A study suggests that geckos evolved rapidly after human-caused isolation. Previous studies have found that human-caused ecosystem changes can drive rapid adaptive changes in local organisms. Thomas W. Schoener and colleagues explored how approximately 15 years of isolation affected the diet and morphology of a termite-eating gecko (Gymnodactylus amarali) in the Brazilian Cerrado, a biodiversity hotspot. The construction of a hydroelectric dam flooded a Cerrado valley in 1997, isolating G. amarali populations on islands. The authors focused on five newly created islands and five mainland locations. Compared with G. amarali on the mainland, G. amarali on the islands consume larger termites as well as prey with a wider range of body sizes. Island G. amarali also have proportionally larger heads than mainland G. amarali, enabling island geckos to consume larger prey without a large increase in energy requirements. Moreover, the adaptive shifts occurred independently on each island, likely driven by similar changes in community structure. The authors suggest that the island G. amarali may consume larger prey due to the likely increase in the availability of larger prey following the extinction of four other termite-eating lizard species—all of which were larger than G. amarali—on the islands. According to the authors, island G. amarali represent rapid and parallel adaptive change to human-caused ecological disturbance.
Article #17-09080: “Lizards on newly created islands independently and rapidly adapt in morphology and diet,” by Mariana Eloy de Amorim et al.