Fecundity comes from the Latin word fecundus, meaning fruitful, rich, or abundant. It is the rate at which individual organisms in the population produce offspring. Although the term can apply to plants, it is typically restricted to animals.

There are two aspects of reproduction: 1) fertility, referring to the physiological ability to breed, and 2) fecundity, referring to the ecological ability to produce offspring. Thus, higher fecundity is dependent on advantageous conditions in the environment that favor reproduction (e.g., abundant food, space, water and mates; limited predation, parasitism, and competition). The intrinsic rate of increase (denoted as "r") equals the birth rate minus the death rate. It is a population characteristic that takes into account that not all individuals have equal birth rates and death rates. It therefore refers to the reproductive capacity in the population made up of individual organisms. Fecundity, on the other hand, is an individual...