Mortality - Population Parameters and Regulation
The death of an individual in a population is known as mortality. Mortality rate like natality rate can be expressed as the number of individuals dying per unit time. Specific mortality rate is expressed in terms of units of total population. Again like natality, mortality can also be potential or ecological. Potential mortality also called minimum mortality represents the death of an individual living under ideal or non limiting environmental and physiological conditions.
It is constant for a population. Ecological mortality also called realised mortality is the loss of individuals in a population under a given environmental and physiological conditions. It varies with populations and environmental conditions. This means that under the best environmental conditions individuals will die of old age determined by their physiological longevity. In most populations in nature the average longevity is far less than the physiological inherent longevity and so the realised mortality rate is much greater than the potential rate.