Final answer:
Variations in a population are primarily caused by random mutations in genes, creating new alleles that contribute to genetic diversity. These heritable changes coupled with gene flow, genetic drift, and natural selection drive evolutionary processes.
Step-by-step explanation:
What causes variations to arise in a population? The correct answer is 'Random mutation in genes'. Variations in a population occur due to several factors which are integral to the process of evolution. These factors include mutation, gene flow, genetic drift, and natural selection. Mutations are the ultimate source of new genetic variety, creating new alleles in a gene pool. Gene flow happens when individuals migrate between populations, mixing their genetic material with new populations. Genetic drift refers to changes in allele frequencies due to random chance, and natural selection involves differential survival and reproduction based on trait advantages in a given environment.
Mutations can be random changes in the DNA sequence, and these provide the raw material for evolution by introducing new traits into a population. Heritable genetic variation is necessary for natural selection to act upon, as selection can only amplify or diminish traits that can be passed on to the next generation.