What is the key concept for this section? Define population. Define population size and explain how it is estimated, Why do most populations live in clumps? List four variables that govern changes in...

What is the key concept for this section? Define population. Define population size and explain how it is estimated, Why do most populations live in clumps? List four variables that govern changes in population size. Write an equation showing how these variables interact. Define range of tolerance. Define limiting factor and give three examples. Define population density and explain how some limiting factors can become more important as a population’s density increases.