Prey composition, diversity, availability, and selectivity in the diet of the desert wall gecko (Tarentola deserti)

Abstract

This study investigated for the first time the diet diversity and composition of the desert wall gecko ( Tarentola deserti Boulenger, 1891) for both sexes during different phenological phases (wintering, pre-reproduction, reproduction, and post-reproduction) in an oasis of date palms located in the Algerian Sahara Desert. By comparing the diet of the studied species with that of congeneric lizards, the study aimed to determine the trophic niche of T. deserti relative to sympatric Tarentola species. The diet was studied by analyzing prey fragments isolated from the feces of individuals foraging in their natural habitat. The availability of potential prey in the foraging habitat was assessed to provide a baseline for prey selectivity, allowing us to determine which prey items were preferentially consumed relative to their environmental abundance. The abundances of prey taxa identified in the diet were used to examine the variation in alpha diversity (indices of diversity, structure, and organization of prey communities), beta diversity (similarity analyses), curves of accumulation (rarefaction and interpolation), and prey electivity according to species phenological phases and sexes. Study of prey availability in foraging habitats revealed the presence of 67 potential prey species. In the feces of T. deserti , the diet included 33 species classified into 3 classes, 10 orders, and 24 families. Insects were dominant in T. deserti diet, with Blattodea, Coleoptera, and Hymenoptera constituting 46.8%, 30.9%, and 7.4% of the total abundance, respectively. Regardless of sex, Blattodea followed by Coleoptera were the preferred prey during all life-history phases, whereas Hymenoptera, Orthoptera, and Diptera, although consumed, exhibited negative selectivity scores (i.e., available in the environment but relatively avoided), indicating that these prey were ingested less frequently than expected based on their environmental availability. The relationship between prey availability and selectivity highlighted that T. deserti preferentially consumed prey that were either abundant or easily captured, whereas some numerically abundant prey were avoided, reflecting active prey selection rather than passive feeding. Variations in prey diversity and selectivity parameters between different phenological phases and sexes were not significant. The presence of a congeneric lizard in T. deserti diet indicates that it either exhibits cannibalistic behavior or preys on sympatric species at early growth stages. Both rarefaction and interpolation curves of prey taxon richness suggested the need to increase the number of fecal samples to achieve an exhaustive inventory of prey diversity in T. deserti ’s diet in the Sahara Desert. • Diet diversity and composition of Tarentola deserti were analyzed for the first time. • In terms of abundances, the dominate prey orders were Blattodea and Coleoptera. • No difference was observed between phenological stages and sexes for prey diversity and prey selectivity. • Analysis of similarity revealed strong resemblances between species phenological stages.