As a result of breeding between Pachnodus velutinus and the closely related snail, Pachnodus niger, a hybrid species was created, Pachnodus niger x velutinus. This species, still in existence, has features of both parent species, but, most importantly, it has the strong, well-calcified shell of Pachnodus niger, allowing it to undergo aestivation. Both Pachnodus velutinus and the hybrid co-existed on Mahé as regionally separate populations until the 1960s, when clearance of mid-altitude forest (3), and possibly global climate change (6), may have caused the local climate within the ranges of both species to become significantly less humid (3) (6). Since it was able to aestivate, the hybrid species was better adapted to survive in the mid-altitude regions than Pachnodus velutinus and, as a result, from 1972 to 1987 it rapidly expanded its range. As the hybrid encroached on the range of Pachnodus velutinus the two snail species bred together, producing hybrid offspring, and thereby causing the range of pure Pachnodus velutinus individuals to contract. By 1987, the only surviving pure populations of Pachnodus velutinus were in the dampest, most climatically stable part of its former range, the high-altitude Congo Rouge mountain region. At this point the range of Pachnodus velutinus had become so small that random mating with the hybrid snails gradually bred this species out of existence (3).