At a broad scale, I am
interested in using theoretical models to understand real ecological
systems at scales larger and longer than can be addressed with
traditional experimental and observational studies. At the same time, I
am committed to connecting my models to observations of real systems.
Exploring methods for challenging models with real data (Tyre and
Tenhumberg, 2000 Austral Ecology; McCarthy et al., 2001 Conservation
Biology) has lead me to model the observation process itself, and to
work on modern statistical methods to quantitatively fit ecological
models to empirical data (Tyre et al. in press Ecological
My work with survey data leads me to use very simple models that can be
fit directly to ecological data. My other interest is in identifying
the limits of what simple models can tell us about ecological systems
(e.g. Tyre et al. 2001, Ecological Applications). In this work I have
used spatially explicit simulation models to create artificial
realities sampled by virtual ecologists. In this way I am able to
directly link the kinds of data collected by ecologists with the
underlying dynamic processes.
In pretty much everything
I do I work together with Dr.
false negative rates in presence/absence surveys
A presence/absence survey
conducted at two different times can have four possible outcomes; in
two cases it is possible that there was an ecological change, either
the species has disappeared locally, or it has recolonised the area.
The other possibility is that in one survey the species was simply
missed, although it was still present. This is a ‘false
negative’ observation. I developed a method based on fitting
mixtures of binomial distributions to repeated visits to estimate the
false negative rate. My collaborators and I have used the method to
quantify false negative errors in bird, frog, and aquatic invertebrate
surveys (Tyre et
al. in press, Ecological
regulation in ticks on reptiles
I'm collaborating with
Prof. Mike Bull of Flinder's University on understanding the population
dynamics of two ixodid tick species that share the same lizard host in
Southern Australia. The biogeographic distributions of the two species
abut along a narrow parapatric boundary thousands of kilometres long. I
am using individual based simulation models, mark recapture statistics,
and maximum likelihood methods in an effort to extract more information
from the existing data, and reveal the mechanisms responsible for the
monitoring in the presence of survey errors
I'm working with Dr.
Scott Field, Prof. Hugh
Possingham, and doctoral students Jonathan Rhodes and Liana Joseph at The Ecology Centre
on designing ecological surveys that account for observation error.
Scott is working on the woodland birds of the Mt. Lofty Ranges in South
Australia, Jonathan is working on Koala populations in northern New
South Wales, and Liana is studying the interaction between observation
errors and rarity in bird communities of the wet tropics in Queensland.
dynamics of mound spring invertebrates
Around the edge of
the Great Artesian Basin in the Austrlian outback are a large number of
natural artesian springs. These permanent wetlands in the middle of one
of the most arid regions on earth are home to an astonishing diversity
of endemic invertebrates. I am collaborating with Dr. Chris Wilcox,
Prof. Hugh Possingham, and Darren Niejalke of Western Mining
Corporation on a project to model the dynamics of, and develop survey
methods to accurately assess the status and trend of these populations.
I have a passing interest in using optimisation methods developed by
Dr. Ian Ball (Australian Antarctic Division) and Prof Hugh Possingham
for marine reserve design. In collaboration with Dr. Rodrigo Bustamante
and Ian Mcleod of CSIRO Marine
Research I employed the software
to explore the distribution of biodiversity in deep waters in the
southeast marine region of Australia.