Relationships between helminth communities and diet in Canarian lizards: the evidence fromGallotia atlantica(Squamata: Lacertidae)

Abstract

Diet and helminth fauna were analysed in the lizard Gallotia atlantica (Squamata: Lacertidae), the smallest species of this genus endemic to Lanzarote and Fuerteventura (Canary Islands), in an attempt to confirm previous claims of relationships between these ecological traits in this genus. A total of 70 lizards belonging to the subspecies atlantica (central southern Lanzarote), laurae (northern Lanzarote) and mahoratae (Fuerteventura) were examined. Compared with other Gallotia, the helminth fauna was impoverished, particularly in Fuerteventura, where the absence of larval cestodes suggests low predation pressure. Diet was omnivorous, the plant fraction (73.03-84.26%) included seeds and fruits while the animal fraction was quite diverse, at least in Lanzarote. Contrary to other Gallotia, the intestinal Pharyngodonidae nematodes were all typical of carnivorous reptiles. An individual association between the complexities of helminth communities and diet reinforces previous findings in other Gallotia species suggesting functional relationships between parasites and prey items inside the digestive tract.

Your infections are what you eat: How host ecology shapes the helminth parasite communities of lizards

“…While previous studies have shown that the helminth communities of vertebrate hosts are influenced by a wide variety of different factors (Poulin & Morand, 2004), we found diet to be the host trait most strongly associated with the range of helminth types found in lizards, with the other significant host traits likely showing some association with host diet as well. This association between diet and composition of helminth communities in lizards has been noted in previous studies of specific host species (e.g., Brito et al, 2014;Carretero, Jorge, Llorente, & Roca, 2014;Carretero et al, 2006;Martin & Roca, 2004;Roca, Carretero, Llorente, Montori, & Martin, 2005), and our comparative analysis demonstrates its broad influence.…”

“…Additionally, the helminth community of a host species can be influenced by its trophic level and the types of predator-prey interactions in which it is engaged. Similarly, Carretero et al (2014) suggested that the absence of larval cestodes in a population of Gallotia atlantica (Atlantic lizard) may be due to its low predation pressure. In addition, while some studies have found that the diversity of adult parasites harboured by fish was associated with host diet, the proportion of larval helminths present in those communities was correlated with the diversity of the host's predators and/or vulnerability to predation (Locke, Marcogliese, & Valtonen, 2014;Muñoz, Grutter, & Cribb, 2006;Poulin & Leung, 2011).…”

“…Consequently, host species which are preyed upon by few predators may be infected by fewer or no larval helminths as these would effectively represent "dead ends" for the parasite. Similarly, Carretero et al (2014) suggested that the absence of larval cestodes in a population of Gallotia atlantica (Atlantic lizard) may be due to its low predation pressure.…”

Cannibalism of an endemic island lizard (genus Gallotia )

“…Reptile populations on islands with few heterospecific predators may lead to increased intra-specific competition and select for larger hatchlings, which perform better physiologically (Olsson et al, 2002) and more successfully avoid cannibalism (Novosolov et al, 2013;Pafilis et al, 2009); although we must not forget that cannibalism is also shown by some continental lizards (e.g., Amat et al, 2008;Busack and Jaksic, 1982). At last, because of Canarian lizards exhibit a similar adaptation in terms of ecomorphs (sensu Losos et al, 1998) in five of the islands, we predict cannibalism in another Gallotia species from that archipelago; that prediction has been supported by the recent finding of that behavior in G. atlantica (Carretero et al, 2014). Line represents slope of the equation.…”

“…Hitherto, cannibalism has failed to be detected in most Canary Island lizards, even in the giant species (information compiled in www.vertebradosibericos.org). However, we suggest that detecting cannibalism in these lizards is simply matter of sample size in studying their diet, and a recent study supported by a rather great sample size in G. atlantica (Peters and Doria, 1882) (2155 prey) also detected cannibalism (Carretero et al, 2014).…”