While doing research today, I noticed that the tulip tree genus, Liriodendron, has only two representatives: one in the US and part of Canada, and one in China/Vietnam. This wouldn’t strike me as unusual if not for the fact that there’s another genus with its only two species in these locations: Alligator, with the American Alligator in the US and the Chinese Alligator in China (duh).
So: does anyone know what geographic/biological phenomena caused these odd distributions? Is it the same for both organisms, or just a coincidence? And are there other examples of species/genera/family/etc. which only have representatives in North America and China? It doesn’t have to be just two species.
There are loads of examples, from Sassafras to Symplocarpus to Podophyllum. I don’t know the specific histories of any of them, but many times it has to do with the same reason humans are found in both china and in the Americas- they migrated from Asia into the Americas fairly recently, and just haven’t had a lot of time to undergo speciation. Other times they just happen to be the sole survivors after the ice age, etc.
I can’t say I know much about biogeography, but I mostly just wanted to post this youtube video you might find interesting: https://www.youtube.com/watch?v=W94Rth-aIkc
This is a well-known phenomenon called the Eastern Asian–Eastern North American biogeographic disjunction. There are papers and books that talk about it and you can find a lot of good info and hypotheses if you dig a little bit into the literature. It has also come up in this thread before.
Sassafras albidum – Eastern U.S.
Sassafras tzumu – Southeastern China
Sassafras randaiensis – Taiwan
And here’s a twist: two maple species with compound (“ash-like”) leaves instead of the usual maple leaves:
Acer negundo – Eastern North America
Acer griseum – Central China