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I use
mathematical tools to address ecological questions from a theoretical
perspective as well as a statistical perspective. My work has
crossed systems from plants to predators, from antler flies to Pacific
salmon.
Implications of Temporal Variation
I am interested in examining the implications of temporal variation for
fundamental ecological theory. Much of ecological theory has been
developed with the assumption that populations will reach stable
equilibria over the long term. However, environmental conditions
fluctuate with time and are predicted to undergo increased fluctuations
by global climate models. I examined how
temporal fluctuations in the environment alters the indirect
interaction in a simple three-species food web, two prey and a shared
predator (Brassil 2006).
Besides environmental fluctuations, population sizes may fluctuate due
to population interactions such as predator-prey interactions.
Interaction-driven fluctuations can result in a wide range of
population dynamics and have important consequences for species
co-existence (Abrams,
Brassil, and Holt 2003). The manner in which predators choose
between prey can change the type of population fluctuations (Ma, Abrams, and
Brassil 2003). I have found that interaction-driven
fluctuations can alter indirect interactions as well as
environmental-driven fluctuations (Brassil and Abrams 2004).
My current research is examining mechanisms by which environmental
variation might dampen fluctuations in population sizes. The
theoretical work is inspired by the empirical work of Mathew
Leibold.
Development of Maximum Likelihood
Analysis
I have developed maximum likelihood analyses as a powerful quantitative
tool linking theoretical hypotheses and empirical data. Many
collaborations have addressed senescence in wild populations, including
the first demonstration of senescence in wild insect populations (Bonduriansky and
Brassil 2002). Additional analysis utilized specific
distribution functions to uncover important trade-offs between body
size and ageing rate in these same wild populations (Bonduriansky and
Brassil 2005). Variation in senescence was examined across
multiple wild populations of salmon (Morbey, Brassil,
and Hendry 2005).
I developed analytic tools that could examine the serial transfer of
pollen from pollinators to flowers but still account for the extremely
skewed data that results from clumped, sticky pollen (Castellanos,
Wilson, and Thomson 2003). Currently I am collaborating with Meghan Duffy on a technique
to analyze disruptive selection in a wild population of daphnia.
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