From species responses to biodiversity change

Details

Supervisors

De Laender

Faculty

Faculté des sciences

Degree label

Master [120] en biologie des organismes et écologie, à finalité approfondie

Abstract

Global change is certainly one of the major challenges of the 21st century. It poses a serious threat to the entire biosphere, so it is only natural for biologists to study this phenomenon from all its facets to understand its effects. Unfortunately, even today, scientific literature lacks an effective framework for multi-species analyses. To address this issue, I propose using the variance of species' intrinsic growth rates (μ) as a predictor of species coexistence feasibility within computer-simulated communities. Temperature and pollutant concentration have been chosen as representative stressors of global change. The values of μ were calculated based on functions established in the literature and parameterized with realistic data taken from scientific databases. The variance of μ and the fraction of species expressing μ > 0 were calculated as a function of temperature and pollution. The μ values were then used to simulate the growth rates of species in random networks, which allowed the feasibility of ecological communities under gradients of temperature and pollution to be assessed. It proved impossible to identify a clear link between growth rate variance and feasibility. Indeed, the fraction of species with positive μ values appears to be more closely correlated with feasibility than variance. It seems that variance is not an effective predictor of feasibility. However, the fraction of species with positive μ values directly influences the variance. This relationship is more easily seen in the analyses concerning pollution, given that the μ values can only decrease when the pollutant dose increases. Additionally, my analyses reveal that species interaction strengths are as crucial as stress in influencing feasibility, generating situations where, despite relatively minor stress, antagonistic interactions prevent any coexistence. Future work should investigate how the interaction between temperature or pollution and interaction strengths can influence species coexistence in random networks.