Data from: Lizards on newly created islands independently and rapidly adapt in morphology and diet

Rapid adaptive changes can result from the drastic alterations humans
impose on ecosystems. For example, flooding large areas for hydroelectric
dams converts mountaintops into islands and leaves surviving populations
in a new environment. We report differences in morphology and diet of the
termite-eating gecko Gymnodactylus amarali between five such newly created
islands and five nearby mainland sites located in the Brazilian Cerrado, a
biodiversity hotspot. Mean prey size and dietary prey-size breadth were
larger on islands than mainlands, expected because four larger lizard
species that also consume termites, but presumably prefer larger prey,
went extinct on the islands. In addition, island populations had larger
heads relative to their body length than mainland populations; larger
heads are more suited to the larger prey taken, and disproportionately
larger heads allow that functional advantage without an increase in
energetic requirements resulting from larger body size. Parallel
morphological evolution is strongly suggested, because there are
indications that, before flooding, relative head size did not differ
between future island and future mainland sites. Females and males showed
the same trend of relatively larger heads on islands, so the difference
between island and mainland sites is unlikely to be due to greater
male–male competition for mates on islands. We thus discovered a very fast
(at most 15 y) case of independent parallel adaptive change in response to
catastrophic human disturbance.