Question

Describe two types of postzygotic reproductive isolating barriers and the process by which such barriers may arise.

Answer 1

post zygotic reproductive isolating barriers may be termed as those barriers which comes into play by which the fertile offspring fail to grow, ie prevention of formation of fertile offspring by inductive somekind of barrier mechanism

there are many barrier mechanism., two of them are mentioned below -

1) Hybrid sterility/hybrid infertility - in this case, hybrid individual can produce but cannot further reproduce and becomes sterile. example - mule and hinney

2) hybrid breakdown - the f1 generation is fertile but the f2 generation is infertile.

example - lion(male) and tiger(female) produces liger and lion(female) and tiger(male) produces tigon.

when liger and tigon are fused they produce f2 sterile

3)hybrid invuability - hybrids are produced but fail to develop reproductive maturity . ex - certain type of frogs form hybrid tadpole and die even before they can become frog.

these are few of the example of post zygotic isolating mechanism