1
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Wohlleben AM, Tabima JF, Meyer NP, Steinel NC. Population-level immunologic variation in wild threespine stickleback (Gasterosteusaculeatus). FISH & SHELLFISH IMMUNOLOGY 2024; 149:109580. [PMID: 38663464 DOI: 10.1016/j.fsi.2024.109580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/25/2024] [Accepted: 04/19/2024] [Indexed: 05/09/2024]
Abstract
Wild organisms are regularly exposed to a wide range of parasites, requiring the management of an effective immune response while avoiding immunopathology. Currently, our knowledge of immunoparasitology primarily derives from controlled laboratory studies, neglecting the genetic and environmental diversity that contribute to immune phenotypes observed in wild populations. To gain insight into the immunologic variability in natural settings, we examined differences in immune gene expression of two Alaskan stickleback (Gasterosteus aculeatus) populations with varying susceptibility to infection by the cestode Schistocephalus solidus. Between these two populations, we found distinct immune gene expression patterns at the population level in response to infection with fish from the high-infection population displaying signs of parasite-driven immune manipulation. Further, we found significant differences in baseline immune gene profiles between the populations, with uninfected low-infection population fish showing signatures of inflammation compared to uninfected high-infection population fish. These results shed light on divergent responses of wild populations to the same parasite, providing valuable insights into host-parasite interactions in natural ecosystems.
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Affiliation(s)
- Anika M Wohlleben
- Institute of Zoology and Evolutionary Research, Friedrich Schiller University Jena, Jena, Germany; Biology Department, Clark University, Worcester, MA, USA.
| | | | - Néva P Meyer
- Biology Department, Clark University, Worcester, MA, USA
| | - Natalie C Steinel
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA; Center for Pathogen Research and Training, University of Massachusetts Lowell, Lowell, MA, USA
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2
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Peuß R, Box AC, Chen S, Wang Y, Tsuchiya D, Persons JL, Kenzior A, Maldonado E, Krishnan J, Scharsack JP, Slaughter BD, Rohner N. Adaptation to low parasite abundance affects immune investment and immunopathological responses of cavefish. Nat Ecol Evol 2020; 4:1416-1430. [PMID: 32690906 PMCID: PMC11062081 DOI: 10.1038/s41559-020-1234-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 05/22/2020] [Indexed: 02/07/2023]
Abstract
Reduced parasitic infection rates in the developed world are suspected to underlie the rising prevalence of autoimmune disorders. However, the long-term evolutionary consequences of decreased parasite exposure on an immune system are not well understood. We used the Mexican tetra Astyanax mexicanus to understand how loss of parasite diversity influences the evolutionary trajectory of the vertebrate immune system, by comparing river with cave morphotypes. Here, we present field data affirming a strong reduction in parasite diversity in the cave ecosystem, and show that cavefish immune cells display a more sensitive pro-inflammatory response towards bacterial endotoxins. Surprisingly, other innate cellular immune responses, such as phagocytosis, are drastically decreased in cavefish. Using two independent single-cell approaches, we identified a shift in the overall immune cell composition in cavefish as the underlying cellular mechanism, indicating strong differences in the immune investment strategy. While surface fish invest evenly into the innate and adaptive immune systems, cavefish shifted immune investment to the adaptive immune system, and here, mainly towards specific T-cell populations that promote homeostasis. Additionally, inflammatory responses and immunopathological phenotypes in visceral adipose tissue are drastically reduced in cavefish. Our data indicate that long-term adaptation to low parasite diversity coincides with a more sensitive immune system in cavefish, which is accompanied by a reduction in the immune cells that play a role in mediating the pro-inflammatory response.
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Affiliation(s)
- Robert Peuß
- Stowers Institute for Medical Research, Kansas City, MO, USA.
| | - Andrew C Box
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Shiyuan Chen
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Yongfu Wang
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Dai Tsuchiya
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Jenna L Persons
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | | | - Ernesto Maldonado
- EvoDevo Research Group, Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Mexico
| | - Jaya Krishnan
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Jörn P Scharsack
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
- Thünen Institute of Fisheries Ecology, Bremerhaven, Germany
| | | | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO, USA.
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA.
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3
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Tibblin P, Hall M, Svensson PA, Merilä J, Forsman A. Phenotypic flexibility in background-mediated color change in sticklebacks. Behav Ecol 2020; 31:950-959. [PMID: 32760177 PMCID: PMC7390996 DOI: 10.1093/beheco/araa041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 03/31/2020] [Accepted: 04/15/2020] [Indexed: 01/04/2023] Open
Abstract
Phenotypic flexibility may incur a selective advantage in changing and heterogeneous environments, and is increasingly recognized as an integral aspect of organismal adaptation. Despite the widespread occurrence and potential importance of rapid and reversible background-mediated color change for predator avoidance, knowledge gaps remain regarding its adaptive value, repeatability within individuals, phenotypic correlates, and whether its expression is context dependent. We used manipulative experiments to investigate these issues in two fish species, the three-spined stickleback (Gasterosteus aculeatus) and nine-spined stickleback (Pungitius pungitius). We sequentially exposed individuals to dark and light visual background treatments, quantified color change from video recordings, and examined associations of color change with phenotypic dimensions that can influence the outcome of predator-prey interactions. G. aculeatus expressed a greater degree of color change compared to P. pungitius. In G. aculeatus, the color change response was repeatable within individuals. Moreover, the color change response was independent of body size but affected by sex and boldness, with males and bolder individuals changing less. Infection by the parasite Schistocephalus solidus did not affect the degree of color change, but it did modulate its association with sex and boldness. G. aculeatus adjusted the expression of color change in response to predation risk, with enhanced color change expression in individuals exposed to either simulated attacks, or olfactory cues from a natural predator. These results provide novel evidence on repeatability, correlated traits, and context dependence in the color change response and highlight how a suite of factors can contribute to individual variation in phenotypic flexibility.
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Affiliation(s)
- Petter Tibblin
- Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Marcus Hall
- Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - P Andreas Svensson
- Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Juha Merilä
- Ecological Genetics Research Unit, Organismal and Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Anders Forsman
- Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
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4
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Maciejewski MF, Jiang C, Stuart YE, Bolnick DI. Microhabitat contributes to microgeographic divergence in threespine stickleback. Evolution 2020; 74:749-763. [PMID: 32058582 DOI: 10.1111/evo.13942] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 01/22/2020] [Accepted: 01/27/2020] [Indexed: 12/20/2022]
Abstract
Since the New Synthesis, most migration-selection balance theory has predicted that there should be negligible differentiation over small spatial scales (relative to dispersal), because gene flow should erode any effect of divergent selection. Nevertheless, there are classic examples of microgeographic divergence, which theory suggests can arise under specific conditions: exceptionally strong selection, phenotypic plasticity in philopatric individuals, or nonrandom dispersal. Here, we present evidence of microgeographic morphological variation within lake and stream populations of threespine stickleback (Gasterosteus aculeatus). It seems reasonable to assume that a given lake or stream population of fish is well-mixed. However, we found this assumption to be untenable. We examined trap-to-trap variation in 34 morphological traits measured on stickleback from 16 lakes and 16 streams. Most traits varied appreciably among traps within populations. Both between-trap distance and microhabitat characteristics such as depth and substrate explained some of the within-population morphological variance. Microhabitat was also associated with genotype at particular loci but there was no genetic isolation by distance, implying that heritable habitat preferences may contribute to microgeographic variation. Our study adds to growing evidence that microgeographic divergence can occur across small spatial scales within individuals' daily dispersal neighborhood where gene flow is expected to be strong.
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Affiliation(s)
- Meghan F Maciejewski
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269
| | - Cynthia Jiang
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78705.,Long School of Medicine, UT Health Science Center San Antonio, San Antonio, Texas, 78229
| | - Yoel E Stuart
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78705.,Loyola University Chicago, Chicago, Illinois, 60660
| | - Daniel I Bolnick
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269.,Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78705
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5
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Ishikawa A, Kitano J. Diversity in reproductive seasonality in the three-spined stickleback, Gasterosteus aculeatus. ACTA ACUST UNITED AC 2020; 223:223/Suppl_1/jeb208975. [PMID: 32034046 DOI: 10.1242/jeb.208975] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The annual timing of reproduction is a key life history trait with a large effect on fitness. Populations often vary in the timing and duration of reproduction to adapt to different seasonality of ecological and environmental variables between habitats. However, little is known about the molecular genetic mechanisms underlying interpopulation variation in reproductive seasonality. Here, we demonstrate that the three-spined stickleback (Gasterosteus aculeatus) is a good model for molecular genetic analysis of variations in reproductive seasonality. We first compiled data on reproductive seasons of diverse ecotypes, covering marine-anadromous, lake and stream ecotypes, of three-spined stickleback inhabiting a wide range of latitudes. Our analysis showed that both ecotype and latitude significantly contribute to variation in reproductive seasons. Stream ecotypes tend to start breeding earlier and end later than other ecotypes. Populations from lower latitudes tend to start breeding earlier than those from higher latitudes in all three ecotypes. Additionally, stream ecotypes tend to have extended breeding seasons at lower latitudes than at higher latitudes, leading to nearly year-round reproduction in the most southern stream populations. A review of recent progress in our understanding of the physiological mechanisms underlying seasonal reproduction in the three-spined stickleback indicates that photoperiod is an important external cue that stimulates and/or suppresses reproduction in this species. Taking advantage of genomic tools available for this species, the three-spined stickleback will be a good model to investigate what kinds of genes and mutations underlie variations in the physiological signalling pathways that regulate reproduction in response to photoperiod.
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Affiliation(s)
- Asano Ishikawa
- Ecological Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan .,Department of Genetics, Graduate University for Advanced Studies (SOKENDAI), Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Jun Kitano
- Ecological Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, Graduate University for Advanced Studies (SOKENDAI), Yata 1111, Mishima, Shizuoka 411-8540, Japan
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6
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Gygax M, Rentsch AK, Rudman SM, Rennison DJ. Differential predation alters pigmentation in threespine stickleback (Gasterosteus aculeatus). J Evol Biol 2018; 31:1589-1598. [PMID: 30055069 DOI: 10.1111/jeb.13354] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 07/10/2018] [Indexed: 11/27/2022]
Abstract
Animal pigmentation plays a key role in many biological interactions, including courtship and predator avoidance. Sympatric benthic and limnetic ecotypes of threespine stickleback (Gasterosteus aculeatus) exhibit divergent pigment patterns. To test whether differential predation by cutthroat trout contributes to the differences in pigmentation seen between the ecotypes, we used a within-generation selection experiment on F2 benthic-limnetic hybrids. After 10 months of differential selection, we compared the pigmentation of fish under trout predation to control fish not exposed to trout predation. We found that stickleback exhibited more lateral barring in ponds with trout predation. Ponds with trout were also less turbid, and a greater degree of barring was negatively correlated with the magnitude of turbidity across pond replicates. A more benthic diet, a proxy for habitat use, was also correlated with greater lateral barring and green dorsal pigmentation. These patterns suggest that differential exposure to cutthroat trout predation may explain the divergence in body pigmentation between benthic and limnetic ecotypes.
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Affiliation(s)
- Michelle Gygax
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
| | - Ana K Rentsch
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
| | - Seth M Rudman
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.,Department of Biology, University of Pennsylvania, Pennsylvania, PA, USA
| | - Diana J Rennison
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.,Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
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7
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Bui S, Dalvin S, Dempster T, Skulstad OF, Edvardsen RB, Wargelius A, Oppedal F. Susceptibility, behaviour, and retention of the parasitic salmon louse (Lepeophtheirus salmonis) differ with Atlantic salmon population origin. JOURNAL OF FISH DISEASES 2018; 41:431-442. [PMID: 28921589 DOI: 10.1111/jfd.12707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 07/18/2017] [Accepted: 07/25/2017] [Indexed: 06/07/2023]
Abstract
Atlantic salmon populations across the world have diverse ecological and evolutionary histories, from wild anadromous or landlocked, to domestication and genetic modification. The natural host behaviours confer protection from infestation by ectoparasitic salmon lice Lepeophtheirus salmonis, yet whether genetic origin results in different behaviours and thus susceptibility to infestation is unknown. In common garden experiments, we tested antiparasite behaviours, susceptibility and retention of salmon lice in wild anadromous, wild landlocked, domesticated and genetically modified domesticated strains. Within domesticated strains, we tested two infestation histories (previously infested and naïve) and a new phenotype (albino colouring). Farmed stocks initially acquired 24%-44% higher levels of parasite density than the wild and landlocked strains. Burst swimming and displacement behaviours were higher in the domesticated groups, and jumping was more prevalent in the domesticated strains. At 34 days post-infestation, domesticated strains and the wild anadromous strain did not differ significantly from each other; however, landlocked salmon had increased infestation levels considerably. Domesticated strains lost ~20% (±9.9%-16.5%; 95% CI) of their initial parasite load, while parasite load increased by 5.5% (±30.1%) for wild salmon and 20.1% (±28.5%) in landlocked salmon. This study provides early evidence for diverged host-parasite interactions associated with domestication in this system.
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Affiliation(s)
- S Bui
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Parkville, Vic, Australia
- Institute of Marine Research, Bergen, Norway
| | - S Dalvin
- Institute of Marine Research, Bergen, Norway
| | - T Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Parkville, Vic, Australia
- Institute of Marine Research, Bergen, Norway
| | | | | | - A Wargelius
- Institute of Marine Research, Bergen, Norway
| | - F Oppedal
- Institute of Marine Research, Bergen, Norway
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8
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Hanson D, Hu J, Hendry AP, Barrett RDH. Heritable gene expression differences between lake and stream stickleback include both parallel and antiparallel components. Heredity (Edinb) 2017; 119:339-348. [PMID: 28832577 PMCID: PMC5637370 DOI: 10.1038/hdy.2017.50] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/05/2017] [Accepted: 07/13/2017] [Indexed: 12/19/2022] Open
Abstract
The repeated phenotypic patterns that characterize populations undergoing parallel evolution provide support for a deterministic role of adaptation by natural selection. Determining the level of parallelism also at the genetic level is thus central to our understanding of how natural selection works. Many studies have looked for repeated genomic patterns in natural populations, but work on gene expression is less common. The studies that have examined gene expression have found some support for parallelism, but those studies almost always used samples collected from the wild that potentially confounds the effects of plasticity with heritable differences. Here we use two independent pairs of lake and stream threespine stickleback (Gasterosteus aculeatus) raised in common garden conditions to assess both parallel and antiparallel (that is, similar versus different directions of lake–stream expression divergence in the two watersheds) heritable gene expression differences as measured by total RNA sequencing. We find that more genes than expected by chance show either parallel (22 genes, 0.18% of expressed genes) or antiparallel (24 genes, 0.20% of expressed genes) lake–stream expression differences. These results correspond well with previous genomic studies in stickleback ecotype pairs that found similar levels of parallelism. We suggest that parallelism might be similarly constrained at the genomic and transcriptomic levels.
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Affiliation(s)
- D Hanson
- Redpath Museum and Department of Biology, McGill University, Montreal, Quebec, Canada
| | - J Hu
- Redpath Museum and Department of Biology, McGill University, Montreal, Quebec, Canada
| | - A P Hendry
- Redpath Museum and Department of Biology, McGill University, Montreal, Quebec, Canada
| | - R D H Barrett
- Redpath Museum and Department of Biology, McGill University, Montreal, Quebec, Canada
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9
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Brock CD, Cummings ME, Bolnick DI. Phenotypic plasticity drives a depth gradient in male conspicuousness in threespine stickleback,Gasterosteus aculeatus. Evolution 2017; 71:2022-2036. [DOI: 10.1111/evo.13282] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 05/04/2017] [Indexed: 01/04/2023]
Affiliation(s)
- Chad D. Brock
- Department of Integrative Biology; University of Texas at Austin; Texas 78712
- Biodiversity Institute and the Department of Botany; University of Wyoming; Laramie Wyoming 82071
| | - Molly E. Cummings
- Department of Integrative Biology; University of Texas at Austin; Texas 78712
| | - Daniel I. Bolnick
- Department of Integrative Biology; University of Texas at Austin; Texas 78712
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10
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Abstract
Evolutionary biologists typically represent clines as spatial gradients in a univariate character (or a principal-component axis) whose mean changes as a function of location along a transect spanning an environmental gradient or ecotone. This univariate approach may obscure the multivariate nature of phenotypic evolution across a landscape. Clines might instead be plotted as a series of vectors in multidimensional morphospace, connecting sequential geographic sites. We present a model showing that clines may trace nonlinear paths that arc through morphospace rather than elongating along a single major trajectory. Arcing clines arise because different characters diverge at different rates or locations along a geographic transect. We empirically confirm that some clines arc through morphospace, using morphological data from threespine stickleback sampled along eight independent transects from lakes down their respective outlet streams. In all eight clines, successive vectors of lake-stream divergence fluctuate in direction and magnitude in trait space, rather than pointing along a single phenotypic axis. Most clines exhibit surprisingly irregular directions of divergence as one moves downstream, although a few clines exhibit more directional arcs through morphospace. Our results highlight the multivariate complexity of clines that cannot be captured with the traditional graphical framework. We discuss hypotheses regarding the causes, and implications, of such arcing multivariate clines.
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11
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Bolnick DI, Hendrix K, Jordan LA, Veen T, Brock CD. Intruder colour and light environment jointly determine how nesting male stickleback respond to simulated territorial intrusions. Biol Lett 2016; 12:20160467. [PMID: 27512135 PMCID: PMC5014039 DOI: 10.1098/rsbl.2016.0467] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 07/18/2016] [Indexed: 11/12/2022] Open
Abstract
Variation in male nuptial colour signals might be maintained by negative frequency-dependent selection. This can occur if males are more aggressive towards rivals with locally common colour phenotypes. To test this hypothesis, we introduced red or melanic three-dimensional printed-model males into the territories of nesting male stickleback from two optically distinct lakes with different coloured residents. Red-throated models were attacked more in the population with red males, while melanic models were attacked more in the melanic male lake. Aggression against red versus melanic models also varied across a depth gradient within each lake, implying that the local light environment also modulated the strength of negative frequency dependence acting on male nuptial colour.
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Affiliation(s)
- Daniel I Bolnick
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | | | | | - Thor Veen
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Chad D Brock
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
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12
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Stutz WE, Schmerer M, Coates JL, Bolnick DI. Among-lake reciprocal transplants induce convergent expression of immune genes in threespine stickleback. Mol Ecol 2015; 24:4629-46. [PMID: 26118468 DOI: 10.1111/mec.13295] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/22/2015] [Accepted: 06/24/2015] [Indexed: 12/25/2022]
Abstract
Geographic variation in parasite communities can drive evolutionary divergence in host immune genes. However, biotic and abiotic environmental variation can also induce plastic differences in immune function among populations. At present, there is little information concerning the relative magnitudes of heritable vs. induced immune divergence in natural populations. We examined immune gene expression profiles of threespine stickleback (Gasterosteus aculeatus) from six lakes on Vancouver Island, British Columbia. Parasite community composition differs between lake types (large or small, containing limnetic- or benthic-like stickleback) and between watersheds. We observed corresponding differences in immune gene expression profiles among wild-caught stickleback, using a set of seven immune genes representing distinct branches of the immune system. To evaluate the role of environmental effects on this differentiation, we experimentally transplanted wild-caught fish into cages in their native lake, or into a nearby foreign lake. Transplanted individuals' immune gene expression converged on patterns typical of their destination lake, deviating from their native expression profile. Transplant individuals' source population had a much smaller effect, suggesting relatively weak genetic underpinning of population differences in immunity, as viewed through gene expression. This strong environmental regulation of immune gene expression provides a counterpoint to the large emerging literature documenting microevolution and genetic diversification of immune function. Our findings illustrate the value of studying immunity in natural environmental settings where the immune system has evolved and actively functions.
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Affiliation(s)
- William E Stutz
- Department of Integrative Biology, University of Texas at Austin, One University Station C0990, Austin, TX, 78712, USA
| | - Matthew Schmerer
- Department of Integrative Biology, University of Texas at Austin, One University Station C0990, Austin, TX, 78712, USA
| | - Jessica L Coates
- Department of Biology, Spelman College, 350 Spelman Lane SW, Atlanta, GA, 30314, USA
| | - Daniel I Bolnick
- Department of Integrative Biology, University of Texas at Austin, One University Station C0990, Austin, TX, 78712, USA.,Howard Hughes Medical Institute, University of Texas at Austin, One University Station C0990, Austin, TX, 78712, USA
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