Prezygotic Isolation
Geographic isolation: physical barriers (rivers, oceans, mountains) prevent mixing of populations
Ecological isolation: species occur in the same are but inhabit different habitats so they don’t encounter each other
Temporal isolation: species reproduce in different seasons or at different times of the day
Behavioral isolation: species differ in their mating rituals (e.g. differing bird songs, mating colors, dances, pheromones)
Mechanical isolation: body structure prevents mating
Prevention of gamete fusion: gametes cannot fuse with egg cell, penetrate egg cell surrounding layers, pollen tube cannot grow