1 Population ecology is the science that measures changes in population size and composition and identifies the causes of these fluctuations．Population ecology is not concerned solely with the human population．In ecological terms．a population consists of the individuals of one species that simultaneously occupy the same general area．rely on the same resources, and are affected by similar environmental factors．The characteristics of a population are shaped by its size and by the interactions among individuals and between individuals and their environment． 2 Population size is a balance between factors that increase numbers and factors that decrease numbers．Some factors that increase populations are favorable light and temperature，adequate food supply, suitable habitat, ability to compete for resources, and ability to adapt to environmental change．Factors that decrease populations are insufficient or excessive A. resources B. trees C. insects D. logs
