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Moraiti CA, Verykouki E, Papadopoulos NT. Fitness cost of Rhagoletis cerasi (Diptera: Tephritidae) adults emerged from pupae with different dormancy regimes: the case of prolonged chilling. BULLETIN OF ENTOMOLOGICAL RESEARCH 2023; 113:11-20. [PMID: 36229960 DOI: 10.1017/s0007485321000535] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is a univoltine species that overwinters at pupal stage. Under optimum overwintering conditions pupae will develop into adults the next spring. Shorter or longer than optimum chilling periods induce prolonged pupae dormancy. Pupae that enter prolonged dormancy due to a short chilling period exhibit high emergence rates after a second cycle of cold/warm periods. Adults found to be larger and less fecund compared to their counterparts from pupae with annual diapause. On the other hand, extreme long chilling periods at pupal stage results in high mortality rates. However, for one Greek population, a substantial number of adults emerged following prolonged chilling of pupae (ca. 18 consecutive months). In this study, we used three R. cerasi populations in order to address possible geographical variation in fitness cost of adults from pupae with prolonged dormancy. In addition, the fitness traits of these adults emerging after prolonged pupae chilling were compared with that of their counterparts from pupae with annual diapause or prolonged dormancy. Our results reveal no population-specific variation in fitness cost of adults from pupae with prolonged dormancy. Within a population, lifetime fecundity did not differ between adults emerged from pupae with prolonged dormancy and those emerged after prolonged pupae chilling. Adults emerged from pupae exposed to prolonged chilling suffer an additional reduction in adult longevity compared to adults from pupae with prolonged dormancy. Hence, fitness of R. cerasi adults is regulated by diapause regimes of pupae.
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Affiliation(s)
- Cleopatra A Moraiti
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Fytokou St., N. Ionia Volou, 384 46, Magnesia, Greece
| | - Eleni Verykouki
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Fytokou St., N. Ionia Volou, 384 46, Magnesia, Greece
| | - Nikos T Papadopoulos
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Fytokou St., N. Ionia Volou, 384 46, Magnesia, Greece
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2
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Karp X. Hormonal Regulation of Diapause and Development in Nematodes, Insects, and Fishes. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.735924] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Diapause is a state of developmental arrest adopted in response to or in anticipation of environmental conditions that are unfavorable for growth. In many cases, diapause is facultative, such that animals may undergo either a diapause or a non-diapause developmental trajectory, depending on environmental cues. Diapause is characterized by enhanced stress resistance, reduced metabolism, and increased longevity. The ability to postpone reproduction until suitable conditions are found is important to the survival of many animals, and both vertebrate and invertebrate species can undergo diapause. The decision to enter diapause occurs at the level of the whole animal, and thus hormonal signaling pathways are common regulators of the diapause decision. Unlike other types of developmental arrest, diapause is programmed, such that the diapause developmental trajectory includes a pre-diapause preparatory phase, diapause itself, recovery from diapause, and post-diapause development. Therefore, developmental pathways are profoundly affected by diapause. Here, I review two conserved hormonal pathways, insulin/IGF signaling (IIS) and nuclear hormone receptor signaling (NHR), and their role in regulating diapause across three animal phyla. Specifically, the species reviewed are Austrofundulus limnaeus and Nothobranchius furzeri annual killifishes, Caenorhabditis elegans nematodes, and insect species including Drosophila melanogaster, Culex pipiens, and Bombyx mori. In addition, the developmental changes that occur as a result of diapause are discussed, with a focus on how IIS and NHR pathways interact with core developmental pathways in C. elegans larvae that undergo diapause.
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3
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Wilsterman K, Ballinger MA, Williams CM. A unifying, eco‐physiological framework for animal dormancy. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13718] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Kathryn Wilsterman
- Biological Sciences University of Montana Missoula MT USA
- Integrative Biology University of California Berkeley CA USA
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4
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Erickson PA, Weller CA, Song DY, Bangerter AS, Schmidt P, Bergland AO. Unique genetic signatures of local adaptation over space and time for diapause, an ecologically relevant complex trait, in Drosophila melanogaster. PLoS Genet 2020; 16:e1009110. [PMID: 33216740 PMCID: PMC7717581 DOI: 10.1371/journal.pgen.1009110] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 12/04/2020] [Accepted: 09/10/2020] [Indexed: 02/07/2023] Open
Abstract
Organisms living in seasonally variable environments utilize cues such as light and temperature to induce plastic responses, enabling them to exploit favorable seasons and avoid unfavorable ones. Local adapation can result in variation in seasonal responses, but the genetic basis and evolutionary history of this variation remains elusive. Many insects, including Drosophila melanogaster, are able to undergo an arrest of reproductive development (diapause) in response to unfavorable conditions. In D. melanogaster, the ability to diapause is more common in high latitude populations, where flies endure harsher winters, and in the spring, reflecting differential survivorship of overwintering populations. Using a novel hybrid swarm-based genome wide association study, we examined the genetic basis and evolutionary history of ovarian diapause. We exposed outbred females to different temperatures and day lengths, characterized ovarian development for over 2800 flies, and reconstructed their complete, phased genomes. We found that diapause, scored at two different developmental cutoffs, has modest heritability, and we identified hundreds of SNPs associated with each of the two phenotypes. Alleles associated with one of the diapause phenotypes tend to be more common at higher latitudes, but these alleles do not show predictable seasonal variation. The collective signal of many small-effect, clinally varying SNPs can plausibly explain latitudinal variation in diapause seen in North America. Alleles associated with diapause are segregating in Zambia, suggesting that variation in diapause relies on ancestral polymorphisms, and both pro- and anti-diapause alleles have experienced selection in North America. Finally, we utilized outdoor mesocosms to track diapause under natural conditions. We found that hybrid swarms reared outdoors evolved increased propensity for diapause in late fall, whereas indoor control populations experienced no such change. Our results indicate that diapause is a complex, quantitative trait with different evolutionary patterns across time and space.
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Affiliation(s)
- Priscilla A. Erickson
- Department of Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Cory A. Weller
- Department of Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Daniel Y. Song
- Department of Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Alyssa S. Bangerter
- Department of Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Paul Schmidt
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alan O. Bergland
- Department of Biology, University of Virginia, Charlottesville, Virginia, United States of America
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5
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Sarikaya DP, Cridland J, Tarakji A, Sheehy H, Davis S, Kochummen A, Hatmaker R, Khan N, Chiu J, Begun DJ. Phenotypic coupling of sleep and starvation resistance evolves in D. melanogaster. BMC Evol Biol 2020; 20:126. [PMID: 32962630 PMCID: PMC7507639 DOI: 10.1186/s12862-020-01691-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/13/2020] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND One hypothesis for the function of sleep is that it serves as a mechanism to conserve energy. Recent studies have suggested that increased sleep can be an adaptive mechanism to improve survival under food deprivation in Drosophila melanogaster. To test the generality of this hypothesis, we compared sleep and its plastic response to starvation in a temperate and tropical population of Drosophila melanogaster. RESULTS We found that flies from the temperate population were more starvation resistant, and hypothesized that they would engage in behaviors that are considered to conserve energy, including increased sleep and reduced movement. Surprisingly, temperate flies slept less and moved more when they were awake compared to tropical flies, both under fed and starved conditions, therefore sleep did not correlate with population-level differences in starvation resistance. In contrast, total sleep and percent change in sleep when starved were strongly positively correlated with starvation resistance within the tropical population, but not within the temperate population. Thus, we observe unexpectedly complex relationships between starvation and sleep that vary both within and across populations. These observations falsify the simple hypothesis of a straightforward relationship between sleep and energy conservation. We also tested the hypothesis that starvation is correlated with metabolic phenotypes by investigating stored lipid and carbohydrate levels, and found that stored metabolites partially contributed towards variation starvation resistance. CONCLUSIONS Our findings demonstrate that the function of sleep under starvation can rapidly evolve on short timescales and raise new questions about the physiological correlates of sleep and the extent to which variation in sleep is shaped by natural selection.
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Affiliation(s)
- Didem P Sarikaya
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA.
- Department of Molecular and Cellular Biology, University of California Davis, Davis, California, USA.
| | - Julie Cridland
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA
| | - Adam Tarakji
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA
| | - Hayley Sheehy
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA
| | - Sophia Davis
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA
| | - Ashley Kochummen
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA
| | - Ryan Hatmaker
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA
| | - Nossin Khan
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA
| | - Joanna Chiu
- Department of Nematology and Entomology, University of California Davis, Davis, California, USA
| | - David J Begun
- Department of Evolution and Ecology, University of California Davis, Davis, California, USA
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6
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Chang V, Meuti ME. Circadian transcription factors differentially regulate features of the adult overwintering diapause in the Northern house mosquito, Culex pipiens. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 121:103365. [PMID: 32247760 DOI: 10.1016/j.ibmb.2020.103365] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 03/10/2020] [Accepted: 03/22/2020] [Indexed: 06/11/2023]
Abstract
The short days of late summer and early fall are the environmental cues that most temperate insects and other animals use to predict winter's arrival. Although it is still unclear precisely how insects measure daylength, there is mounting evidence that the circadian clock regulates seasonal responses including photoperiodic diapause. Females of the Northern house mosquito, Culex pipiens, enter an adult reproductive diapause in response to short daylengths. While in this state, females divert their resources from reproduction to survival, arresting egg follicle development and increasing fat content. Here, we characterized the expression profile of two circadian transcription factors, vrille (vri) and Par domain protein 1 (Pdp1), as well as genes downstream of the clock, takeout (to) and Nocturnin (Noc) and under different seasonal conditions. We saw that while vri mRNA oscillated under both long day and short day conditions, Pdp1 expression oscillated only under long day conditions and was constitutively upregulated in diapausing females. We saw similar expression profiles for to and Noc, suggesting that PDP1 might regulate their expression or that Pdp1, to and Noc might be regulated by the same transcription factor. We suppressed vri and Pdp1 using RNA interference. dsRNA against vri provided inconsistent results, sometimes stimulating autogenous egg follicle development in both long and short day-reared females, and other times had no effect. In contrast, knocking down Pdp1 prevented short day-reared females from accumulating fat reserves, but increased expression of to and Noc. Taken together, these data suggest that the circadian transcription factors Vri and Pdp1 may independently regulate signaling pathways underlying arrested egg follicle development and fat accumulation in diapausing females of Cx. pipiens.
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Affiliation(s)
- Vivian Chang
- Department of Entomology, The Ohio State University, 2021 Coffey Rd., Room 216 Kottman Hall, Columbus, OH, 43210, USA
| | - Megan E Meuti
- Department of Entomology, The Ohio State University, 2021 Coffey Rd., Room 216 Kottman Hall, Columbus, OH, 43210, USA.
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7
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Flatt T. Life-History Evolution and the Genetics of Fitness Components in Drosophila melanogaster. Genetics 2020; 214:3-48. [PMID: 31907300 PMCID: PMC6944413 DOI: 10.1534/genetics.119.300160] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 10/03/2019] [Indexed: 12/28/2022] Open
Abstract
Life-history traits or "fitness components"-such as age and size at maturity, fecundity and fertility, age-specific rates of survival, and life span-are the major phenotypic determinants of Darwinian fitness. Analyzing the evolution and genetics of these phenotypic targets of selection is central to our understanding of adaptation. Due to its simple and rapid life cycle, cosmopolitan distribution, ease of maintenance in the laboratory, well-understood evolutionary genetics, and its versatile genetic toolbox, the "vinegar fly" Drosophila melanogaster is one of the most powerful, experimentally tractable model systems for studying "life-history evolution." Here, I review what has been learned about the evolution and genetics of life-history variation in D. melanogaster by drawing on numerous sources spanning population and quantitative genetics, genomics, experimental evolution, evolutionary ecology, and physiology. This body of work has contributed greatly to our knowledge of several fundamental problems in evolutionary biology, including the amount and maintenance of genetic variation, the evolution of body size, clines and climate adaptation, the evolution of senescence, phenotypic plasticity, the nature of life-history trade-offs, and so forth. While major progress has been made, important facets of these and other questions remain open, and the D. melanogaster system will undoubtedly continue to deliver key insights into central issues of life-history evolution and the genetics of adaptation.
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Affiliation(s)
- Thomas Flatt
- Department of Biology, University of Fribourg, CH-1700, Switzerland
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8
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Durmaz E, Rajpurohit S, Betancourt N, Fabian DK, Kapun M, Schmidt P, Flatt T. A clinal polymorphism in the insulin signaling transcription factor foxo contributes to life-history adaptation in Drosophila. Evolution 2019; 73:1774-1792. [PMID: 31111462 PMCID: PMC6771989 DOI: 10.1111/evo.13759] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 05/04/2019] [Accepted: 05/06/2019] [Indexed: 12/11/2022]
Abstract
A fundamental aim of adaptation genomics is to identify polymorphisms that underpin variation in fitness traits. In Drosophila melanogaster, latitudinal life-history clines exist on multiple continents and make an excellent system for dissecting the genetics of adaptation. We have previously identified numerous clinal single-nucleotide polymorphism in insulin/insulin-like growth factor signaling (IIS), a pathway known from mutant studies to affect life history. However, the effects of natural variants in this pathway remain poorly understood. Here we investigate how two clinal alternative alleles at foxo, a transcriptional effector of IIS, affect fitness components (viability, size, starvation resistance, fat content). We assessed this polymorphism from the North American cline by reconstituting outbred populations, fixed for either the low- or high-latitude allele, from inbred DGRP lines. Because diet and temperature modulate IIS, we phenotyped alleles across two temperatures (18°C, 25°C) and two diets differing in sugar source and content. Consistent with clinal expectations, the high-latitude allele conferred larger body size and reduced wing loading. Alleles also differed in starvation resistance and expression of insulin-like receptor, a transcriptional target of FOXO. Allelic reaction norms were mostly parallel, with few GxE interactions. Together, our results suggest that variation in IIS makes a major contribution to clinal life-history adaptation.
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Affiliation(s)
- Esra Durmaz
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
- Department of BiologyUniversity of FribourgFribourgSwitzerland
| | - Subhash Rajpurohit
- Department of BiologyUniversity of PennsylvaniaPhiladelphiaPennsylvania19140
- Division of Biological and Life SciencesAhmedabad UniversityAhmedabadIndia
| | - Nicolas Betancourt
- Department of BiologyUniversity of PennsylvaniaPhiladelphiaPennsylvania19140
| | - Daniel K. Fabian
- European Molecular Biology LaboratoryEuropean Bioinformatics InstituteWellcome Genome Campus, HinxtonCambridgeUnited Kingdom
- Institut für PopulationsgenetikVetmeduni ViennaViennaAustria
- Vienna Graduate School of Population, GeneticsViennaAustria
| | - Martin Kapun
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
- Department of BiologyUniversity of FribourgFribourgSwitzerland
| | - Paul Schmidt
- Department of BiologyUniversity of PennsylvaniaPhiladelphiaPennsylvania19140
| | - Thomas Flatt
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
- Department of BiologyUniversity of FribourgFribourgSwitzerland
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9
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Brenman-Suttner DB, Yost RT, Frame AK, Robinson JW, Moehring AJ, Simon AF. Social behavior and aging: A fly model. GENES BRAIN AND BEHAVIOR 2019; 19:e12598. [PMID: 31286644 DOI: 10.1111/gbb.12598] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 07/02/2019] [Accepted: 07/05/2019] [Indexed: 12/16/2022]
Abstract
The field of behavioral genetics has recently begun to explore the effect of age on social behaviors. Such studies are particularly important, as certain neuropsychiatric disorders with abnormal social interactions, like autism and schizophrenia, have been linked to older parents. Appropriate social interaction can also have a positive impact on longevity, and is associated with successful aging in humans. Currently, there are few genetic models for understanding the effect of aging on social behavior and its potential transgenerational inheritance. The fly is emerging as a powerful model for identifying the basic molecular mechanisms underlying neurological and neuropsychiatric disorders. In this review, we discuss these recent advancements, with a focus on how studies in Drosophila melanogaster have provided insight into the effect of aging on aspects of social behavior, including across generations.
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Affiliation(s)
- Dova B Brenman-Suttner
- Department of Biology, Faculty of Science, Western University, London, Ontario, Canada.,Department of Biology, York University, Toronto, Ontario, Canada
| | - Ryley T Yost
- Department of Biology, Faculty of Science, Western University, London, Ontario, Canada
| | - Ariel K Frame
- Department of Biology, Faculty of Science, Western University, London, Ontario, Canada
| | - J Wesley Robinson
- Department of Biology, Faculty of Science, Western University, London, Ontario, Canada
| | - Amanda J Moehring
- Department of Biology, Faculty of Science, Western University, London, Ontario, Canada
| | - Anne F Simon
- Department of Biology, Faculty of Science, Western University, London, Ontario, Canada
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10
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Kapun M, Flatt T. The adaptive significance of chromosomal inversion polymorphisms inDrosophila melanogaster. Mol Ecol 2018; 28:1263-1282. [DOI: 10.1111/mec.14871] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/01/2018] [Accepted: 09/10/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Martin Kapun
- Department of BiologyUniversity of Fribourg Fribourg Switzerland
| | - Thomas Flatt
- Department of BiologyUniversity of Fribourg Fribourg Switzerland
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11
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Durmaz E, Benson C, Kapun M, Schmidt P, Flatt T. An inversion supergene in Drosophila underpins latitudinal clines in survival traits. J Evol Biol 2018; 31:1354-1364. [PMID: 29904977 DOI: 10.1111/jeb.13310] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/09/2018] [Accepted: 06/04/2018] [Indexed: 01/18/2023]
Abstract
Chromosomal inversions often contribute to local adaptation across latitudinal clines, but the underlying selective mechanisms remain poorly understood. We and others have previously shown that a clinal inversion polymorphism in Drosophila melanogaster, In(3R)Payne, underpins body size clines along the North American and Australian east coasts. Here, we ask whether this polymorphism also contributes to clinal variation in other fitness-related traits, namely survival traits (lifespan, survival upon starvation and survival upon cold shock). We generated homokaryon lines, either carrying the inverted or standard chromosomal arrangement, isolated from populations approximating the endpoints of the North American cline (Florida, Maine) and phenotyped the flies at two growth temperatures (18 °C, 25 °C). Across both temperatures, high-latitude flies from Maine lived longer and were more stress resistant than low-latitude flies from Florida, as previously observed. Interestingly, we find that this latitudinal pattern is partly explained by the clinal distribution of the In(3R)P polymorphism, which is at ~ 50% frequency in Florida but absent in Maine: inverted karyotypes tended to be shorter-lived and less stress resistant than uninverted karyotypes. We also detected an interaction between karyotype and temperature on survival traits. As In(3R)P influences body size and multiple survival traits, it can be viewed as a 'supergene', a cluster of tightly linked loci affecting multiple complex phenotypes. We conjecture that the inversion cline is maintained by fitness trade-offs and balancing selection across geography; elucidating the mechanisms whereby this inversion affects alternative, locally adapted phenotypes across the cline is an important task for future work.
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Affiliation(s)
- Esra Durmaz
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Clare Benson
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,School of Biological Sciences, University of Manchester, Manchester, UK
| | - Martin Kapun
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Paul Schmidt
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Thomas Flatt
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Department of Biology, University of Fribourg, Fribourg, Switzerland
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12
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Williams CM, Ragland GJ, Betini G, Buckley LB, Cheviron ZA, Donohue K, Hereford J, Humphries MM, Lisovski S, Marshall KE, Schmidt PS, Sheldon KS, Varpe Ø, Visser ME. Understanding Evolutionary Impacts of Seasonality: An Introduction to the Symposium. Integr Comp Biol 2018; 57:921-933. [PMID: 29045649 DOI: 10.1093/icb/icx122] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Seasonality is a critically important aspect of environmental variability, and strongly shapes all aspects of life for organisms living in highly seasonal environments. Seasonality has played a key role in generating biodiversity, and has driven the evolution of extreme physiological adaptations and behaviors such as migration and hibernation. Fluctuating selection pressures on survival and fecundity between summer and winter provide a complex selective landscape, which can be met by a combination of three outcomes of adaptive evolution: genetic polymorphism, phenotypic plasticity, and bet-hedging. Here, we have identified four important research questions with the goal of advancing our understanding of evolutionary impacts of seasonality. First, we ask how characteristics of environments and species will determine which adaptive response occurs. Relevant characteristics include costs and limits of plasticity, predictability, and reliability of cues, and grain of environmental variation relative to generation time. A second important question is how phenological shifts will amplify or ameliorate selection on physiological hardiness. Shifts in phenology can preserve the thermal niche despite shifts in climate, but may fail to completely conserve the niche or may even expose life stages to conditions that cause mortality. Considering distinct environmental sensitivities of life history stages will be key to refining models that forecast susceptibility to climate change. Third, we must identify critical physiological phenotypes that underlie seasonal adaptation and work toward understanding the genetic architectures of these responses. These architectures are key for predicting evolutionary responses. Pleiotropic genes that regulate multiple responses to changing seasons may facilitate coordination among functionally related traits, or conversely may constrain the expression of optimal phenotypes. Finally, we must advance our understanding of how changes in seasonal fluctuations are impacting ecological interaction networks. We should move beyond simple dyadic interactions, such as predator prey dynamics, and understand how these interactions scale up to affect ecological interaction networks. As global climate change alters many aspects of seasonal variability, including extreme events and changes in mean conditions, organisms must respond appropriately or go extinct. The outcome of adaptation to seasonality will determine responses to climate change.
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Affiliation(s)
- Caroline M Williams
- Department of Integrative Biology, University of California, 3040 Valley Life Sciences Building, Berkeley, CA 94705, USA
| | - Gregory J Ragland
- Department of Integrative Biology, University of Colorado, Denver, CO, USA
| | - Gustavo Betini
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Lauren B Buckley
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Zachary A Cheviron
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | | | - Joe Hereford
- Department of Ecology and Evolution, University of California, Davis, CA, USA
| | - Murray M Humphries
- Department of Natural Resource Sciences, McGill University, Quebec, Canada
| | - Simeon Lisovski
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA, USA
| | | | - Paul S Schmidt
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Kimberly S Sheldon
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
| | - Øystein Varpe
- Department of Arctic Biology, The University Centre in Svalbard, Longyearbyen, Norway.,Akvaplan-niva, Fram Centre, Tromsø, Norway
| | - Marcel E Visser
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB Wageningen, The Netherlands
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13
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Lirakis M, Dolezal M, Schlötterer C. Redefining reproductive dormancy in Drosophila as a general stress response to cold temperatures. JOURNAL OF INSECT PHYSIOLOGY 2018; 107:175-185. [PMID: 29649483 DOI: 10.1016/j.jinsphys.2018.04.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 04/07/2018] [Accepted: 04/08/2018] [Indexed: 06/08/2023]
Abstract
Organisms regularly encounter unfavorable conditions and the genetic adaptations facilitating survival have been of long-standing interest to evolutionary biologists. Winter is one particularly stressful condition for insects, during which they encounter low temperatures and scarcity of food. Despite dormancy being a well-studied adaptation to facilitate overwintering, there is still considerable controversy about the distribution of dormancy among natural populations and between species in Drosophila. The current definition of dormancy as developmental arrest of oogenesis at the previtellogenic stage (stage 7) distinguishes dormancy from general stress related block of oogenesis at early vitellogenic stages (stages 8 - 9). In an attempt to resolve this, we scrutinized reproductive dormancy in D. melanogaster and D. simulans. We show that dormancy shows the same hallmarks of arrest of oogenesis at stage 9, as described for other stressors and propose a new classification for dormancy. Applying this modified classification, we show that both species express dormancy in cosmopolitan and African populations, further supporting that dormancy uses an ancestral pathway induced by environmental stress. While we found significant differences between individuals and the two Drosophila species in their sensitivity to cold temperature stress, we also noted that extreme temperature stress (8 °C) resulted in very strong dormancy incidence, which strongly reduced the differences seen at less extreme temperatures. We conclude that dormancy in Drosophila should not be considered a special trait, but is better understood as a generic stress response occurring at low temperatures.
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Affiliation(s)
- Manolis Lirakis
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria; Vienna Graduate School of Population Genetics, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria.
| | - Marlies Dolezal
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| | - Christian Schlötterer
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
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14
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Diniz DFA, de Albuquerque CMR, Oliva LO, de Melo-Santos MAV, Ayres CFJ. Diapause and quiescence: dormancy mechanisms that contribute to the geographical expansion of mosquitoes and their evolutionary success. Parasit Vectors 2017. [PMID: 28651558 PMCID: PMC5485599 DOI: 10.1186/s13071-017-2235-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Mosquitoes are insects belonging to the order Diptera and family Culicidae. They are distributed worldwide and include approximately 3500 species, of which about 300 have medical and veterinary importance. The evolutionary success of mosquitoes, in both tropical and temperate regions, is due to the various survival strategies these insects have developed throughout their life histories. Of the many adaptive mechanisms, diapause and quiescence, two different types of dormancy, likely contribute to the establishment, maintenance and spread of natural mosquito populations. This review seeks to objectively and coherently describe the terms diapause and quiescence, which can be confused in the literature because the phenotypic effects of these mechanisms are often similar.
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Affiliation(s)
- Diego Felipe Araujo Diniz
- Entomology Department, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n - Cidade Universitária, Recife, PE, Brazil
| | | | - Luciana Oliveira Oliva
- Zoology Department, Federal University of Pernambuco, Av. Professor Moraes Rego, 1235 - Cidade Universitária, Recife, PE, Brazil
| | - Maria Alice Varjal de Melo-Santos
- Entomology Department, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n - Cidade Universitária, Recife, PE, Brazil
| | - Constância Flávia Junqueira Ayres
- Entomology Department, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n - Cidade Universitária, Recife, PE, Brazil.
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15
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Pegoraro M, Zonato V, Tyler ER, Fedele G, Kyriacou CP, Tauber E. Geographical analysis of diapause inducibility in European Drosophila melanogaster populations. JOURNAL OF INSECT PHYSIOLOGY 2017; 98:238-244. [PMID: 28131702 DOI: 10.1016/j.jinsphys.2017.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/18/2017] [Accepted: 01/23/2017] [Indexed: 06/06/2023]
Abstract
Seasonal overwintering in insects represents an adaptation to stressful environments and in European Drosophila melanogaster females, low temperatures and short photoperiods can induce an ovarian diapause. Diapause may represent a recent (<15Ky) adaptation to the colonisation of temperate Europe by D. melanogaster from tropical sub-Saharan Africa, because African D. melanogaster and the sibling species D. simulans, have been reported to fail to undergo diapause. Over the past few centuries, D. melanogaster have also invaded North America and Australia, and eastern populations on both continents show a predictable latitudinal cline in diapause induction. In Europe however, a new diapause-enhancing timeless allele, ls-tim, is observed at high levels in southern Italy (∼80%), where it appears to have arisen and has spread throughout the continent with a frequency of ∼20% in Scandinavia. Given the phenotype of ls-tim and its geographical distribution, we might predict that it would work against any latitudinal cline in diapause induction within Europe. Indeed we reveal that any latitudinal cline for diapause in Europe is very weak, as predicted by ls-tim frequencies. In contrast, we determine ls-tim frequencies in North America and observe that they would be expected to strengthen the latitudinal pattern of diapause. Our results reveal how a newly arisen mutation, can, via the stochastic nature of where it initially arose, blur an otherwise adaptive geographical pattern.
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Affiliation(s)
- Mirko Pegoraro
- Department of Genetics, University of Leicester, Leicester LE1 7RH, UK
| | - Valeria Zonato
- Department of Genetics, University of Leicester, Leicester LE1 7RH, UK
| | - Elizabeth R Tyler
- Department of Genetics, University of Leicester, Leicester LE1 7RH, UK
| | - Giorgio Fedele
- Department of Genetics, University of Leicester, Leicester LE1 7RH, UK
| | | | - Eran Tauber
- Department of Genetics, University of Leicester, Leicester LE1 7RH, UK; Department of Evolutionary & Environmental Biology, University of Haifa, Haifa 3498838, Israel
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16
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Betini GS, McAdam AG, Griswold CK, Norris DR. A fitness trade-off between seasons causes multigenerational cycles in phenotype and population size. eLife 2017; 6:e18770. [PMID: 28164780 PMCID: PMC5340529 DOI: 10.7554/elife.18770] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 02/06/2017] [Indexed: 11/17/2022] Open
Abstract
Although seasonality is widespread and can cause fluctuations in the intensity and direction of natural selection, we have little information about the consequences of seasonal fitness trade-offs for population dynamics. Here we exposed populations of Drosophila melanogaster to repeated seasonal changes in resources across 58 generations and used experimental and mathematical approaches to investigate how viability selection on body size in the non-breeding season could affect demography. We show that opposing seasonal episodes of natural selection on body size interacted with both direct and delayed density dependence to cause populations to undergo predictable multigenerational density cycles. Our results provide evidence that seasonality can set the conditions for life-history trade-offs and density dependence, which can, in turn, interact to cause multigenerational population cycles.
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Affiliation(s)
- Gustavo S Betini
- Department of Integrative Biology, University of Guelph, Guelph, Canada
| | - Andrew G McAdam
- Department of Integrative Biology, University of Guelph, Guelph, Canada
| | | | - D Ryan Norris
- Department of Integrative Biology, University of Guelph, Guelph, Canada
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17
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Mathur V, Schmidt PS. Adaptive patterns of phenotypic plasticity in laboratory and field environments in Drosophila melanogaster. Evolution 2016; 71:465-474. [PMID: 27925178 DOI: 10.1111/evo.13144] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Revised: 11/08/2016] [Accepted: 11/13/2016] [Indexed: 01/19/2023]
Abstract
Identifying mechanisms of adaptation to variable environments is essential in developing a comprehensive understanding of evolutionary dynamics in natural populations. Phenotypic plasticity allows for phenotypic change in response to changes in the environment, and as such may play a major role in adaptation to environmental heterogeneity. Here, the plasticity of stress response in Drosophila melanogaster originating from two distinct geographic regions and ecological habitats was examined. Adults were given a short-term, 5-day exposure to combinations of temperature and photoperiod to elicit a plastic response for three fundamental aspects of stress tolerance that vary adaptively with geography. This was replicated both in the laboratory and in outdoor enclosures in the field. In the laboratory, geographic origin was the primary determinant of the stress response. Temperature and the interaction between temperature and photoperiod also significantly affected stress resistance. In the outdoor enclosures, plasticity was distinct among traits and between geographic regions. These results demonstrate that short-term exposure of adults to ecologically relevant environmental cues results in predictable effects on multiple aspects of fitness. These patterns of plasticity vary among traits and are highly distinct between the two examined geographic regions, consistent with patterns of local adaptation to climate and associated environmental parameters.
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Affiliation(s)
- Vinayak Mathur
- Department of Biology, University of Pennsylvania, 433 S. University Avenue, Philadelphia, Pennsylvania, 19104.,Current Address: Department of Biology, Georgetown University, Washington, District of Columbia, 20057
| | - Paul S Schmidt
- Department of Biology, University of Pennsylvania, 433 S. University Avenue, Philadelphia, Pennsylvania, 19104
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18
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Kubrak OI, Kučerová L, Theopold U, Nylin S, Nässel DR. Characterization of Reproductive Dormancy in Male Drosophila melanogaster. Front Physiol 2016; 7:572. [PMID: 27932997 PMCID: PMC5121231 DOI: 10.3389/fphys.2016.00572] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/09/2016] [Indexed: 11/13/2022] Open
Abstract
Insects are known to respond to seasonal and adverse environmental changes by entering dormancy, also known as diapause. In some insect species, including Drosophila melanogaster, dormancy occurs in the adult organism and postpones reproduction. This adult dormancy has been studied in female flies where it is characterized by arrested development of ovaries, altered nutrient stores, lowered metabolism, increased stress and immune resistance and drastically extended lifespan. Male dormancy, however, has not been investigated in D. melanogaster, and its physiology is poorly known in most insects. Here we show that unmated 3-6 h old male flies placed at low temperature (11°C) and short photoperiod (10 Light:14 Dark) enter a state of dormancy with arrested spermatogenesis and development of testes and male accessory glands. Over 3 weeks of diapause we see a dynamic increase in stored carbohydrates and an initial increase and then a decrease in lipids. We also note an up-regulated expression of genes involved in metabolism, stress responses and innate immunity. Interestingly, we found that male flies that entered reproductive dormancy do not attempt to mate females kept under non-diapause conditions (25°C, 12L:12D), and conversely non-diapausing males do not mate females in dormancy. In summary, our study shows that male D. melanogaster can enter reproductive dormancy. However, our data suggest that dormant male flies deplete stored nutrients faster than females, studied earlier, and that males take longer to recover reproductive capacity after reintroduction to non-diapause conditions.
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Affiliation(s)
- Olga I Kubrak
- Department of Zoology, Stockholm University Stockholm, Sweden
| | - Lucie Kučerová
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University Stockholm, Sweden
| | - Ulrich Theopold
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University Stockholm, Sweden
| | - Sören Nylin
- Department of Zoology, Stockholm University Stockholm, Sweden
| | - Dick R Nässel
- Department of Zoology, Stockholm University Stockholm, Sweden
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19
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Eanes WF. New views on the selection acting on genetic polymorphism in central metabolic genes. Ann N Y Acad Sci 2016; 1389:108-123. [PMID: 27859384 DOI: 10.1111/nyas.13285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 09/20/2016] [Accepted: 09/29/2016] [Indexed: 12/14/2022]
Abstract
Studies of the polymorphism of central metabolic genes as a source of fitness variation in natural populations date back to the discovery of allozymes in the 1960s. The unique features of these genes and their enzymes and our knowledge base greatly facilitates the systems-level study of this group. The expectation that pathway flux control is central to understanding the molecular evolution of genes is discussed, as well as studies that attempt to place gene-specific molecular evolution and polymorphism into a context of pathway and network architecture. There is an increasingly complex picture of the metabolic genes assuming additional roles beyond their textbook anabolic and catabolic reactions. In particular, this review emphasizes the potential role of these genes as part of the energy-sensing machinery. It is underscored that the concentrations of key cellular metabolites are the reflections of cellular energy status and nutritional input. These metabolites are the top-down signaling messengers that set signaling through signaling pathways that are involved in energy economy. I propose that the polymorphisms in central metabolic genes shift metabolite concentrations and in that fashion act as genetic modifiers of the energy-state coupling to the transcriptional networks that affect physiological trade-offs with significant fitness consequences.
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Affiliation(s)
- Walter F Eanes
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York
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20
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Zonato V, Fedele G, Kyriacou CP. An Intronic Polymorphism in couch potato Is Not Distributed Clinally in European Drosophila melanogaster Populations nor Does It Affect Diapause Inducibility. PLoS One 2016; 11:e0162370. [PMID: 27598401 PMCID: PMC5012703 DOI: 10.1371/journal.pone.0162370] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 08/22/2016] [Indexed: 12/24/2022] Open
Abstract
couch potato (cpo) encodes an RNA binding protein that has been reported to be expressed in the peripheral and central nervous system of embryos, larvae and adults, including the major endocrine organ, the ring gland. A polymorphism in the D. melanogaster cpo gene coding region displays a latitudinal cline in frequency in North American populations, but as cpo lies within the inversion In(3R)Payne, which is at high frequencies and itself shows a strong cline on this continent, interpretation of the cpo cline is not straightforward. A second downstream SNP in strong linkage disequilibrium with the first has been claimed to be primarily responsible for the latitudinal cline in diapause incidence in USA populations.Here, we investigate the frequencies of these two cpo SNPs in populations of Drosophila throughout continental Europe. The advantage of studying cpo variation in Europe is the very low frequency of In(3R)Payne, which we reveal here, does not appear to be clinally distributed. We observe a very different geographical scenario for cpo variation from the one in North America, suggesting that the downstream SNP does not play a role in diapause. In an attempt to verify whether the SNPs influence diapause we subsequently generated lines with different combinations of the two cpo SNPs on known timeless (tim) genetic backgrounds, because polymorphism in the clock gene tim plays a significant role in diapause inducibility. Our results reveal that the downstream cpo SNP does not seem to play any role in diapause induction in European populations in contrast to the upstream coding cpo SNP. Consequently, all future diapause studies on strains of D. melanogaster should initially determine their tim and cpo status.
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Affiliation(s)
- Valeria Zonato
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, United Kingdom
| | - Giorgio Fedele
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, United Kingdom
| | - Charalambos P. Kyriacou
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, United Kingdom
- * E-mail:
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21
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Kankare M, Parker DJ, Merisalo M, Salminen TS, Hoikkala A. Transcriptional Differences between Diapausing and Non-Diapausing D. montana Females Reared under the Same Photoperiod and Temperature. PLoS One 2016; 11:e0161852. [PMID: 27571415 PMCID: PMC5003386 DOI: 10.1371/journal.pone.0161852] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 08/13/2016] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND A wide range of insects living at higher latitudes enter diapause at the end of the warm season, which increases their chances of survival through harsh winter conditions. In this study we used RNA sequencing to identify genes involved in adult reproductive diapause in a northern fly species, Drosophila montana. Both diapausing and non-diapausing flies were reared under a critical day length and temperature, where about half of the emerging females enter diapause enabling us to eliminate the effects of varying environmental conditions on gene expression patterns of the two types of female flies. RESULTS RNA sequencing revealed large differences between gene expression patterns of diapausing and non-diapausing females, especially in genes involved with metabolism, fatty acid biosynthesis, and metal and nucleotide binding. Differently expressed genes included several gene groups, including myosin, actin and cytochromeP450 genes, which have been previously associated with diapause. This study also identified new candidate genes, including some involved in cuticular hydrocarbon synthesis or regulation (desat1 and desat2), and acyl-CoA Δ11-desaturase activity (CG9747), and few odorant-binding protein genes (e.g. Obp44A). Also, several transposable elements (TEs) showed differential expression between the two female groups motivating future research on their roles in diapause. CONCLUSIONS Our results demonstrate that the adult reproductive diapause in D. montana involves changes in the expression level of a variety of genes involved in key processes (e.g. metabolism and fatty acid biosynthesis) which help diapausing females to cope with overwintering. This is consistent with the view that diapause is a complex adaptive phenotype where not only sexual maturation is arrested, but also changes in adult physiology are required in order to survive over the winter.
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Affiliation(s)
- Maaria Kankare
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, Jyväskylä, Finland
| | - Darren J. Parker
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, Jyväskylä, Finland
- Centre for Biological Diversity, School of Biology, University of St Andrews, Fife, KY16 9TH, St Andrews, United Kingdom
| | - Mikko Merisalo
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, Jyväskylä, Finland
| | - Tiina S. Salminen
- BioMediTech, Biokatu 6, F1-33014, University of Tampere, Tampere, Finland
| | - Anneli Hoikkala
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, Jyväskylä, Finland
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22
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Meuti ME, Stone M, Ikeno T, Denlinger DL. Functional circadian clock genes are essential for the overwintering diapause of the Northern house mosquito, Culex pipiens. ACTA ACUST UNITED AC 2016; 218:412-22. [PMID: 25653422 DOI: 10.1242/jeb.113233] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The short day lengths of late summer are used to program the overwintering adult diapause (dormancy) of the Northern house mosquito, Culex pipiens. Here, we investigated the role of clock genes in initiating this diapause and asked whether the circadian cycling of clock gene expression persists during diapause. We provide evidence that the major circadian clock genes continue to cycle throughout diapause and after diapause has been terminated. RNA interference (RNAi) was used to knock down the core circadian clock genes and to then assess the impact of the various clock genes on the ability of females to enter diapause. RNAi directed against negative circadian regulators (period, timeless and cryptochrome2) caused females that were reared under diapause-inducing, short day conditions to avert diapause. In contrast, knocking down the circadian-associated gene pigment dispersing factor caused females that were reared under diapause-averting, long day conditions to enter a diapause-like state. Our results implicate the circadian clock in the initiation of diapause in C. pipiens.
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Affiliation(s)
- Megan E Meuti
- The Ohio State University, Department of Entomology, 318 W. 12th Avenue, Room 400 Aronoff Laboratory, Columbus, OH 43210, USA
| | - Mary Stone
- The Ohio State University, Department of Entomology, 318 W. 12th Avenue, Room 400 Aronoff Laboratory, Columbus, OH 43210, USA
| | - Tomoko Ikeno
- The Ohio State University, Department of Entomology, 318 W. 12th Avenue, Room 400 Aronoff Laboratory, Columbus, OH 43210, USA Michigan State University, Psychology Department, East Lansing, MI 48824, USA
| | - David L Denlinger
- The Ohio State University, Department of Entomology, 318 W. 12th Avenue, Room 400 Aronoff Laboratory, Columbus, OH 43210, USA
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23
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Zhao X, Bergland AO, Behrman EL, Gregory BD, Petrov DA, Schmidt PS. Global Transcriptional Profiling of Diapause and Climatic Adaptation in Drosophila melanogaster. Mol Biol Evol 2016; 33:707-20. [PMID: 26568616 PMCID: PMC5009998 DOI: 10.1093/molbev/msv263] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Wild populations of the model organism Drosophila melanogaster experience highly heterogeneous environments over broad geographical ranges as well as over seasonal and annual timescales. Diapause is a primary adaptation to environmental heterogeneity, and in D. melanogaster the propensity to enter diapause varies predictably with latitude and season. Here we performed global transcriptomic profiling of naturally occurring variation in diapause expression elicited by short day photoperiod and moderately low temperature in two tissue types associated with neuroendocrine and endocrine signaling, heads, and ovaries. We show that diapause in D. melanogaster is an actively regulated phenotype at the transcriptional level, suggesting that diapause is not a simple physiological or reproductive quiescence. Differentially expressed genes and pathways are highly distinct in heads and ovaries, demonstrating that the diapause response is not uniform throughout the soma and suggesting that it may be comprised of functional modules associated with specific tissues. Genes downregulated in heads of diapausing flies are significantly enriched for clinally varying single nucleotide polymorphism (SNPs) and seasonally oscillating SNPs, consistent with the hypothesis that diapause is a driving phenotype of climatic adaptation. We also show that chromosome location-based coregulation of gene expression is present in the transcriptional regulation of diapause. Taken together, these results demonstrate that diapause is a complex phenotype actively regulated in multiple tissues, and support the hypothesis that natural variation in diapause propensity underlies adaptation to spatially and temporally varying selective pressures.
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Affiliation(s)
- Xiaqing Zhao
- Department of Biology, University of Pennsylvania
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24
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Božičević V, Hutter S, Stephan W, Wollstein A. Population genetic evidence for cold adaptation in European Drosophila melanogaster populations. Mol Ecol 2016; 25:1175-91. [PMID: 26558479 DOI: 10.1111/mec.13464] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 01/05/2023]
Abstract
We studied Drosophila melanogaster populations from Europe (the Netherlands and France) and Africa (Rwanda and Zambia) to uncover genetic evidence of adaptation to cold. We present here four lines of evidence for genes involved in cold adaptation from four perspectives: (i) the frequency of SNPs at genes previously known to be associated with chill-coma recovery time (CCRT), startle reflex (SR) and resistance to starvation stress (RSS) vary along environmental gradients and therefore among populations; (ii) SNPs of genes that correlate significantly with latitude and altitude in African and European populations overlap with SNPs that correlate with a latitudinal cline from North America; (iii) at the genomewide level, the top candidate genes are enriched in gene ontology (GO) terms that are related to cold tolerance; (iv) GO enriched terms from North American clinal genes overlap significantly with those from Africa and Europe. Each SNP was tested in 10 independent runs of Bayenv2, using the median Bayes factors to ascertain candidate genes. None of the candidate genes were found close to the breakpoints of cosmopolitan inversions, and only four candidate genes were linked to QTLs related to CCRT. To overcome the limitation that we used only four populations to test correlations with environmental gradients, we performed simulations to estimate the power of our approach for detecting selection. Based on our results, we propose a novel network of genes that is involved in cold adaptation.
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Affiliation(s)
- Vedran Božičević
- Section of Evolutionary Biology, Department of Biology II, University of Munich, D-82152, Planegg-Martinsried, Germany
| | - Stephan Hutter
- Section of Evolutionary Biology, Department of Biology II, University of Munich, D-82152, Planegg-Martinsried, Germany
| | - Wolfgang Stephan
- Section of Evolutionary Biology, Department of Biology II, University of Munich, D-82152, Planegg-Martinsried, Germany
| | - Andreas Wollstein
- Section of Evolutionary Biology, Department of Biology II, University of Munich, D-82152, Planegg-Martinsried, Germany
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25
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Kučerová L, Kubrak OI, Bengtsson JM, Strnad H, Nylin S, Theopold U, Nässel DR. Slowed aging during reproductive dormancy is reflected in genome-wide transcriptome changes in Drosophila melanogaster. BMC Genomics 2016; 17:50. [PMID: 26758761 PMCID: PMC4711038 DOI: 10.1186/s12864-016-2383-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 01/06/2016] [Indexed: 12/28/2022] Open
Abstract
Background In models extensively used in studies of aging and extended lifespan, such as C. elegans and Drosophila, adult senescence is regulated by gene networks that are likely to be similar to ones that underlie lifespan extension during dormancy. These include the evolutionarily conserved insulin/IGF, TOR and germ line-signaling pathways. Dormancy, also known as dauer stage in the larval worm or adult diapause in the fly, is triggered by adverse environmental conditions, and results in drastically extended lifespan with negligible senescence. It is furthermore characterized by increased stress resistance and somatic maintenance, developmental arrest and reallocated energy resources. In the fly Drosophila melanogaster adult reproductive diapause is additionally manifested in arrested ovary development, improved immune defense and altered metabolism. However, the molecular mechanisms behind this adaptive lifespan extension are not well understood. Results A genome wide analysis of transcript changes in diapausing D. melanogaster revealed a differential regulation of more than 4600 genes. Gene ontology (GO) and KEGG pathway analysis reveal that many of these genes are part of signaling pathways that regulate metabolism, stress responses, detoxification, immunity, protein synthesis and processes during aging. More specifically, gene readouts and detailed mapping of the pathways indicate downregulation of insulin-IGF (IIS), target of rapamycin (TOR) and MAP kinase signaling, whereas Toll-dependent immune signaling, Jun-N-terminal kinase (JNK) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways are upregulated during diapause. Furthermore, we detected transcriptional regulation of a large number of genes specifically associated with aging and longevity. Conclusions We find that many affected genes and signal pathways are shared between dormancy, aging and lifespan extension, including IIS, TOR, JAK/STAT and JNK. A substantial fraction of the genes affected by diapause have also been found to alter their expression in response to starvation and cold exposure in D. melanogaster, and the pathways overlap those reported in GO analysis of other invertebrates in dormancy or even hibernating mammals. Our study, thus, shows that D. melanogaster is a genetically tractable model for dormancy in other organisms and effects of dormancy on aging and lifespan. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2383-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lucie Kučerová
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm, Sweden.
| | - Olga I Kubrak
- Department of Zoology, Stockholm University, S-106 91, Stockholm, Sweden.
| | - Jonas M Bengtsson
- Department of Zoology, Stockholm University, S-106 91, Stockholm, Sweden.
| | - Hynek Strnad
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
| | - Sören Nylin
- Department of Zoology, Stockholm University, S-106 91, Stockholm, Sweden.
| | - Ulrich Theopold
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm, Sweden.
| | - Dick R Nässel
- Department of Zoology, Stockholm University, S-106 91, Stockholm, Sweden.
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26
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Serga SV, Maistrenko OM, Rozhok AI, Mousseau TA, Kozeretska IA. Colonization of a temperate-zone region by the fruit fly Drosophila simulans (Diptera: Drosophilidae). CAN J ZOOL 2015. [DOI: 10.1139/cjz-2015-0018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The fruit flies Drosophila simulans Sturtevant, 1919 and Drosophila melanogaster Meigen, 1830 are sibling species that occupy similar niches. However, unlike D. simulans, D. melanogaster has spread far beyond tropical and subtropical regions deep into temperate climate zones. A number of invasion events by D. simulans into temperate climate zones have been reported; however, its ability to overwinter and establish local populations in these areas is disputed. Here, we report the wide dispersal of D. simulans in mixed populations with D. melanogaster in Ukraine. Drosophila simulans flies found in Ukraine belong to the siII mtDNA haplogroup and are infected with maternally inherited intracellular symbiotic bacteria of the genus Wolbachia Hertig, 1936 of the strain wRi. These genetic markers indicate a common origin of the Ukrainian D. simulans flies from a subgroup of the species found to invade other temperate climate areas worldwide. Here, we report for the first time detection of D. simulans flies early in the breeding season in a temperate climate area with severe winter conditions. We also report a moderate negative relationship between relative abundance of D. simulans and mean temperature in the month of sampling reflecting this species’ known lower tolerance of high temperatures.
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Affiliation(s)
- Svitlana V. Serga
- Taras Shevchenko National University of Kyiv, 01601, 64 Volodymyrska str, Kyiv, Ukraine
| | | | - Andrii I. Rozhok
- University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Timothy A. Mousseau
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Iryna A. Kozeretska
- Taras Shevchenko National University of Kyiv, 01601, 64 Volodymyrska str, Kyiv, Ukraine
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27
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Reis M, Valer FB, Vieira CP, Vieira J. Drosophila americana Diapausing Females Show Features Typical of Young Flies. PLoS One 2015; 10:e0138758. [PMID: 26398836 PMCID: PMC4580583 DOI: 10.1371/journal.pone.0138758] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 09/03/2015] [Indexed: 11/18/2022] Open
Abstract
Diapause is a period of arrested development which is controlled physiologically, preprogrammed environmentally and characterized by metabolic depression that can occur during any stage of insect development. Nevertheless, in the genus Drosophila, diapause is almost always associated with the cessation of ovarian development and reproductive activity in adult females. In this work, we show that, in D. americana (a temperate species of the virilis group), diapause is a genetically determined delay in ovarian development that is triggered by temperature and/or photoperiod. Moreover, we show that in this species diapause incidence increases with latitude, ranging from 13% in the southernmost to 91% in the northernmost range of the distribution. When exposed to diapause inducing conditions, both diapausing and non-diapausing females show a 10% increase in lifespan, that is further increased by 18.6% in diapausing females, although senescence is far from being negligible. ActinD1 expression levels suggest that diapausing females are biologically much younger than their chronological age, and that the fly as a whole, rather than the ovarian development alone, which is phenotypically more evident, is delayed by diapause. Therefore, diapause candidate genes that show expression levels that are compatible with flies younger than their chronological age may not necessarily play a role in reproductive diapause and in adaptation to seasonally varying environmental conditions.
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Affiliation(s)
- Micael Reis
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Felipe B. Valer
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
- Instituto de Biologia, Universidade Federal de Pelotas—UFPel, Pelotas, Rio Grande do Sul, Brazil
| | - Cristina P. Vieira
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Jorge Vieira
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
- * E-mail:
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28
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Behrman EL, Watson SS, O'Brien KR, Heschel MS, Schmidt PS. Seasonal variation in life history traits in two Drosophila species. J Evol Biol 2015; 28:1691-704. [PMID: 26174167 DOI: 10.1111/jeb.12690] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 06/30/2015] [Accepted: 07/01/2015] [Indexed: 01/16/2023]
Abstract
Seasonal environmental heterogeneity is cyclic, persistent and geographically widespread. In species that reproduce multiple times annually, environmental changes across seasonal time may create different selection regimes that may shape the population ecology and life history adaptation in these species. Here, we investigate how two closely related species of Drosophila in a temperate orchard respond to environmental changes across seasonal time. Natural populations of Drosophila melanogaster and Drosophila simulans were sampled at four timepoints from June through November to assess seasonal change in fundamental aspects of population dynamics as well as life history traits. D. melanogaster exhibit pronounced change across seasonal time: early in the season, the population is inferred to be uniformly young and potentially represents the early generation following overwintering survivorship. D. melanogaster isofemale lines derived from the early population and reared in a common garden are characterized by high tolerance to a variety of stressors as well as a fast rate of development in the laboratory environment that declines across seasonal time. In contrast, wild D. simulans populations were inferred to be consistently heterogeneous in age distribution across seasonal collections; only starvation tolerance changed predictably over seasonal time in a parallel manner as in D. melanogaster. These results suggest fundamental differences in population and evolutionary dynamics between these two taxa associated with seasonal heterogeneity in environmental parameters and associated selection pressures.
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Affiliation(s)
- E L Behrman
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - S S Watson
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - K R O'Brien
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.,School of Biological Sciences, University of Nebraska, Lincoln, NE, USA
| | - M S Heschel
- Department of Organismal Biology & Ecology, Colorado College, Colorado Springs, CO, USA
| | - P S Schmidt
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
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29
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Jha AR, Miles CM, Lippert NR, Brown CD, White KP, Kreitman M. Whole-Genome Resequencing of Experimental Populations Reveals Polygenic Basis of Egg-Size Variation in Drosophila melanogaster. Mol Biol Evol 2015; 32:2616-32. [PMID: 26044351 PMCID: PMC4576704 DOI: 10.1093/molbev/msv136] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Complete genome resequencing of populations holds great promise in deconstructing complex polygenic traits to elucidate molecular and developmental mechanisms of adaptation. Egg size is a classic adaptive trait in insects, birds, and other taxa, but its highly polygenic architecture has prevented high-resolution genetic analysis. We used replicated experimental evolution in Drosophila melanogaster and whole-genome sequencing to identify consistent signatures of polygenic egg-size adaptation. A generalized linear-mixed model revealed reproducible allele frequency differences between replicated experimental populations selected for large and small egg volumes at approximately 4,000 single nucleotide polymorphisms (SNPs). Several hundred distinct genomic regions contain clusters of these SNPs and have lower heterozygosity than the genomic background, consistent with selection acting on polymorphisms in these regions. These SNPs are also enriched among genes expressed in Drosophila ovaries and many of these genes have well-defined functions in Drosophila oogenesis. Additional genes regulating egg development, growth, and cell size show evidence of directional selection as genes regulating these biological processes are enriched for highly differentiated SNPs. Genetic crosses performed with a subset of candidate genes demonstrated that these genes influence egg size, at least in the large genetic background. These findings confirm the highly polygenic architecture of this adaptive trait, and suggest the involvement of many novel candidate genes in regulating egg size.
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Affiliation(s)
- Aashish R Jha
- Institute for Genomics and Systems Biology, The University of Chicago Department of Human Genetics, The University of Chicago Department of Ecology and Evolution, The University of Chicago
| | | | | | - Christopher D Brown
- Institute for Genomics and Systems Biology, The University of Chicago Department of Genetics, Perelman School of Medicine, University of Pennsylvania
| | - Kevin P White
- Institute for Genomics and Systems Biology, The University of Chicago Department of Human Genetics, The University of Chicago Department of Ecology and Evolution, The University of Chicago Committee on Genetics, Genomics & Systems Biology, The University of Chicago
| | - Martin Kreitman
- Institute for Genomics and Systems Biology, The University of Chicago Department of Ecology and Evolution, The University of Chicago Committee on Genetics, Genomics & Systems Biology, The University of Chicago
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30
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Ullastres A, Petit N, González J. Exploring the Phenotypic Space and the Evolutionary History of a Natural Mutation in Drosophila melanogaster. Mol Biol Evol 2015; 32:1800-14. [PMID: 25862139 PMCID: PMC4476160 DOI: 10.1093/molbev/msv061] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A major challenge of modern Biology is elucidating the functional consequences of natural mutations. Although we have a good understanding of the effects of laboratory-induced mutations on the molecular- and organismal-level phenotypes, the study of natural mutations has lagged behind. In this work, we explore the phenotypic space and the evolutionary history of a previously identified adaptive transposable element insertion. We first combined several tests that capture different signatures of selection to show that there is evidence of positive selection in the regions flanking FBti0019386 insertion. We then explored several phenotypes related to known phenotypic effects of nearby genes, and having plausible connections to fitness variation in nature. We found that flies with FBti0019386 insertion had a shorter developmental time and were more sensitive to stress, which are likely to be the adaptive effect and the cost of selection of this mutation, respectively. Interestingly, these phenotypic effects are not consistent with a role of FBti0019386 in temperate adaptation as has been previously suggested. Indeed, a global analysis of the population frequency of FBti0019386 showed that climatic variables explain well the FBti0019386 frequency patterns only in Australia. Finally, although FBti0019386 insertion could be inducing the formation of heterochromatin by recruiting HP1a (Heterochromatin Protein 1a) protein, the insertion is associated with upregulation of sra in adult females. Overall, our integrative approach allowed us to shed light on the evolutionary history, the relevant fitness effects, and the likely molecular mechanisms of an adaptive mutation and highlights the complexity of natural genetic variants.
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Affiliation(s)
- Anna Ullastres
- Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Barcelona, Spain
| | - Natalia Petit
- Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Barcelona, Spain
| | - Josefa González
- Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Barcelona, Spain
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31
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Fabian DK, Lack JB, Mathur V, Schlötterer C, Schmidt PS, Pool JE, Flatt T. Spatially varying selection shapes life history clines among populations of Drosophila melanogaster from sub-Saharan Africa. J Evol Biol 2015; 28:826-40. [PMID: 25704153 DOI: 10.1111/jeb.12607] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/12/2015] [Accepted: 02/17/2015] [Indexed: 01/31/2023]
Abstract
Clines in life history traits, presumably driven by spatially varying selection, are widespread. Major latitudinal clines have been observed, for example, in Drosophila melanogaster, an ancestrally tropical insect from Africa that has colonized temperate habitats on multiple continents. Yet, how geographic factors other than latitude, such as altitude or longitude, affect life history in this species remains poorly understood. Moreover, most previous work has been performed on derived European, American and Australian populations, but whether life history also varies predictably with geography in the ancestral Afro-tropical range has not been investigated systematically. Here, we have examined life history variation among populations of D. melanogaster from sub-Saharan Africa. Viability and reproductive diapause did not vary with geography, but body size increased with altitude, latitude and longitude. Early fecundity covaried positively with altitude and latitude, whereas lifespan showed the opposite trend. Examination of genetic variance-covariance matrices revealed geographic differentiation also in trade-off structure, and QST -FST analysis showed that life history differentiation among populations is likely shaped by selection. Together, our results suggest that geographic and/or climatic factors drive adaptive phenotypic differentiation among ancestral African populations and confirm the widely held notion that latitude and altitude represent parallel gradients.
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Affiliation(s)
- D K Fabian
- Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria; Vienna Graduate School of Population Genetics, Vienna, Austria
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32
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Paaby AB, Bergland AO, Behrman EL, Schmidt PS. A highly pleiotropic amino acid polymorphism in the Drosophila insulin receptor contributes to life-history adaptation. Evolution 2014; 68:3395-409. [PMID: 25319083 DOI: 10.1111/evo.12546] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 10/05/2014] [Indexed: 12/24/2022]
Abstract
Finding the specific nucleotides that underlie adaptive variation is a major goal in evolutionary biology, but polygenic traits pose a challenge because the complex genotype-phenotype relationship can obscure the effects of individual alleles. However, natural selection working in large wild populations can shift allele frequencies and indicate functional regions of the genome. Previously, we showed that the two most common alleles of a complex amino acid insertion-deletion polymorphism in the Drosophila insulin receptor show independent, parallel clines in frequency across the North American and Australian continents. Here, we report that the cline is stable over at least a five-year period and that the polymorphism also demonstrates temporal shifts in allele frequency concurrent with seasonal change. We tested the alleles for effects on levels of insulin signaling, fecundity, development time, body size, stress tolerance, and life span. We find that the alleles are associated with predictable differences in these traits, consistent with patterns of Drosophila life-history variation across geography that likely reflect adaptation to the heterogeneous climatic environment. These results implicate insulin signaling as a major mediator of life-history adaptation in Drosophila, and suggest that life-history trade-offs can be explained by extensive pleiotropy at a single locus.
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Affiliation(s)
- Annalise B Paaby
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, 19104; Current Address: Department of Biology, Center for Genomics & Systems Biology, New York University, New York, New York, 10003.
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33
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Kubrak OI, Kučerová L, Theopold U, Nässel DR. The sleeping beauty: how reproductive diapause affects hormone signaling, metabolism, immune response and somatic maintenance in Drosophila melanogaster. PLoS One 2014; 9:e113051. [PMID: 25393614 PMCID: PMC4231144 DOI: 10.1371/journal.pone.0113051] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/17/2014] [Indexed: 12/28/2022] Open
Abstract
Some organisms can adapt to seasonal and other environmental challenges by entering a state of dormancy, diapause. Thus, insects exposed to decreased temperature and short photoperiod enter a state of arrested development, lowered metabolism, and increased stress resistance. Drosophila melanogaster females can enter a shallow reproductive diapause in the adult stage, which drastically reduces organismal senescence, but little is known about the physiology and endocrinology associated with this dormancy, and the genes involved in its regulation. We induced diapause in D. melanogaster and monitored effects over 12 weeks on dynamics of ovary development, carbohydrate and lipid metabolism, as well as expression of genes involved in endocrine signaling, metabolism and innate immunity. During diapause food intake diminishes drastically, but circulating and stored carbohydrates and lipids are elevated. Gene transcripts of glucagon- and insulin-like peptides increase, and expression of several target genes of these peptides also change. Four key genes in innate immunity can be induced by infection in diapausing flies, and two of these, drosomycin and cecropin A1, are upregulated by diapause independently of infection. Diapausing flies display very low mortality, extended lifespan and decreased aging of the intestinal epithelium. Many phenotypes induced by diapause are reversed after one week of recovery from diapause conditions. Furthermore, mutant flies lacking specific insulin-like peptides (dilp5 and dilp2-3) display increased diapause incidence. Our study provides a first comprehensive characterization of reproductive diapause in D. melanogaster, and evidence that glucagon- and insulin-like signaling are among the key regulators of the altered physiology during this dormancy.
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Affiliation(s)
- Olga I. Kubrak
- Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden
| | - Lucie Kučerová
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Ulrich Theopold
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Dick R. Nässel
- Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden
- * E-mail:
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34
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Bergland AO, Behrman EL, O'Brien KR, Schmidt PS, Petrov DA. Genomic evidence of rapid and stable adaptive oscillations over seasonal time scales in Drosophila. PLoS Genet 2014; 10:e1004775. [PMID: 25375361 PMCID: PMC4222749 DOI: 10.1371/journal.pgen.1004775] [Citation(s) in RCA: 329] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 09/24/2014] [Indexed: 01/06/2023] Open
Abstract
In many species, genomic data have revealed pervasive adaptive evolution indicated by the fixation of beneficial alleles. However, when selection pressures are highly variable along a species' range or through time adaptive alleles may persist at intermediate frequencies for long periods. So called “balanced polymorphisms” have long been understood to be an important component of standing genetic variation, yet direct evidence of the strength of balancing selection and the stability and prevalence of balanced polymorphisms has remained elusive. We hypothesized that environmental fluctuations among seasons in a North American orchard would impose temporally variable selection on Drosophila melanogaster that would drive repeatable adaptive oscillations at balanced polymorphisms. We identified hundreds of polymorphisms whose frequency oscillates among seasons and argue that these loci are subject to strong, temporally variable selection. We show that these polymorphisms respond to acute and persistent changes in climate and are associated in predictable ways with seasonally variable phenotypes. In addition, our results suggest that adaptively oscillating polymorphisms are likely millions of years old, with some possibly predating the divergence between D. melanogaster and D. simulans. Taken together, our results are consistent with a model of balancing selection wherein rapid temporal fluctuations in climate over generational time promotes adaptive genetic diversity at loci underlying polygenic variation in fitness related phenotypes. Herein, we investigate the genomic basis of rapid adaptive evolution in response to seasonal fluctuations in the environment. We identify hundreds of polymorphisms (seasonal SNPs) that undergo dramatic shifts in allele frequency – on average between 40 and 60% – and oscillate between seasons repeatedly over multiple years, likely inducing high levels of genome-wide genetic differentiation. We provide evidence that seasonal SNPs are functional, being both sensitive to an acute frost event and associated with two stress tolerance traits. Finally, we show that some seasonal SNPs are possibly ancient balanced polymorphisms. Taken together, our results suggest that environmental heterogeneity can promote the long-term persistence of functional polymorphisms within populations that fuels fast directional adaptive response at any one time.
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Affiliation(s)
- Alan O. Bergland
- Department of Biology, Stanford University, Stanford, California, United States of America
- * E-mail:
| | - Emily L. Behrman
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Katherine R. O'Brien
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Paul S. Schmidt
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Dmitri A. Petrov
- Department of Biology, Stanford University, Stanford, California, United States of America
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35
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Maguire SE, Schmidt PS, Sehgal A. Natural Populations of Drosophila melanogaster Reveal Features of an Uncharacterized Circadian Property: The Lower Temperature Limit of Rhythmicity. J Biol Rhythms 2014; 29:167-180. [PMID: 24916390 DOI: 10.1177/0748730414537801] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Most cyclic biological processes are under control of a circadian molecular timing system that synchronizes these phenomena to the 24-h day. One generic property of circadian-controlled processes is that they operate within a specific temperature range, below which the manifestation of rhythm ceases. Little is known about the evolutionary relevance of the lower temperature limit of rhythmicity or about the mechanism underlying the loss of overt circadian behavior below this lower limit, especially in one model organism of chronobiology, Drosophila melanogaster. Natural populations of Drosophila are evolving under divergent selection pressures and so provide a source of diversity necessary to address these issues. Using lines derived from African populations, we find that there is natural variation in the expression of rhythmic behavior under low-temperature conditions. We found evidence that this variability is evolutionarily relevant at extremely low temperature (12 °C) because high-altitude populations exhibit selection for locally adapted genomes that contribute to rhythmic behavior. Lines resistant to 15 °C show an additional layer of diversity in their response to temperature extremes because some lines are resistant to low temperature (15 °C) only, whereas others are cross-resistant to high and low temperature (15 °C and 30 °C). Genetic analysis of one cold-resistant circadian line at 15 °C reveals that the phenotype maps to the X-chromosome but not to the core clock genes, per and sgg. Analysis of the central clock cells of this line reveals that maintenance of rhythm is associated with robust clock function, which is compromised in a standard laboratory strain. These data indicate that the cold-resistant circadian phenotype is clock based. This study highlights the importance of using natural populations to inform us of the basic features of circadian traits, especially those that might be under temperature-based selection.
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Affiliation(s)
- Sarah E Maguire
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Paul S Schmidt
- Department of Biology, University of Pennsylvania School of Arts and Sciences, Philadelphia, PA, USA
| | - Amita Sehgal
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA, USA Howard Hughes Medical Institute, Chevy Chase, MD, USA
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36
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Mockett RJ, Matsumoto Y. Effect of prolonged coldness on survival and fertility of Drosophila melanogaster. PLoS One 2014; 9:e92228. [PMID: 24632815 PMCID: PMC3954892 DOI: 10.1371/journal.pone.0092228] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 02/19/2014] [Indexed: 11/19/2022] Open
Abstract
The laboratory fruit fly, Drosophila melanogaster, is used widely in biological research, but the requirement to maintain stocks with a roughly biweekly generation time imposes substantial burdens of labor, potential cross-contamination and mutation accumulation. The purpose of this study was to assess the impact of prolonged cold stress or milder cooling on survivorship and fertility. The hypothesis was that cold storage would result in postponement of reproduction and a longer generation time. Flies of several genotypes were maintained continuously at 4–11°C; recovery rates and subsequent yields of adult progeny were recorded. Adults and pupae of a relatively long-lived y w lineage were more resistant to severe cold stress than embryos and larvae. Adults exhibited minimal mortality up to at least 5 d at 4°C, 20 d at 8°C and 12 weeks at 11°C. Reproduction did not occur at these temperatures, but progeny were obtained after recovery at 25°C. At all temperatures, chilling caused a rapid, severe and progressive decrease in fertility during the first 2 d of recovery. The impact on fertility during the subsequent 2–4 d was much milder and it occurred only after prolonged incubation at low temperatures. The total reproductive output during the first 6 d of recovery was sufficient to replace the parental population after 12 weeks at 11°C. Food spoilage had an unexpectedly low impact on survivorship and fertility, and the reproductive output of F1 progeny was not affected by storing parental flies at 11°C for 8–10 weeks. In the case of w1118 flies, replacement of the parents within 6 d of recovery was possible for up to 60 d at 11°C. Among less fertile genotypes, replacement of the parents was possible within 18 d after 4–10 weeks at 11°C. These results show that the 2-week maintenance interval of stocks of D. melanogaster can be extended 3–7 fold, at least for 1 generation, by storing adult flies at 11°C.
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Affiliation(s)
- Robin J. Mockett
- Department of Biomedical Sciences, University of South Alabama, Mobile, Alabama, United States of America
- * E-mail:
| | - Yuri Matsumoto
- Department of Biomedical Sciences, University of South Alabama, Mobile, Alabama, United States of America
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37
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Abstract
Diapause, a dominant feature in the life history of many mosquito species, offers a mechanism for bridging unfavorable seasons in both temperate and tropical environments and serves to synchronize development within populations, thus directly affecting disease transmission cycles. The trait appears to have evolved independently numerous times within the Culicidae, as exemplified by the diverse developmental stages of diapause in closely related species. Its impact is pervasive, not only influencing the arrested stage, but also frequently altering physiological processes both before and after diapause. How the diapause response can be molded evolutionarily is critical for understanding potential range expansions of native and newly introduced species. The study of hormonal regulation of mosquito diapause has focused primarily on adult diapause, with little current information available on larval diapause or the intriguing maternal effects that regulate egg diapause. Recent quantitative trait locus, transcriptome, and RNA interference studies hold promise for interpreting the complex suite of genes that subserve the diapause phenotype.
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Affiliation(s)
- David L Denlinger
- Departments of Entomology and Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, Ohio 43210;
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38
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Flatt T, Amdam GV, Kirkwood TBL, Omholt SW. Life-history evolution and the polyphenic regulation of somatic maintenance and survival. QUARTERLY REVIEW OF BIOLOGY 2013; 88:185-218. [PMID: 24053071 DOI: 10.1086/671484] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Here we discuss life-history evolution from the perspective of adaptive phenotypic plasticity, with a focus on polyphenisms for somatic maintenance and survival. Polyphenisms are adaptive discrete alternative phenotypes that develop in response to changes in the environment. We suggest that dauer larval diapause and its associated adult phenotypes in the nematode (Caenorhabditis elegans), reproductive dormancy in the fruit fly (Drosophila melanogaster) and other insects, and the worker castes of the honey bee (Apis mellifera) are examples of what may be viewed as the polyphenic regulation of somatic maintenance and survival. In these and other cases, the same genotype can--depending upon its environment--express either of two alternative sets of life-history phenotypes that differ markedly with respect to somatic maintenance, survival ability, and thus life span. This plastic modulation of somatic maintenance and survival has traditionally been underappreciated by researchers working on aging and life history. We review the current evidence for such adaptive life-history switches and their molecular regulation and suggest that they are caused by temporally and/or spatially varying, stressful environments that impose diversifying selection, thereby favoring the evolution of plasticity of somatic maintenance and survival under strong regulatory control. By considering somatic maintenance and survivorship from the perspective of adaptive life-history switches, we may gain novel insights into the mechanisms and evolution of aging.
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Affiliation(s)
- Thomas Flatt
- Institut für Populationsgenetik, Vetmeduni Vienna, A-1210 Vienna, Austria.
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39
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Latitudinal Variation in Starvation Resistance is Explained by Lipid Content in Natural Populations of Drosophila melanogaster. Evol Biol 2013. [DOI: 10.1007/s11692-013-9235-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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40
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Kobey RL, Montooth KL. Mortality from desiccation contributes to a genotype-temperature interaction for cold survival in Drosophila melanogaster. ACTA ACUST UNITED AC 2012. [PMID: 23197100 DOI: 10.1242/jeb.076539] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Survival at cold temperatures is a complex trait, primarily because of the fact that the physiological cause of injury may differ across degrees of cold exposure experienced within the lifetime of an ectothermic individual. In order to better understand how chill-sensitive insects experience and adapt to low temperatures, we investigated the physiological basis for cold survival across a range of temperature exposures from -4 to 6°C in five genetic lines of the fruit fly Drosophila melanogaster. Genetic effects on cold survival were temperature dependent and resulted in a significant genotype-temperature interaction for survival across cold temperature exposures that differ by as little as 2°C. We investigated desiccation as a potential mechanism of injury across these temperature exposures. Flies were dehydrated following exposures near 6°C, whereas flies were not dehydrated following exposures near -4°C. Furthermore, decreasing humidity during cold exposure decreased survival, and increasing humidity during cold exposure increased survival at 6°C, but not at -4°C. These results support the conclusion that in D. melanogaster there are multiple physiological mechanisms of cold-induced mortality across relatively small differences in temperature, and that desiccation contributes to mortality for exposures near 6°C but not for subzero temperatures. Because D. melanogaster has recently expanded its range from tropical to temperate latitudes, the complex physiologies underlying cold tolerance are likely to be important traits in the recent evolutionary history of this fruit fly.
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Affiliation(s)
- Robert L Kobey
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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41
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Fabian DK, Kapun M, Nolte V, Kofler R, Schmidt PS, Schlötterer C, Flatt T. Genome-wide patterns of latitudinal differentiation among populations of Drosophila melanogaster from North America. Mol Ecol 2012; 21:4748-69. [PMID: 22913798 PMCID: PMC3482935 DOI: 10.1111/j.1365-294x.2012.05731.x] [Citation(s) in RCA: 177] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 06/29/2012] [Accepted: 07/04/2012] [Indexed: 01/18/2023]
Abstract
Understanding the genetic underpinnings of adaptive change is a fundamental but largely unresolved problem in evolutionary biology. Drosophila melanogaster, an ancestrally tropical insect that has spread to temperate regions and become cosmopolitan, offers a powerful opportunity for identifying the molecular polymorphisms underlying clinal adaptation. Here, we use genome-wide next-generation sequencing of DNA pools ('pool-seq') from three populations collected along the North American east coast to examine patterns of latitudinal differentiation. Comparing the genomes of these populations is particularly interesting since they exhibit clinal variation in a number of important life history traits. We find extensive latitudinal differentiation, with many of the most strongly differentiated genes involved in major functional pathways such as the insulin/TOR, ecdysone, torso, EGFR, TGFβ/BMP, JAK/STAT, immunity and circadian rhythm pathways. We observe particularly strong differentiation on chromosome 3R, especially within the cosmopolitan inversion In(3R)Payne, which contains a large number of clinally varying genes. While much of the differentiation might be driven by clinal differences in the frequency of In(3R)P, we also identify genes that are likely independent of this inversion. Our results provide genome-wide evidence consistent with pervasive spatially variable selection acting on numerous loci and pathways along the well-known North American cline, with many candidates implicated in life history regulation and exhibiting parallel differentiation along the previously investigated Australian cline.
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Affiliation(s)
- Daniel K Fabian
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, A-1210, Vienna, Austria
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COOPER BS, CZARNOLESKI M, ANGILLETTA MJ. Acclimation of thermal physiology in natural populations of Drosophila melanogaster : a test of an optimality model. J Evol Biol 2010; 23:2346-55. [DOI: 10.1111/j.1420-9101.2010.02095.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Rand DM, Weinreich DM, Lerman D, Folk D, Gilchrist GW. Three selections are better than one: clinal variation of thermal QTL from independent selection experiments in Drosophila. Evolution 2010; 64:2921-34. [PMID: 20497214 DOI: 10.1111/j.1558-5646.2010.01039.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: 01/23/2023]
Abstract
We report the results of two independent selection experiments that have exposed distinct populations of Drosophila melanogaster to different forms of thermal selection. A recombinant population derived from Arvin California and Zimbabwe isofemale lines was exposed to laboratory natural selection at two temperatures (T(AZ): 18°C and 28°C). Microsatellite mapping identified quantitative trait loci (QTL) on the X-chromosome between the replicate "Hot" and "Cold" populations. In a separate experiment, disruptive selection was imposed on an outbred California population for the "knockdown" temperature (T(KD)) in a thermal column. Microsatellite mapping of the "High" and "Low" populations also uncovered primarily X-linked QTL. Notably, a marker in the shaggy locus at band 3A was significantly differentiated in both experiments. Finer scale mapping of the 3A region has narrowed the QTL to the shaggy gene region, which contains several candidate genes that function in circadian rhythms. The same allele that was increased in frequency in the High T(KD) populations is significantly clinal in North America and is more common at the warm end of the cline (Florida vs. Maine; however, the cline was not apparent in Australia). Together, these studies show that independent selection experiments can uncover the same target of selection and that evolution in the laboratory can recapitulate putatively adaptive clinal variation in nature.
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Affiliation(s)
- David M Rand
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912, USA.
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PAABY ANNALISEB, BLACKET MARKJ, HOFFMANN ARYA, SCHMIDT PAULS. Identification of a candidate adaptive polymorphism forDrosophilalife history by parallel independent clines on two continents. Mol Ecol 2010; 19:760-74. [DOI: 10.1111/j.1365-294x.2009.04508.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Emerson KJ, Uyemura AM, McDaniel KL, Schmidt PS, Bradshaw WE, Holzapfel CM. Environmental control of ovarian dormancy in natural populations of Drosophila melanogaster. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2009; 195:825-9. [PMID: 19669646 DOI: 10.1007/s00359-009-0460-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 07/03/2009] [Accepted: 07/09/2009] [Indexed: 11/24/2022]
Abstract
Drosophila melanogaster from Australia, Europe and North America enter an adult ovarian dormancy in response to short days and low temperatures. The independent effects of temperature and day length in the determination of dormancy have been examined only in one long-established laboratory line (Canton-S). In all other studies of natural or laboratory populations, dormancy has been assessed at either a single short day or a single moderately low temperature. Herein, we determine the relative roles of temperature, photoperiod, and their interaction in the control of ovarian dormancy in D. melanogaster from two natural populations representing latitudinal extremes in eastern North America (Florida at 27 degrees N and Maine at 44 degrees N). In both natural populations, temperature is the main determinant of dormancy, alone explaining 67% of the total variation among replicate isofemale lines, whereas photoperiod has no significant effect. We conclude that ovarian dormancy in D. melanogaster is a temperature-initiated syndrome of winter-tolerant traits that represents an adaptive phenotypic plasticity in temperate seasonal environments.
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Affiliation(s)
- Kevin J Emerson
- Center for Ecology and Evolutionary Biology, University of Oregon, Eugene, OR 97403-5289, USA.
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Kothera L, Zimmerman EM, Richards CM, Savage HM. Microsatellite characterization of subspecies and their hybrids in Culex pipiens complex (Diptera: Culicidae) mosquitoes along a north-south transect in the central United States. JOURNAL OF MEDICAL ENTOMOLOGY 2009; 46:236-248. [PMID: 19351074 DOI: 10.1603/033.046.0208] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Mosquitoes in the Culex pipiens complex, Cx. p. pipiens L. and Cx. p. quinquefasciatus Say are morphologically similar and important vectors of West Nile and St. Louis Encephalitis viruses in the United States. The subspecies differ with respect to overwintering strategies, with Cx. p. pipiens entering diapause in response to winter conditions and Cx. p. quinquefasciatus lacking this ability, yet they hybridize when found in sympatry. Specimens (n = 646) were collected using gravid traps set along a transect from New Orleans, LA, to Chicago, IL. Microsatellite markers were used to: genetically characterize subspecies and hybrids, determine the degree and extent of hybridization to better define the hybrid zone, and examine the efficacy of hybrid detection between microsatellites and a single-gene assay based on the acetylcholinesterase.2 gene (HotAce.2). The results support the presence of two distinct genetic entities, with abroad, stable hybrid zone in between. Admixture analyses classified >40% of individuals as hybrids. Allelic richness was markedly different at the northern and southern ends of the transect, and there was a significant isolation by distance effect. The hybrid zone seems to be wider and extends further to the south than previous work indicated, and as a result, we propose new boundaries compared with those indicated by a previous study. Microsatellites detected more hybrids than the HotAce.2 assay, although the latter assay remains useful as a screening tool. We suggest that the parental subspecies and the hybrid zone are maintained by heterosis combined with selection for diapause at northern latitudes.
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Affiliation(s)
- Linda Kothera
- Centers for Disease Control and Prevention, Division of Vector-Borne Infectious Diseases, 3150 Rampart Rd., Fort Collins, CO 80521, USA.
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An amino acid polymorphism in the couch potato gene forms the basis for climatic adaptation in Drosophila melanogaster. Proc Natl Acad Sci U S A 2008; 105:16207-11. [PMID: 18852464 DOI: 10.1073/pnas.0805485105] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Diapause is the classic adaptation to seasonality in arthropods, and its expression can result in extreme lifespan extension as well as enhanced resistance to environmental challenges. Little is known about the underlying evolutionary genetic architecture of diapause in any organism. Drosophila melanogaster exhibits a reproductive diapause that is variable within and among populations; the incidence of diapause increases with more temperate climates and has significant pleiotropic effects on a number of life history traits. Using quantitative trait mapping, we identified the RNA-binding protein encoding gene couch potato (cpo) as a major genetic locus determining diapause phenotype in D. melanogaster and independently confirmed this ability to impact diapause expression through genetic complementation mapping. By sequencing this gene in samples from natural populations we demonstrated through linkage association that variation for the diapause phenotype is caused by a single Lys/Ile substitution in one of the six cpo transcripts. Complementation analyses confirmed that the identified amino acid variants are functionally distinct with respect to diapause expression, and the polymorphism also shows geographic variation that closely mirrors the known latitudinal cline in diapause incidence. Our results suggest that a naturally occurring amino acid polymorphism results in the variable expression of a diapause syndrome that is associated with the seasonal persistence of this model organism in temperate habitats.
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Samis KE, Heath KD, Stinchcombe JR. Discordant longitudinal clines in flowering time and phytochrome C in Arabidopsis thaliana. Evolution 2008; 62:2971-83. [PMID: 18752603 DOI: 10.1111/j.1558-5646.2008.00484.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Using seasonal cues to time reproduction appropriately is crucial for many organisms. Plants in particular often use photoperiod to signal the time to transition to flowering. Because seasonality varies latitudinally, adaptation to local climate is expected to result in corresponding clines in photoperiod-related traits. By experimentally manipulating photoperiod cues and measuring the flowering responses and photoperiod plasticity of 138 Eurasian accessions of Arabidopsis thaliana, we detected strong longitudinal but not latitudinal clines in flowering responses. The presence of longitudinal clines suggests that critical photoperiod cues vary among populations occurring at similar latitudes. Haplotypes at PHYC, a locus hypothesized to play a role in adaptation to light cues, were also longitudinally differentiated. Controlling for neutral population structure revealed that PHYC haplotype influenced flowering time; however, the distribution of PHYC haplotypes occurred in the opposite direction to the phenotypic cline, suggesting that loci other than PHYC are responsible for the longitudinal pattern in photoperiod response. Our results provide previously missing empirical support for the importance of PHYC in mediating photoperiod sensitivity in natural populations of A. thaliana. However, they also suggest that other loci and epistatic interactions likely play a role in the determination of flowering time and that the environmental factors influencing photoperiod in plants vary longitudinally as well as latitudinally.
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Affiliation(s)
- Karen E Samis
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
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