Need quick on bio final lt: describe how natural selection causes organisms on earth to change over time. lt: describe how factors like genetic drift and sexual selection can affect how populations evolve. the graph below shows frequency of moths in a population. the original population had more black and white speckled moths, but the new population has more dark colored moths. image result for directional selection a. what type of selective pressure was taking place in this population? b. come up with a hypothesis related to genetic drift or sexual selection about why this shift may have occurred in the population.