Lecture 1- Monday, September 9, 2013
◊ Test of Hypothesis What is Ecology?
◊ The study of relationships between organisms & the environment.
◊ The scientific study of the factors that determine the distribution and
abundance of organisms.
◊ Multidisciplinary in nature, forming a continuum among other areas
including genetics, physiology, evolution, behaviour, chemistry,
geology, physics and meteorology.
Factors influencing population structure & process:
The study of interactions among organisms:
To understand the controls on nutrient cycling and energy flow through
ecosystem. Considers abiotic and biotic factors.
The study of the exchanges of materials, energy or organisms among
◊ All other organisms found in the environment Readings
Molles & Cahill (2nd Edition) Chapter 1: 1-10
Ecology: the branch of science dedicated to the study of relationships between organisms and
the environment. It is about understanding the mechanisms that are causing the patterns that
occur in the natural world.
Largest spatial scale and highest level of ecological organization.
Subject to large-scale and long-tern regional processes.
Identify and study isolated communities and ecosystems. Study of the exchanges
of materials, energy and organisms.
The biological, chemical, physical processes and interactions that occur within a
Individuals interacting with others from a number of species.
Centered on the factors influencing population structure and dynamics, where a
population is a group of individuals inhabiting a defined area.
The domain of behavioural and physiological ecologists.
Paul & Elder 2003 Lecture 2- Monday, September 16,2013
Assignment is due October 21
Start September 30
(Lecture 3 & 4 switch)
I. Energy & Nutrients
d. Estimating abundance
I. Energy & Nutrients
Two energy sources:
1. Autotrophs - self feeders (sun main energy source; plants)
2. Heterotrophs - other feeders
Types of Plants
◊ C3 (Ex. tomatoes); product has three carbons in it
○ Stoma releases water when it's open
○ If it's hot and the plant is stressed for water the stoma will not open, resulting in
no sugar production
○ High transpiration
◊ C4 (Ex. sugar cane)
○ Able to make sugar without stressing water
○ Low transpiration
○ Able to handle heat
○ More C4 plants with increased temperatures Transpiration: process of moving water through plant
Nutrient Requirements of Different Organisms
93-95 of biomass of most organisms comprised of:
Plants are relatively rich in carbon and poor in nitrogen. Living leaves contain twice the
nitrogen as dead leaves.
Soil moisture and temperature are important features in the actions of detritivore.
○ Eat plants
○ Plants high in carbon and low in nitrogen, so eat a lot of plants to get energy
○ Plants have defenses against being eaten (thorns, toxins, etc.)
○ Different parts of the plant have different C:N ratios
◊ Isotope analysis
◊ Animals, fungi, and bacteria are rich in nitrogen.
Population: a group of individuals of a single species inhabiting a specific area.
Biological: reproductive isolation; need to be able to have viable offspring
Genetic: criteria continually changing
Morphological: commonly used by taxonomists Morphological: commonly used by taxonomists
3 Main Population Characteristics
1. Distribution - range
○ The breaking up of Pangea, species in different areas that could not have moved
○ Temperature changes; global warming and glaciers
2. Density - abundance
3. Dynamics - factors that influence size & structure
Ecological Niche - a combination of variables that allow individuals to survive and reproduce
and for populations to persist.
Geographic Range - a spatial reflection of a species niche.
Commonness & Rarity
1. Geographic range (restrictive vs. extensive)
2. Habitat tolerance (narrow vs. broad)
3. Local population size (large vs. small) Readings
Energy & Nutrients
Nutrients are the raw materials an organism must acquire from the environment to build the
organic and inorganic compounds critical to life.
Three Major Concepts
1. Organisms use one of three main sources of energy: solar radiation, organic molecules,
or inorganic molecules.
2. The rates at which organisms can take in energy and nutrients are limited.
3. Natural selection will influence hoe organisms feed, and this process can be understood
through the use of optimal foraging theory.
The chemical composition of nearly all organisms is quite similar with just five elements:
carbon, oxygen, hydrogen, nitrogen, and phosphorous.
Three Major Categories of Consumers
Ø Organisms that feed on non-living organic matter
Ø Primarily small-bodied insects, fungi, and bacteria
Ø Control the movement of energy and nutrients in most ecosystems
Ø Three main problems related to feeding: the search, the handling, and the quality of food
Ø Preferred food sources: leaves, fruits, dead animals, and other sources of relatively high
concentration of nitrogen
Ø Organisms that eat living plants
Ø Plants are a low quality and potentially toxic food source
Ø Organisms that mainly eat living animals
Ø Consume prey that are nutritionally rich, and with a chemical composition similar to
Ø Size-selective prey: choose prey similar in size (small too hard to find and catch and big
can hurt the animal)
Physical and ecological processes interact with selection and drift to produce new species.
What is a Species?
Biological Species Concept: groups of actually or potentially interbreeding populations,
which are reproductively isolated from other such groups (Ernst Mayr). Poor definition for
many of the organisms that exist on the planet. Many bacteria, fungi and plants rarely
interbreed. Instead reproduction is often asexual.
Ecocline (Cline): a gradual change in genotype and/or phenotype of a species over a large
Ecotypes: a genetically identifiable subclass of a species that has evolved in response to local
environmental conditions. Lecture 3- Monday, September 23, 2013
Communities & Ecosystems: Landscape & Geographic Ecology
I. Landscape Ecology
b. Landscape processes
c. Organisms influencing structure
II. Geographic Ecology
a. Species richness
III. Global Ecology
b. Human influence over atmospheric composition
c. Changes in land cover
I. Landscape Ecology
What is a Landscape?
A heterogeneous area consisting of distinctive patches or ecosystems (also called landscape
elements in ecology jargon) which together form a patch work or mosaic of ecosystems. The
patches are quite distinctive.
Landscapes that contain a diversity of ecosystems are more biologically diverse
because there is habitat diversity
What is landscape Ecology?
The study of the relationship between spatial pattern (landscape structure) and ecological
processes and structure over a range of scales.
What defines landscape structure?
• Number & position of ecosystems within a landscape
Has been altered by humans for thousands of years for agriculture and settlements
Landscape Ecology: Landscape Processes
Processes include exchange of nutrients, materials or organisms among the ecosystems in a
How does structure affect processes?
Urban landscapes with lots of infrastructure (roads, buildings, bridges, power lines, etc)
typically include some natural features like forest fragments and streams. There are not
many natural fragments downtown but there are more further upstream along the Don
Experiment with a fragmented prairie habitat in Kansas measured movement of three small
mammals within and between fragments of different sizes.
1. In fragmented landscape animals will move further (to find mates, food, cover).
2. Animals will stay longer in a particular spot in a landscape with more fragments,
perhaps because moving between patches is dangerous. Consequently, the proportion of
animals moving decreases with increasing habitat fragmentation. The role of corridors in landscape ecology
Corridors are sections of habitat that connect patches. Connections are supposed to increase
successful dispersal of (some) organisms between patches and prevent extirpation (i.e., local
Landscape Ecology: Organisms change landscape structure
African elephants knock down trees and change woodland to grassland
Kangaroo rats dig burrow systems that modify soil structure and plant distributions
Flooding caused by beaver dams changes boreal forest landscape to a more complex
mosaic of upland forest, meadows and ponds
II. Geographic Ecology
Distribution patterns of plant and animal life among fragments.
Islands can be seen as natural fragments within a ‘matrix’ of water. The water is a barrier to
dispersal of terrestrial plants and animals.
Studies of islands show that biodiversity increases with island area because of more ‘niches’
or patches (like landscape mosaic).
We can generalize about the effect of fragment size on biodiversity (there is a positive
statistical correlation) from the study of natural fragments like islands and mountain tops.
One additional factor affecting biodiversity is isolation: increasing distance between
fragments should make it harder for plants and animals to reach adjacent fragments; species
III. Global Ecology
Composition of clean, dry air at the earths surface is approximately:
• 78.1 nitrogen
• 20.9 oxygen
• 0.93 Argon
• 0.003 carbon dioxide
• 0.00005 ozone • 0.00005 ozone
Incoming and outgoing (reflected) solar radiation (primarily in the infra-red region) is
converted to heat near the earth’s surface by atmospheric gases called greenhouse gases
◊ Water vapour
◊ Carbon dioxide
◊ Nitrous oxide
30 % of incoming solar energy reflected back into space by clouds, particulate matter,
70 % absorbed by atmosphere or surface
The earth would be -18 Celsius if not for the atmosphere
Mean global temps is 15 Celsius and getting warmer
About ½ of the carbon pumped into the atmosphere from fossil fuel burning remains in
the atmosphere and the remainder is stored in the biosphere Missed Lecture Monday, September 7, 2013
I. Evolution by natural selection
a. Evolution by natural selection - what's required for it to happen?
b. Empirical examples
c. Conclusions - Natural Selection
II. Other mechanisms of evolution
a. Population size
b. Genetic drift
III. Population dynamics
a. Patterns of survival
b. Age distribution
b. should have said hypothesis
2. They washed with sea water
3. Lack of food driven by weather
4. Medium ground finch
5. Evolution by natural selection
6. specie's competition, why some populations are so variable and how species were
Islands are geographically isolated.
Darwin did not keep track of which finches came from which islands. He killed them and
took them home.
Hypothesis: the 13 species of finch derived from one specie from South America.
Need model to account for diversity of life and for their inter-relatedness. Model is NOT for
the origin of life. Over a million known species.
1. Special creation: cannot be tested (based on faith, not observation) and therefore outside
the realm of science.
2. Spontaneous generation: an early hypothesis used to explain how species arose.
Methodological materialism: must be observable and detectable. Science is inherently limited
by ability to make reliable observations. Dependence on evidence is not a problem of science