Answer: Natural selection is one of the concepts of evolution,it was propounded by a scientist known as Charles Darwin. In natural selection, organisms that have a more suitable traits survive and have a higher adaptation to the environment giving them more room to reproduce and give rise to new offsprings of their kind.
From the question, A male walrus that mates with 45 females has a higher favour than the walrus that mates with 18 females.
This is because,the walrus that mates with 45 females will have a larger number of offsprings than the other walrus making it to pass it's alleles(traits) to the next generation of walrus.
With this,the impact his alleles will have will be greater than the one of the walrus that mates with only 18 females.