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Universidade do Porto (2017)

A metabarcoding approach to assess the diet of lacertid lizards from the High Atlas Mountains

Antunes Pereira Ana Isabel

Titre : A metabarcoding approach to assess the diet of lacertid lizards from the High Atlas Mountains

Auteur : Antunes Pereira Ana Isabel

Université de soutenance : Universidade do Porto

Grade : Mestrado em Biodiversidade, Genética e Evolução 2017

Résumé partiel
Dietary analyses are a fundamental tool in helping to define ecological niches and trophic relationships. Closely related species sharing the same habitat might reduce competition by exploiting different resources, which might be reflected into different microhabitat use and foraging modes. Although lizards are mainly opportunistic feeders, some foraging strategies might be more advantageous than others, shaping the types of consumed prey. Two extreme foraging modes are recognized : sit and wait foraging and active foraging. Sit and wait foragers wait for prey to approach from a stationary place and quickly attack them, and thus are expected to find more mobile prey and have a less diverse diet. On the other hand, active foragers are more likely to find sedentary, clumped and unpredictably distributed prey as they look actively for food. These distinct foraging strategies are also dependent on different morphological features, and acceleration and speed are two key features since the way lizards move in the field influences both exposure to predators and the ability of catching prey. Another important feature is dorsal coloration, where cryptic spotted patterns are more common in sit and wait predators, whereas active foragers are more likely to present striped patterns creating a ‘motion dazzle’ phenomenon when moving. Scelarcis perspicillata is a species complex of lacertid lizards endemic to Morocco. Two forms are known to live in strict syntopy in a specific location, Taza - S. p. chabanaudi and S. p. pellegrini. In this thesis, we studied the dietary habits of these two forms, using a DNA metabarcoding approach, in order to understand to which extent they can be segregating food niches to reduce intraspecific competition. Based on their dorsal pigmentation patterns, and on previous studies regarding escape tactics and diet, we expected S. p. chabanaudi to be a sit and wait forager and S. p. pellegrini an active forager. Only one dietary study was previously performed for this species in Taza, about on decade ago, based on microscopic examination of faeces. My results confirmed the differences previously found between the two forms. However, we concluded that although the diet diversity of the two species conformed with the expectations regarding foraging modes, diet composition suggests both species are able to adopt both foraging strategies. Morocco harbours other endemic cryptic species complexes, such as the case of the lizard Atlantolacerta andreanskyi. The diet of this species was already assessed in the selected study area, Oukaïmeden, where a community study was performed more than a decade ago. My aim was to investigate diet partitioning between males and females, as well as ontogenetic differences.

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