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Unformatted text preview: Biology 307: Ecology
http://mason.gmu.edu/~lrockwoo/newecologyfrontpage.html For Power Points, Lab and Lecture syllabi
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Go to iclicker.com to register your iclicker Google ‘iclicker registration” Ecology
Ecology Dedicated to an understanding of the
relationships between organisms and
their Ecology is often the center of public
1. Decline of
-Two kinds of
rockfish. 2. Collapse of Chesapeake Bay oyster, blue
crab and fish populations.
3. 4. Collapse of human
societies due to
other abuses of the
droughts as a result
of destruction of
montane 5. Connected with
this are the “dead
zones” in the Gulf
of Mexico due to
fertilizer run off
Before the oil
spill in 2010! Ecology The dead zone is caused by nutrient enrichment
from the Mississippi River, particularly nitrogen
Watersheds within the Mississippi River Basin
drain much of the United States, from Montana to
Pennsylvania and extending southward along the
Most of the nitrogen input comes from major
farming states in the Mississippi River Valley. Ecology Nitrogen and phosphorous enter the river through
upstream runoff of fertilizers, soil erosion, animal
wastes and sewage.
With increased nitrogen and phosphorus input,
algae growth is no longer limited.
Consequently, algal blooms develop, followed
thereafter by massive die offs.
The dissolved oxygen is depleted, resulting in
deaths of commercial and non-commercial animal
7. Global climate change resulting from
deforestation and greenhouse gas
8. The introduction of exotic species
resulting in the disruption of both natural
and human dominated ecosystems and
the spread of diseases (West Nile Virus).
the Specific Goals of Biology 307
1. Develop an appreciation for the modern
scope of scientific inquiry in ecology.
scope 2. Become familiar with the variety of ways
that organisms interact with both the
physical and the biological environment.
physical Specific Goals of Biology 307
3. Develop an
understanding of the
differences in the
function of different
types of ecosystems
versus Marsh at Mason Neck Specific Goals of Biology 307
4. Become familiar with mathematical
models, especially those dealing with
Deterministic growth using arithmetic
Stochastic growth with low variance
Stochastic growth with high variance
"Most Likely" stochastic growth
uising the geometric mean (1.04) 70 00
0 10 20 30 40 50 Time 60 70 80 90 1 00 Specific Goals of Biology 307
5. Learn techniques of data analysis as well
as methods for presenting scientific
information in appropriate figures and
0.3 Probability 0.25
0 1 2 3 4 5 6 7 Number of female individuals in the next generation Figure 1.7. Stochastic growth in a population of three females based on the parameters of Table 1.7 Specific Goals of Biology 307
6. Become proficient in writing a scientific
paper. This course fulfills the faculty
senate mandated “writing intensive”
requirement in the biology major.
requirement 7. Learn techniques for data gathering in
the Specific Goals of Biology 307
8. Develop an
applied ecology and
issues facing the
world May Apples in Spring Specific Goals of Biology 307
9. Develop an
appreciation for the
local Grassland at
Banshee Reeks in
Loudoun What is Ecology?
1. The study of the relationships between
organisms and their environment.
organisms 2. The study of the interactions (both with
the physical environment and other
organisms) that determine the
distribution and abundance of a species.
distribution Ernst Haeckel: German Zoologist in 1870
“By Ecology we mean the body of knowledge
concerning the economy of nature—the
investigation of the total relations of the
animal both to its organic and to its inorganic
environment; above all, its friendly and
inimical relation with those animals and plants
with which it comes directly or indirectly into
contact in a word, ecology is the study of all
the complex interrelationships referred to by
Darwin as the conditions of the struggle for
existence.” What is the Environment?
1. 2. The sum total of all physical and
biological factors influencing a particular
The external physical and biological
factors that influence growth,
survivorship, development and
reproduction of organisms. What is the Environment?
What Physical environment = Abiotic factors
Abiotic Climate, soil, nutrients, etc. What is the Environment?
What Biological environment = Biotic factors
Biotic Competitors, predators, parasites, diseases,
etc. What is the Environment?
What Habitat = a place where organisms live
and the environmental factors found there
and General Principles of Ecology
1. Ecological systems function according to
the laws of thermodynamics
(Ecosystems). 2. The physical environment exerts a
controlling influence on the productivity
of ecological systems (Ecosystems).
of General Principles of Ecology
3. The structure and dynamics of ecological
communities are regulated by population
processes 4. Over generations, organisms respond to
change in the environment through
evolution within populations (Evolution).
evolution Sample Quiz: Question One
Sample Which of the following is a general
principle of ecology?
D. Populations tend to grow linearly.
Community ecology concerns populations of
Ecological systems function according to the
laws of thermodynamics.
The first definition of ecology was articulated
by Laws of Thermodynamics
First Law: Energy can neither be created
nor destroyed but may change form.
nor Important transformations include:
1. 2. Electromagnetic energy to chemical energy
(photosynthesis) and to heat energy
Chemical energy to kinetic energy (energy
of motion) and to heat energy.
of Laws of Thermodynamics
Second Law: In each energetic
transformation, potential energy is
reduced, as some energy is lost to the
system as heat; or
Entropy increases in a closed system. Laws of Thermodynamics
Laws The second law
says that energetic
always less than
100% Laws of Thermodynamics
Laws Ecosystems do not degrade over time, in
spite of the fact that they use energy,
because they are not closed systems.
not Without a constant input of energy,
ecosystems would degrade and life would
perish. Laws of Thermodynamics
Laws Applying the Second Law of
Thermodynamics to energy flow in
ecosystems tells us that the transfer of
energy from one trophic (energy) level
(plants to herbivores, for example) to
another always involves a dissipation of
energy. Laws of Thermodynamics
Laws The second law places a limit on the
number of trophic levels in an ecosystem.
number Levels of Organization in Ecology
Levels Units of study:
1. Individual organisms (adaptations to their
1. Individual environment)
4. Ecosystems Levels of Organization in Ecology
1. Population = A group of interbreeding
individuals of the same species found in
the same place at the same time
(sympatric). Levels of Organization in Ecology
2. Species = A group of actually or
potentially interbreeding individuals that
are reproductively isolated from all other
kinds of organisms (more later).
kinds Levels of Organization in Ecology
3. Community = the assemblage of plants,
animals, microbes or other organisms
living in the same habitat, and that
interact and affect one another.
interact Levels of Organization in Ecology
4. Ecosystem = An environmental unit
consisting of biotic and abiotic
components related through exchanges
of energy and nutrients.
of The emphasis in ecosystem ecology is on
the movement of energy and nutrients
within Levels of Organization in Ecology
5. Metapopulation = assemblages of
populations or individualsof a particular
species within a large spatial scale, with
the long-term survival of the species or
population depending on a shifting
balance between local population
extinctions and colonizations in the
patchwork of a fragmented landscape.
In a metapopulation,
local populations in
all habitat patches
are assumed to
but all can receive
other populations. Patches Connected by
Immigration and Emigration Plant Hopper Movie Levels of Organization in Ecology
theory is of particular
in which species are
thought to undergo
extinctions. Levels of Organization in Ecology
Levels Trophic (Energy) Levels
1. Producers (autotrophs) Can be
organisms Local Primary Production Based on Photosynthesis Levels of Organization in Ecology
A. Consumers: Organisms
Organisms that consume other
predators, Levels of Organization in Ecology
(many fungi, bacteria,
flies Levels of Organization in Ecology
Levels A. Consumers are
defined more directly
by their functional
that feed directly on
wildebeest). Levels of Organization in Ecology
B. Primary Carnivores:
animals that feed on
crocodiles). Levels of Organization in Ecology
C. Secondary Carnivores: animals that
feed on primary carnivores (e.g. birds
such as chickadees that feed on insects).
such D. Tertiary Carnivores: animals that feed
on secondary carnivores (e.g. hawks).
on Trophic Pyramids
Trophic Food chains or food
Based on trophic
Limited number of
trophic links due to
Thermodynamics. Trophic Pyramids
Trophic Declining energy in higher trophic levels,
produces the “Trophic Pyramid”.
produces Rule of Thumb: approximately 10% of
energy transferred to next trophic level.
energy Trophic Pyramids
Energy lost from one trophic level to the next
is due to:
1. Not all organisms are consumed.
consumed 2. Not all parts of organisms are consumed.
consumed Trophic Pyramids
3. Not all energy consumed is assimilated.
consumed assimilated 4. Most energy assimilated is lost to
respiration (2nd Law of Thermodynamics).
respiration 5. Energy from points 1-3 goes to the
decomposer food chain.
decomposer Trophic Pyramids
Food webs (and ecosystems) work in
unknown and unexpected ways:
unknown Ecosystems are unpredictable. “The law of unintended consequences.” Robert Merton (1970s): Complex systems create
unanticipated or undesirable outcomes.
unanticipated Lake Victoria and the Nile Perch Lake Victoria is the world's second largest
freshwater lake by surface area and is the
largest lake in Africa. It is surrounded by
Uganda, Tanzania and Kenya It has dried
out three times; it last dried out 17,300
years ago, and it refilled beginning about
14,700 years ago. Lake Victoria and the Nile Perch Before 1954, Lake Victoria's ecology was
characterized by enormous biodiversity. It
was inhabited by over 500 species of fish,
90% of which were cichlids belonging to
the genus Haplochromis. Lake Victoria and the Nile Perch In the late 1950s the Nile Perch Lates
niloticus was introduced as a “sport fish”
into Lake Victoria because the British
colonial fishermen had driven the most
popular local fish to near extinction.
popular Lake Victoria and the Nile Perch Lake Victoria and the Nile Perch Results of this introduction: 1. Extinction or near extinction of many
native endemic fish species. About half
of the 400 species of Tilapia are now
extinct. Lake Victoria and the Nile Perch
2. Loss of phytoplankton eating fish
species. 3. Great increase in algae (“blooms”) Followed by: Lake Victoria and the Nile Perch
4. Die off of algae; decomposition of algae;
anoxia for much of the lake.
anoxia 5. Further die off of fish from lack of
oxygen. Lake Victoria and the Nile Perch
6. Proliferation of snails due to loss of snail
eating Lake Victoria and the Nile Perch
7. Spread of snail borne diseases among
the people (Schistosomyosis).
the Lake Victoria and the Nile Perch
8. Necessity of wood fires to smoke the Nile
Perch. Native fish could be air dried.
Perch. 9. Cutting of forest around lake to provide
wood for fire. Lake Victoria and the Nile Perch
10. 11. 12. Erosion of land around lake due to tree
Pollution and sedimentation of lake.
Further loss of fish species.
Further Lake Victoria and the Nile Perch Nevertheless, it has now become a major
export from several countries surrounding
Lake But the Nile Perch itself showing evidence
of being over fished and its populations
are Export of Nile Perch
Kenya Uganda Tanzania Landings 104,000 120,000 159,000 Exports in fillets 16,493 18,000 13,500 Export Value
(million USD) 49.0 53.5 37.9 Food webs work in unknown and
unexpected Nature is constantly changing and
ecosystem change is not necessarily
“unnatural.” What is unnatural and problematic is the
accelerated rate of change caused by
human interventions and disturbances.
human Sample Quiz: Question Two
The Nile Perch is:
A. a native fish in Lake Victoria.
B. can be preserved by air drying.
C. was introduced as a sport fish.
D. was introduced in order to control
schistosomyosis. Questions? ...
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This note was uploaded on 01/23/2012 for the course BIOL/EVPP 307 taught by Professor Crerar during the Summer '11 term at George Mason.
- Summer '11