Dr Trenton W J Garner

Curriculum Vitae:

• 2009-present: Senior Research Fellow, Institute of Zoology.
• 2005-2010: RCUK Research Fellow, Institute of Zoology.
• 2004-2005: Postdoctoral Research Fellow, Institute of Zoology.
• 2001-2004: Postdoctoral Research Assistant, Zoologisches Institute and Zoologisches Museum, Universität Zürich.
• 1998-2001: PhD candidate, Zoologisches Institute, Universität Zürich.
• 1994-1998: MSc candidate, Department of Biology, University of Victoria.
• 1992-1994: BSc candidate, Department of Biology, University of Victoria.
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Research Interests:

Broadly speaking, my research has always contrasted biological conflicts with compatibilities. My previous research interests include polyandrous mating systems, how they affect population genetic structure, and how demography affects mate choice. More recently I’ve mostly worked on host/parasite relationships; I am interested in determining how parasites are maintained and incur costs in hosts, and how this may affect host or parasite population dynamics and persistence. This, in turn, has led me back to sexual selection.

Much ado has been made about infectious disease as a conservation issue, notably in amphibian hosts. Some of the attention may be misplaced, but in some cases parasites pose grave and immediate threats to host populations and species. Conservation operates with limited resources - we aim to identify conditions where parasites are most likely to be conservation threats, and so advise on the optimal use of conservation resources. We use a suite of approaches, methods, systems and most importantly, collaborations to ascertain when conservation actions to mitigate the effects of amphibian parasites are warranted (and how to do so when warranted).

Measuring the costs of parasitism using experiments

Host/parasite relationships are not straightforward: a variety of factors can affect infection dynamics, virulence and transmission probabilities. Infectious disease can also shape mating strategies and other behaviours of the hosts. This kind of complexity is difficult to unravel in the field, so I use experiments to examine under what conditions hosts are expected to suffer the most or the least from parasitism. I use different hosts and parasites to do this, and work with several collaborators:

Amphibian/Fungal system: Mat Fisher , Marcus Rowcliffe , Jon Bielby
Amphibian/Viral system: Amanda Duffus , Peter Pearman
Dung fly/Fungal system: Rob Knell , Vicky Pook.

Relevant team publications:

• Garner TWJ, Rowcliffe JM, Fisher MC (in press) Climate, chytridiomycosis or condition: an experimental test of amphibian survival. Global Change Biology.
• Fisher MC, Bosch J, Yin Z, Stead DA, Walker J, Selway L, Brown AJP, Walker LA, Gow NAR, Stajich JE, Garner TWJ (2009) Proteomic and phenotypic profiling of the amphibian pathogen Batrachochytrium dendrobatidis shows that genotype is linked to virulence. Molecular Ecology, 18, 415-429.
• Garner TWJ, Walker S, Bosch J, Leech S, Rowcliffe JM, Cunningham AA, Fisher MC (2009) Life history trade-offs influence mortality associated with the amphibian pathogen Batrachochytrium dendrobatidis. Oikos, 118, 783-791.
• Ribas L, Li M-S, Doddington B, Robert J, Seidel JA, Kroll JS, Zimmerman L, Grassly NC, Garner TWJ, Fisher MC (2009) Expression profiling the temperature-dependent amphibian response to infection by Batrachochytrium dendrobatidis. PLoS ONE, 4, e8408.
• Pearman PB, Garner TWJ (2005) Susceptibility of Italian Agile Frog populations to an emerging Ranavirus parallels population genetic diversity. Ecology Letters, 8, 401-408.
• Pearman PB, Garner TWJ, Straub M, Greber UF (2004) Response of Rana latastei to the Ranavirus FV3: a model for viral emergence in a naïve population. Journal of Wildlife Disease, 40, 600-609.
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Emergence of a global amphibian pathogen in Europe: Batrachochytrium dendrobatidis

Batrachochytrium dendrobatidis (Bd) is a chytridiomycete fungus causing declines of amphibian populations and species extinctions across the world. Although a recently emerged pathogen, it is arguably the most virulent wildlife disease known today. In response to the potential threat to European amphibians posed by the emergence of this infectious disease, we have formed a consortium of European researchers, funded by the EU’s BiodivERsA programme, NERC and various other organizations, to determine the range of this disease across Europe and explore what ecological, demographic and community factors influence prevalence and virulence (see R.A.C.E .).
We are using field work, population genetics and experiments to determine how disease establishment and propagation may occur and what conditions lead to amphibian mortality. We’re also developing treatments and mitigation methodologies.

BiodivERsA team and collaborators:

David Aanensen , Jon Bielby , Jaime Bosch , Frances Clare, Andrew Cunningham , Rhys Farrer , Mat Fisher , Klaus Henle , Emilien Luquet , Claude Miaud (unfortunately a supporter of the French national rugby side), Peter Minting , Sandrine Plenet , Chris Powell , Dirk Schmeller , Benedikt Schmidt , Jennifer Sears, Ursina Tobler , Susan Walker and Zirichiltaggi, along with a host of other researchers, students and technicians.

Relevant team publications:

• Tobler U, Schmidt B (2010) Within- and among-population variation in chytridiomycosis-induced mortality in the toad Alytes obstetricans. PLoS ONE, 5, e10927.
• Walker SF, Bosch J, Gomez V, Garner TWJ, Cunningham AA, Schmeller DS, Ninyerola M, Henk D, Ginestet C, Christian-Philippe A, Fisher MC (2010) Factors driving pathogenicity versus prevalence of the amphibian pathogen Batrachochytrium dendrobatidis and chytridiomycosis in Iberia. Ecology Letters, 13, 372-382.
• Bielby J, Bovero S, Sotgiu G, Tessa G, Favelli M, Angelini C, Doglio S, Clare F, Gazzaniga E, Lapietra F, Garner TWJ (2009) Fatal chytridiomycosis in the Tyrrhenian painted frog. Ecohealth, 6, 27-32.
• Fisher MC, Garner TWJ, Walker SF (2009) The global emergence of Batrachochytrium dendrobatidis in space, time and host. Annual Review of Microbiology, 63, 291-310.
• Garner TWJ, Garcia G, Carroll B, Fisher MC (2009) Using itraconazole to clear Batrachochytrium dendrobatidis infection in Alytes muletensis tadpoles. Diseases of Aquatic Organisms, 83, 257-260.
• Bielby J, Cooper N, Cunningham AA, Garner TWJ, Purvis A (2008) Predictors of rapid decline in frog species. Conservation Letters, 1, 82-90.
• Bovero S, Sotgiu G, Angelini C, Doglio S, Gazzaniga E, Cunningham AA, Garner TWJ (2008) Detection of chytridiomycosis caused by Batrachochytrium dendrobatidis in the endangered Sardinian newt Euproctus platycephalus in Southern Sardinia, Italy. Journal of Wildlife Diseases, 44, 712-715.
• Mitchell KM, Churcher TS, Garner TWJ, Fisher MC (2008) Persistence of the emerging infectious pathogen Batrachochytrium dendrobatidis outside the amphibian host greatly increases the probability of host extinction. Proceedings of the Royal Society of London, Series B, 275, 329-334.
• Walker SF, Baldi Salas M, Jenkins D, Garner TWJ, Cunningham AA, Hyatt AD, Bosch J, Fisher MC (2007) Environmental detection of Batrachochytrium dendrobatidis in a temperate climate. Diseases of Aquatic Organisms, 77, 105-112.
• Garner TWJ, Walker S, Bosch J, Hyatt AD, Cunningham AA, Fisher MJ (2005) Chytrid fungus in Europe. Emerging Infectious Diseases, 11, 1639-1641.
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Consequences of emerging viral disease for amphibian populations

We have several projects involved in understanding the impact of ranavirus on wild amphibians, first and foremost determining if the emergence of ranavirus is a serious conservation issue. In some circumstances amphibians and virus can enter into co-evolutionary dynamics, suggesting that ranavirus may not pose an extinction risk to a host. However, recent work by our team showed that amphibian populations may experience large and persistent population declines that presumably could increase the risk of population extirpation. Other findings were that selection on both host immunity and behaviour may be occurring in populations experiencing persistent disease. Thus disease emergence has the potential to modify host genetics in turn. This suggests that extinction due exclusively to ranavirus emergence in the U.K. may be unlikely, but overall ranavirus appears to contribute to population regulation, and, in some cases, strongly. However, ranavirus is a multihost parasite, so we also wonder if disease maintenance due to disease dynamics in the host exhibiting clinical signs of disease, or is maintenance due to host community disease dynamics?

Ranavirus team, past and present: Amber Teacher , Richard Nichols , Amanda Duffus , Stephen Price .

Relevant team publications:

• Teacher AGF, Cunningham AA, Garner TWJ (2010) Assessing the long-term impact of Ranavirus infection in wild common frog populations. Animal Conservation, 13, 514-522.
• Teacher AGF, Garner TWJ, Nichols RA (2009) Evidence for directional selection at a novel Major Histocompatability Class 1 marker in wild common frogs (Rana temporaria) exposed to a viral pathogen. PLoS ONE, 4, E4616.
• Teacher AGF, Garner TWJ, Nichols RA (2009) Population genetic patterns suggest a behavioural change in wild common frogs (Rana temporaria) following disease outbreaks (Ranavirus). Molecular Ecology, 18, 3163-3172.
• Duffus ALJ, Pauli BD, Wozney K, Brunetti CR, Berrill M (2008) Frog virus 3-like infections in aquatic amphibian communities. Journal of Wildlife Diseases, 44, 109-120.
• Pearman PB, Garner TWJ (2005) Susceptibility of Italian Agile Frog populations to an emerging Ranavirus parallels population genetic diversity. Ecology Letters, 8, 401-408.
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Invasive species as vectors of emerging parasites and the impact of amphibian trade

Species introductions are a common occurrence, and these introductions often also inadvertently introduce novel parasites, potentially resulting in conservation issues. Although it is likely many factors have led to the worldwide spread of the parasites of amphibians, it appears that the global trade in amphibians contributes greatly to the past and ongoing global spread of amphibian infectious disease. Every year, thousands of tons of amphibians are traded around the globe as food, pets, for captive breeding programs, zoo displays, fishing bait, decorations for garden ponds and research and many of these shipments carry infected animals. My colleagues and I are currently determining how introductions are associated with the emergence of amphibian parasites, the likelihood of establishment after translocated native and introduced non-native amphibian species invade and what the consequences are for the native amphibians.

Introductions collaborators and students: Francesco Ficetola , Mat Fisher , Purnima Govindarajulu , Richard Griffiths , Claude Miaud , Jennifer Sears, Emma Wombwell

Relevant team publications:

• Fisher MC, Garner TWJ, Walker SF (2009) The global emergence of Batrachochytrium dendrobatidis in space, time and host. Annual Review of Microbiology, 63, 291-310.
• Garner TWJ, Stephen I, Wombwell E, Fisher MC (2009) The amphibian trade: bans or best practice? Ecohealth 6, 148-151.
• Walker SF, Bosch J, James TY, Litvintseva AP, Valls JAO, Piña S, Garcia G, Rosa GA, Cunningham AA, Hole S, Griffiths R, Fisher MC (2008) Invasive pathogens threaten species recovery programs. Current Biology, 18, R853-R854.
• Fisher MC, and Garner TWJ (2007) The relationship between the introduction of Batrachochytrium dendrobatidis, the international trade in amphibians and introduced amphibian species. Fungal Biology Reviews, 21, 2-9.
• Garner TWJ, Perkins M, Govindarajulu P, Seglie D, Walker SJ, Cunningham AA , Fisher MC (2006) The emerging amphibian pathogen Batrachochytrium dendrobatidis globally infects introduced populations of the North American bullfrog, Rana catesbeiana. Biology Letters, 2, 455-459.
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Habitat alteration amphibian decline and amphibian parasites

Human-induced habitat alteration is expected to alter amphibian behaviour and populationdynamics, and lead to species declines, especially in those amphibian species that are more specialized in their life and natural histories. Habitat alteration may also destabilize existing host/parasite dynamics or facilitate the introduction of new parasites often through associated non-native host invasions, as well as directly affect amphibian populations and behaviour. My colleagues and I are examining the pattern of amphibian community structure in altered versus more natural habitats, as well as relating amphibian parasite communities to patterns of habitat alteration.

Students and collaborators: Aisyah Faruk , Rob Knell , and David Lesbarrères .

Relevant team publications:

• St-Amour V, Wong WM, Garner TWJ, Lesbarrères D (2008) Anthropogenic influence on the prevalence of two amphibian pathogens. Emerging Infectious Diseases, 14, 1175-1176.
• Garner TWJ, Nishimura D, Antwi J, Oliver N (2008) Human disturbance influences behaviour and local density of juvenile frogs. Ethology, 114, 1006-1013.
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Other Publications:

Population and Adaptive Genetics:

• Ficetola GF, Garner TWJ, Wang J, De Bernardi F (2010) Rapid selection against inbreeding in a wild population of a rare frog. Evolutionary Applications.
• Ficetola GF, Padoa-Schioppa E, Wang J, Garner TWJ (2010) Polygyny, census and effective population size in the threatened frog, Rana latastei. Animal Conservation.
• Teacher AGF, Garner TWJ, Nichols RA (2009) European phylogeography of the common frog (Rana temporaria): routes of postglacial colonisation into Britain and evidence for an Irish glacial refugium. Heredity, 102, 490-496.
• Demont M. Blanckenhorn WU, Hosken DJ, Garner TWJ (2008) Molecular and quantitative genetic differentiation across Europe in the yellow dung fly. Journal of Evolutionary Biology, 21, 1492-1503.
• Ficetola GF, Garner TWJ, De Bernardi F (2007) Genetic diversity and fitness in the threatened frog, Rana latastei, are influenced by the joint effect of post glacial colonization and isolation. Molecular Ecology, 16, 1787-1797.
• Garner TWJ, Pearman PB, Angelone S (2004) Genetic diversity across a vertebrate species’ range. A test of the central-peripheral hypothesis. Molecular Ecology, 13, 1047-1053.

Sexual Selection:

• Hoeck P, Garner TWJ (2007) Female alpine newts (Triturus alpestris) mate first with males signalling fertility benefits. Biological Journal of the Linnean Society, 91, 483-491.
• Garner TWJ, Larsen K (2005) Multiple paternity in the western terrestrial garter snake, Thamnophis elegans. Canadian Journal of Zoology, 83, 656-663.
• Garner TWJ, Schmidt B (2003) Relatedness, body size, and paternity in the Alpine newt, Triturus alpestris. Proceedings of the Royal Society London, Series B, 270, 619-624.
• Hosken DJ, Garner TWJ, Tregenza T, Wedell N, Ward PI (2003) Superior sperm competitors sire higher quality young. Proceedings of the Royal Society of London, Series B, 270, 1933-1938.
• Garner TWJ, Gregory PT, McCracken GF, Burghardt GM, Koop BF, McLain SE, Nelson RJ (2002) Geographic variation of multiple paternity in the Common Garter Snake (Thamnophis sirtalis). Copeia, 2002(1), 15-23.
• Hosken DJ, Blanckenhorn WU, Garner TWJ (2002) Heteropopulation males have a fertilization advantage during sperm competition in the yellow dung fly (Scathophaga stercoraria). Proceedings of the Royal Society London, Series B, 269, 1701-1707.
• Hosken DJ, Garner TWJ, Ward PI (2001) Sexual conflict selects for male and female reproductive characters. Current Biology, 11, 489-493.

I’m always on the look-out for motivated people who have strong interests in conservation, evolutionary biology, ecology and a good appreciation of theory. Our various projects have benefited from the inputs of many Master’s students and undergraduate research projects, and my colleagues and I often advertise PhD positions. I am also keen to write proposals with post doctoral candidates. The Institute of Zoology (IoZ) is an outstanding place to work and by its very nature collaborative: we do not confer degrees so all our PhD students are co-supervised and registered at universities. It’s not uncommon for post docs to get cross-postings. This provides the novel opportunity to experience research environments at two institutions, dependent on the researcher’s needs and wants. Do have a look at the web pages of other researchers at the IoZ, we’re quite proud of our team, the breadth of research done by it and the impacts our research has had on the conservation of animal species.