Rapid species displacement during the invasion of Florida by the tropical house gecko Hemidactylus mabouia

Abstract

There is considerable interest in understanding how invasive species disperse across landscapes, and how they affect resident species. However, quantifying these processes using mark recapture or manipulative experiments can be time consuming and costly. A different approach is to study density changes across a broader landscape, and take advantage of naturally existing replicate locations that are imperfect, but plentiful. We documented sites of recent colonization and measured density changes in the invasive gecko Hemidactylus mabouia and the prior resident gecko Hemidactylus garnotii in Florida. We surveyed geckos at 398 locations from 19 regional sites distributed across central and southern Florida. We documented changes in abundance through repeated censuses of 56 locations in areas of sympatry between 2001 and 2009. Complete displacement occurred in \7 years at several locations, and overall there was a [10% increase in H. mabouia per year. There was evidence that H. mabouia reaches a higher carrying capacity than H. garnotii, which likely contributes to its competitive dominance. Changes in relative abundance within patches were consistent with a density dependent mechanism of displacement, suggesting the decline of H. garnotii is functionally linked to increases in H. mabouia abundance, which allows us to rule out coincidental factors not directly associated with H. mabouia. However, simulations showed that even highly asymmetric differences in carrying capacity and competitive ability were not sufficient to account for the rapid displacement we observed. We conclude that mechanisms other than resource competition must be at work to drive species displacement in this system.

Disentangling the Influence of Urbanization and Invasion on Endemic Geckos in Tropical Biodiversity Hot Spots: A Case Study ofPhyllodactylus martini(Squamata: Phyllodactylidae) along an Urban Gradient in Curaçao

“…Although we cannot rule out the hypothesis that H. mabouia may promote sex-specific differences in foraging behavior, neither our study nor others documenting the decline of P. martini have provided sufficient evidence in favor of this hypothesis (Hughes et al 2015). Although the combination of interference and exploitative competition may explain the decline of P. martini in urban areas, the rate at which H. mabouia displaces other gecko species exceeds the theoretical expectations of displacement by competition alone (Short and Petren 2012).…”

“…In addition to being potentially more efficient at harvesting spatially aggregated resources, H. mabouia may also be limiting access to food resources through territorial interactions. Hemidactylus mabouia is highly aggressive, and the defense of territories by this species has been linked to the decline of other gecko species in Florida (Meshaka et al 2006;Short and Petren 2012). Following the colonization of H. mabouia on structures previously colonized by Phyllodactylus martini in Curaçao, the latter species becomes noticeably absent (Van Buurt 2010;Hughes et al 2015).…”

Going feral: Time and propagule pressure determine range expansion of Asian house geckos into natural environments

“…The species spreads readily with international cargo transport, along transport networks within regions, and through urban areas (Hoskin ), a multimodal pattern of dispersal reported for other invasive gecko species globally (e.g. Short & Petren ).…”

Terrestrial Vertebrate Invasions in South Africa

“…Populations of H. mabouia species have invaded West Africa, the Caribbean, South America and Florida (Weterings and Vetter 2018). Invasions have resulted in displacement of native geckos in Florida and Curaçao (Dornburg et al 2016;Short and Petren 2012, but see also Williams et al 2016). The first extralimital records in South Africa for this species are for East London and Port Elizabeth in the 1980s (Brooke et al 1986;Rebelo et al 2019), although, like the common dwarf gecko (see below), first sightings in Port Elizabeth may be biased to the activities of a keen resident herpetologist and the true dates for other cities may be earlier than reported.…”