 The most significant population recovery was that of the Española tortoise ( C. n. <unk> ) , which was saved from near @-@ certain extinction . The population had been depleted to three males and 12 females that had been so widely dispersed that no mating in the wild had occurred . <unk> attempts to breed one of the tortoises , Lonesome George for example , is speculated to be attributed to a lack of postnatal cues , and confusion over which would be the most appropriate genetic subspecies would be the most appropriate to mate him with on the islands . The 15 remaining tortoises were brought to the Charles Darwin Research Station in 1971 for a captive breeding program and , in the following 33 years , they gave rise to over 1 @,@ 200 progeny which were released onto their home island and have since begun to reproduce naturally . 
