Reproductive Isolation

Question 1

What is reproductive isolation?

Answer 1

• a mechanism that prevents 2 or more species from exchanging genes (interbreeding)
• and producing viable, fertile hybrids
• even though they are not geographically separated
• such species that live together are called sympatric species

Question 2

How can mechanisms of reproductive isolation operate?

Answer 2

• pre-zygotically (pre-mating)
• post-zygotically (post-mating)

Question 3

What are the mechanisms of reproductive isolation?

Answer 3

1. breeding at different times of the year
2. species-specific courtship behaviour
3. adaptation of plants to different pollinators
4. infertile offspring

Question 4

How does breeding at different times of the year function as a mechanism of reproductive isolation?

Answer 4

• different animal species often have different mating seasons
• plants flower at different times of the year
• this prevents mating opportunities

Question 5

How does species-specific courtship behaviour function as a mechanism of reproductive isolation?

Answer 5

• courtship behaviour is an animal activity to signal sexual readiness for pair formation, mating and reproduction
• it prevents different species from interbreeding even though their territories overlap

Question 6

How does adaptation by plants to different pollinators function as a mechanism of reproductive isolation?

Answer 6

• plants and their flowers have groups of traits that are an adaptation for particular pollinators
• these traits attract particular animals and prevent different species from getting to the pollen

Question 7

How do infertile offspring function as a mechanism of reproductive isolation?

Answer 7

• even if 2 different species mate and produce hybrid offspring that are vigorous
• the species are still reproductively isolated if the hybrid offspring are sterile
• e.g. a mule