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.
They hold DNA( hope this helps)
Like Geography, climate, times and environment system
Answer:
there is no evidence of the big band or evolution, even Charles Darwin himself said that is was untrue
Answer:
Coronary Artery
Explanation:
A blockage by blood clot formation is coronary artery called as thrombus reduces the blood flow to the heart. The reduced blood flow causes the heart to dysfunction and the myocardial infarction occurs. Heart tissue can sustain serious damage upon such a shock.
