Fossorial life does not constrain diet selection in the amphisbaenian Trogonophis wiegmanni

Abstract

Morphological adaptations of amphisbaenians for a fossorial life constrain their ecological demands in a greater way than for epigeal reptiles. Studies on the diet of amphisbaenians suggest that most species are generalists, although others seem more selective. However, there is no information on the diet preferences of almost any species because most studies did not evaluate the availability of prey in the environment. We analysed the spring diet selection of a population of the amphisbaenian Trogonophis wiegmanni from the Chafarinas Islands, in North Africa. We specifically examined diet estimated from faecal material collected from live amphisbaenians and compared diet with the availability of invertebrates in the soil. Results indicate that the diet of T. wiegmanni amphisbaenians consists of some of the types of invertebrates that are more commonly found under rocks used by amphisbaenians, such as insect larvae, snails, isopods, beetles and ants. This diet could be initially considered generalist, and probably opportunistic. However, the comparison of proportions of prey types in the diet and those available in the habitat revealed that T. wiegmanni does not eat prey at random, but selects some particular prey types (insect larvae and pupae and, surprisingly, snails), while others (ants and isopods) are consumed less than expected by their abundance. We did not found differences between sexes or age classes in diet composition. We discuss how diet preferences could be due to selection of the more profitable or easily captured prey. There are many aspects of the feeding and foraging biology of amphisbaenians that remain unknown and further studies are clearly needed.

Occurrence and ecological aspects of the two-fingered skinkChalcides mauritanicusin the Chafarinas Islands in North Africa

“…Larvae provide a great energetic contribution to the diet of skinks, which would compensate for the energetic foraging costs of skinks in the subterranean environment. Similarly, some fossorial amphisbaenians Martín et al 2013b) and skinks (McCoy et al 2010) select insect larvae in spite of their relatively low abundance. This apparently restricted diet probably also reflects the restricted amount of available prey in the sandy foraging sites.…”

“…We included invertebrates that escaped when the rock was lifted. We also gently excavated soil with a small stick inside a 25 cm radius circle surrounding the rock to look for buried invertebrates (for similar procedures, see Martín & Salvador 1993;Goldsbrough et al 2003;Civantos et al 2013;Martín et al 2013b).…”

A complete mandible of a new amphisbaenian reptile (Squamata, Amphisbaenia) from the late middle eocene (Bartonian, Mp 16) of France

“…Most amphisbaenian species are dietary generalists (Cabrera and Merlini, 1990;Colli and Zamboni, 1999;Kearney, 2003;Bernardo-Silva et al, 2006;Gomes et al, 2009), although the narrow diets of some species suggest that they could be more selective (L opez et al, 1991;Cruz Neto and Abe, 1993;Gil et al, 1993;e902379-6 JOURNAL OF VERTEBRATE PALEONTOLOGY Webb et al, 2000;Mart ın et al, 2013). These studies show that the diet of amphisbaenians is mainly limited to the types of small arthropods often found in the soil, including ants, termites, adult and larval beetles, and spiders.…”

“…In addition to vegetable matter, Vanhooydonck et al (2007) recognized eight animal taxa as potential prey for durophagous lizards, including shelled invertebrates, arthropods, and vertebrates. Snails are highly unusual in the diets of modern amphisbaenian species and have been reported as the main prey for only two species: (1) Amphisbaena ridleyi (Pregill, 1984), which has robust, but still somewhat pointed teeth compared with Cuvieribaena; and (2) Trogonophis wiegmanni (Gans, 1960;Mart ın et al, 2013), which has robust, blunt teeth, with acrodont implantation. In addition, the diet of extant subterranean lizards is difficult to categorize because of insufficient field data (Anderson, 2007;Vitt and Pianka, 2007).…”

Chemosensory Prey Detection by the AmphisbaenianTrogonophis wiegmanni

“…Little research has been carried out on this species, but there is some information on its thermal biology (Gatten and McClung, 1981;L´opez et al, 2002b), metabolism (Kamel and Gatten, 1983), microhabitat selection (Civantos et al, 2003;Martín et al, 2013a), reproduction (Bons andSaint Girons, 1963), sexual dimorphism (Martin et al, 2012), and social behavior and population structure (Martin et al, 2011a,b). The diet of T. wiegmanni consists mainly of insect larvae, isopods, ants, and other invertebrates (Bons and Saint Girons, 1963;Martín et al, 2013b).…”