Question

Explain how sexual reproduction gives rise to more viable variations than asexual reproduction.

Answer 1

Variations arising during sexual reproduction occur due to
(i) Chance separation of homologous chromosomes during gametogenesis.
(ii) Crossing over between homologous chromosomes.
(iii) Chance coming together of chromosomes during fertilization.
(iv) Errors or mutations occurring during DNA replication. Only the last method of variations is found in asexually reproducing organisms. The rate of appearance of variations is quite high in sexually reproducing organisms as compared to asexually reproducing organisms. Therefore, the rate of evolution is also high in sexually reproducing organisms. Their variations are quite viable because most of them are due to reshuffling of genetic material. Changes in DNA that occur during replication are fewer. Most of them are harmful. They have a negative impact on evolution except when the changing environment finds them useful.