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Santos MA, Antunes MA, Grandela A, Carromeu-Santos A, Quina AS, Santos M, Matos M, Simões P. Past history shapes evolution of reproductive success in a global warming scenario. J Therm Biol 2023; 112:103478. [PMID: 36796921 DOI: 10.1016/j.jtherbio.2023.103478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/10/2022] [Accepted: 01/06/2023] [Indexed: 01/13/2023]
Abstract
Adaptive evolution is critical for animal populations to thrive in the fast-changing natural environments. Ectotherms are particularly vulnerable to global warming and, although their limited coping ability has been suggested, few real-time evolution experiments have directly accessed their evolutionary potential. Here, we report a long-term experimental evolution study addressing the evolution of Drosophila thermal reaction norms, after ∼30 generations under different dynamic thermal regimes: fluctuating (daily variation between 15 and 21 °C) or warming (daily fluctuation with increases in both thermal mean and variance across generations). We analyzed the evolutionary dynamics of Drosophila subobscura populations as a function of the thermally variable environments in which they evolved and their distinct background. Our results showed clear differences between the historically differentiated populations: high latitude D. subobscura populations responded to selection, improving their reproductive success at higher temperatures whereas their low latitude counterparts did not. This suggests population variation in the amount of genetic variation available for thermal adaptation, an aspect that needs to be considered to allow for better predictions of future climate change responses. Our results highlight the complex nature of thermal responses in face of environmental heterogeneity and emphasize the importance of considering inter-population variation in thermal evolution studies.
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Affiliation(s)
- Marta A Santos
- cE3c - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute, Lisboa, Portugal; Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Marta A Antunes
- cE3c - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute, Lisboa, Portugal; Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Afonso Grandela
- cE3c - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute, Lisboa, Portugal; Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Ana Carromeu-Santos
- CESAM - Centre for Environmental and Marine Studies, Universidade de Aveiro and Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Ana S Quina
- CESAM - Centre for Environmental and Marine Studies, Universidade de Aveiro and Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Mauro Santos
- cE3c - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute, Lisboa, Portugal; Departament de Genètica i de Microbiologia, Grup de Genòmica, Bioinformàtica i Biologia Evolutiva (GBBE), Universitat Autònoma de Barcelona, Spain
| | - Margarida Matos
- cE3c - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute, Lisboa, Portugal; Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Pedro Simões
- cE3c - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute, Lisboa, Portugal; Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
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2
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Mularo AJ, Bernal XE, DeWoody JA. Dominance can increase genetic variance after a population bottleneck: a synthesis of the theoretical and empirical evidence. J Hered 2022; 113:257-271. [PMID: 35143665 DOI: 10.1093/jhered/esac007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 02/07/2022] [Indexed: 11/13/2022] Open
Abstract
Drastic reductions in population size, or population bottlenecks, can lead to a reduction in additive genetic variance and adaptive potential. Genetic variance for some quantitative genetic traits, however, can increase after a population reduction. Empirical evaluations of quantitative traits following experimental bottlenecks indicate that non-additive genetic effects, including both allelic dominance at a given locus and epistatic interactions among loci, may impact the additive variance contributed by alleles that ultimately influences phenotypic expression and fitness. The dramatic effects of bottlenecks on overall genetic diversity have been well studied, but relatively little is known about how dominance and demographic events like bottlenecks can impact additive genetic variance. Herein, we critically examine how the degree of dominance among alleles affects additive genetic variance after a bottleneck. We first review and synthesize studies that document the impact of empirical bottlenecks on dominance variance. We then extend earlier work by elaborating on two theoretical models that illustrate the relationship between dominance and the potential increase in additive genetic variance immediately following a bottleneck. Furthermore, we investigate the parameters that influence the maximum level of genetic variation (associated with adaptive potential) after a bottleneck, including the number of founding individuals. Finally, we validated our methods using forward-time population genetic simulations of loci with varying dominance and selection levels. The fate of non-additive genetic variation following bottlenecks could have important implications for conservation and management efforts in a wide variety of taxa, and our work should help contextualize future studies (e.g., epistatic variance) in population genomics.
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Affiliation(s)
- Andrew J Mularo
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Ximena E Bernal
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA.,Smithsonian Tropical Research Institute, Balboa, Republic of Panamá
| | - J Andrew DeWoody
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA.,Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN
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3
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Population genetics and independently replicated evolution of predator-associated burst speed ecophenotypy in mosquitofish. Heredity (Edinb) 2022; 128:45-55. [PMID: 34876658 PMCID: PMC8733020 DOI: 10.1038/s41437-021-00487-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 01/03/2023] Open
Abstract
Many species show replicated ecophenotypy due to recurring patterns of natural selection. Based on the presence or absence of pursuit predators, at least 17 species of fish repeatedly differentiated in body shape in a manner that increases burst swimming speed and the likelihood of predator escape. The predator-associated burst speed (PABS) ecophenotype is characterized by a small head and trunk and enlarged caudal region. Mechanisms promoting replicated phenotype-environment association include selection (without evolution), a single instance of adaptive evolution followed by biased habitat occupation, repeated instances of local adaptation, or adaptive phenotypic plasticity. Common garden rearing of mosquitofish, Gambusia affinis, demonstrated a likely heritable basis for PABS phenotypy, but it is unknown whether populations are otherwise genetically distinct or whether replicated ecophenotypy represents a single or replicated instances of adaptation. To genetically characterize the populations and test hypotheses of single or multiple adaptations, we characterized variation in 12 polymorphic DNA microsatellites in the previously studied G. affinis populations. Populations were genetically distinct by multilocus analysis, exhibited high allelic diversity, and were heterozygote deficient, which effects were attributed to G. affinis's shoaling nature and habitat patchiness. Genetic and phenotypic distances among populations were correlated for non-PABS but not PABS morphology. Multilocus analysis demonstrated ecophenotype polyphyly and scattered multivariate genetic structure which support only the replicated-adaptation model. As all of the diverse tests performed demonstrated lack of congruence between patterns of molecular genetic and PABS differentiation, it is likely that divergent natural selection drove multiple instances of adaptive evolution.
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4
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Sendell-Price AT, Ruegg KC, Robertson BC, Clegg SM. An island-hopping bird reveals how founder events shape genome-wide divergence. Mol Ecol 2021; 30:2495-2510. [PMID: 33826187 DOI: 10.1111/mec.15898] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/09/2021] [Accepted: 03/18/2021] [Indexed: 12/16/2022]
Abstract
When populations colonize new areas, both strong selection and strong drift can be experienced due to novel environments and small founding populations, respectively. Empirical studies have predominantly focused on the phenotype when assessing the role of selection, and limited neutral-loci when assessing founder-induced loss of diversity. Consequently, the extent to which processes interact to influence evolutionary trajectories is difficult to assess. Genomic-level approaches provide the opportunity to simultaneously consider these processes. Here, we examine the roles of selection and drift in shaping genomic diversity and divergence in historically documented sequential island colonizations by the silvereye (Zosterops lateralis). We provide the first empirical demonstration of the rapid appearance of highly diverged genomic regions following population founding, the position of which are highly idiosyncratic. As these regions rarely contained loci putatively under selection, it is most likely that these differences arise via the stochastic nature of the founding process. However, selection is required to explain rapid evolution of larger body size in insular silvereyes. Reconciling our genomic data with these phenotypic patterns suggests there may be many genomic routes to the island phenotype, which vary across populations. Finally, we show that accelerated divergence associated with multiple founding steps is the product of genome-wide rather than localized differences, and that diversity erodes due to loss of rare alleles. However, even multiple founder events do not result in divergence and diversity levels seen in evolutionary older subspecies, and therefore do not provide a shortcut to speciation as proposed by founder-effect speciation models.
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Affiliation(s)
- Ashley T Sendell-Price
- Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, Oxford, UK
| | - Kristen C Ruegg
- Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, Oxford, UK.,Department of Biology, Colorado State University, Fort Collins, CO, USA
| | | | - Sonya M Clegg
- Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, Oxford, UK.,Environmental Futures Research Institute, Griffith University, Nathan, Qld, Australia
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5
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Lacy RC, Malo AF, Alaks G. Maintenance of genetic variation in quantitative traits of a woodland rodent during generations of captive breeding. CONSERV GENET 2018. [DOI: 10.1007/s10592-018-1054-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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6
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Templeton AR. EXPERIMENTAL EVIDENCE FOR THE GENETIC-TRANSILIENCE MODEL OF SPECIATION. Evolution 2017; 50:909-915. [PMID: 28568937 DOI: 10.1111/j.1558-5646.1996.tb03899.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/1994] [Accepted: 01/13/1995] [Indexed: 11/28/2022]
Affiliation(s)
- Alan R Templeton
- Department of Biology, Washington University, St. Louis, Missouri, 63130
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7
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Cheverud JM, Routman EJ. EPISTASIS AS A SOURCE OF INCREASED ADDITIVE GENETIC VARIANCE AT POPULATION BOTTLENECKS. Evolution 2017; 50:1042-1051. [PMID: 28565298 DOI: 10.1111/j.1558-5646.1996.tb02345.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/1995] [Accepted: 07/06/1995] [Indexed: 11/29/2022]
Abstract
The role of epistasis in evolution and speciation has remained controversial. We use a new parameterization of physiological epistasis to examine the effects of epistasis on levels of additive genetic variance during a population bottleneck. We found that all forms of epistasis increase average additive genetic variance in finite populations derived from initial populations with intermediate allele frequencies. Average additive variance continues to increase over many generations, especially at larger population sizes (N = 32 to 64). Additive-by-additive epistasis is the most potent source of additive genetic variance in this situation, whereas dominance-by-dominance epistasis contributes smaller amounts of additive genetic variance. With additive-by-dominance epistasis, additive genetic variance decreases at a relatively high rate immediately after a population bottleneck, rebounding to higher levels after several generations. Empirical examples of epistasis for murine adult body weight based on measured genotypes are provided illustrating the varying effects of epistasis on additive genetic variance during population bottlenecks.
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Affiliation(s)
- James M Cheverud
- Department of Anatomy and Neurobiology, Washington University School of Medicine, Saint Louis, Missouri, 63110
| | - Eric J Routman
- Department of Anatomy and Neurobiology, Washington University School of Medicine, Saint Louis, Missouri, 63110
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8
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Cheverud JM, Vaughn TT, Pletscher LS, King-Ellison K, Bailiff J, Adams E, Erickson C, Bonislawski A. EPISTASIS AND THE EVOLUTION OF ADDITIVE GENETIC VARIANCE IN POPULATIONS THAT PASS THROUGH A BOTTLENECK. Evolution 2017; 53:1009-1018. [PMID: 28565535 DOI: 10.1111/j.1558-5646.1999.tb04516.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/1998] [Accepted: 03/19/1999] [Indexed: 12/01/2022]
Abstract
Traditional models of genetic drift predict a linear decrease in additive genetic variance for populations passing through a bottleneck. This perceived lack of heritable variance limits the scope of founder-effect models of speciation. We produced 55 replicate bottleneck populations maintained at two male-female pairs through four generations of inbreeding (average F = 0.39). These populations were formed from an F2 intercross of the LG/J and SM/J inbred mouse strains. Two contemporaneous control strains maintained with more than 60 mating pairs per generation were formed from this same source population. The average level of within-strain additive genetic variance for adult body weight was compared between the control and experimental lines. Additive genetic variance for adult body weight within experimental bottleneck strains was significantly higher than expected under an additive genetic model This enhancement of additive genetic variance under inbreeding is likely to be due to epistasis, which retards or reverses the loss of additive genetic variance under inbreeding for adult body weight in this population. Therefore, founder-effect speciation processes may not be constrained by a loss of heritable variance due to population bottlenecks.
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Affiliation(s)
- James M Cheverud
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, 63110
| | - Ty T Vaughn
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, 63110
| | - L Susan Pletscher
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, 63110
| | - Kelly King-Ellison
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, 63110
| | - Jeff Bailiff
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, 63110
| | - Emily Adams
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, 63110
| | - Christopher Erickson
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, 63110
| | - Adam Bonislawski
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, 63110
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9
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Bryant EH, Meffert LM. QUANTITATIVE GENETIC ESTIMATES OF MORPHOMETRIC VARIATION IN WILD‐CAUGHT AND LABORATORY‐REARED HOUSEFLIES. Evolution 2017; 52:626-630. [DOI: 10.1111/j.1558-5646.1998.tb01662.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/1997] [Accepted: 12/09/1997] [Indexed: 11/28/2022]
Affiliation(s)
- Edwin H. Bryant
- Department of Biology University of Houston Houston Texas 77204‐5513
| | - Lisa M. Meffert
- Department of Biology University of Houston Houston Texas 77204‐5513
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10
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Grant PR, Grant BR. THE FOUNDING OF A NEW POPULATION OF DARWIN'S FINCHES. Evolution 2017; 49:229-240. [PMID: 28565010 DOI: 10.1111/j.1558-5646.1995.tb02235.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/1993] [Accepted: 05/23/1994] [Indexed: 11/27/2022]
Abstract
We report the natural colonization of the small Galápagos island Daphne Major by the large ground finch (Geospiza magnirostris). Immigrants of this species were present in every year of a 22-yr study, 1973-1994. Typically they arrived after a breeding season and left at the beginning of the next one. Geospiza magnirostris bred on the island for the first time in the exceptionally wet El Niño year of 1982-1983, and bred in all subsequent years except drought years. In agreement with theoretical expectations the frequency of inbreeding was unusually high. Pronounced fluctuating asymmetry in tarsus length, together with slightly reduced breeding success of inbreeding pairs, suggests a low level of inbreeding depression. Despite this, the population increased from 5 breeding individuals in 1983 to 20 breeding individuals in 1992, and probably more than twice that number in 1993, largely through recruitment of locally born birds.
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Affiliation(s)
- Peter R Grant
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, 08544-1003
| | - B Rosemary Grant
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, 08544-1003
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11
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Wade MJ, Goodnight CJ. PERSPECTIVE: THE THEORIES OF FISHER AND WRIGHT IN THE CONTEXT OF METAPOPULATIONS: WHEN NATURE DOES MANY SMALL EXPERIMENTS. Evolution 2017; 52:1537-1553. [PMID: 28565332 DOI: 10.1111/j.1558-5646.1998.tb02235.x] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/1997] [Accepted: 09/08/1998] [Indexed: 11/30/2022]
Affiliation(s)
- Michael J. Wade
- Department of Biology Indiana University Bloomington Indiana 47405
| | - Charles J. Goodnight
- Department of Biology, 115 Marsh Life Science Building University of Vermont, Burlington Vermont 05405‐0086
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12
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Bryant EH, Meffert LM. MORPHOMETRIC DIFFERENTIATION IN SERIALLY BOTTLENECKED POPULATIONS OF THE HOUSEFLY. Evolution 2017; 50:935-940. [DOI: 10.1111/j.1558-5646.1996.tb03904.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/1994] [Accepted: 01/18/1995] [Indexed: 11/28/2022]
Affiliation(s)
- Edwin H. Bryant
- Department of Biology University of Houston Houston Texas 77204‐5513
| | - Lisa M. Meffert
- Department of Biology University of Houston Houston Texas 77204‐5513
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13
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Podolsky RH, Shaw RG, Shaw FH. POPULATION STRUCTURE OF MORPHOLOGICAL TRAITS IN
CLARKIA DUDLEYANA
. II. CONSTANCY OF WITHIN‐POPULATION GENETIC VARIANCE. Evolution 2017; 51:1785-1796. [DOI: 10.1111/j.1558-5646.1997.tb05102.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/1996] [Accepted: 07/22/1997] [Indexed: 11/29/2022]
Affiliation(s)
- Robert H. Podolsky
- Department of Botany and Plant Sciences University of California Riverside California 92521
- Department of Biology University of Michigan—Flint Flint Michigan 48502
| | - Ruth G. Shaw
- Department of Botany and Plant Sciences University of California Riverside California 92521
- Department of Ecology, Evolution and Behavior University of Minnesota Saint Paul Minnesota 55108
| | - Frank H. Shaw
- Department of Ecology, Evolution and Behavior University of Minnesota Saint Paul Minnesota 55108
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14
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Bryant EH, Meffert LM. AN ANALYSIS OF SELECTIONAL RESPONSE IN RELATION TO A POPULATION BOTTLENECK. Evolution 2017; 49:626-634. [DOI: 10.1111/j.1558-5646.1995.tb02299.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/1993] [Accepted: 08/31/1994] [Indexed: 11/28/2022]
Affiliation(s)
- Edwin H. Bryant
- Department of Biology University of Houston Houston Texas 77204‐5513
| | - Lisa M. Meffert
- Department of Biology University of Houston Houston Texas 77204‐5513
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15
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Shaw FH, Shaw RG, Wilkinson GS, Turelli M. CHANGES IN GENETIC VARIANCES AND COVARIANCES: G WHIZ! Evolution 2017; 49:1260-1267. [DOI: 10.1111/j.1558-5646.1995.tb04452.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/1994] [Accepted: 12/19/1994] [Indexed: 11/29/2022]
Affiliation(s)
- Frank H. Shaw
- Institute for Mathematics and Its Applications, University of Minnesota Minneapolis Minnesota 55455
| | - Ruth G. Shaw
- Department of Ecology, Evolution and Behavior University of Minnesota St. Paul Minnesota 55108
| | | | - Michael Turelli
- Section of Evolution and Ecology and Center for Population Biology University of California Davis California 95616
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16
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Fowler K, Whitlock MC. THE DISTRIBUTION OF PHENOTYPIC VARIANCE WITH INBREEDING. Evolution 2017; 53:1143-1156. [DOI: 10.1111/j.1558-5646.1999.tb04528.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/1998] [Accepted: 02/10/1999] [Indexed: 10/19/2022]
Affiliation(s)
- Kevin Fowler
- The Galton Laboratory, Department of Biology; University College London; 4 Stephenson Way London NW1 2HE United Kingdom
| | - Michael C. Whitlock
- Department of Zoology; University of British Columbia; Vancouver British Columbia V6T 1Z4 Canada
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17
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Willis JH, Orr HA. INCREASED HERITABLE VARIATION FOLLOWING POPULATION BOTTLENECKS: THE ROLE OF DOMINANCE. Evolution 2017; 47:949-957. [DOI: 10.1111/j.1558-5646.1993.tb01249.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/1992] [Accepted: 12/07/1992] [Indexed: 11/28/2022]
Affiliation(s)
- John H. Willis
- Department of Biology University of Oregon Eugene Oregon 97403
| | - H. Allen Orr
- Center for Population Biology University of California Davis California 95616
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18
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Abstract
Seasonal clocks (e.g., circannual clocks, seasonal interval timers) permit anticipation of regularly occurring environmental events by timing the onset of seasonal transitions in reproduction, metabolism, and behavior. Implicit in the concept that seasonal clocks reflect adaptations to the local environment is the unexamined assumption that heritable genetic variance exists in the critical features of such clocks, namely, their temporal properties. These experiments quantified the intraspecific variance in, and heritability of, the photorefractoriness interval timer in Siberian hamsters ( Phodopus sungorus), a seasonal clock that provides temporal information to mechanisms that regulate seasonal transitions in body weight. Twenty-seven families consisting of 54 parents and 109 offspring were raised in a long-day photoperiod and transferred as adults to an inhibitory photoperiod (continuous darkness; DD). Weekly body weight measurements permitted specification of the interval of responsiveness to DD, a reflection of the duration of the interval timer, in each individual. Body weights of males and females decreased after exposure to DD, but 3 to 5 months later, somatic recrudescence occurred, indicative of photorefractoriness to DD. The interval timer was approximately 5 weeks longer and twice as variable in females relative to males. Analyses of variance of full siblings revealed an overall intraclass correlation of 0.71 ± 0.04 (0.51 ± 0.10 for male offspring and 0.80 ± 0.06 for female offspring), suggesting a significant family resemblance in the duration of interval timers. Parent-offspring regression analyses yielded an overall heritability estimate of 0.61 ± 0.2; h2 estimates from parent-offspring regression analyses were significant for female offspring (0.91 ± 0.4) but not for male offspring (0.35 ± 0.2), indicating strong additive genetic components for this trait, primarily in females. In nature, individual differences, both within and between sexes, in the timekeeping properties of seasonal interval timers, and a strong heritable basis thereof, would provide ample substrate for selection to rapidly influence seasonal clocks. Balancing selection in environments where the onset of spring conditions varies from year to year could maintain genetic variance in interval timers and yield interval timers tuned to the local environment.
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19
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Complex patterns of global spread in invasive insects: eco-evolutionary and management consequences. Biol Invasions 2016. [DOI: 10.1007/s10530-016-1082-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Fuerst C, James JW, Sölkner J, Essl A. Impact of dominance and epistasis on the genetic make-up of simulated populations under selection: a model development. J Anim Breed Genet 2012; 114:163-75. [PMID: 21395812 DOI: 10.1111/j.1439-0388.1997.tb00502.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
SUMMARY A two-locus genetic model was used to simulate different levels of additive, dominance, and additive-by-additive genetic effects. The character under phenotypic selection was controlled by 30 pairs of diallelic loci, located on different chromosomes. Initial gene frequencies were set to 0.5 for all loci and the recombination probability was 0.20 between adjacent loci. The broad-sense heritability was varied at levels of 0.03, 0.30, and 0.60. After building up a random mating population with 200 males and 400 females, the phenotypic best individuals per year were selected over 200 years (approx. 35 overlapping generations), keeping the population size constant. The results of the simulations showed extreme differences between eight models with the same initial heritability, but different amounts of additive, dominance, and additive-by-additive variance components. A model with additive, dominance, and additive-by-additive variance at the same initial magnitude, and negative dominance and positive additive-by-additive effect, led to the highest genetic response in the long term for all heritabilities simulated. The additive model showed the best selection advance in the short term. Some of the initial dominance and additive-by-additive variance was converted to additive genetic variance during the selection period, which in turn contributed to the selection response. ZUSAMMENFASSUNG: Auswirkungen von Dominanz and Epistasie auf den genetischen Aufbau von simulierten Populationen unter Selektion: Eine Modellentwicklung Ein 2-Locus-Genmodell wurde zur Simulation verschiedener Ausprägungen von additiven, Dominanz und additiv mal additiv genetischen Effekten verwendet. Das Merkmal under phänotypischer Selektion wurde von 30 diallelen Locuspaaren auf verschiedenen Chromosomen kontrolliert. Die Anfangsgenfrequenz wurde für alle Loci mit 0.5 angenommen und die Rekombinationsrate betrug 0.20 zwischen benachbarten Loci. Die Heritabilität im weiteren Sinn wurde zwischen 0.03, 0.30 und 0.60 variiert. Nach dem Aufbau einer Population durch Zufallspaarung von 200 männlichen und 400 weiblichen Individuen wurden die phänotypisch besten Individuen pro Jahr unter Konstanthaltung der Populationsgröße über einen Zeitraum von 200 Jahren (ca. 35 überlappende Generationen) selektiert. Die Ergebnisse der Simulationen zeigten extreme Unterschiede zwischen den acht Modellen mit der gleichen Anfangsheritabilität aber verschiedenen Anteilen von additiven, Dominanz und additiv mal additiven Varianzkomponenten. Ein Modell mit zu Beginn gleich hoher additiver, Dominanz und additiv mal additiver Varianz und negativem Dominanz- und positivem additiv mal additiven Effekt führte bei allen simulierten Heritabilitäten langfristig zum höchsten Selektionserfolg. Kurzfristig zeigte das additive Modell den höchsten Selektionsfortschritt. Ein Teil der Anfangs-Dominanz- und -Additiv mal additiv-Varianz wurde während der Selektionsperiode in additive Varianz umgewandelt, die wiederum zum Selektionserfolg beitrug.
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Affiliation(s)
- C Fuerst
- Institut für Nutztierwissenschaften, Universität für Bodenkultur, Vienna, Austria Department of Wool and Animal Science, University of New South Wales, Kensington, Australia
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Kawecki TJ, Lenski RE, Ebert D, Hollis B, Olivieri I, Whitlock MC. Experimental evolution. Trends Ecol Evol 2012; 27:547-60. [PMID: 22819306 DOI: 10.1016/j.tree.2012.06.001] [Citation(s) in RCA: 477] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 06/03/2012] [Accepted: 06/13/2012] [Indexed: 12/26/2022]
Abstract
Experimental evolution is the study of evolutionary processes occurring in experimental populations in response to conditions imposed by the experimenter. This research approach is increasingly used to study adaptation, estimate evolutionary parameters, and test diverse evolutionary hypotheses. Long applied in vaccine development, experimental evolution also finds new applications in biotechnology. Recent technological developments provide a path towards detailed understanding of the genomic and molecular basis of experimental evolutionary change, while new findings raise new questions that can be addressed with this approach. However, experimental evolution has important limitations, and the interpretation of results is subject to caveats resulting from small population sizes, limited timescales, the simplified nature of laboratory environments, and, in some cases, the potential to misinterpret the selective forces and other processes at work.
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Affiliation(s)
- Tadeusz J Kawecki
- Department of Ecology and Evolution, University of Lausanne, CH 1015 Lausanne, Switzerland.
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Jarvis JP, Cropp SN, Vaughn TT, Pletscher LS, King-Ellison K, Adams-Hunt E, Erickson C, Cheverud JM. The effect of a population bottleneck on the evolution of genetic variance/covariance structure. J Evol Biol 2011; 24:2139-52. [PMID: 21726329 DOI: 10.1111/j.1420-9101.2011.02347.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is well known that standard population genetic theory predicts decreased additive genetic variance (V(a) ) following a population bottleneck and that theoretical models including interallelic and intergenic interactions indicate such loss may be avoided. However, few empirical data from multicellular model systems are available, especially regarding variance/covariance (V/CV) relationships. Here, we compare the V/CV structure of seventeen traits related to body size and composition between control (60 mating pairs/generation) and bottlenecked (2 mating pairs/generation; average F = 0.39) strains of mice. Although results for individual traits vary considerably, multivariate analysis indicates that V(a) in the bottlenecked populations is greater than expected. Traits with patterns and amounts of epistasis predictive of enhanced V(a) also show the largest deviations from additive expectations. Finally, the correlation structure of weekly weights is not significantly different between control and experimental lines but correlations between necropsy traits do differ, especially those involving the heart, kidney and tail length.
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Affiliation(s)
- J P Jarvis
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
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Jarvis JP, Cheverud JM. Epistasis and the evolutionary dynamics of measured genotypic values during simulated serial bottlenecks. J Evol Biol 2009; 22:1658-68. [PMID: 19523039 DOI: 10.1111/j.1420-9101.2009.01776.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The evolutionary effects of epistasis have been primarily explored analytically and most empirical studies have utilized yeast, viral and bacterial populations. Empirical analyses in multi-cellular organisms are rare because of experimental constraints. Here, we report the results of a genome-wide scan for two-way epistasis in 16 traits related to body size and composition in F(2) mice from the LG/J by SM/J intercross. We analyze two-locus genotypic values at quantitative trait loci (QTL), which provides an especially detailed view of epistatic architectures, to evaluate their predicted evolutionary consequences via Monte Carlo simulations. Epistatic profiles vary, but all traits show complicated genetic architectures which are largely hidden in single locus QTL scans. On average, detected epistatic effects are comparable in size to marginal effects. Simulations demonstrate an expected preservation, and often inflation, of heritable variance across several generations of small effective population size for many identified epistatic pairs over a range of starting allele frequencies.
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Affiliation(s)
- J P Jarvis
- Department of Anatomy & Neurobiology, Washington University School of Medicine, St. Louis, MO, USA.
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Population bottlenecks increase additive genetic variance but do not break a selection limit in rain forest Drosophila. Genetics 2008; 179:2135-46. [PMID: 18689893 DOI: 10.1534/genetics.107.082768] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
According to neutral quantitative genetic theory, population bottlenecks are expected to decrease standing levels of additive genetic variance of quantitative traits. However, some empirical and theoretical results suggest that, if nonadditive genetic effects influence the trait, bottlenecks may actually increase additive genetic variance. This has been an important issue in conservation genetics where it has been suggested that small population size might actually experience an increase rather than a decrease in the rate of adaptation. Here we test if bottlenecks can break a selection limit for desiccation resistance in the rain forest-restricted fly Drosophila bunnanda. After one generation of single-pair mating, additive genetic variance for desiccation resistance increased to a significant level, on average higher than for the control lines. Line crosses revealed that both dominance and epistatic effects were responsible for the divergence in desiccation resistance between the original control and a bottlenecked line exhibiting increased additive genetic variance for desiccation resistance. However, when bottlenecked lines were selected for increased desiccation resistance, there was only a small shift in resistance, much less than predicted by the released additive genetic variance. The small selection response in the bottlenecked lines was no greater than that observed in the control lines. Thus bottlenecks might produce a statistically detectable change in additive genetic variance but this change has no impact on the response to selection.
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Willi Y, Van Buskirk J, Hoffmann AA. Limits to the Adaptive Potential of Small Populations. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2006. [DOI: 10.1146/annurev.ecolsys.37.091305.110145] [Citation(s) in RCA: 593] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yvonne Willi
- Centre for Environmental Stress and Adaptation Research, Department of Zoology and Department of Genetics, University of Melbourne, Parkville, VIC 3010 Australia; ,
| | - Josh Van Buskirk
- Department of Zoology, University of Melbourne, Parkville, VIC 3010 Australia; and Institute of Zoology, University of Zürich, CH-8057 Zürich, Switzerland;
| | - Ary A. Hoffmann
- Centre for Environmental Stress and Adaptation Research, Department of Zoology and Department of Genetics, University of Melbourne, Parkville, VIC 3010 Australia; ,
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Swindell WR, Bouzat JL. MODELING THE ADAPTIVE POTENTIAL OF ISOLATED POPULATIONS: EXPERIMENTAL SIMULATIONS USING DROSOPHILA. Evolution 2005. [DOI: 10.1111/j.0014-3820.2005.tb00925.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kristensen TN, Sørensen AC, Sorensen D, Pedersen KS, Sørensen JG, Loeschcke V. A test of quantitative genetic theory using Drosophila- effects of inbreeding and rate of inbreeding on heritabilities and variance components. J Evol Biol 2005; 18:763-70. [PMID: 16033547 DOI: 10.1111/j.1420-9101.2005.00883.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Inbreeding is expected to decrease the heritability within populations. However, results from empirical studies are inconclusive. In this study, we investigated the effects of three breeding treatments (fast and slow rate of inbreeding - inbred to the same absolute level - and a control) on heritability, phenotypic, genetic and environmental variances of sternopleural bristle number in Drosophila melanogaster. Heritability, and phenotypic, genetic and environmental variances were estimated in 10 replicate lines within each of the three treatments. Standard least squares regression models and Bayesian methods were used to analyse the data. Heritability and additive genetic variance within lines were higher in the control compared with both inbreeding treatments. Heritabilities and additive genetic variances within lines were higher in slow compared with fast inbred lines, indicating that slow inbred lines retain more evolutionary potential despite the same expected absolute level of inbreeding. The between line variance was larger with inbreeding and more than twice as large in the fast than in the slow inbred lines. The different pattern of redistribution of genetic variance within and between lines in the two inbred treatments cannot be explained invoking the standard model based on selective neutrality and additive gene action. Environmental variances were higher with inbreeding, and more so with fast inbreeding, indicating that inbreeding and the rate of inbreeding affect environmental sensitivity. The phenotypic variance decreased with inbreeding, but was not affected by the rate of inbreeding. No inbreeding depression for mean sternopleural bristle number was observed in this study. Considerable variance between lines in additive genetic variance within lines was observed, illustrating between line variation in evolutionary potential.
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Affiliation(s)
- T N Kristensen
- Aarhus Centre for Environmental Stress Research (ACES), Department of Ecology and Genetics, University of Aarhus, Ny Munkegade, Aarhus C, Denmark.
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Swindell WR, Bouzat JL. MODELING THE ADAPTIVE POTENTIAL OF ISOLATED POPULATIONS: EXPERIMENTAL SIMULATIONS USING DROSOPHILA. Evolution 2005. [DOI: 10.1554/05-097.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Reed DH, Lowe EH, Briscoe DA, Frankham R. FITNESS AND ADAPTATION IN A NOVEL ENVIRONMENT: EFFECT OF INBREEDING, PRIOR ENVIRONMENT, AND LINEAGE. Evolution 2003; 57:1822-8. [PMID: 14503623 DOI: 10.1111/j.0014-3820.2003.tb00589.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ability of populations to undergo adaptive evolution depends on the presence of genetic variation for ecologically important traits. The maintenance of genetic variation may be influenced by many variables, particularly long-term effective population size and the strength and form of selection. The roles of these factors are controversial and there is very little information on their impacts for quantitative characters. The aims of this study were to determine the impacts of population size and variable versus constant prior environmental conditions on fitness and the magnitude of response to selection. Outbred and inbred populations of Drosophila melanogaster were maintained under benign, constant stressful, and variably stressful conditions for seven generations, and then forced to adapt to a novel stress for seven generations. Fitness and adaptability were assayed in each replicate population. Our findings are that: (1) populations inbred in a variable environment were more adaptable than those inbred in a constant environment; (2) populations adapted to a prior stressful environment had greater fitness when reared in a novel stress than those less adapted to stress; (3) inbred populations had lower fitness and were less adaptable than the outbred population they were derived from; and (4) strong lineage effects were detectable across environments in the inbred populations.
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Affiliation(s)
- David H Reed
- Key Centre for Biodiversity and Bioresources, Department of Biological Sciences, Macquarie University, New South Wales 2109, Australia.
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Regan JL, Meffert LM, Bryant EH. A direct experimental test of founder-flush effects on the evolutionary potential for assortative mating. J Evol Biol 2003; 16:302-12. [PMID: 14635869 DOI: 10.1046/j.1420-9101.2003.00521.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Founder-flush speciation models propose that population bottlenecks can enhance evolutionary potential for reproductive isolation. To test this prediction, we subjected bottlenecked (three-pair founder-flush) and nonbottlenecked populations of the housefly to 18 generations of selection for assortative mating. After the selection regime, we analysed videotaped courtship bouts in these lines to identify correlated responses to the selection protocol. The realized heritabilities for assortative mating for both the bottlenecked and nonbottlenecked treatments were very low, but still significant. The founder-flush populations had thus responded to selection as well as the nonbottlenecked populations, although not significantly greater (i.e. total increases in assortative mating were 9.6 and 8.6%, respectively). Multivariate analyses on the courtship repertoires found that, although both bottlenecked and nonbottlenecked treatments attained similar levels of assortative mating, the treatments exhibited different evolutionary solutions in their correlated responses. Specifically, the bottlenecked lines demonstrated a significantly more diverse set of evolutionary trajectories (i.e. significant shifts along the second principal component for courtship). This suggests that the bottlenecked lines had greater potential for the evolution of novel phenotypes as predicted by founder-induced speciation models. Our results, however, cannot distinguish whether the more variable evolutionary responses resulted from increased heritabilities in courtship components, reduced potential to follow the convergent evolutionary trajectories noted for the nonbottlenecked lines, or some combination of both general processes in determining the resultant multivariate phenotype.
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Affiliation(s)
- J L Regan
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA.
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Reed DH, Lowe EH, Briscoe DA, Frankham R. FITNESS AND ADAPTATION IN A NOVEL ENVIRONMENT: EFFECT OF INBREEDING, PRIOR ENVIRONMENT, AND LINEAGE. Evolution 2003. [DOI: 10.1554/02-601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Noor MA, Pascual M, Smith KR. Genetic variation in the spread of Drosophila subobscura from a nonequilibrium population. Evolution 2000; 54:696-703. [PMID: 10937245 DOI: 10.1111/j.0014-3820.2000.tb00071.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Drosophila subobscura was first identified in North America in the early 1980s, and a newer D. subobscura population in Utah appears to have been established more than 10 years later. In this study, we use nuclear microsatellite allele frequencies, mitochondrial restriction fragment length polymorphism (RFLP) allele frequencies, and computer simulations to investigate possible scenarios of how this species has spread across North America. Our method develops a 95% confidence interval for the maximum and minimum number of founders that could have colonized the new population given various scenarios for spread. Unlike many other methods, it may be applied to nonequilibrium source populations given certain conditions. We find that observed allele frequency differences between newer and older D. subobscura populations are consistent with very few inseminated females being transported east from the coast in a single step or with larger numbers of colonizers invading after several intermediate steps. They are not consistent with a large, panmictic population of D. subobscura colonizing Utah in a single step.
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Affiliation(s)
- M A Noor
- Department of Biological Sciences, Louisiana State University, Baton Rouge 70803, USA.
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Noor MAF, Pascual M, Smith KR. GENETIC VARIATION IN THE SPREAD OF DROSOPHILA SUBOBSCURA FROM A NONEQUILIBRIUM POPULATION. Evolution 2000. [DOI: 10.1554/0014-3820(2000)054[0696:gvitso]2.0.co;2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Frankham R, Lees K, Montgomery ME, England PR, Lowe EH, Briscoe DA. Do population size bottlenecks reduce evolutionary potential? Anim Conserv 1999. [DOI: 10.1111/j.1469-1795.1999.tb00071.x] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Meffert LM, Regan JL, Brown BW. Convergent evolution of the mating behaviour of founder-flush populations of the housefly. J Evol Biol 1999. [DOI: 10.1046/j.1420-9101.1999.00105.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Whitlock MC, Fowler K. The changes in genetic and environmental variance with inbreeding in Drosophila melanogaster. Genetics 1999; 152:345-53. [PMID: 10224265 PMCID: PMC1460612 DOI: 10.1093/genetics/152.1.345] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We performed a large-scale experiment on the effects of inbreeding and population bottlenecks on the additive genetic and environmental variance for morphological traits in Drosophila melanogaster. Fifty-two inbred lines were created from the progeny of single pairs, and 90 parent-offspring families on average were measured in each of these lines for six wing size and shape traits, as well as 1945 families from the outbred population from which the lines were derived. The amount of additive genetic variance has been observed to increase after such population bottlenecks in other studies; in contrast here the mean change in additive genetic variance was in very good agreement with classical additive theory, decreasing proportionally to the inbreeding coefficient of the lines. The residual, probably environmental, variance increased on average after inbreeding. Both components of variance were highly variable among inbred lines, with increases and decreases recorded for both. The variance among lines in the residual variance provides some evidence for a genetic basis of developmental stability. Changes in the phenotypic variance of these traits are largely due to changes in the genetic variance.
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Affiliation(s)
- M C Whitlock
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
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Wang J, Caballero A, Hill WG. The effect of linkage disequilibrium and deviation from Hardy–Weinberg proportions on the changes in genetic variance with bottlenecking. Heredity (Edinb) 1998. [DOI: 10.1046/j.1365-2540.1998.00390.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Jiang C, Wright RJ, El-Zik KM, Paterson AH. Polyploid formation created unique avenues for response to selection in Gossypium (cotton). Proc Natl Acad Sci U S A 1998; 95:4419-24. [PMID: 9539752 PMCID: PMC22504 DOI: 10.1073/pnas.95.8.4419] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A detailed restriction fragment length polymorphism map was used to determine the chromosomal locations and subgenomic distributions of quantitative trait loci (QTLs) segregating in a cross between cultivars of allotetraploid (AADD) Gossypium hirsutum ("Upland" cotton) and Gossypium barbadense ("Sea Island," "Pima," or "Egyptian" cotton) that differ markedly in the quality and quantity of seed epidermal fibers. Most QTLs influencing fiber quality and yield are located on the "D" subgenome, derived from an ancestor that does not produce spinnable fibers. D subgenome QTLs may partly account for the fact that domestication and breeding of tetraploid cottons has resulted in fiber yield and quality levels superior to those achieved by parallel improvement of "A" genome diploid cottons. The merger of two genomes with different evolutionary histories in a common nucleus appears to offer unique avenues for phenotypic response to selection. This may partly compensate for reduction in quantitative variation associated with polyploid formation and be one basis for the prominence of polyploids among extant angiosperms. These findings impel molecular dissection of the roles of divergent subgenomes in quantitative inheritance in many other polyploids and further exploration of both "synthetic" polyploids and exotic diploid genotypes for agriculturally useful variation.
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Affiliation(s)
- C Jiang
- Plant Genome Mapping Laboratory, Department of Soil and Crop Science, Texas A & M University, College Station, TX 77843-2474, USA
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Selection versus random drift: long-term polymorphism persistence in small populations (evidence and modelling). Philos Trans R Soc Lond B Biol Sci 1997; 352:381-389. [PMCID: PMC1691934 DOI: 10.1098/rstb.1997.0028] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/26/2024] Open
Abstract
Our data on a subterranean mammal, Spalax ehrenbergi , and other evidence, indicate that appreciable polymorphism can be preserved in small isolated populations consisting of several dozens of, or a hundred, individuals. Current theoretical models predict fast gene fixation in small panmictic populations without selection, mutation, or gene inflow. Using simple multilocus models, we demonstrate here that moderate stabilizing selection (with stable or fluctuating optimum) for traits controlled by additive genes could oppose random fixation in such isolates during thousands of generations. We also show that in selection-free models polymorphism persists only for a few hundred generations even under high mutation rates. Our multi-chromosome models challenge the hitchhiking hypothesis of polymorphism maintenance for many neutral loci due to close linkage with few selected loci.
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Bryant EH, Meffert LM. Nonadditive genetic structuring of morphometric variation in relation to a population bottleneck. Heredity (Edinb) 1996. [DOI: 10.1038/hdy.1996.121] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Quantum shifts in the genetic control of a colour polymorphism in Theridion grallator (Araneae: Theridiidae), the Hawaiian happy-face spider. Heredity (Edinb) 1996. [DOI: 10.1038/hdy.1996.38] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Backus VL, Bryant EH, Hughes CR, Meffert LM. Effect of Migration or Inbreeding Followed by Selection on Low-Founder-Number Populations: Implications for Captive Breeding Programs. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 1995; 9:1216-1224. [PMID: 34261285 DOI: 10.1046/j.1523-1739.1995.9051208.x-i1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Using the housefly, Musca domestica (L), as a model system, we tested the ability of two extrems in the range of possible captive breeding protocols to yield sustainable populations following founding with low founder numbers. The protocols tested included two levels of migration as well as inbreeding followed by selection, each with appropriate controls. Each low-founder-number population was founded with two pairs of flies. The maximum migration scheme had 50% migration per generation, and the minimum migration populations experienced a migration rate of 2.5% per generation. The control level of migration was 0%. A fourth low-founder-number treatment was designed to test the effect of inbreeding followed by selection. Two sets of high-founder-number control groups were also derived from the stock population. Two fitness measures, viability and productivity of the populations, were recorded at the fifth generation. Populations in the minimum-migration and zero migration treatment groups had lower fitness than populations in any other treatment for both measures. Populations that experienced inbreeding and selection for high fitness levels, high levels of migration, or large high-founder-number populations were equally fit. These results demonstrate that a captive-breeding scheme that contains substantial levels of migration or inbreeding followed by selection can yield highly adapted populations. Efecto de la migración o intracruza seguido por la selección de poblacions originadas a partir de un número pequeño de fundadores.
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Affiliation(s)
- Vickie L Backus
- Department of Biology, University of Houston, Houston, TX 77204, U.S.A
| | - Edwin H Bryant
- Department of Biology, University of Houston, Houston, TX 77204, U.S.A
| | - Colin R Hughes
- Department of Biology, University of Houston, Houston, TX 77204, U.S.A
| | - Lisa M Meffert
- Department of Biology, University of Houston, Houston, TX 77204, U.S.A
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Templeton AR. Biodiversity at the molecular genetic level: experiences from disparate macroorganisms. Philos Trans R Soc Lond B Biol Sci 1994; 345:59-64. [PMID: 7972356 DOI: 10.1098/rstb.1994.0086] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Genetic variation is the basis of adaptive flexibility in populations and is the ultimate evolutionary basis of much species and community-level diversity. Accordingly, the preservation and maintenance of genetic diversity has a high priority in many conservation programmes. This paper discusses how genetic diversity is measured at the molecular level, including some newer measures made possible with restriction site or DNA sequence data as well as the development of a phylogenetic approach to assessing the significance of genetic variation within a species. These measures of genetic diversity are then used to re-examine the validity of the 50/500 rule of conservation biology; a rule that states that populations should have no fewer than 50 individuals for short-term maintenance of genetic variation and no fewer than 500 individuals for long-term maintenance. Both the 50 and 500 parts of this rule are found to be invalid and frequently misleading. Instead of invoking 'universal' rules, conservation biologists should recognize the role of biodiversity in management policies. Not all species are the same, and we need more research and a willingness to try novel approaches rather than naively apply a 'rule' that has no demonstrable generality.
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Affiliation(s)
- A R Templeton
- Department of Biology, Washington University, St. Louis, Missouri 63130
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