Towards a Unifying Theory of Mass Extinctions: Relating Rates of Global Climate Change and Evolutionary Adaptation
Sergei Petrovskii
School of Computing and Mathematical Sciences
University of Leicester, Leicester, LE1 7RH, UK
Species get extinct all the time with a certain background extinction rate; this is a normal course of macroevolution. However, several times through the 540 Ma of the recorded history of life on Earth, the extinction rates exceeded the average background rate by more than an order of magnitude, resulting in 50-90% loss in the global biodiversity. Apart from the “Big Five”, there were many smaller mass extinctions with the global biodiversity loss ranging between 10-50%. Mass extinctions came into the focus of scientific community in early 1980s and significant progress has been made over the last few decades. However, given the inherent deficiency of the fossil data, statistical analysis alone (which is the main research tool used in paleontology) does not always allow to distinguish between the effect of different processes, which hampers further progress. Process-based mathematical models are needed.
In my talk, I introduce a novel modelling approach that counterpoise the effect of a fast climate change on the population dynamics with species evolutionary response. Different variants of the model may or may not also take into account species’ active feedback on the global energy balance and/or the dependence of population growth rate on the ambient temperature, which is a generic property of many plant and animal species. The model shows that species extinction or survival following a climate change depends on a subtle interplay between the magnitude of the climate change and the rate of species’s adaptive evolution. The model predicts a distribution of extinction frequencies which is generally consistent with the fossil data. Our study therefore suggests that mass extinctions in the Earth history occurred due to r-tipping on the global scale.