Barrier Type
Different corals' released gametes won't touch.
Timing
Freshwater fish and seawater fish wouldn't reproduce.
Geography
Fireflies with different ways of flying and shining.
Behavior
A group of individuals that can successfully reproduce fertile offspring in nature.
Species
Beetles with different reproductive organs.
Anatomy
What stops the flow of genes between populations?
Reproductive Barrier
Sea urchins with different proteins are impossible to merge.
Genetic Incompatibility
What happens when 2 or more populations no longer successfully reproduce?
Speciation