In population ecology, what best defines physiological population density?

• A. The total number of individuals in a population at a given time, regardless of area
• B. The maximum number of individuals an environment can support indefinitely (carrying capacity)
• C. The number of individuals per unit area across the entire geographic range of the species, including unsuitable habitat
• D. The number of individuals per unit area of habitat that is suitable or available for the species (excluding unusable space)

Answer: (D)

Verified step by step guidance

1. Understand that population density generally refers to how many individuals of a species live in a given area.
2. Recognize that there are different ways to measure population density depending on what area is considered: total geographic range or only suitable habitat.
3. Physiological population density specifically measures the number of individuals per unit area of habitat that is actually suitable or available for the species, excluding areas where the species cannot survive or reproduce.
4. This contrasts with crude population density, which counts individuals per unit area across the entire geographic range, including unsuitable habitats.
5. Therefore, physiological population density provides a more accurate reflection of how crowded a population is within the environment it can realistically occupy.