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INTRODUCTION TO ECOLOGY
I. Ecology
A. Ecology = the systematic study of how organisms interact with one
another and with their environment
B. The word ecology comes from the Greek oikos, meaning
house or home
C. Environment consists of both a living component, the biotic
environment (other organisms) and a non-living component, the abiotic
environment, e.g. physical factors such as soil, rainfall, sunlight,
temperatures
D. Ecology is an extremely complex and very diverse subject and it includes
a variety of disciplines in addition to biology, e.g. geology, chemistry,
physics, meteorology, and mathematics
II. Four levels of ecological organization:
A. Population - group of individuals of the same species
occupying a common geographical area
B. Community - two or more populations of different species
occupying the same geographical area
1. Populations and communities include only biotic factors
C. Ecosystem - a community plus its abiotic factors, e.g.
soil, rain, temperatures, etc.
D. Biosphere - the portion of the earth that contains
living species. It includes the atmosphere, oceans, soils and the physical and
biological cycles that affect them
III. Recent developments
A. The radicalism of the 1960's, coupled with concerns about a deteriorating
environment and the publication of two influential books brought the science of
ecology into the popular culture:
1. Silent
Spring by Rachael Carson - awoke the general public and made them
aware of the dangers of pollution and environmental degradation
a. This book deserves most of the credit for starting the environmental
movement in the United States. Supreme Court Justice William O. Douglas said
"This book is the most important chronicle of this century for the
human race"
b. Carson envisioned a "silent spring" sometime in the near
future because all the song birds might eventually become extinct due to the
use of pesticides, e.g. the American Bald Eagle nearly went extinct due to
the pesticide DDT
2. Population Bomb by Paul Ehrlich said much the same as Essay
on the Principle of Population written by Malthus 200 hundred years
earlier
a. Both argued that the earth could support only so many people and
that population growth should be slowed
b. Ehrlich founded the organization Zero
Population Growth which works to limit population growth
IV. Angel Island
A. Angel Island is a game reserve in San Francisco Bay near Sausalito
B. In the early 1900's well-meaning nature lovers introduced deer to the
island
C. With no natural predators to control them the population quickly rose to
a level much higher than the island could support
D. Well meaning people brought food to the island to feed the deer, causing
the population to further increase
E. Eventually the population grew to over 300, much too large for the
island to support
F. As the deer began to starve they ate most of the native vegetation.
Without vegetation the soil started washing away and the island environment
rapidly deteriorated
G. It was proposed that hunters kill some of the deer and/or that coyotes,
the deer’s natural predators, be introduced to the island. However many
people objected because they viewed both alternatives as cruel
H. Eventually two thirds of the population was rounded up and moved to the
mainland, at a cost of $3,000 per deer
I. However, tracking studies revealed that the majority of the deer moved
to the mainland were killed by cars, dogs, coyotes and hunters within 60 days
J. The story of Angel Island illustrates a basic ecological principle: a
population's growth is dependent on the resources of its environment. Human
intervention could only postpone, not prevent the inevitable
K. Many environmental problems are simply the result of a lack of
understanding of basic ecological principles by politicians, lawyers,
economists, the general public and even well intentioned
"environmentalists". Human ignorance of simple ecological principles
often leads to disastrous results
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