BIOS 6150: ECOLOGY
Dr Stephen B. Malcolm
Department of Biological Sciences, Western Michigan University.
Course Description:
“The structure and dynamics of plant and animal populations are considered with critical
evaluations of current concepts. Emphases include the relative roles of competition and
trophic interactions in population dynamics and how communities are structured.
Applications of ecological concepts will consider aspects of conservation biology, pest
control, agroecosystem function, and risks of genetic engineering.”
Prerequisite: A course in Ecology or consent of instructor.
Course Rationale: BIOS 6150 – Ecology is a graduate core course for both the Master
of Science in Biological Sciences and the Doctor of Philosophy in Biological Sciences.
INTRODUCTION
As you know this course in ecology is part of the graduate core curriculum in the
Department of Biological Sciences and is designed to reflect the historical background
to population ecology, the dominant theoretical themes, as well as recent developments
in theory and application. The emphasis is on population ecology and its interface with
community ecology.
Although we will touch on how populations influence community structure, the
primary focus of the course will be on Population Ecology. Of course, ecology
encompasses the study of how organisms interact with their "home" or "oikos", which as
you know reflects their "niche", and we can study these interactions at any level of
organization from individuals, through populations, communities and ecosystems, to
landscapes and biomes. Arguably, for most ecologists the population level of
organization, with its inherent variability, is the level that most of us study whether or not
we want to understand the ecologies of any of the changing scales of organization from
individuals to biomes. Thus population ecology has become central to much of
ecological theory and practice and it is at the population level that ecologists have tried
hardest to understand the processes that structure observed patterns of interaction.
Moreover, population ecology is becoming increasingly important in biomedical
applications because it provides some valuable epidemiological, behavioral and
dynamical tools for understanding molecular and cellular interactions as well as those
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Stephen Malcolm
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between microparasitic diseases and their hosts (e.g. viral, bacterial, protozoan, fungal
diseases etc.).
Pattern and process are the lifeblood of ecology and it is through our efforts to
understand the processes that structure observed patterns of distribution and
abundance of organisms that the science of ecology advances.
COURSE THEME
As long ago as 1798 the British political economist Thomas Robert Malthus
realized that human populations were increasing exponentially through logarithmic or
geometric progression in the absence of any apparent checks to growth. Forty years
later in 1838, the Belgian mathematician Pierre-François Verhulst was the first to
describe mathematically a sigmoid curve for population growth that was constrained to
an asymptote. This curve he called the "logistique" as opposed to the "logarithmique" of
Malthus. However, Malthus was also aware of the logistic relationship in his "principle
of population" and so this curve is perhaps best described as the "Malthus-Verhulst
logistic equation" (Berryman, 1992).
Although largely ignored for more than 80 years this logistic curve became a
central theme throughout ecology, once the Americans, Pearl and Reed resurrected the
logistic formula in 1920 (Kingsland, 1991). Raymond Pearl was a statistician and he
also called this relationship the "logistic curve" which is described by the differential
equation,
dN/dt = rN[(K-N)/K] .... the same as dN/dt = rN(1-N/K),
in which:
N = the number of individuals in the population,
t = time,
r = the intrinsic rate of natural increase, and
K = the upper limit of population growth (the "carrying capacity").
The logistic relationship was used particularly extensively by fisheries biologists
who developed population models to manage fish harvests and in some texts and
papers the logistic is also called the Verhulst-Pearl equation to reflect its pedigree.
In addition to these single species uses, the logistic equation has also been used
to describe interactions between two species. The Italian physicist Vito Volterra used
the logistic in 1926 to model interspecific competition. He also modeled prey-predator
interactions, but with a “mass-action” approach, and this work was mirrored at the same
time in the USA by Alfred Lotka, a mathematician and demographer. Thus this twospecies model of predation is now known as the Lotka-Volterra predation model and
provides a starting point for most considerations of predation, and despite the fact that
this is not a logistic model it is simple to add a self-limiting, logistic term to the model.
Although Lotka did not work on competitive interactions to the same extent as Volterra
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Stephen Malcolm
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(Kingsland, 1991), the logistic model of interspecific competition is also widely known as
the Lotka-Volterra competition model.
Many well known researchers have built on this foundation and we will examine a
variety of these contributions throughout our course. As the course develops you will be
given reading lists that will direct you to the classical primary literature as well as to
some very recent developments and applications of basic theory in population ecology.
The course text will be Begon, Townsend and Harper (2006) which is also the text I use
for
the
undergraduate
course,
BIOS
3010:
Ecology
(see
http://www.wiley.com/WileyCDA/WileyTitle/productCd-1405111178.html). In my opinion
this is the best ecology text available and although it is somewhat advanced for an
undergraduate course, it has sufficient depth to provide a great basis for a graduate
course.
Course Texts
Begon, M., C.R. Townsend and J.L. Harper. 2006. Ecology: From individuals to
ecosystems. 4th Edition. Wiley-Blackwell, Oxford, 738 pp. (required)
Alstad, D. 2001. Basic Populus Models of Ecology. Prentice Hall, 144 pp. (optional)
Literature Cited
Begon, M., J.L. Harper & C.R. Townsend. 1996. Ecology: Individuals, Populations and
Communities. 3rd Edition. Blackwell Science, Oxford, 1068 pp.
Begon, M., M. Mortimer, & D.J. Thompson. 1996. Population Ecology: A unified study of
animals and plants. Third Edition. Blackwell Science: Oxford, 247 pp.
Berryman, A.A. 1992. The origins and evolution of predator-prey theory. Ecology 73(5):
1530-1535.
Kingsland, S.E. 1991. Defining ecology as a science. Pages 1-13, In, L.A. Real & J.H.
Brown (editors), Foundations of Ecology: Classic Papers with
Commentaries. The University of Chicago Press, Chicago, 905 pp.
Royama, T. 1992. Analytical Population Dynamics. Chapman & Hall, London, 371 pp.
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Stephen Malcolm
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