AP Bio Chaoter 24 Flashcards
Gametes fail to fuse
Temporal isolation
How are prezygotic and postzygotic barriers different?
Prezygotic means “before the zygote.” These barriers occur before fertilization. Postzygotic barriers happen after the zygote is formed, after fertilization. These barriers prevent a hybrid from developing into a viable and fertile individual.
Egg and sperm don’t recognize each other
Gametic isolation
Differences in sexual or anatomical structures
Mechanical isolation
Members of population separated by a mountain range
Habitat isolation
Male flowers of some members of a plant species produce pollen before most of the female flowers are open
Temporal isolation
Variation in mating ritual not recognized by female
Behavioral isolation
Male reproductive organs in insect populations vary enormously in size and shape, preventing the effective transfer of sperm to females of different species.
Gametic isolation
Structure of flower restricts access of insects without specific physical and behavioral adaptations
Mechanical isolation
Zygote fails to develop; fails to reach sexual maturity
Hybrid inviability
Hybrid fails to produce functional gametes
Hybrid sterility
Offspring not viable or infertile; offspring of hybrid have reduced viability or fertility
Hybrid breakdown
Two lab species of frogs are mated in the lab and produce viable, but sterile offspring.
Reduced hybrid fertility
Postzygotic barrier
Two species if sea urchin release their gametes at the same time, but cross-specific fertilization does not occur
Mechanical isolation
Pre
Two species of orchid have different length nectar tubes and are pollinated by different species of birds.
Game tic isolation
Pre
Two species of mayflies merge during different weeks in springtime
Temporal isolation
Pre
Two species of salamanders will mate in the lab and produce viable fertile offspring, but offspring of the hybrids are sterile
Hybrid breakdown
Post
Two similar species of birds have different mating rituals
Behavioral isolation
Pre
When two species of mice are bred in the lab, embryos usually abort
Reduced hybrid viability
Post
Peepers breed in woodland ponds, whereas leopard frogs breed in swamps.
Habitat isolation
Pre
The result of a cross between a donkey and a horse is a mule.n mules are usually sterile. What type of reproductive barrier does this represent?
Hybrid fertility which is a barrier where even if hybrids are vigorous they may be sterile.
