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Sun D, Herath J, Zhou S, Ellepola G, Meegaskumbura M. Associations of Batrachochytrium dendrobatidis with skin bacteria and fungi on Asian amphibian hosts. ISME COMMUNICATIONS 2023; 3:123. [PMID: 37993728 PMCID: PMC10665332 DOI: 10.1038/s43705-023-00332-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 11/07/2023] [Accepted: 11/09/2023] [Indexed: 11/24/2023]
Abstract
Amphibian skin harbors microorganisms that are associated with the fungal pathogen Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis, one of the most significant wildlife diseases known. This pathogen originated in Asia, where diverse Bd lineages exist; hence, native amphibian hosts have co-existed with Bd over long time periods. Determining the nuances of this co-existence is crucial for understanding the prevalence and spread of Bd from a microbial context. However, associations of Bd with the natural skin microbiome remain poorly understood for Asian hosts, especially in relation to skin-associated fungi. We used 16 S rRNA and fungal internal transcribed spacer (ITS) gene sequencing to characterize the skin microbiome of four native Asian amphibian species and examined the relationships between Bd infection and their skin bacterial and fungal communities; we also analyzed the correlates of the putative anti-Bd bacteria. We show that both skin bacterial and fungal community structure and composition had significant associations with infection status (Bd presence/absence) and infection intensity (frequency of Bd sequence reads). We also found that the putative anti-Bd bacterial richness was correlated with Bd infection status and infection intensity, and observed that the relative abundance of anti-Bd bacteria roughly correspond with changes in both Bd prevalence and mean infection intensity in populations. Additionally, the microbial co-occurrence network of infected frogs was significantly different from that of uninfected frogs that were characterized by more keystone nodes (connectors) and larger proportions in correlations between bacteria, suggesting stronger inter-module bacterial interactions. These results indicate that the mutual effects between Bd and skin-associated microbiome, including the interplay between bacteria and fungi, might vary with Bd infection in susceptible amphibian species. This knowledge will help in understanding the dynamics of Bd from a microbial perspective, potentially contributing to mitigate chytridiomycosis in other regions of the world.
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Affiliation(s)
- Dan Sun
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China
| | - Jayampathi Herath
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China
- School of Biomedical Sciences, International Institute of Health Sciences (IIHS), No 704 Negombo Rd, Welisara, 71722, Sri Lanka
| | - Shipeng Zhou
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China
| | - Gajaba Ellepola
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China
- Department of Zoology, Faculty of Science, University of Peradeniya, Peradeniya, KY20400, Sri Lanka
| | - Madhava Meegaskumbura
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China.
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Clarke E, Heugten KAV, Tollefson TN, Ridgley FN, Smith D, Brown JL, Scott H, Minter LJ. Comparison of Corticosterone Concentrations in Dermal Secretions and Urine in Free-Ranging Marine Toads ( Rhinella marina) in Human Care. Vet Med Int 2023; 2023:1467549. [PMID: 37766874 PMCID: PMC10522434 DOI: 10.1155/2023/1467549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 08/25/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Corticosterone concentrations have been measured in amphibians by collecting blood or urine samples. However, blood sampling is invasive, and urine can be difficult to collect. A novel method of swabbing the skin of an amphibian has been utilized in numerous species but has not been verified in marine toads (Rhinella marina). This pilot study tested dermal swabs as a noninvasive method for collecting and measuring dermal corticosterone secretions. Swabs were used to collect dermal secretion samples from sixty-six free-ranging marine toads collected on Zoo Miami grounds. The subsequent day the toads were shipped to the North Carolina Zoo where dermal samples were collected again. Additional dermal and urine samples were collected on days 9, 15, 32, and 62 under human care to measure corticosterone concentrations. There was no significant correlation (P ≥ 0.05) noted between corticosterone concentrations reported in dermal swabs and those in urine samples at all four of the euthanasia time points or between the corticosterone concentrations reported in either urine or dermal swabs and the weight of the toads. Dermal swab concentrations (ng/mL) were significantly higher (P ≤ 0.05) on the day of capture (0.64 ± 0.03) and the day of arrival (0.67 ± 0.03) than on day 15 (0.47 ± 0.03). The urine corticosterone concentrations decreased while the toads were in human care with a significant decrease (P ≤ 0.05) between days 9 (0.45 ± 0.07) and 32 (0.21 ± 0.06). This study demonstrated that dermal swabs can be used to collect marine toad corticosterone concentration samples.
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Affiliation(s)
- Emma Clarke
- Department of Clinical Sciences, North Carolina State University, College of Veterinary Medicine, 1060 William Moore Dr., Raleigh, NC 27607, USA
| | - Kimberly Ange-van Heugten
- Department of Animal Science, North Carolina State University, 120 W. Broughton Dr., Raleigh, NC 27695, USA
- Environment Medicine Consortium, North Carolina State University, 1060 William Moore Dr., Raleigh, NC 27607, USA
| | - Troy N. Tollefson
- Mazuri® Exotic Animal Nutrition, PMI Nutrition, 4001 Lexington Ave. North, Arden Hills, MN 55126, USA
| | - Frank N. Ridgley
- The Conservation and Research Department, Zoo Miami, 12400 SW 152nd St., Miami, FL 33177, USA
| | - Dustin Smith
- North Carolina Zoo, 4401 Zoo Pkwy, Asheboro, NC 27205, USA
| | - Janine L. Brown
- Smithsonian Conservation Biology Institute, 1500 Remount Rd., Front Royal, VA 22630, USA
| | - Heather Scott
- North Carolina Zoo, 4401 Zoo Pkwy, Asheboro, NC 27205, USA
| | - Larry J. Minter
- Department of Clinical Sciences, North Carolina State University, College of Veterinary Medicine, 1060 William Moore Dr., Raleigh, NC 27607, USA
- Environment Medicine Consortium, North Carolina State University, 1060 William Moore Dr., Raleigh, NC 27607, USA
- North Carolina Zoo, 4401 Zoo Pkwy, Asheboro, NC 27205, USA
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Weitzman CL, Kaestli M, Rose A, Hudson CM, Gibb K, Brown GP, Shine R, Christian K. Geographic variation in bacterial assemblages on cane toad skin is influenced more by local environments than by evolved changes in host traits. Biol Open 2023; 12:286922. [PMID: 36745034 PMCID: PMC9932784 DOI: 10.1242/bio.059641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 01/16/2023] [Indexed: 02/07/2023] Open
Abstract
Bacterial assemblages on amphibian skin may play an important role in protecting hosts against infection. In hosts that occur over a range of environments, geographic variation in composition of bacterial assemblages might be due to direct effects of local factors and/or to evolved characteristics of the host. Invasive cane toads (Rhinella marina) are an ideal candidate to evaluate environmental and genetic mechanisms, because toads have evolved major shifts in physiology, morphology, and behavior during their brief history in Australia. We used samples from free-ranging toads to quantify site-level differences in bacterial assemblages and a common-garden experiment to see if those differences disappeared when toads were raised under standardised conditions at one site. The large differences in bacterial communities on toads from different regions were not seen in offspring raised in a common environment. Relaxing bacterial clustering to operational taxonomic units in place of amplicon sequence variants likewise revealed high similarity among bacterial assemblages on toads in the common-garden study, and with free-ranging toads captured nearby. Thus, the marked geographic divergence in bacterial assemblages on wild-caught cane toads across their Australian invasion appears to result primarily from local environmental effects rather than evolved shifts in the host.
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Affiliation(s)
- Chava L. Weitzman
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia,Author for correspondence ()
| | - Mirjam Kaestli
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia
| | - Alea Rose
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia
| | - Cameron M. Hudson
- Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Karen Gibb
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia
| | - Gregory P. Brown
- School of Natural Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Richard Shine
- School of Natural Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Keith Christian
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia
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Divergence in host–parasite interactions during the cane toad's invasion of Australia. Ecol Evol 2022. [DOI: 10.1002/ece3.9220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Eyck HJF, Brown GP, Rollins LA, Shine R. In an arms race between host and parasite, a lungworm's ability to infect a toad is determined by host susceptibility not parasite preference. Biol Lett 2022; 18:20210552. [PMID: 35259944 PMCID: PMC8905180 DOI: 10.1098/rsbl.2021.0552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Evolutionary arms races can alter both parasite infectivity and host resistance, and it is difficult to separate the effects of these twin determinants of infection outcomes. We used a co-introduced, invasive host-parasite system (the lungworm Rhabdias pseudosphaerocephala and cane toads Rhinella marina), where rapid adaptation and dispersal have led to population differences in infection resistance. We quantified behavioural responses of parasite larvae to skin-chemical cues of toads from different invasive populations, and rates at which juvenile hosts became infected following standardized exposure to lungworms. Chemical cues from toad skin altered host-seeking behaviour by parasites, similarly among populations. The number of infection attempts (parasite larvae entering the host's body) also did not differ between populations, but rates of successful infection (establishment of adult worm in host lungs) were higher for range-edge toads than for range-core conspecifics. Thus, lower resistance to parasite infection in range-edge juvenile toads appears to be due to less effective immune defences of the host rather than differential behavioural responses of the parasite. In this ongoing host-parasite arms race, changing outcomes appear to be driven by shifts in host immunocompetence.
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Affiliation(s)
- Harrison J F Eyck
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia
| | - Gregory P Brown
- Department of Biological Sciences, Macquarie University, New South Wales, Australia
| | - Lee A Rollins
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia
| | - Richard Shine
- Department of Biological Sciences, Macquarie University, New South Wales, Australia
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Santos B, Bletz MC, Sabino-Pinto J, Cocca W, Fidy JFS, Freeman KL, Kuenzel S, Ndriantsoa S, Noel J, Rakotonanahary T, Vences M, Crottini A. Characterization of the microbiome of the invasive Asian toad in Madagascar across the expansion range and comparison with a native co-occurring species. PeerJ 2021; 9:e11532. [PMID: 34249488 PMCID: PMC8247705 DOI: 10.7717/peerj.11532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 05/07/2021] [Indexed: 12/19/2022] Open
Abstract
Biological invasions are on the rise, with each invader carrying a plethora of associated microbes. These microbes play important, yet poorly understood, ecological roles that can include assisting the hosts in colonization and adaptation processes or as possible pathogens. Understanding how these communities differ in an invasion scenario may help to understand the host's resilience and adaptability. The Asian common toad, Duttaphrynus melanostictus is an invasive amphibian, which has recently established in Madagascar and is expected to pose numerous threats to the native ecosystems. We characterized the skin and gut bacterial communities of D. melanostictus in Toamasina (Eastern Madagascar), and compared them to those of a co-occurring native frog species, Ptychadena mascareniensis, at three sites where the toad arrived in different years. Microbial composition did not vary among sites, showing that D. melanostictus keeps a stable community across its expansion but significant differences were observed between these two amphibians. Moreover, D. melanostictus had richer and more diverse communities and also harboured a high percentage of total unique taxa (skin: 80%; gut: 52%). These differences may reflect the combination of multiple host-associated factors including microhabitat selection, skin features and dietary preferences.
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Affiliation(s)
- Bárbara Santos
- Cibio, Research Centre in Biodiversity and Genetic Resources, InBio, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Portugal, Porto, Portugal
| | - Molly C Bletz
- Department of Biology, University of Massachussetts Boston, Boston, MA, USA
| | - Joana Sabino-Pinto
- Zoological Institute, Braunschweig University of Technology, Mendelssohnstr. 4, Germany, Braunschweig, Germany
| | - Walter Cocca
- Cibio, Research Centre in Biodiversity and Genetic Resources, InBio, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Portugal, Porto, Portugal
| | | | - Karen Lm Freeman
- Madagascar Fauna and Flora Group, BP 442, 501 Toamasina, Madagascar, Toamasina, Madagascar
| | - Sven Kuenzel
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, Germany, Plön, Germany
| | - Serge Ndriantsoa
- Amphibian Survival Alliance c/o Durrell Wildlife Conservation Trust, Madagascar Programme, Lot II Y 49 J 12 Ampasanimalo, BP 8511 101 Antananarivo, Madagascar, Antananarivo, Madagascar
| | - Jean Noel
- Madagascar Fauna and Flora Group, BP 442, 501 Toamasina, Madagascar, Toamasina, Madagascar
| | - Tsanta Rakotonanahary
- Amphibian Survival Alliance c/o Durrell Wildlife Conservation Trust, Madagascar Programme, Lot II Y 49 J 12 Ampasanimalo, BP 8511 101 Antananarivo, Madagascar, Antananarivo, Madagascar
| | - Miguel Vences
- Zoological Institute, Braunschweig University of Technology, Mendelssohnstr. 4, Germany, Braunschweig, Germany
| | - Angelica Crottini
- Cibio, Research Centre in Biodiversity and Genetic Resources, InBio, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Portugal, Porto, Portugal
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Mayer M, Schlippe Justicia L, Shine R, Brown GP. Host defense or parasite cue: Skin secretions mediate interactions between amphibians and their parasites. Ecol Lett 2021; 24:1955-1965. [PMID: 34176205 DOI: 10.1111/ele.13832] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/21/2021] [Accepted: 05/26/2021] [Indexed: 12/30/2022]
Abstract
Amphibian skin secretions (substances produced by the amphibian plus microbiota) plausibly act as a first line of defense against parasite/pathogen attack, but may also provide chemical cues for pathogens. To clarify the role of skin secretions in host-parasite interactions, we conducted experiments using cane toads (Rhinella marina) and their lungworms (Rhabdias pseudosphaerocephala) from the range-core and invasion-front of the introduced anurans' range in Australia. Depending on the geographical area, toad skin secretions can reduce the longevity and infection success of parasite larvae, or attract lungworm larvae and enhance their infection success. These striking differences between the two regions were due both to differential responses of the larvae, and differential effects of the skin secretions. Our data suggest that skin secretions play an important role in host-parasite interactions in anurans, and that the arms race between a host and parasite can rapidly generate spatial variation in critical features of that interaction.
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Affiliation(s)
- Martin Mayer
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Lia Schlippe Justicia
- Department of Animal Biology, University of La Laguna, Tenerife, Canary Islands, Spain
| | - Richard Shine
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Gregory P Brown
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
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8
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First line of defence: Skin microbiota may protect anurans from infective larval lungworms. INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2021; 14:185-189. [PMID: 33898219 PMCID: PMC8056135 DOI: 10.1016/j.ijppaw.2021.02.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 02/07/2023]
Abstract
Functional roles of the rich microbiota of the skin are not fully understood, but include protection against microbial diseases and other environmental challenges. In experimental studies, we show that reducing the microbiota from cane toad (Rhinella marina) skin by gently wiping with absorptive gauze resulted in threefold higher rates of infection by lungworms (Rhabdias pseudosphaerocephala) following standardised exposure to infective skin-penetrating larvae. Higher concentrations of microbial DNA were associated with lower rates of lungworm entry. Our data suggest that microbial activity on the anuran skin comprises an important line of defence against attack by macroparasites as well as by fungi and other microbes.
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Mayer M, Shine R, Brown GP. Rapid divergence of parasite infectivity and host resistance during a biological invasion. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blaa229] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Abstract
By perturbing co-evolved interactions, biological invasions provide an opportunity to study the evolution of interactions between hosts and their parasites on ecological timescales. We studied the interaction between the cane toad (Rhinella marina) and its direct-lifecycle lungworm (Rhabdias pseudosphaerocephala) that was brought from South America to Australia with the toads in 1935. Compared with infective parasite larvae from long-established (range-core) toad populations, parasite larvae from toads near the invasion front were larger, lived longer and were better able to resist exposure to toxin from the parotoid glands of toads. Experimentally, we infected the common-garden-reared progeny of toads from range-core and invasion-front populations within Australia with lungworms from both populations. Infective larvae from invasion-front (vs. range-core) populations of the parasite were more successful at entering toads (by skin penetration) and establishing infections in the lungs. Toads from invasion-front populations were less prone to infection by either type of larvae. Thus, within 84 years, parasites at an invasion front have increased infectivity, whereas hosts have increased resistance to parasite infection compared with range-core populations. Rapid evolution of traits might affect host–parasite interactions during biological invasions, generating unpredictable effects both on the invaders and on native ecosystems.
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Affiliation(s)
- Martin Mayer
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Richard Shine
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Gregory P Brown
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
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Kosmala GK, Brown GP, Shine R. Thin-skinned invaders: geographic variation in the structure of the skin among populations of cane toads (Rhinella marina). Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa128] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Abstract
The structure of the skin may evolve rapidly during a biological invasion, for two reasons. First, novel abiotic challenges such as hydric conditions may modify selection of traits (such as skin thickness) that determine rates of evaporative water loss. Second, invaders might benefit from enhanced rates of dispersal, with locomotion possibly facilitated by thinner (and hence more flexible) skin. We quantified thickness of layers of the skin in cane toads (Rhinella marina) from the native range (Brazil), a stepping-stone population (Hawaii), and the invaded range in Australia. Overall, the skin is thinner in cane toads in Australia than in the native range, consistent with selection on mobility. However, layers that regulate water exchange (epidermal stratum corneum and dermal ground substance layer) are thicker in Australia, retarding water loss in hot dry conditions. Within Australia, epidermal thickness increased as the toads colonized more arid regions, but then decreased in the arid Kimberley region. That curvilinearity might reflect spatial sorting, whereby mobile (thin-skinned) individuals dominate the invasion front; or the toads’ restriction to moist sites in this arid landscape may reduce the importance of water-conservation. Further work is needed to clarify the roles of adaptation versus phenotypic plasticity in generating the strong geographic variation in skin structure among populations of cane toads.
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Affiliation(s)
- Georgia K Kosmala
- School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
| | - Gregory P Brown
- School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
- Department of Biological Sciences, Macquarie University, NSW, Australia
| | - Richard Shine
- School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
- Department of Biological Sciences, Macquarie University, NSW, Australia
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