Minimum viable population (MVP) is the smallest number of individuals in a species needed to survive in the wild. This term is used in the fields of biology, ecology, and conservation biology. MVP refers to the smallest number of individuals needed for a population to survive without going extinct due to natural disasters or random events related to population numbers, environment, or genes. A population is a group of organisms that can mate with each other, live in the same area, and have little to no exchange of genes with other groups of the same species. MVP is usually used for wild populations, but it can also apply to zoo populations, which are part of ex situ conservation efforts.

Estimation

There is no single answer to how many individuals are needed for a species to survive, because a species' survival can be influenced by chance events. Therefore, calculations for the smallest number of individuals needed for survival, called a minimum viable population (MVP), depend on the model used to predict population changes. Scientists might use random projections to estimate the starting population size required for a species to have, for example, a 95% or 99% chance of surviving for 1,000 years. Some models use generations instead of years as a unit of time to ensure fairness when comparing different species. These projections, called population viability analyses (PVA), use computer simulations to predict how populations might change in the future. These predictions are based on information about population characteristics and the environment. The probability used in a PVA is determined by repeating the simulation many times, often thousands of times, to account for uncertainty.

Extinction

Small groups of animals or plants are more likely to become extinct than larger groups because they have a harder time recovering from unexpected events. These events can come from four different causes:

Application

The MVP concept does not consider outside help, such as human actions to support a population. This makes it helpful for conservation managers and environmentalists, who may increase a population above the MVP by using captive breeding programs or introducing individuals from other protected areas.

There is some discussion about how accurate PVAs (Population Viability Analyses) are, as they often rely on many assumptions to predict future outcomes. However, the most important idea is not perfect accuracy but the understanding that every species has an MVP, which can be roughly estimated for conservation planning and biodiversity efforts.

Some species have much lower MVPs than average because they live in isolated areas, survive genetic challenges, or reproduce quickly. In contrast, species that are strongly affected by inbreeding (when close relatives mate) tend to have much higher MVPs. These species are often K-strategists, which means they have small populations spread over large areas. For terrestrial vertebrates, an average MVP of 500 to 1,000 is often used when inbreeding effects are not considered. When inbreeding is included, MVP estimates for many species rise to several thousand. A study by Traill et al. found that, across many species, the typical MVP for vertebrates is around 4,169 individuals, with a range of 3,577 to 5,129.