
The premise of genetic analysis is that a causal link exists between phenotypic and allelic variation. However, it has long been documented that mutant phenotypes are not a simple result of a single DNA lesion, but are instead due to interactions of the focal allele with other genes and the environment. Although an experimentally rigorous approach focused on individual mutations and isogenic control strains has facilitated amazing progress within genetics and related fields, a glimpse back suggests that a vast complexity has been omitted from our current understanding of allelic effects. Armed with traditional genetic analyses and the foundational knowledge they have provided, we argue that the time and tools are ripe to return to the underexplored aspects of gene function and embrace the context-dependent nature of genetic effects. We assert that a broad understanding of genetic effects and the evolutionary dynamics of alleles requires identifying how mutational outcomes depend upon the 'wild type' genetic background. Furthermore, we discuss how best to exploit genetic background effects to broaden genetic research programs.
Collapse
|