Trophic interactions of an invasive gecko in an endemic-rich oceanic island: Insights using DNA metabarcoding

Abstract

Understanding the trophic interactions of introduced predators is key for evidence-based management of biological invasions. This is particularly important in oceanic islands, where predator-prey networks often include numerous endemic and range-restricted species. Geckos are successful island colonizers and in recent years numerous species have established populations in a wide array of oceanic islands. One such species is the Moorish gecko (Tarentola mauritanica), which has colonized multiple islands across the Mediterranean basin, Caribbean and Macaronesia. The species was first reported in Madeira Island in 1993 and over the last 30 years has colonized most of the islands' southern coast and expanded to the nearby island of Porto Santo. Here, we used DNA metabarcoding to provide the first insights into the diet of this successful colonizer in its introduced range. The species' diet was mainly composed of ground-dwelling arthropods belonging to the families Porcellionidae (Isopoda), Julidae (Diplopoda) and Formicidae (Hymenoptera). The diet richness and composition were not affected by neither sex nor size of adult geckos, instead they both change across populations. However, trophic niche-width differed among size classes, with smaller geckos feeding on a wider range of prey. We identified over 160 different Operational Taxonomic Units in the diet of T. mauritanica, with 21.6% of them belonging to introduced invertebrates and 13.6% to native species. Native prey taxa included the endemic Madeira wall lizard (Teira dugesii), the sole native reptile to Madeira. We also detected several agricultural pests and disease vectors in the diet of this exotic predator, and 19 taxa identified as prey had not yet been recorded to Madeira. Of these, several are serious agricultural pests, highlighting how this introduced gecko can be used as a natural sampler, in particular for the early detection of invasive arthropod pests. This study emphasizes the importance of trophic studies for monitoring the impacts of introduced predators in fragile insular systems.

A metabarcoding assessment of the diet of the insectivorous bats of Madeira Island, Macaronesia

“…Four of the 6 orders identified as prey of N. leisleri by Kaňuch et al (2005 ; Neuroptera, Coleoptera, Lepidoptera, and Diptera) were also detected in the diet of N. l. verrucosus . Moreover, N. l. verrucosus was found to share several prey species (e.g., Aiolopus thalassinus ) with a nocturnal gecko ( Tarentola mauritanica ) recently introduced to Madeira Island ( Martins et al 2022 ). Moreover, our results show that N. l. verrucosus prey mostly on flying arthropods (Noctuidae, Blastobasidae, and Cerambycidae), aligning with expectations for an aerial-hawking foraging bat, and matching previous research findings ( Boston et al 2020 ).…”

One gecko’s pain is another gecko’s gain: is the Moorish geckoTarentola mauritanicabecoming invasive in France?

“…The question of high predation pressure also arises, but studies on the trophic ecology of T. mauritanica indicate that it feeds almost exclusively on arthropods (Gil & Perez-Mellado, 1994; Hódar et al, 2006; Martins et al, 2022). However, some cases of predation on several species of Lacertidae (Salvador 1978; Franco 1980; Pellitteri-Rosa et al, 2015) have been documented in other areas.…”

“…However, some cases of predation on several species of Lacertidae (Salvador 1978; Franco 1980; Pellitteri-Rosa et al, 2015) have been documented in other areas. For example, the DNA of the wall lizard Teira dugesii was detected in nearly 27% of T. mauritanica samples from Madeira Island (Martins et al, 2022). Predation of H. turcicus by T. mauritanica has also been observed, (Rieppel 1981; Gonzalès de la Vega 1988; Bauer 1990).…”

“…Given the large difference in body size between T. mauritanica (total length 15 cm) and E. europaea (total length 8 cm), predation may occur occasionally on juvenile or adult E. europaea , but this alone cannot explain the extent of the observed decline. Apart from potential predation by T. mauritanica , competition for food resources cannot be ruled out, given the high similarity in trophic ecology between the two species (Oneto et al, 2008; Hódar et al, 2006; Martins et al, 2022).…”

What does the future hold for a thermophilus and widely introduced gecko, Tarentola mauritanica (Squamata: Phyllodactylidae)?

“…However, T. mauritanica populations in Croatia compete with those of Hemidactylus turcicus through spatial displacement (Lisičić et al 2012). In Madeira Island, they may have some impact on introduced arthropod communities (Martins et al 2022).…”