Answer:
The most likely mechanism of evolution to occur when the population size is very small is genetic drift. Genetic drift is a random process that can cause changes in the genetic makeup of a population due to random sampling errors. When the population size is small, random sampling errors become much more likely to occur, resulting in a higher rate of genetic drift. This can lead to changes in the frequencies of alleles in the population, which can result in changes in the traits expressed by the population.
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