Question

Marsupials, such as kangaroos, koalas, and wombats, are mammals that care for their newborn young in a pouch. All marsupials that are found in Australia are thought to have evolved from a single species that migrated to the island and then adapted to the various niches. What does this example illustrate?

Answer 1

Answer:

Evoultion from a common ancestor

Explanation:

Marsupials are a group of animals with a distinctive characteristic: these animals  carry the young offspring in a pouch. This pouch did not appear independently in each of the species, this pouch was present many millions of years ago in the last common ancestor of all marsupials.  

The last common ancestor of marsupials -the most recent species from which all the marsupials organisms are directly descended-  already had this trait (carrying the young offspring in a pouch)  and this trait was therefore  inherited to all the descendant species.

Answer 2

Answer:

Adaptive Radiation

Explanation:

Adaptive radiation refers to an evolutionary process in which organisms diversify from one ancestral species, which leads to different other forms and species. This tends to happen when organisms are pressured to adapt to a new environment.

Australian terrestrial mammals such as kangaroos, koalas, and wombats, are examples of this process. According to research, these iconic marsupials went through adaptive radiation in response to the expansion of grassland that occurred in the mid-Pliocene. Another example (the most famous one) is the case of Darwin's finches, which all evolved from a single species but then changed in response to their environment.