Rob Colautti
University of Toronto
I am currently in the final year of my Ph.D. thesis but I have been studying the ecology and evolution of invasive species for almost eight years and have published widely on the topic. My work on invasive species ranges from broad-scale biogeographical patterns to small-scale field and glasshouse experiments, as detailed below. In addition to ‘real’ science, I am also quite interested in the history and philosophy of science; particularly the methods and limits of scientific understanding, the ongoing ‘culture wars’ between certain atheistic and religious groups, and the poor quality of reporting of key scientific issues by the popular press.
I completed my Honour’s undergraduate (2001) and Masters (2003) degrees at the Great Lakes Institute, University of Windsor, with Dr. Daniel D. Heath and Dr. H.J. MacIsaac. This was a highly productive time for me as our group published widely invasions in North America’s Great Lakes. Most recent invertebrate invasions, like the zebra mussel (Dreissena polymorpha), are strongly associated with shipping activity. As part of my undergraduate and Masters theses we found that the majority of invertebrate invasions had been first discovered in the narrow corridor of water extending from the south of Lake Huron to the western basin of Lake Erie. This appears to be an effect of releasing ballast water, which ships use for stability, because ballast is routinely released to improve maneuverability in shallow water and narrow passages. Ballast water mixes with residual sediments and releases non-native invertebrates and their ‘resting stages’ (e.g. eggs) back into the Great Lakes.
During this time I also did some work on the use and misuse of terminology in scientific publications on biological invasions, and on the ‘enemy release hypothesis’. This idea proposes that introduced species become invasive because they leave behind many of the enemies that are present in their native range. Enemies are a generic term that could include predators, herbivores, parasites, or diseases. However, my reviews on the topic have questioned the generality of this hypothesis, primarily because (i) many of the most invasive plant species are heavily attacked by herbivores, and (ii) many of the introduced species that have not become invasive have also been released from many of their important ‘enemies’.
I am currently finishing my Ph.D. thesis under the supervision of Prof. Spencer C.H. Barrett in the department of Ecology and Evolutionary Biology at the University Toronto. For the last 5 years I have been conducting a series of experiments in the glasshouse and in the field to better understand the evolution purple loosestrife (Lythrum salicaria). Purple loosestrife was introduced to North America about 200 years ago, and we have been studying populations from eastern North America, many of which are less than 50 years old, according to herbarium records. To identify constraints on rapid evolution I am using a class of statistics known as ‘quantitative genetics’, which uses statistical analyses to understand the genetic basis of traits like growth rate, age of maturity, size at maturity, and seed production. So far I have found that evolution has occurred quite rapidly. Northern populations mature much earlier than southern populations, but suffer a ‘cost’ of reduced size. This appears to be adaptive since shorter growing seasons in northern populations limit flower pollination by insects. In the south however, where the growing season is longer, reproduction is not restricted by season length, but by plant size. The smaller size of plants in the north, combined with the shorter growing season, has important implications for the spread of the species because seed production is almost 20-fold lower in northern populations. This work suggests that there are limits to rapid evolution, which could lead to more effective control methods and the ability to predict the evolutionary response of native and introduced species to climate change.