1. Introduction to Ecology

2. Ecology
A rigorous experimental science that requires a breadth of biological knowledge.
Ecologists observe nature, generate hypotheses, manipulate environmental variables, and observe outcomes.

3. Biological Hierarchy Global ecology- the biosphere
Landscape ecology-energy exchanges
Ecosystem ecology-energy flow and chemical cycling
Community ecology-interactions between species
Population ecology-changes in population size
Organismal ecology- organism’s structure, physiology and behavior

4. Earth’s Climate Influences
The most significant influence on the distribution of organisms on Earth is climate
Climate is composed of 4 abiotic factors
Temperature
Precipitation
Sunlight
Wind

5. Macroclimate
Seasons are caused by variation in sunlight intensity

6. Latitudinal Variation in Sunlight

7. Global Air Circulation and Precipitation
Intense solar radiation near the equation
Warm moist air rises flows toward the poles releasing water
Dry air descends at 30o north and south, absorbing moisture & rises again at 60o releasing precipitation
Movement of air due to Earth’s rotation aids in creating the prevailing westerlies and the trade winds

8. Bodies of Water
Ocean currents influence climates by heating or cooling overlying air masses
Water’s high specific heat moderates climates of nearby land

10. Mountains
Influence air flow and the amount of sunlight an area receives.

11. Terrestrial Biomes
Biomes are characterized by vegetation type, latitude; mean temperature and precipitation .
Named for a major physical or climatic feature and for predominant vegetation.

12. Major Land Biomes

13. Aquatic Biomes
Determined by depth, flow, temperature, and chemistry of the overlying water.
Photic zone- light for photosynthesis
Aphotic zone- little to no light

14. What is Population Density?
The number of individuals of the same species per unit area or volume
i.e. the number of meerkats per square kilometer.

15. Species Distribution
Distribution is a result of ecological and evolutionary interactions
Dispersal – the movement of individuals from their area of origin
Biotic factors – such as predation, herbivory, parasites, food resources.

16. Patterns of Dispersion
Clumped
Most common pattern
Spend much of time in particular microenvironment
Associated with mating behavior

17. Mark-recapture Method
One method used by ecologist to calculate population densities
Traps are set, captured animals are marked with tags then released
After a period of time a second capture is done, researchers estimate numbers based on the yields of marked and unmarked individuals.
Assumes equal probability of being trapped –
Animals may be wary of traps if they were trapped once.

19. Counting
It is possible to count all the individuals in a population to determine the size.
Not practical
Count the number of individuals (oak trees) in randomly selected plots
Calculate the average density in the samples
Extrapolate to estimate the population size
Estimate density from some index of population size.
Number of nests, tracks, etc.

20. Uniform Evenly spaced pattern of dispersion
May result from direct interactions between individuals in population

21. Random Pattern of dispersion with unpredictable spacing
Occurs in the absence of strong attractions or repulsions

23. Exponential & Logistc Growth Curves

24. Density dependent limiting factors
Death rate rises, or birth rate falls as population density rises.
Example of negative feedback regulation
Includes
Competition for resources
Territory space
Health
Predation
Toxic wastes
Intrinsic factors

26. Density Independent
Birth rate or death rate that does not change with population density.
Physical factors kill a similar proportions of a local population regardless of its density.
Natural disasters
Human activity

27. Survivorship Curves
Type I – high death rate in post reproductive years
Type II – constant mortality throughout lifespan
Type III- very high early mortality, but the few survivors live long (stay reproductive)

28. K- selected species vs. r-selected species
Body Size
Life Span
# of Offspring
Relative time of reproduction
Survivorship Curve
Growth Curve
K-selected species
Larger
Low mortality
Few offspring
Late reproduction
Type I
s- shaped
Logistic
r-selected species
Smaller
High mortality
Many offspring
Early reproduction
Type III
Boom and bust
Exponential growth

29. Factors that affect Population Size
Abiotic Factors
Sunlight & temperature
Preciptation/ water
Soil/ nutrients
Biotic Factors
Prey (food)
Competitors
Predators, parasites, disease
Intrinsic factors
Adaptations