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Knutie SA, Webster CN, Vaziri GJ, Albert L, Harvey JA, LaRue M, Verrett TB, Soldo A, Koop JAH, Chaves JA, Wegrzyn JL. Urban living can rescue Darwin's finches from the lethal effects of invasive vampire flies. Glob Chang Biol 2024; 30:e17145. [PMID: 38273516 DOI: 10.1111/gcb.17145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 12/15/2023] [Accepted: 12/21/2023] [Indexed: 01/27/2024]
Abstract
Human activity changes multiple factors in the environment, which can have positive or negative synergistic effects on organisms. However, few studies have explored the causal effects of multiple anthropogenic factors, such as urbanization and invasive species, on animals and the mechanisms that mediate these interactions. This study examines the influence of urbanization on the detrimental effect of invasive avian vampire flies (Philornis downsi) on endemic Darwin's finches in the Galápagos Islands. We experimentally manipulated nest fly abundance in urban and non-urban locations and then characterized nestling health, fledging success, diet, and gene expression patterns related to host defense. Fledging success of non-parasitized nestlings from urban (79%) and non-urban (75%) nests did not differ significantly. However, parasitized, non-urban nestlings lost more blood, and fewer nestlings survived (8%) compared to urban nestlings (50%). Stable isotopic values (δ15 N) from urban nestling feces were higher than those from non-urban nestlings, suggesting that urban nestlings are consuming more protein. δ15 N values correlated negatively with parasite abundance, which suggests that diet might influence host defenses (e.g., tolerance and resistance). Parasitized, urban nestlings differentially expressed genes within pathways associated with red blood cell production (tolerance) and pro-inflammatory response (innate immunological resistance), compared to parasitized, non-urban nestlings. In contrast, parasitized non-urban nestlings differentially expressed genes within pathways associated with immunoglobulin production (adaptive immunological resistance). Our results suggest that urban nestlings are investing more in pro-inflammatory responses to resist parasites but also recovering more blood cells to tolerate blood loss. Although non-urban nestlings are mounting an adaptive immune response, it is likely a last effort by the immune system rather than an effective defense against avian vampire flies since few nestlings survived.
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Affiliation(s)
- Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, USA
| | - Cynthia N Webster
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Grace J Vaziri
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Lauren Albert
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Johanna A Harvey
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
- Department of Science and Technology, University of Maryland, College Park, Maryland, USA
| | - Michelle LaRue
- School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
| | - Taylor B Verrett
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Alexandria Soldo
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Jennifer A H Koop
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, USA
| | - Jaime A Chaves
- Department of Biology, San Francisco State University, San Francisco, California, USA
- Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito, Ecuador
| | - Jill L Wegrzyn
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, USA
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2
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Beausoleil MO, Carrión PL, Podos J, Camacho C, Rabadán-González J, Richard R, Lalla K, Raeymaekers JAM, Knutie SA, De León LF, Chaves JA, Clayton DH, Koop JAH, Sharpe DMT, Gotanda KM, Huber SK, Barrett RDH, Hendry AP. The fitness landscape of a community of Darwin's finches. Evolution 2023; 77:2533-2546. [PMID: 37671423 DOI: 10.1093/evolut/qpad160] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 04/05/2023] [Revised: 06/22/2023] [Accepted: 08/31/2023] [Indexed: 09/07/2023]
Abstract
Divergent natural selection should lead to adaptive radiation-that is, the rapid evolution of phenotypic and ecological diversity originating from a single clade. The drivers of adaptive radiation have often been conceptualized through the concept of "adaptive landscapes," yet formal empirical estimates of adaptive landscapes for natural adaptive radiations have proven elusive. Here, we use a 17-year dataset of Darwin's ground finches (Geospiza spp.) at an intensively studied site on Santa Cruz (Galápagos) to estimate individual apparent lifespan in relation to beak traits. We use these estimates to model a multi-species fitness landscape, which we also convert to a formal adaptive landscape. We then assess the correspondence between estimated fitness peaks and observed phenotypes for each of five phenotypic modes (G. fuliginosa, G. fortis [small and large morphotypes], G. magnirostris, and G. scandens). The fitness and adaptive landscapes show 5 and 4 peaks, respectively, and, as expected, the adaptive landscape was smoother than the fitness landscape. Each of the five phenotypic modes appeared reasonably close to the corresponding fitness peak, yet interesting deviations were also documented and examined. By estimating adaptive landscapes in an ongoing adaptive radiation, our study demonstrates their utility as a quantitative tool for exploring and predicting adaptive radiation.
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Affiliation(s)
| | - Paola Lorena Carrión
- Redpath Museum and Department of Biology, McGill University, Montréal, Québec, Canada
| | - Jeffrey Podos
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, United States
| | - Carlos Camacho
- Department of Ecology and Evolution, Estación Biológica de Doñana-CSIC, Sevilla, Spain
| | | | - Roxanne Richard
- Redpath Museum and Department of Biology, McGill University, Montréal, Québec, Canada
| | - Kristen Lalla
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Québec, Canada
| | | | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, Institute for Systems Genomics, University of Connecticut, Storrs, CT, United States
| | - Luis F De León
- Department of Biology, University of Massachusetts Boston, Boston, MA, United States
| | - Jaime A Chaves
- Department of Biology, San Francisco State University, San Francisco, CA, United States
- Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito, Ecuador
| | - Dale H Clayton
- School of Biological Sciences, University of Utah, Salt Lake City, UT, United States
| | - Jennifer A H Koop
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL, United States
| | - Diana M T Sharpe
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | - Kiyoko M Gotanda
- Redpath Museum and Department of Biology, McGill University, Montréal, Québec, Canada
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
- Department of Zoology, University of Cambridge, United Kingdom
- Département de biologie, Université de Sherbrooke, Québec, Canada
| | - Sarah K Huber
- Virginia Institute of Marine Science, William and Mary, Gloucester Point, VA, United States
| | - Rowan D H Barrett
- Redpath Museum and Department of Biology, McGill University, Montréal, Québec, Canada
| | - Andrew P Hendry
- Redpath Museum and Department of Biology, McGill University, Montréal, Québec, Canada
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3
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Solomon G, Love AC, Vaziri GJ, Harvey J, Verrett T, Chernicky K, Simons S, Albert L, Chaves JA, Knutie SA. Effect of urbanization and parasitism on the gut microbiota of Darwin's finch nestlings. Mol Ecol 2023; 32:6059-6069. [PMID: 37837269 DOI: 10.1111/mec.17164] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 07/03/2023] [Revised: 09/20/2023] [Accepted: 10/02/2023] [Indexed: 10/15/2023]
Abstract
Host-associated microbiota can be affected by factors related to environmental change, such as urbanization and invasive species. For example, urban areas often affect food availability for animals, which can change their gut microbiota. Invasive parasites can also influence microbiota through competition or indirectly through a change in the host immune response. These interacting factors can have complex effects on host fitness, but few studies have disentangled the relationship between urbanization and parasitism on an organism's gut microbiota. To address this gap in knowledge, we investigated the effects of urbanization and parasitism by the invasive avian vampire fly (Philornis downsi) on the gut microbiota of nestling small ground finches (Geospiza fuliginosa) on San Cristóbal Island, Galápagos. We conducted a factorial study in which we experimentally manipulated parasite presence in an urban and nonurban area. Faeces were then collected from nestlings to characterize the gut microbiota (i.e. bacterial diversity and community composition). Although we did not find an interactive effect of urbanization and parasitism on the microbiota, we did find main effects of each variable. We found that urban nestlings had lower bacterial diversity and different relative abundances of taxa compared to nonurban nestlings, which could be mediated by introduction of the microbiota of the food items or changes in host physiology. Additionally, parasitized nestlings had lower bacterial richness than nonparasitized nestlings, which could be mediated by a change in the immune system. Overall, this study advances our understanding of the complex effects of anthropogenic stressors on the gut microbiota of birds.
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Affiliation(s)
- Gabrielle Solomon
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
| | - Ashley C Love
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
| | - Grace J Vaziri
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
| | - Johanna Harvey
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
| | - Taylor Verrett
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
| | - Kiley Chernicky
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
| | - Shelby Simons
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
| | - Lauren Albert
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
| | - Jaime A Chaves
- Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito, Ecuador
- Galapagos Science Center, Puerto Baquerizo Moreno, Galapagos, Ecuador
- Department of Biology, San Francisco State University, California, San Francisco, USA
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Connecticut, Storrs, USA
- Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito, Ecuador
- Institute for Systems Genomics, University of Connecticut, Connecticut, Storrs, USA
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Yitbarek S, Guittar J, Knutie SA, Ogbunugafor CB. Deconstructing taxa x taxa xenvironment interactions in the microbiota: A theoretical examination. iScience 2023; 26:107875. [PMID: 37860776 PMCID: PMC10583047 DOI: 10.1016/j.isci.2023.107875] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 05/04/2022] [Revised: 03/21/2023] [Accepted: 09/07/2023] [Indexed: 10/21/2023] Open
Abstract
A major objective of microbial ecology is to identify how the composition of microbial taxa shapes host phenotypes. However, most studies focus on pairwise interactions and ignore the potentially significant effects of higher-order microbial interactions.Here, we quantify the effects of higher-order interactions among taxa on host infection risk. We apply our approach to an in silico dataset that is built to resemble a population of insect hosts with gut-associated microbial communities at risk of infection from an intestinal parasite across a breadth of nutrient environmental contexts.We find that the effect of higher-order interactions is considerable and can change appreciably across environmental contexts. Furthermore, we show that higher-order interactions can stabilize community structure thereby reducing host susceptibility to parasite invasion.Our approach illustrates how incorporating the effects of higher-order interactions among gut microbiota across environments can be essential for understanding their effects on host phenotypes.
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Affiliation(s)
- Senay Yitbarek
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - John Guittar
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
- Kellogg Biological Station, Michigan State University, Hickory Corners, MI 49060, USA
| | - Sarah A. Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, CT 06269, USA
| | - C. Brandon Ogbunugafor
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Santa Fe Institute, Santa Fe, NM 87501, USA
- Vermont Complex Systems Center, University of Vermont, Burlington, VT 05405, USA
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5
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Albert L, Rumschlag S, Parker A, Vaziri G, Knutie SA. Elevated nest temperature has opposing effects on host species infested with parasitic nest flies. Oecologia 2023; 201:877-886. [PMID: 37012554 DOI: 10.1007/s00442-023-05343-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 04/23/2022] [Accepted: 02/20/2023] [Indexed: 04/05/2023]
Abstract
Environmental factors, such as elevated temperature, can have varying effects on hosts and their parasites, which can have consequences for the net outcome of this relationship. The individual direct effects of temperature must be disentangled to determine the net-effect in host-parasite relationships, yet few studies have determined the net-effects in a multi-host system. To address this gap, we experimentally manipulated temperature and parasite presence in the nests of two host species infested by parasitic blowflies (Protocalliphora sialia). We conducted a factorial experiment by increasing temperature (or not) and removing all parasites (or not) in the nests of eastern bluebirds (Sialia sialis) and tree swallows (Tachycineta bicolor). We then measured nestling morphometrics, blood loss, and survival and quantified parasite abundance. We predicted that if temperature had a direct effect on parasite abundance, then elevated temperature would cause similar directional effects on parasite abundance across host species. If temperature had a direct effect on hosts, and therefore an indirect effect on the parasite, parasite abundance would differ across host species. Swallow nests with elevated temperature had fewer parasites compared to nests without temperature manipulation. In contrast, bluebird nests with elevated temperatures had more parasites compared to nests without temperature manipulation. The results of our study demonstrate that elevated temperature can have differential effects on host species, which can impact infestation susceptibility. Furthermore, changing climates could have complex net-effects on parasite fitness and host health across multi-host-parasite interactions.
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Affiliation(s)
- Lauren Albert
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA.
- Department of Biology, Indiana University, Bloomington, IN, USA.
| | - Samantha Rumschlag
- Department of Biological Sciences, Environmental Change Initiative, University of Notre Dame, Notre Dame, IN, USA
| | - Alexandra Parker
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Grace Vaziri
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA
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6
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Carrión PL, Raeymaekers JAM, De León LF, Chaves JA, Sharpe DMT, Huber SK, Herrel A, Vanhooydonck B, Gotanda KM, Koop JAH, Knutie SA, Clayton DH, Podos J, Hendry AP. The terroir of the finch: How spatial and temporal variation shapes phenotypic traits in DARWIN'S finches. Ecol Evol 2022; 12:e9399. [PMID: 36225827 PMCID: PMC9534727 DOI: 10.1002/ece3.9399] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 09/18/2022] [Accepted: 09/19/2022] [Indexed: 11/10/2022] Open
Abstract
The term terroir is used in viticulture to emphasize how the biotic and abiotic characteristics of a local site influence grape physiology and thus the properties of wine. In ecology and evolution, such terroir (i.e., the effect of space or “site”) is expected to play an important role in shaping phenotypic traits. Just how important is the pure spatial effect of terroir (e.g., differences between sites that persist across years) in comparison to temporal variation (e.g., differences between years that persist across sites), and the interaction between space and time (e.g., differences between sites change across years)? We answer this question by analyzing beak and body traits of 4388 medium ground finches (Geospiza fortis) collected across 10 years at three locations in Galápagos. Analyses of variance indicated that phenotypic variation was mostly explained by site for beak size (η2 = 0.42) and body size (η2 = 0.43), with a smaller contribution for beak shape (η2 = 0.05) and body shape (η2 = 0.12), but still higher compared to year and site‐by‐year effects. As such, the effect of terroir seems to be very strong in Darwin's finches, notwithstanding the oft‐emphasized interannual variation. However, these results changed dramatically when we excluded data from Daphne Major, indicating that the strong effect of terroir was mostly driven by that particular population. These phenotypic results were largely paralleled in analyses of environmental variables (rainfall and vegetation indices) expected to shape terroir in this system. These findings affirm the evolutionary importance of terroir, while also revealing its dependence on other factors, such as geographical isolation.
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Affiliation(s)
- Paola L. Carrión
- Redpath Museum, Department of BiologyMcGill UniversityMontréalQuébecCanada
| | | | - Luis Fernando De León
- Department of BiologyUniversity of Massachusetts BostonBostonMassachusettsUSA,Centro de Biodiversidad y Descubrimiento de DrogasInstituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT‐AIP)PanamáRepública de Panamá,Smithsonian Tropical Research InstitutePanamáRepública de Panamá
| | - Jaime A. Chaves
- Department of BiologySan Francisco State UniversitySan FranciscoCaliforniaUSA,Colegio de Ciencias Biológicas y AmbientalesUniversidad San Francisco de QuitoQuitoEcuador
| | - Diana M. T. Sharpe
- Smithsonian Tropical Research InstitutePanamáRepública de Panamá,Worcester State UniversityWorcesterMassachusettsUSA
| | - Sarah K. Huber
- Virginia Institute of Marine ScienceCollege of William & MaryGloucester PointVirginiaUSA
| | - Anthony Herrel
- Muséum National d'Histoire NaturelleDépartement Adaptations du VivantBâtiment d'Anatomie ComparéeParisFrance
| | | | - Kiyoko M. Gotanda
- Department of Biological SciencesBrock UniversitySt. CatharinesOntarioCanada,Departement de BiologieUniversite de SherbrookeQuebecCanada
| | - Jennifer A. H. Koop
- Department of Biological SciencesNorthern Illinois UniversityDeKalbIllinoisUSA
| | - Sarah A. Knutie
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsConnecticutUSA,Institute for Systems GenomicsUniversity of ConnecticutStorrsConnecticutUSA
| | - Dale H. Clayton
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Jeffrey Podos
- Department of BiologyUniversity of Massachusetts AmherstAmherstMassachusettsUSA
| | - Andrew P. Hendry
- Redpath Museum, Department of BiologyMcGill UniversityMontréalQuébecCanada
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7
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Romine MG, Knutie SA, Crow CM, Vaziri GJ, Chaves JA, Koop JAH, Lamichhaney S. The genome sequence of the avian vampire fly ( Philornis downsi), an invasive nest parasite of Darwin’s finches in Galápagos. G3 Genes|Genomes|Genetics 2022; 12:6456303. [PMID: 34878103 PMCID: PMC9210292 DOI: 10.1093/g3journal/jkab414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 11/15/2021] [Indexed: 11/14/2022]
Abstract
The invasive avian vampire fly (Philornis downsi, Diptera: Muscidae) is considered one of the greatest threats to the endemic avifauna of the Galápagos Islands. The fly larvae parasitize nearly every passerine species, including Darwin’s finches. Most P. downsi research to date has focused on the effects of the fly on avian host fitness and mitigation methods. A lag in research related to the genetics of this invasion demonstrates, in part, the need to develop full-scale genomic resources with which to address further questions within this system. In this study, an adult female P. downsi was sequenced to generate a high-quality genome assembly. We examined various features of the genome (e.g., coding regions and noncoding transposable elements) and carried out comparative genomics analysis against other dipteran genomes. We identified lists of gene families that are significantly expanding or contracting in P. downsi that are related to insecticide resistance, detoxification, and counter defense against host immune responses. The P. downsi genome assembly provides an important resource for studying the molecular basis of successful invasion in the Galápagos and the dynamics of its population across multiple islands. The findings of significantly changing gene families associated with insecticide resistance and immune responses highlight the need for further investigations into the role of different gene families in aiding the fly’s successful invasion. Furthermore, this genomic resource provides a necessary tool to better inform future research studies and mitigation strategies aimed at minimizing the fly’s impact on Galápagos birds.
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Affiliation(s)
- Melia G Romine
- School of Biomedical Sciences, Kent State University, Kent, OH 44240, USA
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, CT 06269, USA
| | - Carly M Crow
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA
| | - Grace J Vaziri
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Jaime A Chaves
- Department of Biology, San Francisco State University, San Francisco, CA 94132, USA
- Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito 170901, Ecuador
| | - Jennifer A H Koop
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA
| | - Sangeet Lamichhaney
- School of Biomedical Sciences, Kent State University, Kent, OH 44240, USA
- Department of Biological Sciences, Kent State University, Kent, OH 44240, USA
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8
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Ingala MR, Albert L, Addesso A, Watkins MJ, Knutie SA. Differential effects of elevated nest temperature and parasitism on the gut microbiota of wild avian hosts. Anim Microbiome 2021; 3:67. [PMID: 34600588 PMCID: PMC8487522 DOI: 10.1186/s42523-021-00130-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 06/07/2021] [Accepted: 09/22/2021] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Changes in wild animal gut microbiotas may influence host health and fitness. While many studies have shown correlations between gut microbiota structure and external factors, few studies demonstrate causal links between environmental variables and microbiota shifts. Here, we use a fully factorial experiment to test the effects of elevated ambient temperature and natural nest parasitism by nest flies (Protocalliphora sialia) on the gut microbiotas of two species of wild birds, the eastern bluebird (Sialia sialis) and the tree swallow (Tachycineta bicolor). RESULTS We find that bacterial communities from the nestlings of each host species show idiosyncratic responses to both heat and parasitism, with gut microbiotas of eastern bluebirds more disrupted by heat and parasitism than those of tree swallows. Thus, we find that eastern bluebirds are unable to maintain stable associations with their gut bacteria in the face of both elevated temperature and parasitism. In contrast, tree swallow gut microbiotas are not significantly impacted by either heat or nest parasitism. CONCLUSIONS Our results suggest that excess heat (e.g., as a result of climate change) may destabilize natural host-parasite-microbiota systems, with the potential to affect host fitness and survival in the Anthropocene.
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Affiliation(s)
- Melissa R Ingala
- Department of Vertebrate Zoology, National Museum of Natural History, Washington, D.C., USA.
| | - Lauren Albert
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Alyssa Addesso
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Mackenzie J Watkins
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA
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9
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Butler MW, Stierhoff EN, Carpenetti JM, Bertone MA, Addesso AM, Knutie SA. Oxidative damage increases with degree of simulated bacterial infection, but not ectoparasitism, in tree swallow nestlings. J Exp Biol 2021; 224:272162. [PMID: 34427672 DOI: 10.1242/jeb.243116] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 07/01/2021] [Accepted: 08/18/2021] [Indexed: 11/20/2022]
Abstract
The purpose of mounting an immune response is to destroy pathogens, but this response comes at a physiological cost, including the generation of oxidative damage. However, many studies on the effects of immune challenges employ a single high dose of a simulated infection, meaning that the consequences of more mild immune challenges are poorly understood. We tested whether the degree of immunological challenge in tree swallows (Tachycineta bicolor) affects oxidative physiology and body mass, and whether these metrics correlate with parasitic nest mite load. We injected 14 day old nestlings with 0, 0.01, 0.1 or 1 mg lipopolysaccharide (LPS) per kg body mass, then collected a blood sample 24 h later to quantify multiple physiological metrics, including oxidative damage (i.e. d-ROMs), circulating amounts of triglyceride and glycerol, and levels of the acute phase protein haptoglobin. After birds had fledged, we identified and counted parasitic nest mites (Dermanyssus spp. and Ornithonyssus spp.). We found that only nestlings injected with 1 mg LPS kg-1 body mass, which is a common dosage in ecoimmunological studies, lost more body mass than individuals from other treatment groups. However, every dose of LPS resulted in a commensurate increase in oxidative damage. Parasitic mite abundance had no effect on oxidative damage across treatments. The amount of oxidative damage correlated with haptoglobin levels, suggesting compensatory mechanisms to limit self-damage during an immune response. We conclude that while only the highest-intensity immune challenges resulted in costs related to body mass, even low-intensity immune challenges result in detectable increases in oxidative damage.
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Affiliation(s)
| | | | | | - Matthew A Bertone
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
| | - Alyssa M Addesso
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA.,Institute for Systems Genomics, University of Connecticut, Storrs, CT 06269, USA
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10
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Potvin DA, Opitz F, Townsend KA, Knutie SA. Use of anthropogenic-related nest material and nest parasite prevalence have increased over the past two centuries in Australian birds. Oecologia 2021; 196:1207-1217. [PMID: 34236465 DOI: 10.1007/s00442-021-04982-z] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/28/2021] [Indexed: 11/29/2022]
Abstract
Global plastic production has increased exponentially since the 1940s, resulting in the increased presence of anthropogenic debris in the environment. Recent studies have shown that birds incorporate anthropogenic debris into their nests, which can reduce nest ectoparasite loads. However, we know little about the long-term history of interactions among birds, anthropogenic debris, and ectoparasites. Our study took a unique approach to address this issue by determining the prevalence of anthropogenic debris and ectoparasitic nest flies (Protocalliphora and Passeromyia spp.) in 893 bird nests from 224 species between 1832 and 2018, which were sourced from Australian museum collections. The prevalence of anthropogenic material increased from approximately 4% in 1832 to almost 30% in 2018. This change was driven by an increase in the incorporation of synthetic rather than biodegradable anthropogenic debris (by 2018 ~ 25% of all nests contained synthetics), with the first synthetic item being found in a nest from 1956 in the city of Melbourne. Nest parasite prevalence increased over time but contrary to other studies, there was no relationship between habitat type or anthropogenic material and parasite presence. Our study is the first to use museum specimens to quantify temporal and spatial impacts of anthropogenic material on birds, the results of which justifies contemporary concerns regarding the ubiquitous nature of human impacts on terrestrial wildlife.
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Affiliation(s)
- Dominique A Potvin
- University of the Sunshine Coast, Moreton Bay Campus, Petrie, Australia.
| | | | - Kathy A Townsend
- University of the Sunshine Coast, Fraser Coast Campus, Hervey Bay, Australia
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA.,Institute for Systems Genomics, University of Connecticut, Storrs, CT, 06269, USA
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11
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McNew SM, Boquete MT, Espinoza‐Ulloa S, Andres JA, Wagemaker NCAM, Knutie SA, Richards CL, Clayton DH. Epigenetic effects of parasites and pesticides on captive and wild nestling birds. Ecol Evol 2021; 11:7713-7729. [PMID: 34188846 PMCID: PMC8216931 DOI: 10.1002/ece3.7606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 02/12/2021] [Revised: 04/06/2021] [Accepted: 04/07/2021] [Indexed: 12/12/2022] Open
Abstract
Anthropogenic changes to the environment challenge animal populations to adapt to new conditions and unique threats. While the study of adaptation has focused on genetic variation, epigenetic mechanisms may also be important. DNA methylation is sensitive to environmental stressors, such as parasites and pesticides, which may affect gene expression and phenotype. We studied the effects of an invasive ectoparasite, Philornis downsi, on DNA methylation of Galápagos mockingbirds (Mimus parvulus). We used the insecticide permethrin to manipulate P. downsi presence in nests of free-living mockingbirds and tested for effects of parasitism on nestling mockingbirds using epiGBS, a reduced-representation bisulfite sequencing (RRBS) approach. To distinguish the confounding effects of insecticide exposure, we conducted a matching experiment exposing captive nestling zebra finches (Taeniopygia guttata) to permethrin. We used zebra finches because they were the closest model organism to mockingbirds that we could breed in controlled conditions. We identified a limited number of differentially methylated cytosines (DMCs) in parasitized versus nonparasitized mockingbirds, but the number was not more than expected by chance. In contrast, we saw clear effects of permethrin on methylation in captive zebra finches. DMCs in zebra finches paralleled documented effects of permethrin exposure on vertebrate cellular signaling and endocrine function. Our results from captive birds indicate a role for epigenetic processes in mediating sublethal nontarget effects of pyrethroid exposure in vertebrates. Environmental conditions in the field were more variable than the laboratory, which may have made effects of both parasitism and permethrin harder to detect in mockingbirds. RRBS approaches such as epiGBS may be a cost-effective way to characterize genome-wide methylation profiles. However, our results indicate that ecological epigenetic studies in natural populations should consider the number of cytosines interrogated and the depth of sequencing in order to have adequate power to detect small and variable effects.
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Affiliation(s)
- Sabrina M. McNew
- School of Biological SciencesUniversity of UtahSalt Lake CityUTUSA
- Cornell Lab of OrnithologyCornell UniversityIthacaNYUSA
- Department of Ecology and Evolutionary BiologyCornell UniversityIthacaNYUSA
| | - M. Teresa Boquete
- Department of Integrative BiologyUniversity of South FloridaTampaFLUSA
- Department of Evolutionary EcologyEstación Biológica de DoñanaCSICSevillaSpain
| | - Sebastian Espinoza‐Ulloa
- Department of BiologyUniversity of SaskatchewanSaskatoonSKCanada
- Facultad de MedicinaPontifica Universidad Católica del EcuadorQuitoEcuador
| | - Jose A. Andres
- Department of Ecology and Evolutionary BiologyCornell UniversityIthacaNYUSA
- Department of BiologyUniversity of SaskatchewanSaskatoonSKCanada
| | | | - Sarah A. Knutie
- School of Biological SciencesUniversity of UtahSalt Lake CityUTUSA
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsCTUSA
- Institute for Systems GenomicsUniversity of ConnecticutStorrsCTUSA
| | | | - Dale H. Clayton
- School of Biological SciencesUniversity of UtahSalt Lake CityUTUSA
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12
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Harvey JA, Chernicky K, Simons SR, Verrett TB, Chaves JA, Knutie SA. Urban living influences the nesting success of Darwin's finches in the Galápagos Islands. Ecol Evol 2021; 11:5038-5048. [PMID: 34025990 PMCID: PMC8131787 DOI: 10.1002/ece3.7360] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [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: 09/08/2020] [Revised: 01/27/2021] [Accepted: 01/29/2021] [Indexed: 11/23/2022] Open
Abstract
Urbanization is expanding worldwide with major consequences for organisms. Anthropogenic factors can reduce the fitness of animals but may have benefits, such as consistent human food availability. Understanding anthropogenic trade-offs is critical in environments with variable levels of natural food availability, such as the Galápagos Islands, an area of rapid urbanization. For example, during dry years, the reproductive success of bird species, such as Darwin's finches, is low because reduced precipitation impacts food availability. Urban areas provide supplemental human food to finches, which could improve their reproductive success during years with low natural food availability. However, urban finches might face trade-offs, such as the incorporation of anthropogenic debris (e.g., string, plastic) into their nests, which may increase mortality. In our study, we determined the effect of urbanization on the nesting success of small ground finches (Geospiza fuliginosa; a species of Darwin's finch) during a dry year on San Cristóbal Island. We quantified nest building, egg laying and hatching, and fledging in an urban and nonurban area and characterized the anthropogenic debris in nests. We also documented mortalities including nest trash-related deaths and whether anthropogenic materials directly led to entanglement- or ingestion-related nest mortalities. Overall, urban finches built more nests, laid more eggs, and produced more fledglings than nonurban finches. However, every nest in the urban area contained anthropogenic material, which resulted in 18% nestling mortality while nonurban nests had no anthropogenic debris. Our study showed that urban living has trade-offs: urban birds have overall higher nesting success during a dry year than nonurban birds, but urban birds can suffer mortality from anthropogenic-related nest-materials. These results suggest that despite potential costs, finches benefit overall from urban living and urbanization may buffer the effects of limited resource availability in the Galápagos Islands.
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Affiliation(s)
- Johanna A. Harvey
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsCTUSA
- Present address:
Division of Invertebrate ZoologyAmerican Museum of Natural HistoryNew YorkNYUSA
| | - Kiley Chernicky
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsCTUSA
| | - Shelby R. Simons
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsCTUSA
| | - Taylor B. Verrett
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsCTUSA
| | - Jaime A. Chaves
- Department of BiologySan Francisco State UniversitySan FranciscoCAUSA
- Colegio de Ciencias Biológicas y AmbientalesUniversidad San Francisco de QuitoLaboratorio de Biología EvolutivaDiego de Robles y PampiteQuitoEcuador
| | - Sarah A. Knutie
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsCTUSA
- Institute for Systems GenomicsUniversity of ConnecticutStorrsCTUSA
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13
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Brown CR, Hannebaum SL, O’Brien VA, Page CE, Rannala B, Roche EA, Wagnon GS, Knutie SA, Moore AT, Brown MB. The cost of ectoparasitism in Cliff Swallows declines over 35 years. ECOL MONOGR 2021. [DOI: 10.1002/ecm.1446] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Charles R. Brown
- Department of Biological Sciences University of Tulsa 800 S. Tucker Dr. Tulsa Oklahoma 74104 USA
| | - Stacey L. Hannebaum
- Department of Biological Sciences University of Tulsa 800 S. Tucker Dr. Tulsa Oklahoma 74104 USA
| | - Valerie A. O’Brien
- Department of Biological Sciences University of Tulsa 800 S. Tucker Dr. Tulsa Oklahoma 74104 USA
| | - Catherine E. Page
- Department of Biological Sciences University of Tulsa 800 S. Tucker Dr. Tulsa Oklahoma 74104 USA
| | - Bruce Rannala
- Department of Evolution and Ecology University of California Davis California 95616 USA
| | - Erin A. Roche
- Department of Biological Sciences University of Tulsa 800 S. Tucker Dr. Tulsa Oklahoma 74104 USA
| | - Gigi S. Wagnon
- Department of Biological Sciences University of Tulsa 800 S. Tucker Dr. Tulsa Oklahoma 74104 USA
| | - Sarah A. Knutie
- Department of Ecology and Evolutionary Biology University of Connecticut 75 N. Eagleville Rd. Storrs Connecticut 06269 USA
| | - Amy T. Moore
- Department of Biological Sciences University of Tulsa 800 S. Tucker Dr. Tulsa Oklahoma 74104 USA
| | - Mary B. Brown
- Department of Biological Sciences University of Tulsa 800 S. Tucker Dr. Tulsa Oklahoma 74104 USA
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14
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Bulgarella M, Knutie SA, Voss MA, Cunninghame F, Florence-Bennett BJ, Robson G, Keyzers RA, Taylor LM, Lester PJ, Heimpel GE, Causton CE. Sub-lethal effects of permethrin exposure on a passerine: implications for managing ectoparasites in wild bird nests. Conserv Physiol 2020; 8:coaa076. [PMID: 32908668 PMCID: PMC7416766 DOI: 10.1093/conphys/coaa076] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 07/10/2020] [Accepted: 07/26/2020] [Indexed: 06/11/2023]
Abstract
Permethrin is increasingly used for parasite control in bird nests, including nests of threatened passerines. We present the first formal evaluation of the effects of continued permethrin exposure on the reproductive success and liver function of a passerine, the zebra finch (Taeniopygia guttata), for two generations. We experimentally treated all nest material with a 1% permethrin solution or a water control and provided the material to breeding finches for nest building. The success of two consecutive clutches produced by the parental generation and one clutch produced by first-generation birds were tracked. Finches in the first generation were able to reproduce and fledge offspring after permethrin exposure, ruling out infertility. Permethrin treatment had no statistically significant effect on the number of eggs laid, number of days from clutch initiation to hatching, egg hatch rate, fledgling mass or nestling sex ratio in either generation. However, treating nest material with permethrin significantly increased the number of hatchlings in the first generation and decreased fledgling success in the second generation. Body mass for hatchlings exposed to permethrin was lower than for control hatchlings in both generations, but only statistically significant for the second generation. For both generations, an interaction between permethrin treatment and age significantly affected nestling growth. Permethrin treatment had no effect on liver function for any generation. Permethrin was detected inside 6 of 21 exposed, non-embryonated eggs (28.5% incidence; range: 693-4781 ng of permethrin per gram of dry egg mass). Overall, results from exposing adults, eggs and nestlings across generations to permethrin-treated nest material suggest negative effects on finch breeding success, but not on liver function. For threatened bird conservation, the judicious application of this insecticide to control parasites in nests can result in lower nestling mortality compared to when no treatment is applied. Thus, permethrin treatment benefits may outweigh its sub-lethal effects.
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Affiliation(s)
- Mariana Bulgarella
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road, Unit 3043, Storrs, CT, 06269, USA
| | | | - Francesca Cunninghame
- Charles Darwin Research Station, Charles Darwin Foundation, Puerto Ayora, Santa Cruz Island, Galápagos Islands, Ecuador
| | | | - Gemma Robson
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand
| | - Robert A Keyzers
- School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand
| | - Lauren M Taylor
- School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand
| | - Philip J Lester
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand
| | - George E Heimpel
- Department of Entomology, University of Minnesota, 1980 Folwell Avenue, St. Paul, MN, 55108, USA
| | - Charlotte E Causton
- Charles Darwin Research Station, Charles Darwin Foundation, Puerto Ayora, Santa Cruz Island, Galápagos Islands, Ecuador
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15
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Quiroga MA, Hayes TI, Hayes CD, Garrod H, Soares L, Knutie SA, Latta SC, Anderson DL. More than just nestlings: incidence of subcutaneous Philornis (Diptera: Muscidae) nest flies in adult birds. Parasitol Res 2020; 119:2337-2342. [PMID: 32500371 DOI: 10.1007/s00436-020-06696-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 08/23/2019] [Accepted: 04/21/2020] [Indexed: 11/30/2022]
Abstract
Philornis flies Meinert (Diptera: Muscidae) have been documented parasitizing over 250 bird species, some of which are endemic species threatened with extinction. Philornis parasitism is hypothesized to affect nestlings disproportionately more than adult birds because limited mobility and exposed skin of nestlings increase their vulnerability to parasitism. We used a comprehensive literature review and our recent fieldwork in the Dominican Republic, Puerto Rico, and Grenada to challenge the idea that parasitism by subcutaneous Philornis species is a phenomenon primarily found in nestlings, a fact that has not been quantified to date. Of the 265 reviewed publications, 125 (49%) reported incidences of parasitism by subcutaneous Philornis, but only 12 included the sampling of adult breeding birds. Nine of these publications (75%) reported Philornis parasitism in adults of ten bird species. During fieldwork in the Dominican Republic, Puerto Rico, and Grenada, we documented 14 instances of parasitism of adult birds of seven avian species. From literature review and fieldwork, adults of at least fifteen bird species across 12 families and four orders of birds were parasitized by at least five Philornis species. In both the published literature and fieldwork, incidences of parasitism of adult birds occurred predominantly in females and was frequently associated with incubation. Although our findings indicate that Philornis parasitism of adult birds is more common than widely presumed, parasite prevalence is still greater in nestlings. In the future, we recommend surveys of adult birds to better understand host-Philornis relationships across life stages. This information may be essential for the development of effective control measures of Philornis to ensure the long-term protection of bird species of conservation concern.
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Affiliation(s)
- Martín A Quiroga
- The Peregrine Fund, 5668 W Flying Hawk Lane, Boise, ID, 83709, USA. .,Laboratorio de Ecología de Enfermedades (ICiVet Litoral - UNL - CONICET), R.P. Kreder 2805, S3080HOF, Santa Fe, Argentina. .,Department of Biology, Universidad Autónoma de Entre Ríos, Ruta Provincial N 11 Km. 10.5, Oro Verde, E3100XAD, Entre Ríos, Argentina. .,Instituto Tecnológico de Santo Domingo, Avenida de Los Próceres #49, Santo Domingo, 10602, República Dominicana.
| | - Thomas I Hayes
- The Peregrine Fund, 5668 W Flying Hawk Lane, Boise, ID, 83709, USA
| | - Christine D Hayes
- The Peregrine Fund, 5668 W Flying Hawk Lane, Boise, ID, 83709, USA.,Department of Biological Sciences, Boise State University, 1910 W University Drive, Boise, ID, 83725, USA
| | - Holly Garrod
- Department of Biology, Villanova University, 800 Lancaster Ave, Villanova, PA, 19085, USA
| | - Leticia Soares
- Department of Biology, University of Western Ontario, 1151 Richmond Street, Ontario, N6A5B7, Canada
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd., Unit 3043, Storrs, CT, 06269-3043, USA
| | - Steven C Latta
- National Aviary, 700 Arch Street, Pittsburgh, PA, 15212, USA
| | - David L Anderson
- The Peregrine Fund, 5668 W Flying Hawk Lane, Boise, ID, 83709, USA
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16
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Sauer EL, Cohen JM, Lajeunesse MJ, McMahon TA, Civitello DJ, Knutie SA, Nguyen K, Roznik EA, Sears BF, Bessler S, Delius BK, Halstead N, Ortega N, Venesky MD, Young S, Rohr JR. A meta-analysis reveals temperature, dose, life stage, and taxonomy influence host susceptibility to a fungal parasite. Ecology 2020; 101:e02979. [PMID: 31960949 DOI: 10.1002/ecy.2979] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 10/25/2019] [Accepted: 12/05/2019] [Indexed: 12/22/2022]
Abstract
Complex ecological relationships, such as host-parasite interactions, are often modeled with laboratory experiments. However, some experimental laboratory conditions, such as temperature or infection dose, are regularly chosen based on convenience or convention, and it is unclear how these decisions systematically affect experimental outcomes. Here, we conducted a meta-analysis of 58 laboratory studies that exposed amphibians to the pathogenic fungus Batrachochytrium dendrobatidis (Bd) to understand better how laboratory temperature, host life stage, infection dose, and host species affect host mortality. We found that host mortality was driven by thermal mismatches: hosts native to cooler environments experienced greater Bd-induced mortality at relatively warm experimental temperatures and vice versa. We also found that Bd dose positively predicted Bd-induced host mortality and that the superfamilies Bufonoidea and Hyloidea were especially susceptible to Bd. Finally, the effect of Bd on host mortality varied across host life stages, with larval amphibians experiencing lower risk of Bd-induced mortality than adults or metamorphs. Metamorphs were especially susceptible and experienced mortality when inoculated with much smaller Bd doses than the average dose used by researchers. Our results suggest that when designing experiments on species interactions, researchers should carefully consider the experimental temperature, inoculum dose, and life stage, and taxonomy of the host species.
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Affiliation(s)
- Erin L Sauer
- Department of Integrative Biology, University of South Florida, 4202 East Fowler Ave, Tampa, 33620, Florida, USA.,Department of Forest and Wildlife Ecology, University of Wisconsin, 1630 Linden Dr., Madison, 53706, Wisconsin, USA
| | - Jeremy M Cohen
- Department of Integrative Biology, University of South Florida, 4202 East Fowler Ave, Tampa, 33620, Florida, USA.,Department of Forest and Wildlife Ecology, University of Wisconsin, 1630 Linden Dr., Madison, 53706, Wisconsin, USA
| | - Marc J Lajeunesse
- Department of Integrative Biology, University of South Florida, 4202 East Fowler Ave, Tampa, 33620, Florida, USA
| | - Taegan A McMahon
- Department of Biology, University of Tampa, 401 W. Kennedy Blvd., Tampa, 33606, Florida, USA
| | - David J Civitello
- Department of Biology, Emory University, 201 Dowman Dr., Atlanta, 30322, Georgia, USA
| | - Sarah A Knutie
- Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road, Storrs, 06269, Connecticut, USA
| | - Karena Nguyen
- Department of Integrative Biology, University of South Florida, 4202 East Fowler Ave, Tampa, 33620, Florida, USA
| | - Elizabeth A Roznik
- Department of Research and Conservation, Memphis Zoo, 2000 Prentiss Place, Memphis, 38112, Tennessee, USA
| | | | - Scott Bessler
- Department of Integrative Biology, University of South Florida, 4202 East Fowler Ave, Tampa, 33620, Florida, USA
| | - Bryan K Delius
- Department of Integrative Biology, University of South Florida, 4202 East Fowler Ave, Tampa, 33620, Florida, USA
| | - Neal Halstead
- Wildlands Conservation, 15310 Amberly Dr., Suite 250, Tampa, 33647, Florida, USA
| | - Nicole Ortega
- Department of Integrative Biology, University of South Florida, 4202 East Fowler Ave, Tampa, 33620, Florida, USA
| | - Matthew D Venesky
- Department of Biology, Allegheny College, 520 N Main St., Meadville, 16335, Pennsylvania, USA
| | - Suzanne Young
- Environmental Engineering Institute, Ecole polytechnique fédérale de Lausanne (EPFL), Route Cantonale, 1015, Lausanne, Switzerland
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, 4202 East Fowler Ave, Tampa, 33620, Florida, USA.,Department of Biological Science, University of Notre Dame, 100 Galvin Life Science Center, Notre Dame, 46656, Indiana, USA
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17
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Affiliation(s)
- Sarah A. Knutie
- Department of Ecology and Evolutionary Biology University of Connecticut Storrs CT USA
- Institute for Systems Genomics University of Connecticut Storrs CT USA
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18
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Beausoleil MO, Frishkoff LO, M'Gonigle LK, Raeymaekers JAM, Knutie SA, De León LF, Huber SK, Chaves JA, Clayton DH, Koop JAH, Podos J, Sharpe DMT, Hendry AP, Barrett RDH. Temporally varying disruptive selection in the medium ground finch ( Geospiza fortis). Proc Biol Sci 2019; 286:20192290. [PMID: 31795872 DOI: 10.1098/rspb.2019.2290] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Disruptive natural selection within populations exploiting different resources is considered to be a major driver of adaptive radiation and the production of biodiversity. Fitness functions, which describe the relationships between trait variation and fitness, can help to illuminate how this disruptive selection leads to population differentiation. However, a single fitness function represents only a particular selection regime over a single specified time period (often a single season or a year), and therefore might not capture longer-term dynamics. Here, we build a series of annual fitness functions that quantify the relationships between phenotype and apparent survival. These functions are based on a 9-year mark-recapture dataset of over 600 medium ground finches (Geospiza fortis) within a population bimodal for beak size. We then relate changes in the shape of these functions to climate variables. We find that disruptive selection between small and large beak morphotypes, as reported previously for 2 years, is present throughout the study period, but that the intensity of this selection varies in association with the harshness of environment. In particular, we find that disruptive selection was strongest when precipitation was high during the dry season of the previous year. Our results shed light on climatic factors associated with disruptive selection in Darwin's finches, and highlight the role of temporally varying fitness functions in modulating the extent of population differentiation.
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Affiliation(s)
- Marc-Olivier Beausoleil
- Department of Biology and Redpath Museum, McGill University, 859 Rue Sherbrooke Ouest, Montréal, Québec, Canada H3A 0C4
| | - Luke O Frishkoff
- Department of Biology, University of Texas at Arlington, Arlington, TX, USA
| | - Leithen K M'Gonigle
- Department of Biological Sciences, Simon Fraser University, Burnaby BC V5A 1S6, Canada
| | | | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Luis F De León
- Department of Biology, University of Massachusetts Boston, Boston, MA, USA.,Centro de Biodiversidad y Descubrimiento de Drogas, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Panama
| | - Sarah K Huber
- Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA, USA
| | - Jaime A Chaves
- Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito, Pichincha, Ecuador.,Galápagos Science Center, Puerto Baquerizo Moreno, Galápagos, Ecuador
| | - Dale H Clayton
- School of Biological Sciences, University of Utah, 257 South 1400 East, Salt Lake City, 84112 UT, USA
| | - Jennifer A H Koop
- Department of Biological Sciences, Northern Illinois University, 1425 W. Lincoln Hwy., DeKalb, IL 60115, USA
| | - Jeffrey Podos
- Department of Biology, University of Massachusetts, 221 Morrill Science Center, Amherst, MA, USA
| | - Diana M T Sharpe
- Department of Biology, University of Massachusetts Boston, Boston, MA, USA
| | - Andrew P Hendry
- Department of Biology and Redpath Museum, McGill University, 859 Rue Sherbrooke Ouest, Montréal, Québec, Canada H3A 0C4
| | - Rowan D H Barrett
- Department of Biology and Redpath Museum, McGill University, 859 Rue Sherbrooke Ouest, Montréal, Québec, Canada H3A 0C4
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19
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Grab KM, Hiller BJ, Hurlbert JH, Ingram ME, Parker AB, Pokutnaya DY, Knutie SA. Host tolerance and resistance to parasitic nest flies differs between two wild bird species. Ecol Evol 2019; 9:12144-12155. [PMID: 31832149 PMCID: PMC6854101 DOI: 10.1002/ece3.5682] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [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: 06/06/2019] [Revised: 08/31/2019] [Accepted: 09/06/2019] [Indexed: 12/25/2022] Open
Abstract
Hosts have developed and evolved defense strategies to limit parasite damage. Hosts can reduce the damage that parasites cause by decreasing parasite fitness (resistance) or without affecting parasite fitness (tolerance). Because a parasite species can infect multiple host species, determining the effect of the parasite on these hosts and identifying host defense strategies can have important implications for multi-host-parasite dynamics.Over 2 years, we experimentally manipulated parasitic flies (Protocalliphora sialia) in the nests of tree swallows (Tachycineta bicolor) and eastern bluebirds (Sialia sialis). We then determined the effects of the parasites on the survival of nestlings and compared defense strategies between host species. We compared resistance between host species by quantifying parasite densities (number of parasites per gram of host) and measured nestling antibody levels as a mechanism of resistance. We quantified tolerance by determining the relationship between parasite density and nestling survival and blood loss by measuring hemoglobin levels (as a proxy of blood recovery) and nestling provisioning rates (as a proxy of parental compensation for resources lost to the parasite) as potential mechanisms of tolerance.For bluebirds, parasite density was twice as high as for swallows. Both host species were tolerant to the effects of P. sialia on nestling survival at their respective parasite loads but neither species were tolerant to the blood loss to the parasite. However, swallows were more resistant to P. sialia compared to bluebirds, which was likely related to the higher antibody-mediated immune response in swallow nestlings. Neither blood recovery nor parental compensation were mechanisms of tolerance.Overall, these results suggest that bluebirds and swallows are both tolerant of their respective parasite loads but swallows are more resistant to the parasites. These results demonstrate that different host species have evolved similar and different defenses against the same species of parasite.
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Affiliation(s)
- Kirstine M. Grab
- Department of Ecology, Evolution, and BehaviorUniversity of Minnesota Twin CitiesSt. PaulMNUSA
| | | | | | | | - Alexandra B. Parker
- Department of Ecology, Evolution, and BehaviorUniversity of Minnesota Twin CitiesSt. PaulMNUSA
| | | | - Sarah A. Knutie
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsCTUSA
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20
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Trevelline BK, MacLeod KJ, Knutie SA, Langkilde T, Kohl KD. In ovo microbial communities: a potential mechanism for the initial acquisition of gut microbiota among oviparous birds and lizards. Biol Lett 2019; 14:rsbl.2018.0225. [PMID: 30021862 DOI: 10.1098/rsbl.2018.0225] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [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: 03/28/2018] [Accepted: 06/20/2018] [Indexed: 12/16/2022] Open
Abstract
Vertebrate gut microbiota mediate critical physiological processes known to affect host fitness, but the mechanisms that expose wildlife to pioneer members of this important microbial community are not well understood. For example, oviparous vertebrates are thought to acquire gut microbiota through post-natal exposure to the external environment, but recent evidence from placental mammals suggests that the vertebrate reproductive tract harbours microbiota that may inoculate offspring in utero These findings suggest that oviparous vertebrates may be capable of acquiring pioneer microbiota in ovo, but this phenomenon remains unexplored. To fill this knowledge gap, we used culture-independent inventories to determine if the eggs of wild birds and lizards harboured in ovo microbial communities. Our approach revealed distinct in ovo bacterial communities, but fungal communities were indistinguishable from controls. Further, lizard eggs from the same clutch had bacterial community structures that were more similar to each other than to unrelated individuals. These results suggest that oviparous vertebrates may acquire maternal microbiota in ovo, possibly through the inoculation of egg yolk prior to shelling. Therefore, this study may provide a first glimpse of a phenomenon with substantial implications for our understanding of the ecological and evolutionary factors shaping gut microbial communities.
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Affiliation(s)
- Brian K Trevelline
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Kirsty J MacLeod
- Department of Biology, The Pennsylvania State University, University Park, PA 16801, USA.,Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA 16801, USA
| | - Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Tracy Langkilde
- Department of Biology, The Pennsylvania State University, University Park, PA 16801, USA
| | - Kevin D Kohl
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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21
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Knutie SA, Chaves JA, Gotanda KM. Human activity can influence the gut microbiota of Darwin's finches in the Galapagos Islands. Mol Ecol 2019; 28:2441-2450. [DOI: 10.1111/mec.15088] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 03/21/2019] [Accepted: 03/22/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Sarah A. Knutie
- Department of Ecology and Evolutionary Biology University of Connecticut Storrs Connecticut
| | - Jaime A. Chaves
- Colegio de Ciencias Biológicas y Ambientales Universidad San Francisco de Quito Cumbayá Quito Ecuador
- Galápagos Science Center Puerto Baquerizo Moreno Ecuador
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22
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Cohen JM, McMahon TA, Ramsay C, Roznik EA, Sauer EL, Bessler S, Civitello DJ, Delius BK, Halstead N, Knutie SA, Nguyen KH, Ortega N, Sears B, Venesky MD, Young S, Rohr JR. Impacts of thermal mismatches on chytrid fungus
Batrachochytrium dendrobatidis
prevalence are moderated by life stage, body size, elevation and latitude. Ecol Lett 2019; 22:817-825. [DOI: 10.1111/ele.13239] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/04/2018] [Accepted: 12/05/2018] [Indexed: 01/11/2023]
Affiliation(s)
- Jeremy M. Cohen
- Department of Integrative Biology University of South Florida Tampa FL USA
| | | | - Chloe Ramsay
- Department of Integrative Biology University of South Florida Tampa FL USA
| | | | - Erin L. Sauer
- Department of Integrative Biology University of South Florida Tampa FL USA
| | - Scott Bessler
- Department of Integrative Biology University of South Florida Tampa FL USA
| | | | - Bryan K. Delius
- Department of Integrative Biology University of South Florida Tampa FL USA
| | | | - Sarah A. Knutie
- Department of Ecology and Evolutionary Biology University of Connecticut Storrs CT USA
| | - Karena H. Nguyen
- Department of Integrative Biology University of South Florida Tampa FL USA
| | - Nicole Ortega
- Department of Integrative Biology University of South Florida Tampa FL USA
| | - Brittany Sears
- Department of Biological Sciences University of South Florida St. Petersburg St. Petersburg FL USA
| | | | - Suzanne Young
- Ecole polytechnique fédérale de Lausanne (EPFL) Lausanne Switzerland
| | - Jason R. Rohr
- Department of Integrative Biology University of South Florida Tampa FL USA
- Department of Biological Sciences University of Notre Dame Notre Dame IN USA
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23
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McNew SM, Knutie SA, Goodman GB, Theodosopoulos A, Saulsberry A, Yépez R. J, Bush SE, Clayton DH. Annual environmental variation influences host tolerance to parasites. Proc Biol Sci 2019; 286:20190049. [PMID: 30963843 PMCID: PMC6408884 DOI: 10.1098/rspb.2019.0049] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [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: 01/09/2019] [Accepted: 02/06/2019] [Indexed: 12/16/2022] Open
Abstract
When confronted with a parasite or pathogen, hosts can defend themselves by resisting or tolerating the attack. While resistance can be diminished when resources are limited, it is unclear how robust tolerance is to changes in environmental conditions. Here, we investigate the sensitivity of tolerance in a single host population living in a highly variable environment. We manipulated the abundance of an invasive parasitic fly, Philornis downsi, in nests of Galápagos mockingbirds ( Mimus parvulus) over four field seasons and measured host fitness in response to parasitism. Mockingbird tolerance to P. downsi varied significantly among years and decreased when rainfall was limited. Video observations indicate that parental provisioning of nestlings appears key to tolerance: in drought years, mockingbirds likely do not have sufficient resources to compensate for the effects of P. downsi. These results indicate that host tolerance is a labile trait and suggest that environmental variation plays a major role in mediating the consequences of host-parasite interactions.
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Affiliation(s)
- Sabrina M. McNew
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Sarah A. Knutie
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Graham B. Goodman
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
| | | | - Ashley Saulsberry
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Janai Yépez R.
- Charles Darwin Research Station, Santa Cruz Island, Galápagos, Ecuador
| | - Sarah E. Bush
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Dale H. Clayton
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
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24
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Knutie SA, Gotanda KM. A Non-invasive Method to Collect Fecal Samples from Wild Birds for Microbiome Studies. Microb Ecol 2018; 76:851-855. [PMID: 29623358 DOI: 10.1007/s00248-018-1182-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 03/22/2018] [Indexed: 06/08/2023]
Abstract
Over the past few decades, studies have demonstrated that the gut microbiota strongly influences the physiology, behavior, and fitness of its host. Such studies have been conducted primarily in humans and model organisms under controlled laboratory conditions. More recently, researchers have realized the importance of placing host-associated microbiota studies into a more ecological context; however, few non-destructive methods have been established to collect fecal samples from wild birds. Here, we present an inexpensive and easy-to-use kit for the non-invasive collection of feces from small birds. The portability of the collection kit makes this method amenable to field studies, especially those in remote areas. The main components of the collection kit include a flat-bottomed paper bag, a large modified weigh boat (tray), vinyl-coated hardware cloth fencing (grate), a clothespin, and a 10% bleach solution (to sterilize the tray and grate). In the paper bag, a sterile tray is placed under a small grate, which prevents the birds from contacting the feces and reduces the risk of contamination. After capture, the bird is placed in the bag for 3-5 min until it defecates. After the bird is removed from the bag, the tray is extracted and the fecal sample is moved to a collection tube and frozen or preserved. We believe that our method is an affordable and easy option for researchers studying the gut microbiota of wild birds.
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Affiliation(s)
- Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA.
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25
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Knutie SA, Owen JP, McNew SM, Bartlow AW, Arriero E, Herman JM, DiBlasi E, Thompson M, Koop JAH, Clayton DH. Galápagos mockingbirds tolerate introduced parasites that affect Darwin's finches. Ecology 2018; 97:940-950. [PMID: 28792593 DOI: 10.1890/15-0119.1] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 09/28/2015] [Accepted: 11/05/2015] [Indexed: 01/17/2023]
Abstract
Introduced parasites threaten native host species that lack effective defenses. Such parasites increase the risk of extinction, particularly in small host populations like those on islands. If some host species are tolerant to introduced parasites, this could amplify the risk of the parasite to vulnerable host species. Recently, the introduced parasitic nest fly Philornis downsi has been implicated in the decline of Darwin's finch populations in the Galápagos Islands. In some years, 100% of finch nests fail due to P. downsi; however, other common host species nesting near Darwin's finches, such as the endemic Galápagos mockingbird (Mimus parvulus), appear to be less affected by P. downsi. We compared effects of P. downsi on mockingbirds and medium ground finches (Geospiza fortis) on Santa Cruz Island in the Galápagos. We experimentally manipulated the abundance of P. downsi in nests of mockingbirds and finches to measure the direct effect of the parasite on the reproductive success of each species of host. We also compared immunological and behavioral responses by each species of host to the fly. Although nests of the two host species had similar parasite densities, flies decreased the fitness of finches but not mockingbirds. Neither host species had a significant antibody-mediated immune response to P. downsi. Moreover, finches showed no significant increase in begging, parental provisioning, or plasma glucose levels in response to the flies. In contrast, parasitized mockingbird nestlings begged more than nonparasitized mockingbird nestlings. Greater begging was correlated with increased parental provisioning behavior, which appeared to compensate for parasite damage. The results of our study suggest that finches are negatively affected by P. downsi because they do not have such behavioral mechanisms for energy compensation. In contrast, mockingbirds are capable of compensation, making them tolerant hosts, and a possible indirect threat to Darwin's finches.
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Affiliation(s)
- Sarah A Knutie
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Jeb P Owen
- Department of Entomology, Washington State University, Pullman, Washington, 99164, USA
| | - Sabrina M McNew
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Andrew W Bartlow
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Elena Arriero
- Department of Zoology and Physical Anthropology, Complutense University of Madrid, E-28040, Madrid, Spain
| | - Jordan M Herman
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Emily DiBlasi
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Michael Thompson
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Jennifer A H Koop
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
| | - Dale H Clayton
- Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA
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26
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Affiliation(s)
- Sarah A. Knutie
- Department of Ecology and Evolutionary Biology University of Connecticut Storrs Connecticut 06269 USA
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27
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Knutie SA, Gabor CR, Kohl KD, Rohr JR. Do host-associated gut microbiota mediate the effect of an herbicide on disease risk in frogs? J Anim Ecol 2017; 87:489-499. [PMID: 29030867 DOI: 10.1111/1365-2656.12769] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [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: 01/18/2017] [Accepted: 09/21/2017] [Indexed: 12/21/2022]
Abstract
Environmental stressors, such as pollutants, can increase disease risk in wildlife. For example, the herbicide atrazine affects host defences (e.g. resistance and tolerance) of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), but the mechanisms for these associations are not entirely clear. Given that pollutants can alter the gut microbiota of hosts, which in turn can affect their health and immune systems, one potential mechanism by which pollutants could increase infection risk is by influencing host-associated microbiota. Here, we test whether early-life exposure to the estimated environmental concentration (EEC; 200 μg/L) of atrazine affects the gut bacterial composition of Cuban tree frog (Osteopilus septentrionalis) tadpoles and adults and whether any atrazine-induced change in community composition might affect host defences against Bd. We also determine whether early-life changes in the stress hormone corticosterone affect gut microbiota by experimentally inhibiting corticosterone synthesis with metyrapone. With the exception of changing the relative abundances of two bacterial genera in adulthood, atrazine did not affect gut bacterial diversity or community composition of tadpoles (in vivo or in vitro) or adults. Metyrapone did not significantly affect bacterial diversity of tadpoles, but significantly increased bacterial diversity of adults. Gut bacterial diversity during Bd exposure did not predict host tolerance or resistance to Bd intensity in tadpoles or adults. However, early-life bacterial diversity negatively predicted Bd intensity as adult frogs. Specifically, Bd intensity as adults was associated negatively with the relative abundance of phylum Fusobacteria in the guts of tadpoles. Our results suggest that the effect of atrazine on Bd infection risk is not mediated by host-associated microbiota because atrazine does not affect microbiota of tadpoles or adults. However, host-associated microbes seem important in host resistance to Bd because the early-life microbiota, during immune system development, predicted later-life infection risk with Bd. Overall, our study suggests that increasing gut bacterial diversity and relative abundances of Fusobacteria might have lasting positive effects on amphibian health.
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Affiliation(s)
- Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Caitlin R Gabor
- Department of Biology, Texas State University, San Marcos, TX, USA
| | - Kevin D Kohl
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL, USA
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28
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Knutie SA, Shea LA, Kupselaitis M, Wilkinson CL, Kohl KD, Rohr JR. Early-Life Diet Affects Host Microbiota and Later-Life Defenses Against Parasites in Frogs. Integr Comp Biol 2017; 57:732-742. [PMID: 28662573 PMCID: PMC5886343 DOI: 10.1093/icb/icx028] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Food resources can affect the health of organisms by altering their symbiotic microbiota and affecting energy reserves for host defenses against parasites. Different diets can vary in their macronutrient content and therefore they might favor certain bacterial communities of the host and affect the development and maintenance of the immune system, such as the inflammatory or antibody responses. Thus, testing the effect of diet, especially for animals with wide diet breadths, on host-associated microbiota and defenses against parasites might be important in determining infection and disease risk. Here, we test whether the early-life diet of Cuban tree frogs (Osteopilus septentrionalis) affects early- and later-life microbiota as well as later-life defenses against skin-penetrating, gut worms (Aplectana hamatospicula). We fed tadpoles two ecologically common diets: a diet of conspecifics or a diet of algae (Arthrospira sp.). We then: (1) characterized the gut microbiota of tadpoles and adults; and (2) challenged adult frogs with parasitic worms and measured host resistance (including the antibody-mediated immune response) and tolerance of infections. Tadpole diet affected bacterial communities in the guts of tadpoles but did not have enduring effects on the bacterial communities of adults. In contrast, tadpole diet had enduring effects on host resistance and tolerance of infections in adult frogs. Frogs that were fed a conspecific-based diet as tadpoles were more resistant to worm penetration compared with frogs that were fed an alga-based diet as tadpoles, but less resistant to worm establishment, which may be related to their suppressed antibody response during worm establishment. Furthermore, frogs that were fed a conspecific-based diet as tadpoles were more tolerant to the effect of parasite abundance on host mass during worm establishment. Overall, our study demonstrates that the diet of Cuban tree frog tadpoles affects the gut microbiota and defenses against parasitic gut worms of frogs, but these effects depend on the stage of the host and infection, respectively.
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Affiliation(s)
- Sarah A. Knutie
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Lauren A. Shea
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Marinna Kupselaitis
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | | | - Kevin D. Kohl
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Jason R. Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
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29
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McNew SM, Beck D, Sadler-Riggleman I, Knutie SA, Koop JAH, Clayton DH, Skinner MK. Epigenetic variation between urban and rural populations of Darwin's finches. BMC Evol Biol 2017; 17:183. [PMID: 28835203 PMCID: PMC5569522 DOI: 10.1186/s12862-017-1025-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [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: 01/26/2017] [Accepted: 07/26/2017] [Indexed: 11/10/2022] Open
Abstract
Background The molecular basis of evolutionary change is assumed to be genetic variation. However, growing evidence suggests that epigenetic mechanisms, such as DNA methylation, may also be involved in rapid adaptation to new environments. An important first step in evaluating this hypothesis is to test for the presence of epigenetic variation between natural populations living under different environmental conditions. Results In the current study we explored variation between populations of Darwin’s finches, which comprise one of the best-studied examples of adaptive radiation. We tested for morphological, genetic, and epigenetic differences between adjacent “urban” and “rural” populations of each of two species of ground finches, Geospiza fortis and G. fuliginosa, on Santa Cruz Island in the Galápagos. Using data collected from more than 1000 birds, we found significant morphological differences between populations of G. fortis, but not G. fuliginosa. We did not find large size copy number variation (CNV) genetic differences between populations of either species. However, other genetic variants were not investigated. In contrast, we did find dramatic epigenetic differences between the urban and rural populations of both species, based on DNA methylation analysis. We explored genomic features and gene associations of the differentially DNA methylated regions (DMR), as well as their possible functional significance. Conclusions In summary, our study documents local population epigenetic variation within each of two species of Darwin’s finches. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-1025-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sabrina M McNew
- Department of Biology, University of Utah, Salt Lake City, UT, 84112-0840, USA
| | - Daniel Beck
- Center for Reproductive Biology, School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Ingrid Sadler-Riggleman
- Center for Reproductive Biology, School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Sarah A Knutie
- Department of Biology, University of Utah, Salt Lake City, UT, 84112-0840, USA
| | - Jennifer A H Koop
- Department of Biology, University of Utah, Salt Lake City, UT, 84112-0840, USA
| | - Dale H Clayton
- Department of Biology, University of Utah, Salt Lake City, UT, 84112-0840, USA
| | - Michael K Skinner
- Center for Reproductive Biology, School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA.
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30
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Affiliation(s)
- Sarah A. Knutie
- Department of Biology University of Utah Salt Lake City Utah 84112 USA
| | - Jordan M. Herman
- Department of Biology University of Utah Salt Lake City Utah 84112 USA
| | - Jeb P. Owen
- Department of Entomology Washington State University Pullman Washington 99164 USA
| | - Dale H. Clayton
- Department of Biology University of Utah Salt Lake City Utah 84112 USA
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31
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Ehrsam M, Knutie SA, Rohr JR. The herbicide atrazine induces hyperactivity and compromises tadpole detection of predator chemical cues. Environ Toxicol Chem 2016; 35:2239-44. [PMID: 26799769 DOI: 10.1002/etc.3377] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/09/2015] [Accepted: 01/20/2016] [Indexed: 05/20/2023]
Abstract
The ability to detect chemical cues is often critical for freshwater organisms to avoid predation and find food and mates. In particular, reduced activity and avoidance of chemical cues signaling predation risk are generally adaptive behaviors that reduce prey encounter rates with predators. The present study examined the effects of the common herbicide atrazine on the ability of Cuban tree frog (Osteopilus septentrionalis) tadpoles to detect and respond to chemical cues from larval dragonfly (Libellulidae sp.) predators. Tadpoles exposed to an estimated environmental concentration of atrazine (calculated using US Environmental Protection Agency software; measured concentration, 178 μg/L) were significantly hyperactive relative to those exposed to solvent control. In addition, control tadpoles significantly avoided predator chemical cues, but tadpoles exposed to atrazine did not. These results are consistent with previous studies that have demonstrated that ecologically relevant concentrations of atrazine can induce hyperactivity and impair the olfactory abilities of other freshwater vertebrates. The authors call for additional studies examining the role of chemical contaminants in disrupting chemical communication and the quantification of subsequent impacts on the fitness and population dynamics of wildlife. Environ Toxicol Chem 2016;35:2239-2244. © 2016 SETAC.
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Affiliation(s)
- Mackenzie Ehrsam
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Sarah A Knutie
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
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32
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Abstract
Introduced pathogens and other parasites are often implicated in host population level declines and extinctions. However, such claims are rarely supported by rigorous real-time data. Indeed, the threat of introduced parasites often goes unnoticed until after host populations have declined severely. The recent introduction of the parasitic nest fly, Philornis downsi, to the Galápagos Islands provides an opportunity to monitor the current impact of an invasive parasite on endemic land bird populations, including Darwin's finches.In this paper we present a population viability model to explore the potential long-term effect of P. downsi on Darwin's finch populations. The goal of our study was to determine whether P. downsi has the potential to drive host populations to extinction and whether management efforts are likely to be effective.Our model is based on data from five years of experimental field work documenting the effect of P. downsi on the reproductive success of medium ground finch Geospiza fortis populations on Santa Cruz Island. Under two of the three scenarios tested, the model predicted medium ground finches are at risk of extinction within the next century.However, sensitivity analyses reveal that even a modest reduction in the prevalence of the parasite could improve the stability of finch populations. We discuss the practicality of several management options aimed at achieving this goal.Synthesis and applications. Our study demonstrates the predicted high risk of local extinction of an abundant host species, the medium ground finch Geospiza fortis due to an introduced parasite, Philornis downsi. However, our study further suggests that careful management practices aimed at reducing parasite prevalence have the potential to significantly lower the risk of host species extinction.
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Affiliation(s)
| | - Peter S. Kim
- Mathematics Department, University of Utah, Salt Lake City, UT, USA
| | - Sarah A. Knutie
- Department of Biology, University of Utah, Salt Lake City, UT, USA
| | - Fred Adler
- Department of Biology, University of Utah, Salt Lake City, UT, USA
- Mathematics Department, University of Utah, Salt Lake City, UT, USA
| | - Dale H. Clayton
- Department of Biology, University of Utah, Salt Lake City, UT, USA
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33
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Knutie SA, Owen JP, McNew SM, Bartlow AW, Arriero E, Herman JM, DiBlasi E, Thompson M, Koop JAH, Clayton DH. Galápagos mockingbirds tolerate introduced parasites that affect Darwin's finches. Ecology 2016; 97:940-950. [PMID: 27220210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Introduced parasites threaten native host species that lack effective defenses. Such parasites increase the risk of extinction, particularly in small host populations like those on islands. If some host species are tolerant to introduced parasites, this could amplify the risk of the parasite to vulnerable host species. Recently, the introduced parasitic nest fly Philornis downsi has been implicated in the decline of Darwin's finch populations in the Galápagos Islands. In some years, 100% of finch nests fail due to P. downsi; however, other common host species nesting near Darwin's finches, such as the endemic Galápagos mockingbird (Mimus parvulus), appear to be less affected by P. downsi. We compared effects of P. downsi on mockingbirds and medium ground finches (Geospiza fortis) on Santa Cruz Island in the Galápagos. We experimentally manipulated the abundance of P. downsi in nests of mockingbirds and finches to measure the direct effect of the parasite on the reproductive success of each species of host. We also compared immunological and behavioral responses by each species of host to the fly. Although nests of the two host species had similar parasite densities, flies decreased the fitness of finches but not mockingbirds. Neither host species had a significant antibody-mediated immune response to P. downsi. Moreover, finches showed no significant increase in begging, parental provisioning, or plasma glucose levels in response to the flies. In contrast, parasitized mockingbird nestlings begged more than nonparasitized mockingbird nestlings. Greater begging was correlated with increased parental provisioning behavior, which appeared to compensate for parasite damage. The results of our study suggest that finches are negatively affected by P. downsi because they do not have such behavioral mechanisms for energy compensation. In contrast, mockingbirds are capable of compensation, making them tolerant hosts, and a possible indirect threat to Darwin's finches.
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34
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Knutie SA, Owen JP, McNew SM, Bartlow AW, Arriero E, Herman JM, DiBlasi E, Thompson M, Koop JA, Clayton DH. Galápagos mockingbirds tolerate introduced parasites that affect Darwin's finches. Ecology 2016. [DOI: 10.1890/15-0119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Sarah A. Knutie
- Department of Biology; University of Utah; Salt Lake City UT 84112 USA
| | - Jeb P. Owen
- Department of Entomology; Washington State University; Pullman WA 99164 USA
| | - Sabrina M. McNew
- Department of Biology; University of Utah; Salt Lake City UT 84112 USA
| | - Andrew W. Bartlow
- Department of Biology; University of Utah; Salt Lake City UT 84112 USA
| | - Elena Arriero
- Department of Zoology and Physical Anthropology; Complutense University of Madrid; E-28040 Madrid Spain
| | - Jordan M. Herman
- Department of Biology; University of Utah; Salt Lake City UT 84112 USA
| | - Emily DiBlasi
- Department of Biology; University of Utah; Salt Lake City UT 84112 USA
| | - Michael Thompson
- Department of Biology; University of Utah; Salt Lake City UT 84112 USA
| | | | - Dale H. Clayton
- Department of Biology; University of Utah; Salt Lake City UT 84112 USA
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Abstract
The prevailing theory for the molecular basis of evolution involves genetic mutations that ultimately generate the heritable phenotypic variation on which natural selection acts. However, epigenetic transgenerational inheritance of phenotypic variation may also play an important role in evolutionary change. A growing number of studies have demonstrated the presence of epigenetic inheritance in a variety of different organisms that can persist for hundreds of generations. The possibility that epigenetic changes can accumulate over longer periods of evolutionary time has seldom been tested empirically. This study was designed to compare epigenetic changes among several closely related species of Darwin's finches, a well-known example of adaptive radiation. Erythrocyte DNA was obtained from five species of sympatric Darwin's finches that vary in phylogenetic relatedness. Genome-wide alterations in genetic mutations using copy number variation (CNV) were compared with epigenetic alterations associated with differential DNA methylation regions (epimutations). Epimutations were more common than genetic CNV mutations among the five species; furthermore, the number of epimutations increased monotonically with phylogenetic distance. Interestingly, the number of genetic CNV mutations did not consistently increase with phylogenetic distance. The number, chromosomal locations, regional clustering, and lack of overlap of epimutations and genetic mutations suggest that epigenetic changes are distinct and that they correlate with the evolutionary history of Darwin's finches. The potential functional significance of the epimutations was explored by comparing their locations on the genome to the location of evolutionarily important genes and cellular pathways in birds. Specific epimutations were associated with genes related to the bone morphogenic protein, toll receptor, and melanogenesis signaling pathways. Species-specific epimutations were significantly overrepresented in these pathways. As environmental factors are known to result in heritable changes in the epigenome, it is possible that epigenetic changes contribute to the molecular basis of the evolution of Darwin's finches.
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Affiliation(s)
- Michael K Skinner
- Center for Reproductive Biology, School of Biological Sciences, Washington State University
| | - Carlos Gurerrero-Bosagna
- Center for Reproductive Biology, School of Biological Sciences, Washington State UniversityPresent address: Department of Physics, Biology and Chemistry (IFM), Linköping University, Sweden
| | - M Muksitul Haque
- Center for Reproductive Biology, School of Biological Sciences, Washington State University
| | - Eric E Nilsson
- Center for Reproductive Biology, School of Biological Sciences, Washington State University
| | - Jennifer A H Koop
- Department of Biology, University of UtahPresent address: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ
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Knutie SA, Koop JAH, French SS, Clayton DH. Experimental test of the effect of introduced hematophagous flies on corticosterone levels of breeding Darwin's finches. Gen Comp Endocrinol 2013; 193:68-71. [PMID: 23892015 PMCID: PMC4383185 DOI: 10.1016/j.ygcen.2013.07.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 06/12/2013] [Accepted: 07/15/2013] [Indexed: 11/30/2022]
Abstract
Parasites can negatively affect the evolutionary fitness of their hosts by eliciting physiological stress responses. Parasite-induced stress can be monitored by measuring changes in the adrenal steroid hormone corticosterone. We examined the effect of an invasive parasite on the corticosterone concentrations of a common species of Darwin's finch, the medium ground finch (Geospiza fortis). Philornis downsi (Diptera: Muscidae) is a parasitic nest fly recently introduced to the Galapagos Islands, where it feeds on the blood of nestlings and breeding adult female finches. Previous work shows that P. downsi significantly reduces the reproductive success of several species of finches. We predicted that the effect of P. downsi on host reproductive success is mediated by stress responses in breeding female finches. High stress levels could reduce the ability of females to invest in offspring, thus decreasing their reproductive success. To test this hypothesis, we experimentally manipulated the abundance of P. downsi in nests, then measured baseline and acute stress-induced corticosterone levels, body condition, and hematocrit (red blood cell content). Acute stress-induced corticosterone levels increased over baseline levels, but this response did not differ significantly with parasite treatment. There was also no significant difference in the body condition or hematocrit of females from parasitized versus non-parasitized nests. Our results suggest that the lower reproductive success of females from parasitized nests is not mediated by a physiological stress response.
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Affiliation(s)
- Sarah A Knutie
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA.
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Koop JAH, Owen JP, Knutie SA, Aguilar MA, Clayton DH. Experimental demonstration of a parasite-induced immune response in wild birds: Darwin's finches and introduced nest flies. Ecol Evol 2013; 3:2514-23. [PMID: 24567824 PMCID: PMC3930052 DOI: 10.1002/ece3.651] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [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: 02/21/2013] [Revised: 05/10/2013] [Accepted: 05/22/2013] [Indexed: 11/10/2022] Open
Abstract
Ecological immunology aims to explain variation among hosts in the strength and efficacy of immunological defenses. However, a shortcoming has been the failure to link host immune responses to actual parasites under natural conditions. Here, we present one of the first experimental demonstrations of a parasite-induced immune response in a wild bird population. The recently introduced ectoparasitic nest fly Philornis downsi severely impacts the fitness of Darwin's finches and other land birds in the Galápagos Islands. An earlier study showed that female medium ground finches (Geospiza fortis) had P. downsi-binding antibodies correlating with presumed variation in fly exposure over time. In the current study, we experimentally manipulated fly abundance to test whether the fly does, in fact, cause changes in antibody levels. We manipulated P. downsi abundance in nests and quantified P. downsi-binding antibody levels of medium ground finch mothers, fathers, and nestlings. We also quantified host behaviors, such as preening, which can integrate with antibody-mediated defenses against ectoparasites. Philornis downsi-binding antibody levels were significantly higher among mothers at parasitized nests, compared to mothers at (fumigated) nonparasitized nests. Mothers with higher antibody levels tended to have fewer parasites in their nests, suggesting that antibodies play a role in defense against parasites. Mothers showed no behavioral changes that would enhance the effectiveness of the immune response. Neither adult males, nor nestlings, had P. downsi-induced immunological or behavioral responses that would enhance defense against flies. None of the parasitized nests fledged any offspring, despite the immune response by mothers. Thus, this study shows that, while the immune response of mothers appeared to be defensive, it was not sufficient to rescue current reproductive fitness. This study further shows the importance of testing the fitness consequences of immune defenses, rather than assuming that such responses increase host fitness. Host immune responses can protect against the negative fitness consequences of parasitism; however, the strength and effectiveness of these responses vary among hosts. Strong host immune responses are often assumed to correlate with greater host fitness. This study investigates the relationship between host immune response, parasite load, and host fitness using Darwin's finches and an invasive nest parasite. We found that while the immune response of mothers appeared defensive, it did not rescue current reproductive fitness.
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Affiliation(s)
- Jennifer A H Koop
- Department of Biology, University of Utah Salt Lake City, Utah, 84112
| | - Jeb P Owen
- Department of Entomology, Washington State University Pullman, Washington, 99164
| | - Sarah A Knutie
- Department of Biology, University of Utah Salt Lake City, Utah, 84112
| | - Maria A Aguilar
- Department of Biology, University of Utah Salt Lake City, Utah, 84112
| | - Dale H Clayton
- Department of Biology, University of Utah Salt Lake City, Utah, 84112
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Brown CR, Strickler SA, Moore AT, Knutie SA, Padhi A, Brown MB, Young GR, O'Brien VA, Foster JE, Komar N. Winter ecology of Buggy Creek virus (Togaviridae, Alphavirus) in the Central Great Plains. Vector Borne Zoonotic Dis 2010; 10:355-63. [PMID: 19725760 DOI: 10.1089/vbz.2009.0031] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A largely unanswered question in the study of arboviruses is the extent to which virus can overwinter in adult vectors during the cold winter months and resume the transmission cycle in summer. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an unusual arbovirus that is vectored primarily by the swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) and amplified by the ectoparasitic bug's main avian hosts, the migratory cliff swallow (Petrochelidon pyrrhonota) and resident house sparrow (Passer domesticus). Bugs are sedentary and overwinter in the swallows' mud nests. We evaluated the prevalence of BCRV and extent of infection in swallow bugs collected at different times in winter (October-early April) in Nebraska and explored other ecological aspects of this virus's overwintering. BCRV was detected in 17% of bug pools sampled in winter. Virus prevalence in bugs in winter at a site was significantly correlated with virus prevalence at that site the previous summer, but winter prevalence did not predict BCRV prevalence there the following summer. Prevalence was higher in bugs taken from house sparrow nests in winter and (in April) at colony sites where sparrows had been present all winter. Virus detected by reverse transcription (RT)-polymerase chain reaction in winter was less cytopathic than in summer, but viral RNA concentrations of samples in winter were not significantly different from those in summer. Both of the BCRV lineages (A, B) overwintered successfully, with lineage A more common at sites with house sparrows and (in contrast to summer) generally more prevalent in winter than lineage B. BCRV's ability to overwinter in its adult vector probably reflects its adaptation to the sedentary, long-lived bug and the ecology of the cliff swallow and swallow bug host-parasite system. Its overwintering mechanisms may provide insight into those of other alphaviruses of public health significance for which such mechanisms are poorly known.
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Affiliation(s)
- Charles R Brown
- Department of Biological Sciences, University of Tulsa, Tulsa, Oklahoma 74104, USA.
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Brown CR, Moore AT, O'Brien VA, Padhi A, Knutie SA, Young GR, Komar N. Natural infection of vertebrate hosts by different lineages of Buggy Creek virus (family Togaviridae, genus Alphavirus). Arch Virol 2010; 155:745-9. [PMID: 20229115 DOI: 10.1007/s00705-010-0638-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 02/09/2010] [Indexed: 11/26/2022]
Abstract
Buggy Creek virus (BCRV; family Togaviridae, genus Alphavirus) is an arbovirus transmitted by the ectoparasitic swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) to cliff swallows (Petrochelidon pyrrhonota) and house sparrows (Passer domesticus). BCRV occurs in two lineages (A and B) that are sympatric in bird nesting colonies in the central Great Plains, USA. Previous work on lineages isolated exclusively from swallow bugs suggested that lineage A relies on amplification by avian hosts, in contrast to lineage B, which is maintained mostly among bugs. We report the first data on the BCRV lineages isolated from vertebrate hosts under natural conditions. Lineage A was overrepresented among isolates from nestling house sparrows, relative to the proportions of the two lineages found in unfed bug vectors at the same site at the start of the summer transmission season. Haplotype diversity of each lineage was higher in bugs than in sparrows, indicating reduced genetic diversity of virus amplified in the vertebrate host. BCRV appears to have diverged into two lineages based on different modes of transmission.
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Affiliation(s)
- Charles R Brown
- Department of Biological Sciences, University of Tulsa, Tulsa, OK 74104, USA.
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Brown CR, Moore AT, Knutie SA, Komar N. Overwintering of infectious Buggy Creek virus (Togaviridae: Alphavirus) in Oeciacus vicarius (Hemiptera: Cimicidae) in North Dakota. J Med Entomol 2009; 46:391-394. [PMID: 19351093 DOI: 10.1603/033.046.0227] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Arboviruses have seldom been found overwintering in adult vectors at northern latitudes in North America. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an ecologically unusual arbovirus vectored principally by the cimicid swallow bug (Oeciacus vicarius Horvath). The ectoparasitic bugs reside year-round in the mud nests of their host, the cliff swallow (Petrochelidon pyrrhonota Vieillot). We report successful overwintering of infectious BCRV in bugs at a field site in western North Dakota, where mid-winter temperatures routinely reach -11 to -15 degrees C. Approximately 21% of bug pools were positive for virus in early spring just before the cliff swallows' return to their nesting colonies; this proportion did not differ significantly from that in summer at active cliff swallow nesting colonies in the same study area. Fewer of the isolates in early spring were cytopathic on Vero cells, and those that were infectious showed less plaque formation than did summer samples. The results show that infectious BCRV commonly overwinters in the adult stages of its vector at northern latitudes in North America.
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Affiliation(s)
- Charles R Brown
- Department of Biological Sciences, University of Tulsa, Tulsa, OK 74104, USA.
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