Lecture test 1: Postzygotic barriers

Question 1

Types of postzygotic barriers

Answer 1

1. Reduced hybrid viability
2. Reduced hybrid fertility
3. Hybrid breakdown

Question 2

What is a post zygotic barrier

Answer 2

Prevents the hybrid zygote from developing into a viable, fertile adult. Sperm of one species is able to fertilize ovum or another species but hybrid will not develop into a fertile viable organism

Question 3

Reduced hybrid viability

Answer 3

The offspring are frail and probably will not survive

Question 4

Reduced hybrid viability example

Answer 4

Two salamanders of the same genus but different species mate but their offspring fail to thrive, not live very long, or die at an embryonic stage

Question 5

Reduced hybrid fertility

Answer 5

Hybrids may be strong but they are sterile

Question 6

Reduced hybrid fertility example

Answer 6

The horse and donkey reproduce to create a mule. The mule cannot reproduce

Question 7

Hybrid breakdown

Answer 7

Hybrids are viable, fertile, but with each generation they get weaker and weaker. First generation are strong, offspring will be weaker

Question 8

Hybrid breakdown example

Answer 8

Strains of cultivated rice. Inherit rare recessive traits that make them smaller and smaller and eventually sterile