With enough determination, money and smarts, scientists just might revive the woolly mammoth, or some version of it, by splicing genes from ancient mammoths into Asian elephant DNA. The ultimate dream is to generate a sustainable population of mammoths that can once again roam the tundra.

But here’s a sad irony to ponder: What if that dream came at the expense of today’s Asian and African elephants, whose numbers are quickly dwindling because of habitat loss and poaching?

“In 50 years, we might not have those elephants,” said Joseph Bennett, an assistant professor and conservation researcher at Carleton University in Ontario. Dr. Bennett has spent his career asking hard questions about conservation priorities. With only so much funding to go around, deciding which species to save can be a game of triage.