Module 8
1. Module 8
1.37. Page 4
Module 8—Populations, Individuals, and Gene Pools
Lesson Summary
This lesson focused on the following questions:
- How can data be analyzed to study population dynamics?
- How can population data be expressed to give the data meaning?
All population calculations are based on reliable counts of numbers of organisms and their phenotypes and/or genotypes. Simple formulas and methods to consistently and accurately count and analyze population counts are essential.
- Most organisms can be counted by extrapolation from an average of small-density samples.
- Density is determined by
.
- Change in population is calculated by Nfinal – Ninitial.
- Growth rate gives information about how fast the population is changing.
(gr can be positive or negative)
- Per capita growth rate gives information about how much of the change each initial individual is responsible for.
(cgr can be positive or negative)
- Populations can be distributed randomly where there is low competition, organisms can be clumped in the presence of significant competition, and organisms can be distributed uniformly if there is territoriality or if the population is artificial (e.g., agriculture).
Lesson Glossary
Consult the glossary in the textbook for other definitions that you may need to complete your work.
clumped distribution: organisms grouped together; occurs in highly competitive environments
density (Dp): the number of individuals in a given unit of area (land) or volume (air or water)
growth rate (gr): the change in the number of individuals in a unit of time
gr will be positive if the population size is increasing, and negative if it is decreasing.
per capita growth rate (cgr): the rate of change per individual; the amount of change each individual in the initial population is responsible for
cgr can be positive or negative depending on what the initial N is.
random distribution: no pattern exists in organism distribution; occurs in environments with little competition
uniform distribution: organisms are equally spaced apart; occurs in artificial environments (e.g., agricultural crops)