What is the minimum viable population (MVP) and which factors influence it?

• A. The smallest population size needed to persist for a given time under specified extinction risk; factors include environment, demographic variance, genetic factors, and catastrophes.
• B. The maximum population size before inbreeding occurs.
• C. The average population size across time.
• D. The minimum number of migrations per generation.

Answer: (D)

The main idea is that the minimum viable population is the smallest population size that has a reasonable chance of persisting for a defined period given a certain level of extinction risk. This concept factors in the realities that small populations face: environmental variability (changes in habitat quality, resources, or extreme events), demographic stochasticity (random differences in births and deaths that can have big effects when numbers are low), genetic concerns (loss of genetic diversity and inbreeding depression reducing fitness), and the risk of catastrophes (fires, floods, disease outbreaks) that can drastically reduce numbers in a short time. Because these risks vary by species, life history, and the chosen time frame and tolerance for extinction risk, the MVP isn’t a fixed number; it changes with context and the criteria set for persistence. The other ideas describe different notions—how large a population could get before inbreeding becomes a problem, the average size over time, or how many migrations occur per generation—which don’t capture the persistence-under-risk focus of MVP.