Comparing the dietary niche overlap and ecomorphological differences between invasive Hemidactylus mabouia geckos and a native gecko competitor.

Hemidactylus mabouia is one of the most successful, widespread invasive reptile species and has become ubiquitous across tropical urban settings in the Western Hemisphere. Its ability to thrive in close proximity to humans has been linked to the rapid disappearance of native geckos. However, aspects of Hemidactylus mabouia natural history and ecomorphology, often assumed to be linked with this effect on native populations, remain understudied or untested. Here, we combine data from ∂15N and ∂13C stable isotopes, stomach contents, and morphometric analyses of traits associated with feeding and locomotion to test alternate hypotheses of displacement between H . mabouia and a native gecko, Phyllodactylus martini , on the island of Curaçao. We demonstrate substantial overlap of invertebrate prey resources between the species, with H . mabouia stomachs containing larger arthropod prey as well as vertebrate prey. We additionally show that H . mabouia possesses several morphological advantages, including larger sizes in feeding-associated traits and limb proportions that could offer a propulsive locomotor advantage on vertical surfaces. Together, these findings provide the first support for the hypotheses that invasive H . mabouia and native P . martini overlap in prey resources and that H . mabouia possess ecomorphological advantages over P . martini . This work provides critical context for follow-up studies of H . mabouia and P . martini natural history and direct behavioral experiments that may ultimately illuminate the mechanisms underlying displacement on this island and act as a potential model for other systems with Hemidactylus mabouia invasions.