CHARLES DARWIN RESEARCH STATION, Galápagos — Of all the giant tortoises on these islands, where the theory of evolution was born, only a few have received names that stuck. There was Popeye, adopted by sailors at an Ecuadoran naval base. There was Lonesome George, last of his line, who spent years shunning the females with whom he shared a pen.

And there is Diego, an ancient male who is quite the opposite of George.

Diego has fathered hundreds of progeny — 350 by conservative counts, some 800 by more imaginative estimates. Whatever the figure, it is welcome news for his species, Chelonoidis hoodensis, which was stumbling toward the brink of extinction in the 1970s. Barely more than a dozen of his kin were left then, most of them female.

Then came Diego.

“He’ll keep reproducing until death,’’ said Freddy Villalva, who watches over Diego and many of his descendants at a breeding center at this research facility, situated on a rocky volcanic shoreline, where the tortoise has lived since the 1970s. The tortoises typically live more than 100 years.

The tales of Diego and George demonstrate just how much the Galápagos, a province of Ecuador, have served as the world’s laboratory of evolution. So often here, the fate of an entire species, evolved over millions of years, can hinge on whether just one or two individual animals survive from one day to the next.

Diego, estimated to be a century old, is one of the main drivers of a remarkable recovery of the hoodensis species — now more than 1,000 strong on their native island of Española, one of the dozen Galápagos Islands.

The recovery of Diego’s hoodensis species also brings up a quandary. As Diego produces more offspring, and as those he has produced reproduce with one another, the entire species of hoodensis could all begin to look like Diego.

Evolutionary scientists call this process the bottleneck effect — when survivors’ genes come to dominate the gene pool as populations rebound.

James P. Gibbs, a professor of vertebrate conservation biology at the State University of New York College of Environmental Science and Forestry in Syracuse, called it a “dangerous zone,’’ where little genetic diversity could mean susceptibility to a dangerous disease or changes in habitat.

But Linda Cayot of the Galápagos Conservancy dissented, saying island species on the Galápagos have a long history of being decimated to just a few survivors that rebounded without incident — like a population of giant tortoises that chose to live in the caldera of a volcano. After the volcano exploded 100,000 years ago, the tortoises bounced back and returned to the caldera.

“Every species came from a bottleneck,’’ Cayot said. “It’s what happens in the Galápagos.’’