Genetic diversity is not increased by asexual reproduction because asexual reproduction involves the creation of offspring that are genetically identical, or nearly identical, to the parent. This lack of genetic variation occurs because asexual reproduction typically involves the replication of a single parent's genetic material without the mixing of genetic material from two different individuals, as occurs in sexual reproduction.
In sexual reproduction, the combination of genetic material from two parents can lead to a wide range of genetic diversity in the offspring, as the genes from each parent can recombine in various ways. Asexual reproduction, on the other hand, does not have this mechanism for introducing genetic diversity. Instead, it maintains the genetic makeup of the parent, which can be advantageous in stable environments but limits the ability to adapt to changing conditions.
Genetic diversity is important for species' adaptability and evolution, and sexual reproduction is a major driver of genetic diversity in many organisms. Asexual reproduction, while efficient in some situations, tends to maintain genetic uniformity within a population.