香蕉视频

Join McGill grad Dr. Rees Kassen (University Research Chair in Experimental Evolution, Dept of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa) for a talk on the evolution of companionship and predation. His recent work has found that most advantageous mutations have a small effect on fitness, while a few have quite large effects. For example, some of his research reported in the journal "Nature" last year cited predation as a trigger for evolutionary bursts. His lab found that the bacterium Pseudomonas fluorescens (named for its yellow colour), when well nourished, could rapidly evolve into a new variety when competing for dwindling food and oxygen inside a test tube. When a predator species of bacteria is introduced into the mixture, it grazes on the abundant fluorescens, reducing competition and delaying evolution. "What these results mean is that we have, for the first time since Darwin put forward his ideas on evolution by natural selection, a clear picture of what natural selection 'sees' when it chooses among new mutations," says Kassen. "Our results suggest it may be possible to predict the next evolutionary 'move' of a microbial population when faced with a novel environment. This research is essential to the endeavour of answering one key question: why are there so many species in the world?" Free, everyone welcome