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Nicholson RM, Levis NA, Ragsdale EJ. Genetic regulators of a resource polyphenism interact to couple predatory morphology and behaviour. Proc Biol Sci 2024; 291:20240153. [PMID: 38835272 DOI: 10.1098/rspb.2024.0153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/22/2024] [Indexed: 06/06/2024] Open
Abstract
Phenotypic plasticity often requires the coordinated response of multiple traits observed individually as morphological, physiological or behavioural. The integration, and hence functionality, of this response may be influenced by whether and how these component traits share a genetic basis. In the case of polyphenism, or discrete plasticity, at least part of the environmental response is categorical, offering a simple readout for determining whether and to what degree individual components of a plastic response can be decoupled. Here, we use the nematode Pristionchus pacificus, which has a resource polyphenism allowing it to be a facultative predator of other nematodes, to understand the genetic integration of polyphenism. The behavioural and morphological consequences of perturbations to the polyphenism's genetic regulatory network show that both predatory activity and ability are strongly influenced by morphology, different axes of morphological variation are associated with different aspects of predatory behaviour, and rearing environment can decouple predatory morphology from behaviour. Further, we found that interactions between some polyphenism-modifying genes synergistically affect predatory behaviour. Our results show that the component traits of an integrated polyphenic response can be decoupled and, in principle, selected upon individually, and they suggest that multiple routes to functionally comparable phenotypes are possible.
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Affiliation(s)
- Rose M Nicholson
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Nicholas A Levis
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Erik J Ragsdale
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
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Isdaner AJ, Levis NA, Ehrenreich IM, Pfennig DW. Genetic Variants Underlying Plasticity in Natural Populations of Spadefoot Toads: Environmental Assessment versus Phenotypic Response. Genes (Basel) 2024; 15:611. [PMID: 38790242 PMCID: PMC11121243 DOI: 10.3390/genes15050611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/02/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Many organisms facultatively produce different phenotypes depending on their environment, yet relatively little is known about the genetic bases of such plasticity in natural populations. In this study, we describe the genetic variation underlying an extreme form of plasticity--resource polyphenism--in Mexican spadefoot toad tadpoles, Spea multiplicata. Depending on their environment, these tadpoles develop into one of two drastically different forms: a carnivore morph or an omnivore morph. We collected both morphs from two ponds that differed in which morph had an adaptive advantage and performed genome-wide association studies of phenotype (carnivore vs. omnivore) and adaptive plasticity (adaptive vs. maladaptive environmental assessment). We identified four quantitative trait loci associated with phenotype and nine with adaptive plasticity, two of which exhibited signatures of minor allele dominance and two of which (one phenotype locus and one adaptive plasticity locus) did not occur as minor allele homozygotes. Investigations into the genetics of plastic traits in natural populations promise to provide novel insights into how such complex, adaptive traits arise and evolve.
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Affiliation(s)
- Andrew J. Isdaner
- Department of Biology, CB#3280, University of North Carolina, Chapel Hill, NC 27599, USA; (A.J.I.); (N.A.L.)
| | - Nicholas A. Levis
- Department of Biology, CB#3280, University of North Carolina, Chapel Hill, NC 27599, USA; (A.J.I.); (N.A.L.)
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Ian M. Ehrenreich
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA;
| | - David W. Pfennig
- Department of Biology, CB#3280, University of North Carolina, Chapel Hill, NC 27599, USA; (A.J.I.); (N.A.L.)
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Levis NA, Ragsdale EJ. A histone demethylase links the loss of plasticity to nongenetic inheritance and morphological change. Nat Commun 2023; 14:8439. [PMID: 38114491 PMCID: PMC10730525 DOI: 10.1038/s41467-023-44306-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 12/07/2023] [Indexed: 12/21/2023] Open
Abstract
Plasticity is a widespread feature of development, enabling phenotypic change based on the environment. Although the evolutionary loss of plasticity has been linked both theoretically and empirically to increased rates of phenotypic diversification, molecular insights into how this process might unfold are generally lacking. Here, we show that a regulator of nongenetic inheritance links evolutionary loss of plasticity in nature to changes in plasticity and morphology as selected in the laboratory. Across nematodes of Diplogastridae, which ancestrally had a polyphenism, or discrete plasticity, in their feeding morphology, we use molecular evolutionary analyses to screen for change associated with independent losses of plasticity. Having inferred a set of ancestrally polyphenism-biased genes from phylogenetically informed gene-knockouts and gene-expression comparisons, selection signatures associated with plasticity's loss identify the histone H3K4 di/monodemethylase gene spr-5/LSD1/KDM1A. Manipulations of this gene affect both sensitivity and variation in plastic morphologies, and artificial selection of manipulated lines drive multigenerational shifts in these phenotypes. Our findings thus give mechanistic insight into how traits are modified as they traverse the continuum of greater to lesser environmental sensitivity.
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Affiliation(s)
- Nicholas A Levis
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
| | - Erik J Ragsdale
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
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Isdaner AJ, Levis NA, Pfennig DW. Comparative transcriptomics reveals that a novel form of phenotypic plasticity evolved via lineage-specific changes in gene expression. Ecol Evol 2023; 13:e10646. [PMID: 37869437 PMCID: PMC10589077 DOI: 10.1002/ece3.10646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 10/09/2023] [Indexed: 10/24/2023] Open
Abstract
Novel forms of phenotypic plasticity may evolve by lineage-specific changes or by co-opting mechanisms from more general forms of plasticity. Here, we evaluated whether a novel resource polyphenism in New World spadefoot toads (genus Spea) evolved by co-opting mechanisms from an ancestral form of plasticity common in anurans-accelerating larval development rate in response to pond drying. We compared overlap in differentially expressed genes between alternative trophic morphs constituting the polyphenism in Spea versus those found between tadpoles of Old World spadefoot toads (genus Pelobates) when experiencing different pond-drying regimes. Specifically, we (1) generated a de novo transcriptome and conducted differential gene expression analysis in Spea multiplicata, (2) utilized existing gene expression data and a recently published transcriptome for Pelobates cultripes when exposed to different drying regimes, and (3) identified unique and overlapping differentially expressed transcripts. We found thousands of differentially expressed genes between S. multiplicata morphs that were involved in major developmental reorganization, but the vast majority of these were not differentially expressed in P. cultripes. Thus, S. multiplicata's novel polyphenism appears to have arisen primarily through lineage-specific changes in gene expression and not by co-opting existing patterns of gene expression involved in pond-drying plasticity. Therefore, although ancestral stress responses might jump-start evolutionary innovation, substantial lineage-specific modification might be needed to refine these responses into more complex forms of plasticity.
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Affiliation(s)
- Andrew J. Isdaner
- Department of BiologyUniversity of North CarolinaChapel HillNorth CarolinaUSA
| | - Nicholas A. Levis
- Department of BiologyUniversity of North CarolinaChapel HillNorth CarolinaUSA
- Department of BiologyIndiana UniversityBloomingtonIndianaUSA
| | - David W. Pfennig
- Department of BiologyUniversity of North CarolinaChapel HillNorth CarolinaUSA
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Tetrault E, Swenson J, Aaronson B, Marcho C, Albertson RC. The transcriptional state and chromatin landscape of cichlid jaw shape variation across species and environments. Mol Ecol 2023; 32:3922-3941. [PMID: 37160741 PMCID: PMC10524807 DOI: 10.1111/mec.16975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 04/17/2023] [Accepted: 04/24/2023] [Indexed: 05/11/2023]
Abstract
Adaptive phenotypes are shaped by a combination of genetic and environmental forces, but how they interact remains poorly understood. Here, we utilize the cichlid oral jaw apparatus to better understand these gene-by-environment effects. First, we employed RNA-seq in bony and ligamentous tissues important for jaw opening to identify differentially expressed genes between species and across foraging environments. We used two Lake Malawi species adapted to different foraging habitats along the pelagic-benthic ecomorphological axis. Our foraging treatments were designed to force animals to employ either suction or biting/scraping, which broadly mimic pelagic or benthic modes of feeding. We found a large number of differentially expressed genes between species, and while we identified relatively few differences between environments, species differences were far more pronounced when they were challenged with a pelagic versus benthic foraging mode. Expression data carried the signature of genetic assimilation, and implicated cell cycle regulation in shaping the jaw across species and environments. Next, we repeated the foraging experiment and performed ATAC-seq procedures on nuclei harvested from the same tissues. Cross-referencing results from both analyses revealed subsets of genes that were both differentially expressed and differentially accessible. This reduced dataset implicated notable candidate genes including the Hedgehog effector, KIAA0586 and the ETS transcription factor, etv4, which connects environmental stress and craniofacial morphogenesis. Taken together, these data provide novel insights into the epigenetic, genetic and cellular bases of species- and environment-specific bone shapes.
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Affiliation(s)
- Emily Tetrault
- Graduate Program in Molecular and Cell Biology, University of Massachusetts, Amherst MA, 01003, U.S.A
| | - John Swenson
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst MA, 01003, U.S.A
| | - Ben Aaronson
- Biology Department, University of Massachusetts, Amherst MA, 01003, U.S.A
| | - Chelsea Marcho
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst MA, 01003, U.S.A
| | - R. Craig Albertson
- Biology Department, University of Massachusetts, Amherst MA, 01003, U.S.A
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Womack MC, Steigerwald E, Blackburn DC, Cannatella DC, Catenazzi A, Che J, Koo MS, McGuire JA, Ron SR, Spencer CL, Vredenburg VT, Tarvin RD. State of the Amphibia 2020: A Review of Five Years of Amphibian Research and Existing Resources. ICHTHYOLOGY & HERPETOLOGY 2022. [DOI: 10.1643/h2022005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Molly C. Womack
- Department of Biology, Utah State University, Logan, Utah 84322; . ORCID: 0000-0002-3346-021X
| | - Emma Steigerwald
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California 94720; (ES) ; (MSK) ; (JAM) ; (CS) ; (VTV) ; and (RDT)
| | - David C. Blackburn
- Department of Natural History, Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611; . ORCID: 0000-0002-1810-9886
| | - David C. Cannatella
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712; . ORCID: 0000-0001-8675-0520
| | | | - Jing Che
- State Key Laboratory of Genetic Resources and Evolution & Yunnan Key Laboratory of Biodiversity and Ecological Security of Gaoligong Mountain, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China; . ORCID: 0000-0003-4246-6
| | - Michelle S. Koo
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California 94720; (ES) ; (MSK) ; (JAM) ; (CS) ; (VTV) ; and (RDT)
| | - Jimmy A. McGuire
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California 94720; (ES) ; (MSK) ; (JAM) ; (CS) ; (VTV) ; and (RDT)
| | - Santiago R. Ron
- Museo de Zoología, Escuela de Biología, Pontificia Universidad Católica del Ecuador, Quito, Ecuador; . ORCID: 0000-0001-6300-9350
| | - Carol L. Spencer
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California 94720; (ES) ; (MSK) ; (JAM) ; (CS) ; (VTV) ; and (RDT)
| | - Vance T. Vredenburg
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California 94720; (ES) ; (MSK) ; (JAM) ; (CS) ; (VTV) ; and (RDT)
| | - Rebecca D. Tarvin
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, California 94720; (ES) ; (MSK) ; (JAM) ; (CS) ; (VTV) ; and (RDT)
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Levis NA, Ragsdale EJ. Linking Molecular Mechanisms and Evolutionary Consequences of Resource Polyphenism. Front Integr Neurosci 2022; 16:805061. [PMID: 35210995 PMCID: PMC8861301 DOI: 10.3389/fnint.2022.805061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Abstract
Resource polyphenism—the occurrence of environmentally induced, discrete, and intraspecific morphs showing differential niche use—is taxonomically widespread and fundamental to the evolution of ecological function where it has arisen. Despite longstanding appreciation for the ecological and evolutionary significance of resource polyphenism, only recently have its proximate mechanisms begun to be uncovered. Polyphenism switches, especially those influencing and influenced by trophic interactions, offer a route to integrating proximate and ultimate causation in studies of plasticity, and its potential influence on evolution more generally. Here, we use the major events in generalized polyphenic development as a scaffold for linking the molecular mechanisms of polyphenic switching with potential evolutionary outcomes of polyphenism and for discussing challenges and opportunities at each step in this process. Not only does the study of resource polyphenism uncover interesting details of discrete plasticity, it also illuminates and informs general principles at the intersection of development, ecology, and evolution.
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de la Serna Buzon SM, Martin RA, Pfennig DW. Carryover effects and the evolution of polyphenism. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa133] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractAn individual’s early-life environment and phenotype often influence its traits and performance as an adult. We investigated whether such ‘carryover effects’ are associated with alternative, environmentally-induced phenotypes (‘polyphenism’), and, if so, whether they influence the evolution of polyphenism. To do so, we studied Mexican spadefoot toads, Spea multiplicata, which have evolved a polyphenism consisting of two, dramatically different forms: a carnivore morph and an omnivore morph. We sampled both morphs from a fast-drying and a slow-drying pond and reared them to sexual maturity. Larval environment (pond) strongly influenced survival as well as age and size at metamorphosis and sexual maturity; i.e. environment-dependent carryover effects were present. By contrast, larval phenotype (morph) did not affect life-history traits at sexual maturity; i.e. phenotype-dependent carryover effects were absent. These results are consistent with theory, which suggests that by amplifying selective trade-offs in heterogenous environments, environment-dependent carryover effects might foster the evolution of polyphenism. At the same time, by freeing selection to refine a novel phenotype without altering the existing form, the absence of phenotype-dependent carryover effects might enable polyphenism to evolve in the first place. Generally, carryover effects might play an underappreciated role in the evolution of polyphenism.
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Affiliation(s)
| | - Ryan A Martin
- Department of Biology, Case Western Reserve University, Cleveland, OH, USA
| | - David W Pfennig
- Department of Biology, CB#3280, University of North Carolina, Chapel Hill, NC, USA
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