The mechanisms of reproductive isolation prevent the reproduction of two individuals from different species. The prezygotic mechanisms disrupt the stages of reproduction before the forming of the zygote or prevent the mating at the start, and the postzygotic mechanisms affect the stages of reproduction after the forming of the zygote.
So, the first and the third example (the urchins and the grasshoppers) show the prezygotic mechanism, as the two individuals are not able to mate or form a zygote.
The second and the fourth example ( zonkey and the death of a zygote) show the working of the postzygotic mechanisms, as the zygote is formed, but it seems to be inviable, and the zonkeys are sterile, preventing the individual to reproduce.
Answer:
I think it might be the 2nd one or the last one....
Explanation:
The central nervous system is made up of the brain and spinal cord. The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body. Have a good day!!! Pls mark brainliest if helps!! :)
Answer:
For the eggs to survive and have a chance of hatching, sea turtles must lay their eggs on sandy beaches. As they are developing, the embryos breathe air through a membrane in the eggs, and so they cannot survive if they are continuously covered with water.
Explanation:
It would show that is universe in not expanding but contracting
