Extinction+Vortex

The **extinction vortex** shows how a small populations can enter a cycle that reduces their amount to smaller and smaller quantities. As the graphic shows with inbreeding and genetic drift comes a decrease in diversity, so an organism's fitness decreases. Because there isn't as much variety as before, it's harder for the population to adapt to situations where its gene pool contains a selective advantage for a specific environmental change. A change that the population cannot adapt to causes the population to shrink to smaller and smaller sizes in a repeating pattern. Since the cycles go progressively faster as the population shrinks, the phenomenon is called a vortex.

A minimum viable population is the population size that is just large enough to avoid slipping into an extinction vortex.