It is well known that reptiles can act as paratenic hosts for parasites that use mammals as their definitive hosts. However, studies of potential paratenic hosts in the Caribbean have been temporally restricted to only diurnal species of lizards, thereby neglecting a dominant component of the nocturnal reptilian community: geckos. Many gecko species are human commensals with activity periods that overlap temporally with those of domestic cats, making them prime candidates as potential transport hosts for cat parasites. However, no studies have reported geckos as paratenic hosts for felid parasites on any Caribbean island. Here we report the first records of subcutaneous oligacanthorhynchid cystacanths on the Venezuelan Coastal Clawed Gecko (Gonatodes antillensis) based on specimens collected in Curaçao and Bonaire. The cysts were identified as belonging to the genus Oncicola, likely those of Oncicola venezuelensis. This study reports these geckos as a new host record for oligacanthorhynchid cystacanths, as well as Curaçao and Bonaire as new geographic locales for these acanthocephalan parasites. We additionally provide a review of saurian cystacanths, comparing the restricted taxonomic focus of transport hosts in Caribbean islands to the distribution of paratenic squamate hosts both in the Neotropics and globally. We find evidence that the ability of squamate reptiles to act as transport hosts is a pervasive feature across their Tree of Life, suggesting that these animals may serve as important vectors for transporting parasites between intermediate and definitive hosts.
Geckos are among the most diverse radiations of lizards; however, the lack of baseline natural history data on the reproductive biology for many species creates a challenge for predicting their long-term persistence. This study aims to fill a gap in our understanding of the reproductive biology of an enigmatic nocturnal gecko endemic to the islands of Curaçao and Bonaire: Gonatodes antillensis. Using radiographs of specimens from natural history collections, we conduct the first investigation of the potential role of endolymphatic sacs in the reproduction of the species. We find that females have larger endolymphatic sacs than males, with further quantification of endolymphatic sac sizes between females with or without visible eggs supporting the hypothesis that calcium stores are built up in the early reproductive phase and depleted during the development of the egg. Additionally, we combined data on endolymphatic sacs sizes with examinations of gravidity to expand the known reproductive interval of the species into fall and winter months and suggest the possibility of year-round reproduction. Along with providing baseline data, our findings raise a new conservation concern for the species. The spread of the invasive gecko Hemidactylus mabouia has resulted in a notable decline in the abundance of Gonatodes antillensis across its native range. This decline has been attributed to Hemidactylus mabouia acting as both a competitor and possible predator of Gonatodes antillensis. However, stress can inhibit calcium uptake in endolymphatic sacs, and these findings raise the possibility that Hemidactylus mabouia may also be indirectly affecting the reproductive success of this species.
Predicting the response of endemic species to urbanization has emerged as a fundamental chal- lenge in 21st century conservation biology. The factors that underlie population declines of rep- tiles are particularly nebulous, as these are often the least understood class of vertebrates in a given community. In this study, we assess correlations between feeding ecology and phenotypic traits of the Lesser Antillean endemic Dutch leaf-toed gecko, Phyllodactylus martini, along an urban gra- dient in the Caribbean island of Curaçao. There has been a marked decline of this species in de- veloped habitats associated with the invasive tropical house gecko Hemidactylus mabouia. We find a correlation between aspects of locomotor morphology and prey in undeveloped habitats that is absent in developed habitats. Analyses of stomach contents further suggest that Phyllodactylus martini alters primary prey items in developed areas. However, changes in prey promote the over- lap in foraging niches between Phyllodactylus martini and Hemidactylus mabouia, suggesting that direct resource competition is contributing to the decline of Phyllodactylus martini. In addition to competitive exclusion, we suggest that the urban extirpation of Phyllodactylus martini could also be attributed to a top-down control on population growth by Hemidactylus mabouia. Coloniza- tions of walls put Phyllodactylus martini in direct contact with Hemidactylus mabouia increasing the chances for predation events, as evidenced by our observation of a predation event on a Phyl- lodactylus martini juvenile by an adult Hemidactylus mabuoia. In total, our results add to a grow- ing body of literature demonstrating the threat that invasive synanthropic reptiles pose to endemics that might otherwise be able to cope with increased urbanization pressures.
Several hypotheses have been proposed to explain the limitation of brain size in vertebrates. Here, we test three hypotheses of brain size evolution using marine teleost fishes: the direct metabolic constraints hypothesis (DMCH), the expensive tissue hypothesis and the temperature-dependent hypothesis. Our analyses indicate that there is a robust positive correlation between encephalization and basal metabolic rate (BMR) that spans the full range of depths occupied by teleosts from the epipelagic (< 200 m), mesope- lagic (200–1000 m) and bathypelagic (> 4000 m). Our results disentangle the effects of temperature and metabolic rate on teleost brain size evolution, supporting the DMCH. Our results agree with previous findings that teleost brain size decreases with depth; however, we also recover a negative corre- lation between trophic level and encephalization within the mesopelagic zone, a result that runs counter to the expectations of the expensive tissue hypothesis. We hypothesize that mesopelagic fishes at lower trophic levels may be investing more in neural tissue related to the detection of small prey items in a low-light environment. We recommend that comparative encephalization studies control for BMR in addition to controlling for body size and phylogeny.