• A population consists of the individuals of species within a given area.
• The members of a population are distributed over space, and they differ in
age and size.
• The age distribution of individuals are spread over the environment describe
its population structure.
• The number of individuals of a population per unit of area is its population
• The structure of a population changes continually because demographic
events are common occurrences.
Population densities can be estimated from samples
• Estimating population densities is easiest for sedentary organisms.
• Counting mobile organisms is much more difficult because individuals move
into and out of census area. (write equation here).
Birth and death rates can be estimated from population density data
• (Write equation here).
• Individuals born at the same time cohort.
• The number of a population still alive at a given period of time in the future
How Do Ecological Conditions Affect Life Histories?
• An organism’s life history describes how it allocates its time and energy
among the various activities that occupy its life.
• Ecological interactions influence the evolution of life histories.
54.3 What factors Influence Population Densities?
All populations have the potential for exponential growth
• All populations have the potential for explosive growth. As the number of
individuals in a population increase, the number of new individuals added per