Population Growth and Fitness

Abstract

The principal variable in any population ecological model is the population size(s) of the organism(s) under investigation within the habitat or geographical area of interest. The size of a specific population may be measured in numerous units which are more or less equivalent. An obvious unit to consider is the individual organism, and the population size is then expressed as the number of individuals in the population or as the density of individuals within the area of investigation. This approach is well suited for the description of populations of most animals, whereas individual counts may cause problems in some species of plants. Alternatively, we may measure the population size in units of biomass, i.e., the weight or energy content.