1. Population Ecology
Chapter 14

2. Population Ecology Population – group of one species Based on density
Interact and interbreed with each other
Based on density
Number of individ. In a given area
Can vary depending on dispersion
Uniform – evenly spaced
Random – position independent of others
Clumped – end to aggregate in patches

3. Population Dispersion

4. Population Growth Changes in populations
Based on how many organisms are added and how many are taken away
Growth rate- change in population size
can be positive, negative or zero

5. Population Growth Under ideal conditions population will grow
More organisms are born than die
Exponential growth – the larger a population is, the faster it grows
Will not last forever- will slow down
Zero growth – population stays the same

6. Limits to Population Growth
Eventually nutrients run out
Carry Capacity – average number of individuals an area can support
Based on density dependent factors
Limit large, dense populations
Energy, shelter, predators, soil nutrients, water, competition, etc.
Density – Independent Factors
Kill off organisms no matter how large the population is
Examples: weather, natural disasters, human activities

7. Density Dependent Limiting Factors
Competition –
When individuals compete for resources (ie food, energy, etc)
More individuals in an area limits the amount of certain resources available
Helps determine the carrying capacity of an environment

8. Density Dependent Limiting Factors
Predation
When one species eats another.
Tend to live in balance with each other
As one population goes up, so does the other and vise versa
Increase in prey, leads to an increase in predator
Decrease in predator, leads to an increase in prey

9. Density Dependent Limiting Factors
Parasitism
An organism that takes nourishment from its host
Live at the expense of the host
Parasite populations grow only if host population is dense
Easier to spread

10. Density Dependent Limiting Factors
Crowding and Stress
Most animals need a certain amount of space.
Higher the population, the less space available.
Also weaken immune system

11. Demography Study of population growth and other stats
Life Tables – age specific summary of birth and death rates
Determines survivorship curve
Types
Type I – many live to adulthood, then rapid die off
Type II – equal chance of dying at any age
Type III – lots of young, but not many make it to reproductive age