Imagine your scientist, observing rats in the wild as the rats reproduce rats born with white fur begin to outnumber rats with black fur, and 3 to 5 sentences provide two or more different explanations of white rats with white fur might be outnumbering rats with black fur
One possible explanation could be that white fur provides a better camouflage in the rats' natural environment, making them less vulnerable to predators. This advantage could lead to a higher survival rate for white rats, allowing them to reproduce more successfully and eventually outnumber black rats.
Another explanation could be that white fur is a trait that is genetically favored in the rat population, possibly through natural selection or genetic drift. If white fur provides any sort of reproductive advantage, such as attracting more mates or producing healthier offspring, then white rats would be more likely to pass on their genes and increase in number over time.