In the early 80s, science fiction author Brian Aldiss wrote a trilogy of books about a planet called Helliconia in a binary star system which means there are regular years (as Helliconia orbits one star) and “Great Years” (as Helliconia & its closest star orbit another star.) The epic sweep of the story traces the rise and fall of civilizations on this planet, often caused by the changes in these great seasons.
(Come to think of it, I should probably reread these books now that global warming has us heading into a Helliconia Summer. But I digress…)
One of the ideas in the books that has really stuck with me was the intermingling of Helliconia-native species (which had long-since adapted to the vicissitudes of the Great Year) and Earth-introduced species (which always seemed to get caught unaware by the changes in the seasons.) An intermingling which happened so long ago that it has been lost to history.
Australia reminds me of that: indigenous species which evolved to live in this environment with European-introduced species overlayed on top them. The difference between, say, kangaroos & koalas on one hand and cows & sheep on the other is staggering. And yet now they coexist in the same land. Truly fascinating.