Why does gene flow prevent speciation?

Which statement describes how favorable traits in a population relate to natural selection? they are the only traits that ever exist in the population. they build in the population over time. they are rarely passed on to offspring. they are found only in a few individuals within the population.

The polio virus can cause skeletal muscle paralysis by destroying neuron cell bodies. what area of the spinal cord is destroyed

Males of different species of the fruit fly drosophila that live in the same parts of the hawaiian islands have different elaborate courtship rituals. these rituals involve fighting other males and making stylized movements that attract females. what type of reproductive isolation does this represent?