Rapid evolution

One of the important questions in ecology is how evolution affects ecological systems. Conventionally, the evolutionary time scale is usually assumed to be too long, such like millions of years, when compared with the life time of species. However, how exactly the evolutionary process occurs and changes ecological systems to become the contemporary structures is unknown. Moreover, the evolution time scale could be comparable to the ecology, such that antibiotic resistance keeps emerging rapidly in the treatment for bacterial infections. In fact, anomalous dynamics of ecosystems under evolution has been observed in lab experiments, which is so-called "rapid evolution". Rapid evolution may arise from fast response to strong selection among distinct strains. By applying statistical mechanics approach and stochastic simulation to a generic simple model based on the individual-level behaviors, we find the intrinsic stochastic nature of the system can lead to the emergence of rapid evolution. We also worked out the phase diagram where fluctuation-determined extinction is considered. Phys Rev. E 90, 050702(R) (2014).

Ecological collapse and the emergence of traveling waves in transitional turbulence

How a laminar flow becomes turbulence has been a long-standing problem in fluid dynamics and is important in various industrial applications. As Reynolds number increases, a single turbulent puff in a long pipe undergoes spontaneous relaminarization and spatiotemporal intermittency and can expand into turbulent slugs, exhibiting non-trivial statistics in transient times that have been found in experimental observation and hydrodynamics simulations. I am studying transitional turbulence by connecting it to spatially-extended ecosystems. We have found the extinction event and the formation and propagation of spatial patterns in predator-prey systems can be interpreted as the instabilities in fluid systems. I am also studying such connection in other hydrodynamics systems. arXiv:1505.02807 (2015).