6.3.6: Extinction
Not started yet — this one needs some love.
Extinctions occur when there are no remaining individuals of a species still alive.
Extinction factors include environmental change, new predators, new diseases, new competitors and catastrophic events.
Extinction example: if a new disease spreads through a small population with little resistance, the number of surviving individuals may fall to zero.
Common exam mistakes
Do not confuse extinct with endangered; endangered species still have living individuals.
Extinction is permanent for that species.
Avoid vague answers like "it could not adapt"; name a specific factor such as disease, competition, environmental change or a new predator.
In food-web extinction questions, follow the indirect effects carefully; one species disappearing can increase competitors or predators of another species.
Correlation with humans arriving is not proof by itself; consider whether other factors or limited data could explain extinction patterns.