Question

Certain fishes, such as lungfishes, further adapted themselves to the terrestrial mode of life and evolved into today's amphibians. Which evolutionary mechanism is represented by this example?

Answer 1

Adaptive radiation

Moving onto land opened up multiple niches to which different populations adapted.

Answer 2

thank you and to your question I withdraw my answer of epigenetics, I am sticking with envirement

Answer 3

@borntobenerdy14 Lungfishes did not adapt themselves to be anything but what they are. Species that are extinct, thought to be highly similar to today's lungfishes, are likely the ancestors of modern amphibians. @alphadxg is right, but is missing a step before the radiation. The evolution of features that allowed colonization of a terrestrial habitat is an example of key adaptation or key innovation. These means that a trait provides the ability that was not possible before. For colonization of a land, the key adaptation was the ability to capture atmospheric oxygen instead of dissolved oxygen.

Once, this adaptation occurred, completely open and unfilled terrestrial niches results in the adaptive radiation that @alphadxg mentioned.