Thanks to DNA testing, scientists have discovered that a tree in South America is genetically similar to one in Australia. What is one possible evolutionary inference they could make from this discovery

Both species share a common ancestor that lived when the Earth had supercontinents

Explanation:

Gondwana was a supercontinent that existed about 550 million years ago (Neoproterozoic Era) and began to break up about 180 million years ago (Jurassic period). During this period, Gondwana gradually broke up into the continents we know at present, and it has been proposed that about 140 million years ago Africa/South America started to separate from Australasia/India/Antarctica (Cretaceous period). On the other hand, DNA testing is a method based on the comparison of genetic sequences that can help to determine the ancestral history of different individuals, populations and species by determining the homology level between DNA sequences. In this case, sequence homology can be used to infer evolutionary relationships between species separated by a geographic barrier (i.e., South America and Australia are separated by the Pacific Ocean), thereby suggesting the existence of past supercontinents and also suggesting that both species share a common ancestor that lived when the Earth had such supercontinents.