#ESAus18 conference wrap-up!

This week seven members of our team attended the Ecological Society of Australia's annual conference held at the Royal International Convention Centre in Brisbane (25-29th Nov, 2018)!

It was a busy conference, with seven parallel sessions over four days. Doug and Tamika presented their excellent posters at the Barbara Rice Memorial Poster session on Monday, while Thais presented some of her Masters research during the "Conserving imperiled species and ecosystems" symposium on Tuesday. The rest of us (Hamish, Ali, Elle and Laura) gave presentations during the "Parasite ecology In the Anthropocene" symposium on Wednesday afternoon.

You can find abstracts for the presentations and posters from our team below:

Interactions between land use change, flying-fox ecology and Hendra virus dynamics

Dr Alison Peel (1), Assistant Prof Raina Plowright (2), Prof Hamish McCallum (1), Dr Peggy Eby (3) 1 Griffith University, Nathan, Australia

2 Montana State University, Bozeman, USA

3 University of New South Wales, Sydney, Australia

Biography: Dr Peel is a veterinarian and wildlife disease ecologist interested in the dynamics and drivers of viral transmission in bats – particularly African fruit bats and Australian flying foxes. She is an Advance Queensland Postdoctoral Research Fellow at Griffith University.

Abstract: Typically, flying foxes are nomadic nectar feeders and pollinators of native forests. Natural cyclical transitions from El Niño to La Niña periods impact Eucalypt phenology, causing intermittent acute food shortages for flying foxes and temporary fissioning of flying fox roosts. More recently, these ‘fission’ roosts are persisting outside of acute food shortages, manifesting as an exponential increase in flying fox roosts in urban areas. Immediately pre-dating these recent changes in flying fox ecology, the mid-1990’s saw a peak in destruction of their key habitats and the emergence of four novel zoonotic viruses from flying foxes. One of these, Hendra virus, stands out as an excellent model system for understanding bat virus transmission and spillover globally. Hendra virus spillover to horses tends to be associated with seasonal ‘pulses’ of viral excretion within bat populations, but the interactions between proposed broad-scale and roost-level drivers of Hendra virus transmission are complex and have not been fully elucidated. Our results indicate that landscape-scale processes driving flying fox roost fissioning are linked to processes driving Hendra virus excretion and spillover to horses. By gaining insights into the interactions between environmental change, bat ecology, viral dynamics and spillover, we hope to identify the root causes of viral spillover from wildlife hosts and develop of new ecological interventions to prevent bat virus spillover in Australia and globally.

An ecological assessment of Australia’s most common mosquito-borne disease, Ross River virus.

Ms Eloise Stephenson (1), Ms Amanda Murphy (2), Dr Cassie Jansen (3), Dr Alison Peel (1), Prof Hamish McCallum (1)

1 Griffith University, Southport, Australia

2 Queensland University of Technology, Brisbane, Australia

3 Queensland Health, Brisbane, Australia

Biography: I am an early career Scientist with a particular interest in the interactions between wildlife and people; either through the spread of diseases, human-wildlife conflict or the sustainable harvest of fish and game

Abstract:

Ross River virus (RRV) is responsible for the most widespread and frequently reported mosquito-borne disease in Australia. The disease is associated with debilitating symptoms in humans and a significant public health burden, particularly in Queensland where the disease rates are high. At present, there is no treatment or vaccine available. Ross River virus is maintained in the environment through enzootic cycles between mosquitoes and wildlife reservoirs, with subsequent ‘spill-over’ into human populations. More than 30 species of mosquitoes are capable of transmitting RRV, and antibodies to the virus have been found in several vertebrate species including kangaroos, possums, humans, dogs, cats and horses, suggesting a complex reservoir-vector interface. During the past 20 years, increasing numbers of human cases have been observed within metropolitan centres. This may be influenced by urban expansion in proximity to wildlife and mosquito habitats, though the specific risks are unclear. Studies of RRV ecology are needed to manage public health risks and prevent future outbreaks. Here we present ecological assessments comparing wildlife composition among Brisbane locations with high or low human RRV notification rates. Taking a novel multidisciplinary approach, we combine data on reservoir abundance with vector surveillance and wildlife serology. We identify differences in vector host assemblages between locations of high and low human RRV notifications, and find animal diversity levels correlate with human disease rates. Our findings challenge the existing dogma that marsupials are the primary RRV hosts, and highlight the advantages of using ecological approaches to interpret human disease patterns.

Microhabitat use and spatial-temporal abundance of torrent frogs in Brazilian Atlantic forest: a long-term assessment

Ms Thais Sasso Lopes (1), Dr Laura Alencar (2), Dr. Marilia Gaiarsa (3), Prof Marcio Martins (2) 1 Griffith University, Brisbane, Australia

2 University of São Paulo, São Paulo, Brazil

3 University of California, Riverside, United States

(Image courtesy of Eloise Stephenson)

Biography: I am a PhD candidate at Griffith University. I completed a Bachelor in Biology and a Masters in Ecology at the University of São Paulo. I am interested in combining wildlife disease and modelling to explore amphibian communities dynamics.

Abstract: Amphibians are among the most diverse vertebrates regarding geographic distribution. Spatial and temporal occurrences vary widely among species with some requiring specific habitat conditions. Based on long-term data, we described the microhabitat and the spatial-temporal abundance patterns of three torrent frogs endemic to the Brazilian Atlantic forest (Cycloramphus boraceiensis, Hylodes asper and Hylodes phyllodes). From 2007 to 2011, we performed monthly visual survey for post-metamorphic frogs within a 110 m transect at four streams in Núcleo Picinguaba, South eastern Brazil. We classified microhabitats based on five environmental variables and investigated species abundance variation within and between streams, as well as along the year. We observed 6,556 encounters. All species were active mainly on wet or humid rocks without cover, and adjacent to the water. Inactive H. asper and H. phyllodes were mainly on dry leaves without moss. The abundances of C. boraceiensis and H. asper were significantly higher in the wet season, potentially reflecting a higher reproduction rate. Four stream aspects (land area, water area, slope and number of waterfalls) influenced species abundance variation among streams’ sections. Species abundance also varied across streams, with H. phyllodes being the only species in stream 2. This potentially reflects variation between streams habitat suitability. This key ecological information show that although three species use similar microhabitats, they vary in occurrence along and across streams, and during certain months due to abiotic factors. Our results contribute to the understanding of occurrence patterns of amphibians in a biodiversity hot spot while helping to guide future conservation management.

Natural history of disease is central to investigating wildlife disease dynamics: examples from koala chlamydiosis

Dr. Laura Grogan (1), Dr. Alison Peel (1), Dr. Douglas Kerlin (1), Dr. William Ellis (2), Dr. J. Guy Castley (1), Prof. Hamish McCallum (1) 1 Griffith University, Nathan, Australia

2 The University of Queensland, St Lucia, Australia

Biography: I'm a Griffith University Research Fellow with a background in veterinary science, ecology and epidemiology. I work at the interface of disease ecology/epidemiology and pathogenesis/immunology of infectious diseases of wildlife. My current research focuses on koala chlamydiosis and amphibian chytridiomycosis.

Abstract: Infectious disease emergence is on the rise globally and poses dramatic sociocultural, political and economic challenges for human public health, domestic animal agriculture and biodiversity. Infectious diseases of wildlife may drive host population dynamics through alterations in fundamental demographic rates such as survival and recruitment, as well as population structure. Indeed, diseases may cause population declines and species extinctions, as empirically demonstrated in multiple instances. However, despite decades of research, the mechanisms underlying both (1) within-host disease dynamics, and (2) among-host infection transmission dynamics, remain poorly characterized for many systems. This contributes to sparse understanding of the relative importance of within- versus among- host dynamics for driving individual- and population- level outcomes, and limits our capacity to respond to and mitigate disease impacts. Here, we investigate the value of using the natural history of disease as a central framework for preliminary investigation of wildlife disease dynamics in the ecological setting. In particular, we focus on a case study concerning a poorly characterised aspect of koala chlamydiosis, investigating the impact that differing time courses of disease (chronic and latent/persistent versus acute and self-immunising) can have on our ability to model and mitigate disease in wild populations. Using simple epidemiological models in the koala chlamydiosis context, we demonstrate that such fundamental aspects of the natural history of disease need early elucidation in wildlife disease scenarios as they can have dramatic implications for population-level dynamics, and markedly affect decisions concerning appropriate management approaches.

Community structure and viral dynamics in flying-fox roosts: tackling non-linearity and heterogeneity in dynamic systems

Miss Tamika Lunn (1), Dr Alison Peel (1), Miss Maureen Kessler (2), Dr Peggy Eby (3), Assist Prof Raina Plowright (2), Prof Hamish McCallum (1) 1 Griffith University, Nathan, Australia

2 Montana State University, Bozeman, United States

3 University of New South Wales, Sydney, Australia

Biography: Tamika Lunn is a PhD student at Griffith University, investigating mechanisms driving Hendra virus dynamics in flying-foxes. Tamika works collaboratively with an international team of researchers undertaking a large-scale study on bat health, movement and disease under anthropogenic landscape change.

Abstract:

Bats are highly gregarious mammals, with some species roosting in dense, seasonal colonies that can range hundreds to hundreds-of-thousands of animals. This creates frequent opportunities for direct and indirect contact between large numbers of individuals, and contributes to the propensity of bats as important disease reservoirs. Understanding the roosting dynamics of bats is important in the context of infectious disease, as spatio-temporal patterns in abundance and density will influence infectious contacts between individuals, and thus the propensity for infection and spread of disease. However, the underlying functional relationship between abundance and density is complex, being determined by the expansion and contraction of tree occupation in multi-dimensional space. Here, we investigated the roosting structure of two sympatric species of flying-fox (Pteropus alecto and P. poliocephalus), utilising high-resolution spatial mapping. Data collection is underway, but preliminary analyses indicate that density changes non-linearly with increasing overall abundance, with the functional shape dictated by patterns of animal clustering in vertical and horizontal space, and by heterogeneity in the spatial arrangement of preferred roosting habitat. Future analyses will integrate roosting dynamics with matched data on Hendra virus excretion to explore the influence of roosting non-linearity and heterogeneity on disease parameters. As the first study to systematically evaluate roosting patterns in flying-foxes, this study provides valuable ecological information with practical applications for flying-fox conservation and conflict management. Furthermore, it is anticipated that simulations of virus invasion and spread in bat populations will be important for inferring disease dynamics in species with highly unstable, periodically fluctuating densities.

Effects of habitat fragmentation on wildlife pathogens

Prof Hamish McCallum (1), Dr Christina Faust (2), Dr Raina Plowright (3), Dr Nicole Gottdenker (4), Dr Thomas Gillespie (5), Ms Laura Bloomfield (6), Dr Maria Duik-Wasser (7), Dr Colin Torney (2), Professor Andrew Dobson (8) 1 Griffith University, Nathan, Australia

2 University of Glasgow, Glasgow, Scotland

3 Montana State University, Bozeman, USA

4 University of Georgia, Athens, USA

5 Emory University, Atlanta, USA

6 Stanford University, Stanford, USA

7 Columbia University, New York, USA

8 Princeton University, Princeton, USA

(Image courtesy of Eloise Stephenson)

Biography: Hamish McCallum works on the ecology of wildlife disease, with current projects on Tasmanian Devil Facial Tumour, Hendra virus in fruit bats and the amphibian chytrid fungus.

Habitat destruction is one of the most pervasive anthropogenic influences on ecological communities. There has been relatively little attention given to the impact of habitat loss on the ecology of parasites and pathogens. Habitat destruction has two principal effects. First, it reduces the size of remaining patches of undisturbed habitat. Second, it increases fragmentation, isolating patches and also exposing the ecological communities in the patches to the influence of organisms that occupy the disturbed “matrix” surrounding the undisturbed patches. We used a range of modelling tools to explore theoretically the influence of each of these effects on parasites and pathogens. We used an allometrically scaled multihost model to show that declining habitat and thus declining biodiversity can lead to either increasing (amplification) or decreasing (dilution) infectious disease risk. Dilution effects were detected for most frequency -dependent pathogens, and amplification effects for most density dependent pathogens but there were interesting exceptions to these generalisations. We also used a multihost model to investigate the effect of habitat loss on spillover of pathogens between undisturbed and the surrounding human-modified matrix. In most scenarios, the highest spillover risk to species such as humans or livestock occupying disturbed habitat occurred at intermediate levels of habitat loss. A stochastic model showed that, although epidemics are rare at high levels of habitat loss, when they do occur, they can be very severe. This framework provides insights into the mechanisms driving disease emergence and spillover during land conversion and has important implications for conservation and public health policy.

Reproductive plasticity in Tasmanian devils in response to devil facial tumour disease

Dr Douglas Kerlin (1), Dr Konstans Wells (1), Dr Rodrigo Hamade (2), Prof Paul Hohenlohe (3), Prof Andrew Storfer (4), Prof Hamish McCallum (1), Dr Menna Jones (2) 1 Environmental Futures Research Institute, Griffith University, Brisbane, Australia

2 School of Natural Sciences – Biological Sciences, University of Tasmania, Hobart, Australia

3 Institute for Bioinformatics and Evolutionary Studies, Department of Biological Sciences, University of Idaho, Moscow, United States of America

4 School of Biological Sciences, Washington State University, Pullman, United States of America

Biography: Douglas is a postdoctoral research fellow in the Griffith Wildlife Disease Ecology group. His research applies population ecology and spatial methods to study disease ecology of Australian marsupials, with a focus on Koalas and Tasmanian devil facial tumour disease.

Abstract:

Reproductive plasticity in wildlife can play a crucial role in the response of species to the adverse impacts of environmental hazards. Tasmanian devil facial tumour disease (DFTD), a transmissible and deadly cancer of Tasmanian devils (Sarcophilus harrisii), causes demographic shifts in devil population structure through the increased mortality of adult individuals. Precocial reproduction, defined as the early onset of breeding in subadult devils, has been suggested as a response to the loss of adult individuals from the populations, yet the underpinnings of changes in devil reproductive timing are not well understood. We analysed 18 years of longitudinal capture records from devil populations across Tasmania in a Bayesian dynamical state-space model to estimate the probability and timing of reproduction for devils in different age classes. This framework allowed model-based estimates of the timing of reproduction in different devil age groups, in addition to pouch young survival rates to help account for the underlying sampling bias. We demonstrate precocial breeding in certain devil populations congruent with the arrival of DFTD to the local area, however this phenomenon is not observed at all sampling locations. Disease-induced demographic shifts imposed by the selective removal of individuals from populations can cause life history changes in surviving individuals; the loss of adult devils may release subadult devils from density-dependent competition, with subsequent increased access to resources and reproductive plasticity manifesting in precocial reproduction.

In addition to some great presentations and posters, Elle demonstrated her amazing artistic skills by posting a continuous stream of incredible images depicting key presentation themes on Twitter! Tamika also made some im-paw-tant connections with the detection dogs while networking in the poster hall! :)