Question

You are studying speciation in crickets. You find that males and females from different populations will mate, but few eggs get fertilized. This is an example of what type of reproductive isolating barrier?

1) premating
2) postmating-prezygotic
3) intrinsic postzygotic
4) extrinsic postzygotic

Answer 1

In the case of crickets with low fertilization rates between different populations, the reproductive isolation is identified as a postmating-prezygotic barrier, occurring after mating but before zygote formation.

Step-by-step explanation:

The situation described with crickets where males and females from different populations mate but few eggs get fertilized is an example of a postmating-prezygotic reproductive isolating barrier.

In reproductive isolation terms, a prezygotic barrier is a mechanism that prevents reproduction from occurring, such as temporal isolation or structural differences in reproductive organs between species. A postzygotic barrier occurs after the zygote is formed, when the resulting offspring either do not survive to reproductive age or are sterile. When males and females of different cricket populations mate but exhibit a low rate of egg fertilization, it indicates that while mating can occur, there is some issue that prevents successful fertilization thus creating a barrier before the zygote can form. This barrier is referred to as postmating-prezygotic because it occurs after mating has taken place but before a zygote is successfully produced.