1
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Tang S, Peel E, Belov K, Hogg CJ, Farquharson KA. Multi-omics resources for the Australian southern stuttering frog (Mixophyes australis) reveal assorted antimicrobial peptides. Sci Rep 2024; 14:3991. [PMID: 38368484 PMCID: PMC10874372 DOI: 10.1038/s41598-024-54522-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 02/13/2024] [Indexed: 02/19/2024] Open
Abstract
The number of genome-level resources for non-model species continues to rapidly expand. However, frog species remain underrepresented, with up to 90% of frog genera having no genomic or transcriptomic data. Here, we assemble the first genomic and transcriptomic resources for the recently described southern stuttering frog (Mixophyes australis). The southern stuttering frog is ground-dwelling, inhabiting naturally vegetated riverbanks in south-eastern Australia. Using PacBio HiFi long-read sequencing and Hi-C scaffolding, we generated a high-quality genome assembly, with a scaffold N50 of 369.3 Mb and 95.1% of the genome contained in twelve scaffolds. Using this assembly, we identified the mitochondrial genome, and assembled six tissue-specific transcriptomes. We also bioinformatically characterised novel sequences of two families of antimicrobial peptides (AMPs) in the southern stuttering frog, the cathelicidins and β-defensins. While traditional peptidomic approaches to peptide discovery have typically identified one or two AMPs in a frog species from skin secretions, our bioinformatic approach discovered 12 cathelicidins and two β-defensins that were expressed in a range of tissues. We investigated the novelty of the peptides and found diverse predicted activities. Our bioinformatic approach highlights the benefits of multi-omics resources in peptide discovery and contributes valuable genomic resources in an under-represented taxon.
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Affiliation(s)
- Simon Tang
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Emma Peel
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Katherine Belov
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Carolyn J Hogg
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia.
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Katherine A Farquharson
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW, 2006, Australia
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2
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Osborne OG, Jiménez RR, Byrne AQ, Gratwicke B, Ellison A, Muletz-Wolz CR. Phylosymbiosis shapes skin bacterial communities and pathogen-protective function in Appalachian salamanders. THE ISME JOURNAL 2024; 18:wrae104. [PMID: 38861457 PMCID: PMC11195472 DOI: 10.1093/ismejo/wrae104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 05/09/2024] [Accepted: 06/10/2024] [Indexed: 06/13/2024]
Abstract
Phylosymbiosis is an association between host-associated microbiome composition and host phylogeny. This pattern can arise via the evolution of host traits, habitat preferences, diets, and the co-diversification of hosts and microbes. Understanding the drivers of phylosymbiosis is vital for modelling disease-microbiome interactions and manipulating microbiomes in multi-host systems. This study quantifies phylosymbiosis in Appalachian salamander skin in the context of infection by the fungal pathogen Batrachochytrium dendrobatidis (Bd), while accounting for environmental microbiome exposure. We sampled ten salamander species representing >150M years of divergence, assessed their Bd infection status, and analysed their skin and environmental microbiomes. Our results reveal a significant signal of phylosymbiosis, whereas the local environmental pool of microbes, climate, geography, and Bd infection load had a smaller impact. Host-microbe co-speciation was not evident, indicating that the effect stems from the evolution of host traits influencing microbiome assembly. Bd infection is correlated with host phylogeny and the abundance of Bd-inhibitory bacterial strains, suggesting that the long-term evolutionary dynamics between salamander hosts and their skin microbiomes affect the present-day distribution of the pathogen, along with habitat-linked exposure risk. Five Bd-inhibitory bacterial strains showed unusual generalism: occurring in most host species and habitats. These generalist strains may enhance the likelihood of probiotic manipulations colonising and persisting on hosts. Our results underscore the substantial influence of host-microbiome eco-evolutionary dynamics on environmental health and disease outcomes.
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Affiliation(s)
- Owen G Osborne
- School of Environmental and Natural Sciences, Bangor University, Deiniol Road, Bangor, Gwynedd LL57 2DG, United Kingdom
| | - Randall R Jiménez
- Center for Conservation Genomics, Smithsonian’s National Zoological Park and Conservation Biology Institute, Washington, DC 20008, United States
- International Union for Conservation of Nature, C. 39, Los Yoses, San Jose, 146-2150, Costa Rica
| | - Allison Q Byrne
- Center for Conservation Genomics, Smithsonian’s National Zoological Park and Conservation Biology Institute, Washington, DC 20008, United States
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720-3114, United States
| | - Brian Gratwicke
- Center for Species Survival, Smithsonian’s National Zoological Park and Conservation Biology Institute, Front Royal, VA 22630, United States
| | - Amy Ellison
- School of Environmental and Natural Sciences, Bangor University, Deiniol Road, Bangor, Gwynedd LL57 2DG, United Kingdom
| | - Carly R Muletz-Wolz
- Center for Conservation Genomics, Smithsonian’s National Zoological Park and Conservation Biology Institute, Washington, DC 20008, United States
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3
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Roved J. MHCtools 1.5: Analysis of MHC Sequencing Data in R. Methods Mol Biol 2024; 2809:275-295. [PMID: 38907904 DOI: 10.1007/978-1-0716-3874-3_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2024]
Abstract
The genes of the major histocompatibility complex (MHC) play a vital role in the vertebrate immune system and have attracted considerable interest in evolutionary biology. While the MHC has been characterized in detail in humans (human leukocyte antigen, HLA) and in model organisms such as the mouse, studies in non-model organisms often lack prior knowledge about structure, genetic variability, and evolutionary properties of this locus. MHC genotyping in non-model species commonly relies on PCR-based amplicon sequencing, and while several published protocols facilitate generation of MHC sequence data, there is a lack of transparent and standardized tools for downstream data analysis.Here, I present the R package MHCtools version 1.5, which contains 15 tools that (i) assist accurate MHC genotyping from high-throughput amplicon sequencing data, and provide standardized methods to analyze (ii) MHC diversity, (iii) MHC supertypes, and (iv) MHC haplotypes.I hope that MHCtools will be helpful in future studies of the MHC in non-model species and that it may help to advance our understanding of the important roles of the MHC in ecology and evolution.
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Affiliation(s)
- Jacob Roved
- Section for Molecular Ecology and Evolution, GLOBE Institute, University of Copenhagen, Copenhagen, Denmark.
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4
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Trumbo DR, Hardy BM, Crockett HJ, Muths E, Forester BR, Cheek RG, Zimmerman SJ, Corey-Rivas S, Bailey LL, Funk WC. Conservation genomics of an endangered montane amphibian reveals low population structure, low genomic diversity and selection pressure from disease. Mol Ecol 2023; 32:6777-6795. [PMID: 37864490 DOI: 10.1111/mec.17175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 10/07/2023] [Accepted: 10/11/2023] [Indexed: 10/23/2023]
Abstract
Wildlife diseases are a major global threat to biodiversity. Boreal toads (Anaxyrus [Bufo] boreas) are a state-endangered species in the southern Rocky Mountains of Colorado and New Mexico, and a species of concern in Wyoming, largely due to lethal skin infections caused by the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). We performed conservation and landscape genomic analyses using single nucleotide polymorphisms from double-digest, restriction site-associated DNA sequencing in combination with the development of the first boreal toad (and first North American toad) reference genome to investigate population structure, genomic diversity, landscape connectivity and adaptive divergence. Genomic diversity (π = 0.00034-0.00040) and effective population sizes (Ne = 8.9-38.4) were low, likely due to post-Pleistocene founder effects and Bd-related population crashes over the last three decades. Population structure was also low, likely due to formerly high connectivity among a higher density of geographically proximate populations. Boreal toad gene flow was facilitated by low precipitation, cold minimum temperatures, less tree canopy, low heat load and less urbanization. We found >8X more putatively adaptive loci related to Bd intensity than to all other environmental factors combined, and evidence for genes under selection related to immune response, heart development and regulation and skin function. These data suggest boreal toads in habitats with Bd have experienced stronger selection pressure from disease than from other, broad-scale environmental variations. These findings can be used by managers to conserve and recover the species through actions including reintroduction and supplementation of populations that have declined due to Bd.
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Affiliation(s)
- D R Trumbo
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | - B M Hardy
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
- Department of Fish, Wildlife and Conservation Biology, Colorado State University, Fort Collins, Colorado, USA
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
| | - H J Crockett
- Colorado Parks and Wildlife, Fort Collins, Colorado, USA
| | - E Muths
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, USA
| | - B R Forester
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | - R G Cheek
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
| | - S J Zimmerman
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, USA
| | - S Corey-Rivas
- Department of Biology, New Mexico Highlands University, Las Vegas, New Mexico, USA
| | - L L Bailey
- Department of Fish, Wildlife and Conservation Biology, Colorado State University, Fort Collins, Colorado, USA
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
| | - W C Funk
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
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5
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Pröhl H, Rodríguez A. Importance of Genetic-Fitness Correlations for the Conservation of Amphibians. Animals (Basel) 2023; 13:3564. [PMID: 38003181 PMCID: PMC10668650 DOI: 10.3390/ani13223564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/09/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Endangered animals suffer from isolation of their habitats. Isolation leads to a reduction in population size as well as a decrease in genetic diversity and a concomitant increase in the risk of extinction. Amphibians are the most endangered vertebrate class. Besides habitat loss, fragmentation and isolation, amphibians are threatened by emerging diseases e.g., chytrid fungus or Ranavirus. By employing experiments, researchers investigate whether changes in genetic diversity within or among isolated populations affect amphibian fitness. While genetic diversity estimates are based on molecular markers, typically microsatellites, fitness is mostly measured as tadpole performance in rearing experiments often under varying environmental conditions. Tadpole performances (e.g., body mass, growth rate and survival) have been found to be negatively affected by low genetic diversity, as several studies have found a positive association between genetic diversity and these fitness traits. Moreover, infection with pathogens also seems to be more likely in individuals or populations with lower genetic diversity. Overall, these genetic-fitness correlations seem to be more pronounced or detectable in smaller, declining populations but not in larger populations. Genomic studies, which sample a larger fraction of the genome, are still scarce in the conservation genetic literature on amphibians. These are likely to increase in upcoming years and may reveal adaptive variants that protect against dangerous pathogens or environmental changes. Altogether, genetic-fitness correlation studies should be a priority in order to develop effective management plans for the genetic rescue of isolated, imperilled amphibian populations.
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Affiliation(s)
- Heike Pröhl
- Institute of Zoology, University of Veterinary Medicine of Hannover, Bünteweg 17, 30559 Hannover, Germany;
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6
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Zhang J, Wang S, Xu C, Wang S, Du J, Niu M, Yang J, Li Y. Pathogenic selection promotes adaptive immune variations against serious bottlenecks in early invasions of bullfrogs. iScience 2023; 26:107316. [PMID: 37539025 PMCID: PMC10393753 DOI: 10.1016/j.isci.2023.107316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 05/22/2023] [Accepted: 07/04/2023] [Indexed: 08/05/2023] Open
Abstract
Adaptive genetic variations are key for understanding evolutionary processes influencing invasions. However, we have limited knowledge on how adaptive genetic diversity in invasive species responds to new pathogenic environments. Here, we compared variations in immune major histocompatibility complex (MHC) class-II β gene and neutral loci in relation to pathogenic chytrid fungus (Batrachochytrium dendrobatidis, Bd) infection across invasive and native populations of American bullfrog between China and United States (US). Chinese invasive populations show a 60% reduction in neutral cytb variations relative to US native populations, and there were similar MHC variation and functional diversity between them. One MHC allele private to China was under recent positive selection and associated with decreased Bd infection, partly explaining the lower Bd prevalence for Chinese populations than for native US populations. These results suggest that pathogen-mediated selection favors adaptive MHC variations and functional diversity maintenance against serious bottlenecks during the early invasions (within 15 generations) of bullfrogs.
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Affiliation(s)
- Jiaqi Zhang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, Beijing 100101, China
- University of Chinese Academy of Sciences Beijing 100049, China
| | - Supen Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, Beijing 100101, China
| | - Chunxia Xu
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, Beijing 100101, China
- University of Chinese Academy of Sciences Beijing 100049, China
| | - Siqi Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, Beijing 100101, China
- University of Chinese Academy of Sciences Beijing 100049, China
| | - Jiacong Du
- School of Life Sciences, Institute of Life Sciences and Green Development, Hebei University, Baoding 071002, China
| | - Meiling Niu
- School of Life Sciences, Institute of Life Sciences and Green Development, Hebei University, Baoding 071002, China
| | - Jiaxue Yang
- School of Life Sciences, Institute of Life Sciences and Green Development, Hebei University, Baoding 071002, China
| | - Yiming Li
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, Beijing 100101, China
- University of Chinese Academy of Sciences Beijing 100049, China
- School of Life Sciences, Institute of Life Sciences and Green Development, Hebei University, Baoding 071002, China
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7
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Lau Q, Igawa T, Kosch TA, Dharmayanthi AB, Berger L, Skerratt LF, Satta Y. Conserved Evolution of MHC Supertypes among Japanese Frogs Suggests Selection for Bd Resistance. Animals (Basel) 2023; 13:2121. [PMID: 37443920 DOI: 10.3390/ani13132121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/16/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
The chytrid fungus Batrachochytrium dendrobatidis (Bd) is a major threat to amphibians, yet there are no reports of major disease impacts in East Asian frogs. Genetic variation of the major histocompatibility complex (MHC) has been associated with resistance to Bd in frogs from East Asia and worldwide. Using transcriptomic data collated from 11 Japanese frog species (one individual per species), we isolated MHC class I and IIb sequences and validated using molecular cloning. We then compared MHC from Japanese frogs and other species worldwide, with varying Bd susceptibility. Supertyping analysis, which groups MHC alleles based on physicochemical properties of peptide binding sites, identified that all examined East Asian frogs contained at least one MHC-IIb allele belonging to supertype ST-1. This indicates that, despite the large divergence times between some Japanese frogs (up to 145 million years), particular functional properties in the peptide binding sites of MHC-II are conserved among East Asian frogs. Furthermore, preliminary analysis using NetMHCIIpan-4.0, which predicts potential Bd-peptide binding ability, suggests that MHC-IIb ST-1 and ST-2 have higher overall peptide binding ability than other supertypes, irrespective of whether the peptides are derived from Bd, other fungi, or bacteria. Our findings suggest that MHC-IIb among East Asian frogs may have co-evolved under the same selective pressure. Given that Bd originated in this region, it may be a major driver of MHC evolution in East Asian frogs.
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Affiliation(s)
- Quintin Lau
- Research Center for Integrative Evolutionary Science, Sokendai (The Graduate University for Advanced Studies), Hayama 240-0115, Japan
| | - Takeshi Igawa
- Amphibian Research Center, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Tiffany A Kosch
- One Health Research Group, Faculty of Science, University of Melbourne, Parkville 3010, Australia
| | - Anik B Dharmayanthi
- Research Center for Biosystematics and Evolution, National Research and Innovation Agency (BRIN), Bogor 16911, Indonesia
| | - Lee Berger
- One Health Research Group, Faculty of Science, University of Melbourne, Parkville 3010, Australia
| | - Lee F Skerratt
- One Health Research Group, Faculty of Science, University of Melbourne, Parkville 3010, Australia
| | - Yoko Satta
- Research Center for Integrative Evolutionary Science, Sokendai (The Graduate University for Advanced Studies), Hayama 240-0115, Japan
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8
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Cubaynes S, Brandell EE, Stahler DR, Smith DW, Almberg ES, Schindler S, Wayne RK, Dobson AP, vonHoldt BM, MacNulty DR, Cross PC, Hudson PJ, Coulson T. Disease outbreaks select for mate choice and coat color in wolves. Science 2022; 378:300-303. [PMID: 36264784 DOI: 10.1126/science.abi8745] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We know much about pathogen evolution and the emergence of new disease strains, but less about host resistance and how it is signaled to other individuals and subsequently maintained. The cline in frequency of black-coated wolves (Canis lupus) across North America is hypothesized to result from a relationship with canine distemper virus (CDV) outbreaks. We tested this hypothesis using cross-sectional data from wolf populations across North America that vary in the prevalence of CDV and the allele that makes coats black, longitudinal data from Yellowstone National Park, and modeling. We found that the frequency of CDV outbreaks generates fluctuating selection that results in heterozygote advantage that in turn affects the frequency of the black allele, optimal mating behavior, and black wolf cline across the continent.
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Affiliation(s)
- Sarah Cubaynes
- CEFE, University of Montpellier, CNRS, EPHE-PSL University, IRD, 34090 Montpellier, France
| | - Ellen E Brandell
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, State College, PA 16802, USA
| | - Daniel R Stahler
- Yellowstone Center for Resources, Yellowstone National Park, WY 82190, USA
| | - Douglas W Smith
- Yellowstone Center for Resources, Yellowstone National Park, WY 82190, USA
| | - Emily S Almberg
- Wildlife Division, Montana Fish Wildlife & Park, Bozeman, MT 59718, USA
| | - Susanne Schindler
- School of Biological Sciences, University of Bristol, Bristol BS8 1QU, UK
| | - Robert K Wayne
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Andrew P Dobson
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.,Santa Fe Institute, Santa Fe, NM 87501, USA
| | - Bridgett M vonHoldt
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - Daniel R MacNulty
- Department of Wildland Resources and Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Paul C Cross
- US Geological Survey, Northern Rocky Mountain Science Center, Bozeman, MT 59715, USA
| | - Peter J Hudson
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, State College, PA 16802, USA
| | - Tim Coulson
- Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
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9
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Neely WJ, Greenspan SE, Stahl LM, Heraghty SD, Marshall VM, Atkinson CL, Becker CG. Habitat Disturbance Linked with Host Microbiome Dispersion and Bd Dynamics in Temperate Amphibians. MICROBIAL ECOLOGY 2022; 84:901-910. [PMID: 34671826 DOI: 10.1007/s00248-021-01897-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 10/08/2021] [Indexed: 06/13/2023]
Abstract
Anthropogenic habitat disturbances can dramatically alter ecological community interactions, including host-pathogen dynamics. Recent work has highlighted the potential for habitat disturbances to alter host-associated microbial communities, but the associations between anthropogenic disturbance, host microbiomes, and pathogens are unresolved. Amphibian skin microbial communities are particularly responsive to factors like temperature, physiochemistry, pathogen infection, and environmental microbial reservoirs. Through a field survey on wild populations of Acris crepitans (Hylidae) and Lithobates catesbeianus (Ranidae), we assessed the effects of habitat disturbance and connectivity on environmental bacterial reservoirs, Batrachochytrium dendrobatidis (Bd) infection, and skin microbiome composition. We found higher measures of microbiome dispersion (a measure of community variability) in A. crepitans from more disturbed ponds, supporting the hypothesis that disturbance increases stochasticity in biological communities. We also found that habitat disturbance limited microbiome similarity between locations for both species, suggesting greater isolation of bacterial assemblages in more disturbed areas. Higher disturbance was associated with lower Bd prevalence for A. crepitans, which could signify suboptimal microclimates for Bd in disturbed habitats. Combined, our findings show that reduced microbiome stability stemming from habitat disturbance could compromise population health, even in the absence of pathogenic infection.
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Affiliation(s)
- Wesley J Neely
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA.
| | - Sasha E Greenspan
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - Leigha M Stahl
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - Sam D Heraghty
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - Vanessa M Marshall
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - Carla L Atkinson
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - C Guilherme Becker
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
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10
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LaFond J, Martin KR, Dahn H, Richmond JQ, Murphy RW, Rollinson N, Savage AE. Invasive Bullfrogs Maintain MHC Polymorphism Including Alleles Associated with Chytrid Fungal Infection. Integr Comp Biol 2022; 62:262-274. [PMID: 35588059 DOI: 10.1093/icb/icac044] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/19/2022] [Accepted: 05/16/2022] [Indexed: 11/14/2022] Open
Abstract
Maintenance of genetic diversity at adaptive loci may facilitate invasions by non-native species by allowing populations to adapt to novel environments, despite the loss of diversity at neutral loci that typically occurs during founder events. To evaluate this prediction, we compared genetic diversity at major histocompatibility complex (MHC) and cytochrome b (cytb) loci from 20 populations of the American bullfrog (Rana catesbeiana) across theinvasive and native ranges in North America and quantified the presence of the pathogen Batrachochytrium dendrobatidis (Bd). Compared to native populations, invasive populations had significantly higher Bd prevalence and intensity, significantly higher pairwise MHC and cytb FST, and significantly lower cytb diversity, but maintained similar levels of MHC diversity. The two most common MHC alleles (LiCA_B and Rapi_33) were associated with a significant decreased risk of Bd infection, and we detected positive selection acting on four peptide binding residues. Phylogenetic analysis suggested invasive populations likely arose from a single founding population in the American Midwest with a possible subsequent invasion in the northwest. Overall, our study suggests that the maintenance of diversity at adaptive loci may contribute to invasion success and highlights the importance of quantifying diversity at functional loci to assess the evolutionary potential of invasive populations.
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Affiliation(s)
- Jacob LaFond
- Department of Biology, University of Central Florida, Orlando, FL 32816, USA
- Department of Biology, University of Tampa, Tampa, FL 33606, USA
| | - Katherine R Martin
- Department of Biology, University of Central Florida, Orlando, FL 32816, USA
| | - Hollis Dahn
- Department of Biology, University of Toronto, Toronto, ON, Canada
| | - Jonathan Q Richmond
- U.S. Geological Survey, 4165 Spruance Rd. Suite 200, San Diego, CA 92101, USA
| | - Robert W Murphy
- Department of Biology, University of Toronto, Toronto, ON, Canada
| | - Njal Rollinson
- Department of Biology, University of Toronto, Toronto, ON, Canada
| | - Anna E Savage
- Department of Biology, University of Central Florida, Orlando, FL 32816, USA
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11
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Forsman AM, Savage AE, Hoenig BD, Gaither MR. DNA metabarcoding across disciplines: sequencing our way to greater understanding across scales of biological organization. Integr Comp Biol 2022; 62:191-198. [PMID: 35687001 DOI: 10.1093/icb/icac090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/03/2022] [Accepted: 06/06/2022] [Indexed: 11/13/2022] Open
Abstract
DNA metabarcoding describes the use of targeted DNA (i.e., amplicon) sequencing to identify community constituents from a complex sample containing genetic material from multiple organisms, such as water, soil, gut contents, microbiomes, or biofilms. This molecular approach for characterizing mixed DNA samples relies on the development of "universal primers" that allow for effective amplification of target sequences across a broad range of taxa. Armed with optimized lab protocols and rigorous bioinformatics tools, DNA metabarcoding can produce a wealth of information about the hidden biodiversity of various sample types by probing for organisms' molecular footprints. DNA metabarcoding has received considerable popular press over the last few years because of gut microbiome studies in humans and beyond. However, there are many other applications that are continually integrating molecular biology with other fields of study to address questions that have previously been unanswerable, for both prokaryotic and eukaryotic targets. For example, we can now sample mostly-digested gut contents from virtually any organism to learn about ontogeny and foraging ecology. Water samples collected from different locations can be filtered to extract eDNA (i.e., environmental DNA), revealing the biodiversity of fishes and other taxa targeted by carefully selected primer sets. This universal primer metabarcoding approach has even been extended to looking at diverse gene families within single species, which is particularly useful for complex immune system genetics. The purpose of this SICB symposium was to bring together researchers using DNA metabarcoding approaches to (a) showcase the diversity of applications of this technique for addressing questions spanning ecology, evolution, and physiology, and (b) to spark connections among investigators from different fields that are utilizing similar approaches to facilitate optimization and standardization of metabarcoding methods and analyses. The resulting manuscripts from this symposium represent a great diversity of metabarcoding applications and taxonomic groups of interest.
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Affiliation(s)
- Anna M Forsman
- Department of Biology, University of Central Florida, Orlando, FL, USA.,Genomics & Bioinformatics Cluster, University of Central Florida, Orlando, FL, USA
| | - Anna E Savage
- Department of Biology, University of Central Florida, Orlando, FL, USA
| | - Brandon D Hoenig
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michelle R Gaither
- Department of Biology, University of Central Florida, Orlando, FL, USA.,Genomics & Bioinformatics Cluster, University of Central Florida, Orlando, FL, USA
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Smith D, O'Brien D, Hall J, Sergeant C, Brookes LM, Harrison XA, Garner TWJ, Jehle R. Challenging a host-pathogen paradigm: Susceptibility to chytridiomycosis is decoupled from genetic erosion. J Evol Biol 2022; 35:589-598. [PMID: 35167143 PMCID: PMC9306973 DOI: 10.1111/jeb.13987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 02/07/2022] [Indexed: 11/26/2022]
Abstract
The putatively positive association between host genetic diversity and the ability to defend against pathogens has long attracted the attention of evolutionary biologists. Chytridiomycosis, a disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), has emerged in recent decades as a cause of dramatic declines and extinctions across the amphibian clade. Bd susceptibility can vary widely across populations of the same species, but the relationship between standing genetic diversity and susceptibility has remained notably underexplored so far. Here, we focus on a putatively Bd-naive system of two mainland and two island populations of the common toad (Bufo bufo) at the edge of the species' range and use controlled infection experiments and dd-RAD sequencing of >10 000 SNPs across 95 individuals to characterize the role of host population identity, genetic variation and individual body mass in mediating host response to the pathogen. We found strong genetic differentiation between populations and marked variation in their susceptibility to Bd. This variation was not, however, governed by isolation-mediated genetic erosion, and individual heterozygosity was even found to be negatively correlated with survival. Individual survival during infection experiments was strongly positively related to body mass, which itself was unrelated to population of origin or heterozygosity. Our findings underscore the general importance of context-dependency when assessing the role of host genetic variation for the ability of defence against pathogens.
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Affiliation(s)
- Donal Smith
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
- Institute of ZoologyZoological Society of LondonLondonUK
| | | | | | - Chris Sergeant
- Institute of ZoologyZoological Society of LondonLondonUK
| | - Lola M. Brookes
- Institute of ZoologyZoological Society of LondonLondonUK
- Highland Amphibian and Reptile ProjectDingwallUK
- MRC Centre for Global Infectious Disease AnalysisImperial College School of Public HealthLondonUK
- Royal Veterinary CollegeHatfieldUK
| | - Xavier A. Harrison
- Institute of ZoologyZoological Society of LondonLondonUK
- Centre for Ecology and ConservationUniversity of ExeterExeterUK
| | | | - Robert Jehle
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
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