1
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Chavhan Y, Dey S, Lind PA. Bacteria evolve macroscopic multicellularity by the genetic assimilation of phenotypically plastic cell clustering. Nat Commun 2023; 14:3555. [PMID: 37322016 PMCID: PMC10272148 DOI: 10.1038/s41467-023-39320-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 06/05/2023] [Indexed: 06/17/2023] Open
Abstract
The evolutionary transition from unicellularity to multicellularity was a key innovation in the history of life. Experimental evolution is an important tool to study the formation of undifferentiated cellular clusters, the likely first step of this transition. Although multicellularity first evolved in bacteria, previous experimental evolution research has primarily used eukaryotes. Moreover, it focuses on mutationally driven (and not environmentally induced) phenotypes. Here we show that both Gram-negative and Gram-positive bacteria exhibit phenotypically plastic (i.e., environmentally induced) cell clustering. Under high salinity, they form elongated clusters of ~ 2 cm. However, under habitual salinity, the clusters disintegrate and grow planktonically. We used experimental evolution with Escherichia coli to show that such clustering can be assimilated genetically: the evolved bacteria inherently grow as macroscopic multicellular clusters, even without environmental induction. Highly parallel mutations in genes linked to cell wall assembly formed the genomic basis of assimilated multicellularity. While the wildtype also showed cell shape plasticity across high versus low salinity, it was either assimilated or reversed after evolution. Interestingly, a single mutation could genetically assimilate multicellularity by modulating plasticity at multiple levels of organization. Taken together, we show that phenotypic plasticity can prime bacteria for evolving undifferentiated macroscopic multicellularity.
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Affiliation(s)
- Yashraj Chavhan
- Department of Molecular Biology, Umeå University, Umeå, Sweden.
| | - Sutirth Dey
- Indian Institute of Science Education and Research (IISER) Pune, Pune, India
| | - Peter A Lind
- Department of Molecular Biology, Umeå University, Umeå, Sweden.
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden.
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2
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Stevens DR, Graham MA, Bardjis CI, Foster SA, Baker JA, Mathis KA. Evolution of chemical-cue-mediated antipredator behavior in threespine stickleback populations experiencing northern pike predation. Biol Invasions 2023. [DOI: 10.1007/s10530-023-02996-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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3
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Westrick SE, Moss JB, Fischer EK. Who cares? An integrative approach to understanding the evolution of behavioural plasticity in parental care. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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4
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Nielsen ME, Papaj DR. Why study plasticity in multiple traits? New hypotheses for how phenotypically plastic traits interact during development and selection. Evolution 2022; 76:858-869. [PMID: 35274745 PMCID: PMC9313899 DOI: 10.1111/evo.14464] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/12/2021] [Accepted: 12/29/2021] [Indexed: 01/21/2023]
Abstract
Organisms can often respond adaptively to a change in their environment through phenotypic plasticity in multiple traits, a phenomenon termed as multivariate plasticity. These different plastic responses could interact and affect each other's development as well as selection on each other, but the causes and consequences of these interactions have received relatively little attention. Here, we propose a new conceptual framework for understanding how different plastic responses can affect each other's development and why organisms should have multiple plastic responses. A plastic change in one trait could alter the phenotype of a second plastic trait by changing either the cue received by the organism (cue-mediated effect) or the response to that cue (response-mediated effect). Multivariate plasticity could benefit the organism either because the plastic responses work better when expressed together (synergy) or because each response is more effective under different environmental circumstances (complementarity). We illustrate these hypotheses with case studies, focusing on interactions between behavior and morphology, plastic traits that differ in their reversibility. Future empirical and theoretical research should investigate the consequences of these interactions for additional factors important for the evolution of plasticity, such as the limits and costs of plasticity.
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Affiliation(s)
- Matthew E. Nielsen
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonArizona85721,Zoology DepartmentStockholm UniversityStockholm11419Sweden
| | - Daniel R. Papaj
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonArizona85721
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5
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Frommen JG, Thünken T, Santostefano F, Balzarini V, Hettyey A. Effects of chronic and acute predation risk on sexual ornamentation and mating preferences. Behav Ecol 2021. [DOI: 10.1093/beheco/arab116] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Phenotypic plasticity is widespread in animals. Still, how plastic responses to predator presence affect traits under sexual selection and influence mating preferences is not well understood. Here, we examined how simulated chronic predator presence during development and acute predator presence during mate choice affect the expression of male secondary sexual traits and female mating preference in the three-spined stickleback, Gasterosteus aculeatus. Males reared under chronic predator presence developed less intense red breeding coloration but showed higher courtship activity than males that grew up in a predator-free environment. Acute predator presence during mate choice trials did not influence male behavior or ornamentation. Predator presence experienced during development did not affect female mating preferences, whereas acute predator presence altered preferences for male courtship activity. Male body size and eye coloration influenced the intensity of female mating preferences, while the trait changing most in response to predator presence during development (red coloration) had no significant impact. The observed interplay between developmental plasticity in male ornamental traits and environment-dependent female mating preferences may lead to dynamic processes altering the strength and direction of sexual selection depending on both the chronic and acute risk of predation. These processes may contribute to the maintenance of within- and among-population variation in secondary sexual traits, and may, ultimately, facilitate speciation.
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Affiliation(s)
- Joachim G Frommen
- Konrad Lorenz Institute of Ethology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstr. 1a, 1160 Vienna, Austria
- Division of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstr. 50a, 3032 Hinterkappelen, Switzerland
- Conservation, Ecology, Evolution and Behaviour Research Group, Ecology and Environment Research Centre, Manchester Metropolitan University, Manchester, UK
| | - Timo Thünken
- Division of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstr. 50a, 3032 Hinterkappelen, Switzerland
| | - Francesca Santostefano
- Konrad Lorenz Institute of Ethology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstr. 1a, 1160 Vienna, Austria
- Département des Sciences Biologiques, Université du Québec à Montréal, C.P. 8888, Succ. Centre-ville Montréal, QC, Canada
| | - Valentina Balzarini
- Konrad Lorenz Institute of Ethology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstr. 1a, 1160 Vienna, Austria
- Division of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstr. 50a, 3032 Hinterkappelen, Switzerland
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, UK
| | - Attila Hettyey
- Konrad Lorenz Institute of Ethology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstr. 1a, 1160 Vienna, Austria
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, Budapest 1022, Hungary
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6
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Álvarez‐Quintero N, Velando A, Noguera JC, Kim S. Environment-induced changes in reproductive strategies and their transgenerational effects in the three-spined stickleback. Ecol Evol 2021; 11:771-783. [PMID: 33520165 PMCID: PMC7820166 DOI: 10.1002/ece3.7052] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 10/23/2020] [Accepted: 10/23/2020] [Indexed: 01/10/2023] Open
Abstract
An organism may increase its fitness by changing its reproductive strategies in response to environmental cues, but the possible consequences of those changes for the next generation have rarely been explored. By using an experiment on the three-spined stickleback (Gasterosteus aculeatus), we studied how changes in the onset of breeding photoperiod (early versus late) affect reproductive strategies of males and females, and life histories of their offspring. We also explored whether telomeres are involved in the within- and transgenerational effects. In response to the late onset of breeding photoperiod, females reduced their investment in the early clutches, but males increased their investment in sexual signals. Costs of increased reproductive investment in terms of telomere loss were evident only in the late females. The environmentally induced changes in reproductive strategies affected offspring growth and survival. Most notably, offspring growth rate was the fastest when both parents experienced a delayed (i.e., late) breeding photoperiod, and survival rate was the highest when both parents experienced an advanced (i.e., early) breeding photoperiod. There was no evidence of transgenerational effects on offspring telomere length despite positive parents-offspring relationships in this trait. Our results highlight that environmental changes may impact more than one generation by altering reproductive strategies of seasonal breeders with consequences for offspring viability.
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Affiliation(s)
- Náyade Álvarez‐Quintero
- Grupo Ecoloxía Animal (Lab 97)Torre CACTICentro de Investigación MariñaUniversidade de VigoVigoSpain
| | - Alberto Velando
- Grupo Ecoloxía Animal (Lab 97)Torre CACTICentro de Investigación MariñaUniversidade de VigoVigoSpain
| | - Jose C. Noguera
- Grupo Ecoloxía Animal (Lab 97)Torre CACTICentro de Investigación MariñaUniversidade de VigoVigoSpain
| | - Sin‐Yeon Kim
- Grupo Ecoloxía Animal (Lab 97)Torre CACTICentro de Investigación MariñaUniversidade de VigoVigoSpain
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7
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Matthey-Doret R, Draghi JA, Whitlock MC. Plasticity via feedback reduces the cost of developmental instability. Evol Lett 2020; 4:570-580. [PMID: 33312691 PMCID: PMC7719546 DOI: 10.1002/evl3.202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/10/2020] [Accepted: 10/10/2020] [Indexed: 12/11/2022] Open
Abstract
Costs of plasticity are thought to have important physiological and evolutionary consequences. A commonly predicted cost to plasticity is that plastic genotypes are likely to suffer from developmental instability. Adaptive plasticity requires that the developing organism can in some way sense what environment it is in or how well it is performing in that environment. These two information pathways—an “environmental signal” or a “performance signal” that indicates how well a developing phenotype matches the optimum in the current environment—can differ in their consequences for the organism and its evolution. Here, we consider how developmental instability might emerge as a side‐effect of these two distinct mechanisms. Because a performance cue allows a regulatory feedback loop connecting a trait to a feedback signal, we hypothesized that plastic genotypes using a performance signal would be more developmentally robust compared to those using a purely environmental signal. Using a numerical model of a network of gene interactions, we show that plasticity comes at a cost of developmental instability when the plastic response is mediated via an environmental signal, but not when it is mediated via a performance signal. We also show that a performance signal mechanism can evolve even in a constant environment, leading to genotypes preadapted for plasticity to novel environments even in populations without a history of environmental heterogeneity.
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Affiliation(s)
- Remi Matthey-Doret
- Institute of Ecology and Evolution Universität Bern Bern 3012 Switzerland.,Department of Zoology and Biodiversity Research Centre University of British Columbia Vancouver BC V6T 1Z4 Canada.,Department of Biological Sciences Virginia Tech Blacksburg Virginia 24061
| | - Jeremy A Draghi
- Department of Zoology and Biodiversity Research Centre University of British Columbia Vancouver BC V6T 1Z4 Canada.,Department of Biological Sciences Virginia Tech Blacksburg Virginia 24061
| | - Michael C Whitlock
- Department of Zoology and Biodiversity Research Centre University of British Columbia Vancouver BC V6T 1Z4 Canada
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8
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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9
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McGhee KE, Paitz RT, Baker JA, Foster SA, Bell AM. Effects of predation risk on egg steroid profiles across multiple populations of threespine stickleback. Sci Rep 2020; 10:5239. [PMID: 32251316 DOI: 10.1038/s41598-020-61412-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/24/2020] [Indexed: 11/16/2022] Open
Abstract
Predation often has consistent effects on prey behavior and morphology, but whether the physiological mechanisms underlying these effects show similarly consistent patterns across different populations remains an open question. In vertebrates, predation risk activates the hypothalamic-pituitary-adrenal (HPA) axis, and there is growing evidence that activation of the maternal HPA axis can have intergenerational consequences via, for example, maternally-derived steroids in eggs. Here, we investigated how predation risk affects a suite of maternally-derived steroids in threespine stickleback eggs across nine Alaskan lakes that vary in whether predatory trout are absent, native, or have been stocked within the last 25 years. Using liquid chromatography coupled with mass spectroscopy (LC-MS/MS), we detected 20 steroids within unfertilized eggs. Factor analysis suggests that steroids covary within and across steroid classes (i.e. glucocorticoids, progestogens, sex steroids), emphasizing the modularity and interconnectedness of the endocrine response. Surprisingly, egg steroid profiles were not significantly associated with predator regime, although they were more variable when predators were absent compared to when predators were present, with either native or stocked trout. Despite being the most abundant steroid, cortisol was not consistently associated with predation regime. Thus, while predators can affect steroids in adults, including mothers, the link between maternal stress and embryonic development is more complex than a simple one-to-one relationship between the population-level predation risk experienced by mothers and the steroids mothers transfer to their eggs.
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10
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Foster SA, Baker JA. Loss and re-emergence of plastic ancestral behavioural traits: influences on phenotypic and evolutionary pattern. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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11
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Nielsen ME, Levin E, Davidowitz G, Papaj DR. Colour plasticity alters thermoregulatory behaviour in Battus philenor caterpillars by modifying the cue received. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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12
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Casasa S, Moczek AP. The role of ancestral phenotypic plasticity in evolutionary diversification: population density effects in horned beetles. Anim Behav 2018; 137:53-61. [DOI: 10.1016/j.anbehav.2018.01.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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13
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Nielsen ME. No geographic variation in thermoregulatory colour plasticity and limited variation in heat‐avoidance behaviour in
Battus philenor
caterpillars. J Evol Biol 2017; 30:1919-1928. [DOI: 10.1111/jeb.13168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/24/2017] [Accepted: 08/17/2017] [Indexed: 11/29/2022]
Affiliation(s)
- M. E. Nielsen
- Department of Ecology and Evolutionary Biology University of Arizona Tucson AZ USA
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14
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Nielsen ME, Papaj DR. Why Have Multiple Plastic Responses? Interactions between Color Change and Heat Avoidance Behavior in Battus philenor Larvae. Am Nat 2017; 189:657-666. [PMID: 28514633 DOI: 10.1086/691536] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Having multiple plastic responses to a change in the environment, such as increased temperature, can be adaptive for two major reasons: synergy (the plastic responses perform better when expressed simultaneously) or complementarity (each plastic response provides a greater net benefit in a different environmental context). We investigated these hypotheses for two forms of temperature-induced plasticity of Battus philenor caterpillars in southern Arizona populations: color change (from black to red at high temperatures) and heat avoidance behavior (movement from host to elevated refuges at high host temperatures). Field assays using aluminum models showed that the cooling effect of the red color is greatly reduced in a refuge position relative to that on a host. Field assays with live caterpillars demonstrated that refuge seeking is much more important for survival under hot conditions than coloration; however, in those assays, red coloration reduced the need to seek refuges. Our results support the complementarity hypothesis: refuge seeking facilitates survival during daily temperature peaks, while color change reduces the need to leave the host over longer warm periods. We propose that combinations of rapid but costly short-term behavioral responses and slow but efficient long-term morphological responses may be common when coping with temperature change.
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15
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Kaji T, Palmer AR. How reversible is development? Contrast between developmentally plastic gain and loss of segments in barnacle feeding legs. Evolution 2017; 71:756-765. [PMID: 28012177 DOI: 10.1111/evo.13152] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 11/17/2016] [Indexed: 01/14/2023]
Abstract
Segmented organisms and structures have fascinated biologists since William Bateson first described homeotic transformation and recognized the fundamental evolutionary significance of segmental organization. On evolutionary time scales, segments may be lost or gained during major morphological transitions. But how segment loss compares to gain on developmental time scales remains mysterious. Here, we examine the ease of reverse development (opposite to normal growth) by comparing developmentally plastic leg segment loss versus gain in individual barnacles transplanted between different water flow conditions. Plastic segment addition occurred rapidly (one to two molts) and exclusively near the limb base. In contrast, developmentally plastic segment loss-the first observation in any arthropod-took much longer (>10 molts) and, remarkably, occurred throughout the leg (23% of losses occurred mid-limb). Segment loss was not a simple reversal of segment addition. Intersegmental membranes fused first, followed by elimination of duplicate tendons and gradual shortening (but not loss) of duplicate setae. Setal loss, in particular, may impose a severe developmental constraint on arthropod segment fusion. This asymmetric developmental potential (time lag of phenotypic response)-plastic segment addition (amplified normal development) is faster and more orderly than segment loss (reverse development)-adds a new dimension to models of developmental plasticity because the cost of making a developmental mistake in one direction will be greater than in the other.
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Affiliation(s)
- Tomonari Kaji
- Systematics and Evolution Group, Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada.,Bamfield Marine Sciences Centre, Bamfield, British Columbia, V0R 1B0, Canada
| | - A Richard Palmer
- Systematics and Evolution Group, Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada.,Bamfield Marine Sciences Centre, Bamfield, British Columbia, V0R 1B0, Canada
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16
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Sopinka NM, Capelle PM, Semeniuk CAD, Love OP. Glucocorticoids in Fish Eggs: Variation, Interactions with the Environment, and the Potential to Shape Offspring Fitness. Physiol Biochem Zool 2016; 90:15-33. [PMID: 28051944 DOI: 10.1086/689994] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Wild and captive vertebrates face multiple stressors that all have the potential to induce chronic maternal stress (i.e., sustained, elevated plasma glucocorticoids), resulting in embryo exposure to elevated maternally derived glucocorticoids. In oviparous taxa such as fish, maternally derived glucocorticoids in eggs are known for their capacity to shape offspring phenotype. Using a variety of methodologies, scientists have quantified maternally derived levels of egg cortisol, the primary glucocorticoid in fishes, and examined the cascading effects of egg cortisol on progeny phenotype. Here we summarize and interpret the current state of knowledge on egg cortisol in fishes and the relationships linking maternal stress/state to egg cortisol and offspring phenotype/fitness. Considerable variation in levels of egg cortisol exists across species and among females within a species; this variation is hypothesized to be due to interspecific differences in reproductive life history and intraspecific differences in female condition. Outcomes of experimental studies manipulating egg cortisol vary both inter- and intraspecifically. Moreover, while exogenous elevation of egg cortisol (as a proxy for maternal stress) induces phenotypic changes commonly considered to be maladaptive (e.g., smaller offspring size), emerging work in other taxa suggests that there can be positive effects on fitness when the offspring's environment is taken into account. Investigations into (i) mechanisms by which egg cortisol elicits phenotypic change in offspring (e.g., epigenetics), (ii) maternal and offspring buffering capacity of cortisol, and (iii) factors driving natural variation in egg cortisol and how this variation affects offspring phenotype and fitness are all germane to discussions on egg glucocorticoids as signals of maternal stress.
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17
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Schneider RF, Meyer A. How plasticity, genetic assimilation and cryptic genetic variation may contribute to adaptive radiations. Mol Ecol 2016; 26:330-350. [PMID: 27747962 DOI: 10.1111/mec.13880] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 09/30/2016] [Accepted: 10/07/2016] [Indexed: 12/13/2022]
Abstract
There is increasing evidence that phenotypic plasticity can promote population divergence by facilitating phenotypic diversification and, eventually, genetic divergence. When a 'plastic' population colonizes a new habitat, it has the possibility to occupy multiple niches by expressing several distinct phenotypes. These initially reflect the population's plastic range but may later become genetically fixed by selection via the process of 'genetic assimilation' (GA). Through this process multiple specialized sister lineages can arise that share a common plastic ancestor - the 'flexible stem'. Here, we review possible molecular mechanisms through which natural selection could fix an initially plastic trait during GA. These mechanisms could also explain how GA may contribute to cryptic genetic variation that can subsequently be coopted into other phenotypes or traits, but also lead to nonadaptive responses. We outline the predicted patterns of genetic and transcriptional divergence accompanying flexible stem radiations. The analysis of such patterns of (retained) adaptive and nonadaptive plastic responses within and across radiating lineages can inform on the state of ongoing GA. We conclude that, depending on the stability of the environment, the molecular architecture underlying plastic traits can facilitate diversification, followed by fixation and consolidation of an adaptive phenotype and degeneration of nonadaptive ones. Additionally, the process of GA may increase the cryptic genetic variation of populations, which on one hand may serve as substrate for evolution, but on another may be responsible for nonadaptive responses that consolidate local allopatry and thus reproductive isolation.
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Affiliation(s)
- Ralf F Schneider
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitaetstrasse 10, 78457, Konstanz, Germany
| | - Axel Meyer
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitaetstrasse 10, 78457, Konstanz, Germany
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18
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Seebacher F, Webster MM, James RS, Tallis J, Ward AJW. Morphological differences between habitats are associated with physiological and behavioural trade-offs in stickleback (Gasterosteus aculeatus). R Soc Open Sci 2016; 3:160316. [PMID: 27429785 PMCID: PMC4929920 DOI: 10.1098/rsos.160316] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 05/24/2016] [Indexed: 06/06/2023]
Abstract
Local specialization can be advantageous for individuals and may increase the resilience of the species to environmental change. However, there may be trade-offs between morphological responses and physiological performance and behaviour. Our aim was to test whether habitat-specific morphology of stickleback (Gasterosteus aculeatus) interacts with physiological performance and behaviour at different salinities. We rejected the hypothesis that deeper body shape of fish from habitats with high predation pressure led to decreases in locomotor performance. However, there was a trade-off between deeper body shape and muscle quality. Muscle of deeper-bodied fish produced less force than that of shallow-bodied saltmarsh fish. Nonetheless, saltmarsh fish had lower swimming performance, presumably because of lower muscle mass overall coupled with smaller caudal peduncles and larger heads. Saltmarsh fish performed better in saline water (20 ppt) relative to freshwater and relative to fish from freshwater habitats. However, exposure to salinity affected shoaling behaviour of fish from all habitats and shoals moved faster and closer together compared with freshwater. We show that habitat modification can alter phenotypes of native species, but local morphological specialization is associated with trade-offs that may reduce its benefits.
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Affiliation(s)
- Frank Seebacher
- School of Life and Environmental Sciences A08, University of Sydney, New South Wales 2006, Australia
| | | | - Rob S. James
- Centre for Applied Biological and Exercise Sciences, Coventry University, Coventry CV1 5FB, UK
| | - Jason Tallis
- Centre for Applied Biological and Exercise Sciences, Coventry University, Coventry CV1 5FB, UK
| | - Ashley J. W. Ward
- School of Life and Environmental Sciences A08, University of Sydney, New South Wales 2006, Australia
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