individually
based, physiologically structured population modeling; life history
evolution
My research interests span the
interfaces among physiological ecology, evolutionary ecology,
and population biology and are currently focused in three areas:
(1) elucidating the proximal mechanisms whereby environmental
variation affects life history and demographic variation in natural
populations, (2) refining and testing theories of life history
evolution, and (3) testing theories of the evolution of senescence.
Because patterns and mechanisms of
allocation of time and resources by individual organisms are integral
components of any theory that attempts to link environmental variation
to variation in population dynamics, I am particularly interested
in developing approaches to discover the mechanisms whereby individual
organisms allocate limited time and resources. There are two sets
of related questions here that span the two seemingly disparate
areas of ecological investigation. The first involves understanding
the patterns and mechanisms of individual allocation that exist
in any system and the consequences of those patterns and mechanisms
for the transduction of environmental change into change at the
population (and higher) levels of ecological organization. The
development of epistomologically sufficient theory for the transduction
of environmental variation through individual organisms into variation
in population dynamics is potentially of considerable importance
to not only basic ecology but also to conservation biology as
well.
A second and related set of questions
involves the evolution of patterns and mechanisms of allocation
of time and resources by individual organisms. Attempts to answer
these questions comprise much of life history theory. I define
a life history as a heritable set of rules which specify age-
and sex-specific allocations of available time to activities such
as mate and resource acquisition, and allocation of net assimilated
resources into the competing physiological functions of growth,
maintenance, activity, reproduction, and storage and the effects
of these allocation decisions on survival and reproduction. My
goal is to provide a theoretical framework which links environmentally
induced patterns of variation at the individual level to variation
at the population level of ecological organization.
One of the most important, and least
understood, problems in population ecology involves the development
of epistomologically sufficient theory that will allow prediction
of the dynamics of any particular population under conditions
of environmental fluctuation. A major aspect of my current research
centers on the development of mechanistic, physiologically structured,
individual-based models and approaches that will allow prediction
of population dynamics in response to environmental change. The
model system I use in developing and validating this approach
consists of several populations of the small arid-adapted iguanid
lizard Sceloporus merriami that occurs throughout much
of the Chihuahuan Desert of northern Mexico and west Texas. I
have been engaged in detailed studies of the population dynamics
and physiological ecology of this lizard for the past 23 years
in Big Bend National Park, Texas. This research involves a continuing
long-term mark-recapture study of the demographic and life history
variation within and among local populations in relation to proximal
variation in such factors as availability of food resources, the
biophysical environment, and sources of mortality.
selected
publications
Dunham, A. E. and S. J.
Beaupre. 1997. Ecological experiments: Scale, phenomenology, mechanism,
and the illusion of generality. In W. Resitarits and J. Bernardo
[eds.], Issues and Perspectives in Experimental Ecology.
Oxford University Press.
Miles, D. B. and A. E. Dunham.
1996. The paradox of the phylogeny: character displacement
of analyses of body size in island Anolis. Evolution50:594-603.
Petraitis, P., A. E. Dunham,
and P. H. Niewiarowski. 1996. Inferring multiple causality:
the limitations of path analysis. Functional Ecology10:421-431.
Spotilla, J. R., A. E. Dunham,
A. J. Leslie, A. C. Steyermark, P. T. Plotkin, and F. V. Paladino.
1996. Worldwide population decline of Dermochyleys coriacea:
are leatherback turtles going extinct? Chelonian Conservation
and Biology2:209-222.
Dunham, A. E., and Overall,
K.L. 1994. Population responses to environmental change: Life
history variation, individual based models, and the population
dynamics of short-lived organisms. American Zoologist34:382-396.
Niewiarowski, P. H., and A.E. Dunham
1994. The evolution of reproductive effort in squamate reptiles:
costs, tradeoffs, and assumptions reconsidered. Evolution48:137-145.
Miles, D. B., and A.E. Dunham 1993.
Historical perspectives in ecology and evolutionary biology:
The use of phylogenetic comparative analyses. Ann. Rev.
Ecol. and Systematics24:587-619.
People