Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Specialist vs generalist : a study on North African rodent’s camouflage through different spatial and temporal scales

Auteur : Ferreira Borges de Macedo Tiago Afonso

Université de soutenance : Universidade do Porto

Grade : Mestrado em Ecologia e ambiente 2021

Résumé
Anthropogenic climate change is increasing the likelihood of extreme weather conditions that exceed current biological tolerances, posing severe threats to biodiversity, as well as permanent changes to landscape and environment. While plasticity can help individuals to maintain performance, there are limits to their capacity, because of this, animals are forced to adapt to the ongoing changes or face extinction. Deserts are one of the biogeographical regions most prone to suffer from the climate change, that alter geographical structure and temporal dynamic of habitats perceived by diverse community of animals. In this work we have investigated one of the classical adaptations to habitat, camouflage, in a community of North African rodent. Specifically, we tested the spatial resolution of camouflage to distinguish between the generalist and specialist camouflage strategy and investigated the temporal consistency of such strategies. In the study, digital and satellite images were obtained for animals and habitats. Habitat images were obtained and analysed from small spatial (1m) to broad spatial scale (100km). Images were collected for 3 years’ time resolution, to develop a time scale. Here we have presented results from analyses on camouflage in sixteen Sahara Sahel rodent species, conducted on in total 295 individuals. We have showed that species differed in their spatial and temporal resolution of the camouflage adaptation. We also discovered that different colour characteristics (hue, saturation and brightness) have variable importance among studied species, perhaps reflecting species activity patterns, life history strategies and other ecological properties. We concluded that the division between generalist vs specialist camouflage strategies might not be as straightforward as we previously thought. It became evident that animals developed different camouflage strategies depending on the colour properties studied (hue, saturation, and brightness). Our research also allowed that time resolution is something important to consider for adaptation, suggesting that selection might be strongest in depending on the timing and frequency of reproduction among studied species

Mots clés  : Specialist, Generalist, Spatial scale, Temporal scale, Camouflage, Adaptation, Background matching, Colour, Hue, Saturation, Brightness, Rodents, Sahara-Sahel, Desert

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