What makes Hemidactylus invasions successful? A case study on the island of Curaçao

Abstract

43Abstract 44Hemidactylus spp. (House geckos) rank among the most successful invasive reptile species worldwide. 45Hemidactylus mabouia in particular has become ubiquitous across tropical urban settings in the Western 46Hemisphere. H. mabouia's ability to thrive in close proximity to humans has led to the rapid displacement 47 of native geckos in urban areas, however the mechanisms driving this displacement remain understudied. 48Here we combine data from nitrogen and carbon stable isotopes, stomach contents, and morphometric 49 analyses of traits associated with feeding and locomotion to test alternate hypotheses of displacement 50 between H. mabouia and a native gecko, Phyllodactylus martini, on the island of Curaçao. Consistent 51with expectations of direct food resource competition, we demonstrate substantial overlap of invertebrate 52 prey resources between the species. Additionally, we found strong evidence from both diet content and 53 stable isotope analyses that H. mabouia acts as a vertebrate predator, preying upon P. martini as well as 54 other native and non-native reptiles. Finally, we show that H. mabouia possesses several morphological 55 advantages, including larger sizes in feeding-associated traits and limb proportions that could offer a 56propulsive locomotor advantage on vertical surfaces. Together, these findings suggest the successful 57 establishment of H. mabouia likely involves a combination of both exploitative interspecific competition 58 and predation. Given the ubiquity of H. mabouia, illuminating the role of this species as both a competitor 59and a predator casts new concerns on the ecological and demographic impacts of this widespread urban 60invader. 61 62

How the African house gecko (Hemidactylus mabouia) conquered the world

“…Hemidactylus are known to outcompete other geckos in topographically simple habitats with clumped resources (such as below night lights in urban settings; [ 73 ]), and H. mabouia ss is specifically known to outcompete and directly predate on both native and other invasive geckos (e.g. [ 26 , 31 , 74 , 75 ]). Hemidactylus mabouia ss is a scansorial generalist with a preference for open, human-dominated habitats [ 76 ], though it is also found in natural habitats in both the New World and Africa [ 30 ].…”

“…The species seems able to outcompete native species (e.g. [ 26 ]); and where it has become introduced in recent decades appears to have pushed out or out-competed earlier colonizers, as in Florida, where H. turcicus (established since approx. 1910) and the more recent colonizers H. frenatus and H. garnotii have been marginalized or replaced when H. mabouia arrived [ 27 , 28 ].…”

Endocast, brain, and bones: Correspondences and spatial relationships in squamates

“…Additionally, the occipital sinus, endolymphatic sacs and cartilaginous elements surrounding the cerebellum may occupy variable portions of the area and, therefore, affect the resolution of the endocast. As the position, shape and size of these structures appear highly variable in squamates (e.g., Bruner, 1907;Ineich et al, 2018;Lamb et al, 2017;Mangione & Montero, 2001;Porter & Witmer, 2015), it is likely that the impact of these non-neural components on the endocast resolution is different, according to species, and further studies are needed to test it.…”