Influence of agricultural landscapes on reptiles: habitat degradation and exposure to contaminants
Agricultural landscapes represent more than half of French territory and influence on a large scale the available space for biodiversity. The intensification of agriculture and the transition toward industrial practices have greatly modified the landscapes structure (destruction of fallow areas and hedges) and increased the exposure to contaminants in the environment (insecticides, herbicides, fungicides). These two types of disruptions are among the main causes of biodiversity loss, but few studies have focused on the case of reptiles. Yet, these organisms have limited mobility and are very sensitive to the degradation of their habitat. Their high position in the trophic chain and their low metabolism can favor the accumulation of contaminants. Recent studies demonstrate significant populations decrease. The objective of my thesis is to study the impact of these disruptions on squamate reptiles (lizards and snakes).
My project will firstly focus on the question: Where are the reptiles in agricultural landscapes? In a first study, we travel through time by comparing the presence of reptiles in a current landscape, degraded by the intensification of agricultural practices, and in a landscape preserved since the 1960s. Then we will study reptile populations in a gradient of agricultural practices to examine notably the importance of permanent pastures and structured hedgerows.
Secondly, it will focus on contaminants that can have direct effects on the mortality of individuals but also sub-lethal effects by disrupting the physiology of organisms and reducing their ability to reproduce. The organism’s ability to eliminate contaminants becomes critical for its survival. The renewal of integument can provide an effective way of detoxification as demonstrated for insect, mammals and birds. The same mechanisms should be observed for lizards and snakes that regularly shed their skin. This part of the thesis will be carried out in different environments representative of contamination gradients and considering species with contrasting lifestyles.
The overall thesis aims to better undertand the links between reptiles and agricultural practices in order to improve the conservation strategies of these species that are too often neglected.
This work is cosupervised by:
Olivier Lourdais (CEBC CNRS)
Aurélie Goutte (UMR METIS EPHE)
