title: A new simplex approach to highlight multi-scale feeding behaviors in forager species from stomach contents: application to insectivore lizard population.
abstract: Stomach contents represent complex mixture systems which depend on feeding mode and level of forager species (carnivores, herbivores) as well as on natural availability/distribution of food resources (preys, plants). Such mixture systems can be considered as small black boxes condensing wide ecological information on (i) feeding behaviors of predator (or herbivore) and (ii) local diversity of preys (or host plants). Feeding behaviors of a hunter species toward different prey taxa show a complex variability whose investigation requires multivariate statistical tools. This paper presents a new computational approach which statistically analyzes stomach contents' variability in a predator population to graphically highlight different feeding behaviors. It is a simulation approach iteratively combining the variability of different diet patterns by using a simplex mixture design. Average combinatorial results are graphically visualized to highlight scale-dependent relationships between consumption rates of different food types found in the stomachs. The simplex approach was applied on different subpopulations of Phrynosoma douglassi brevirostre, an insectivore lizard species. These subpopulations were initially defined by different criteria including statistical clusters, gender and sampling periods. Results highlighted successive trade-offs over months of captured potential preys switching from small and less mobile preys to large and flying ones. In these dietary transitions, P. douglassi manifested a systematic memorization of previous preys and a gradual foraging learning of the next ones. These results highlighted lightness on dietary flexibility helping this specialist predator to switch between diets based on different potential preys. Adult male and adult female lizards showed different feeding behaviors due to some predation lag-time between them and different dietary ratios toward the same considered preys.
authors.affiliation: Institut Supérieur des Sciences Biologiques Appliquées de Tunis (ISSBAT), Université de Tunis El Manar (UTM), Tunis, Tunisia; Laboratoire de Biomathématiques, Service 462, Faculté des Sciences et Techniques de Saint-Jérômes, Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 13, France. Electronic address: nabilsemmar@yahoo.fr.
authors.forename: Nabil
authors.initials: N
authors.lastname: Semmar
authors.affiliation: Laboratoire de Biomathématiques, Service 462, Faculté des Sciences et Techniques de Saint-Jérômes, Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 13, France.
authors.forename: Maurice
authors.initials: M
authors.lastname: Roux
mesh_terms: D000818:Animals; D003198:Computer Simulation; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D020387:Food Chain; D005766:Gastrointestinal Contents; D007313:Insecta; D008116:Lizards / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D013045:Species Specificity; D013997:Time Factors
keywords: Combinatorial approach; Dietary transitions; Foraging ecology; Geometrical approach; Learning; Memorization; Nutritional trajectories; Simulation