Lecture 13 Flashcards
Ecology
The scientific study of the distribution and abundance of life and the interactions between organisms and their environment
Organism Environment
-Includes physical properties, which can be described as the sum of local abiotic factors, and biotic factors, which are other organisms that share its habitat
Population Ecologists
How and why the number of individuals in a population changes over time
-Population = The group of individuals of the same species that lives in the same area at the same time
What factors determine how many individuals there are in a population and how fast the population can grow?
- Indirectly: Age structure, Sex Ratio
- Directly: Births, Deaths, Immigration, Emigration
- Population Growth Models: Exponential and Logistic
Usefulness of population growth models
- Allows us to make management decisions
- Aids in endangered species recovery programs
- tells us something about the natural world
Exponential Growth
- Rate of expansion under ideal conditions
- No limiting resources, no limit to growth by other species, environment is constant
- Whole population multiplies by a constant factor during constant time intervals
- r does not change over time
N
Number of individuals present in a population
B
Absolute number of births in the population (over a given time interval)
D
Absolute number of deaths in a population (over a given time interval)
I
Absolute number of individuals immigrating in to a population (over a given time interval)
E
Absolute number of individuals emigrating out of a population (over a given time interval)
t
Time
Delta
Represents finite change in numbers in a given time period
N sub 0
Number of individuals present at t=0
b
Number of individuals born per individual in the population per year (Per capita birth rate)
