The Northern leopard frog (Rana pipiens) and Southern leopar…

The Northern leopard frog (Rana pipiens) and Southern leopard frog (Rana utricularia) are morphologically similar, but their mating calls sound very different. Based on this, what is the best explanation for why these frogs are considered separate species?

In a species of salamander, there are two forms, red and yel…

In a species of salamander, there are two forms, red and yellow. As the yellow form becomes less common due to predation and the red form more common, the yellow form becomes less likely to be eaten and more likely to survive and reproduce. The yellow form then becomes more common and roles of red and yellow forms reverse. This is an example of