Which process is the source of genetic variation in organisms that reproduce asexually?

In organisms that reproduce asexually, genetic variation primarily arises through mutations. Asexual reproduction typically involves a single parent organism reproducing through methods such as binary fission, budding, or fragmentation, which generally produce genetically identical offspring or clones.

However, mutations are random changes that occur in the DNA sequence. They can happen during DNA replication or as a result of environmental factors (like radiation or chemicals). These mutations can introduce new alleles into the organism's genetic makeup, thereby contributing to genetic variation. This variation is crucial for adaptation and evolution, even in asexual populations, as it allows for a potential response to changing environments.

While syngamy refers to the fusion of gametes in sexual reproduction and crossing over and independent assortment are processes that occur during meiosis, they are not applicable in asexual reproduction. Thus, mutations stand out as the sole source of genetic diversity in organisms that reproduce asexually.