Royal Society Publishing

Comparative Ecology of the Native and Alien Floras of the British Isles

M. J. Crawley, P. H. Harvey, A. Purvis


Why do different plant species thrive where they do? This is a difficult question to answer because plants have invaded new niches and subsequently evolved to become better adapted within those niches. Distinguishing the traits that allow successful invasion and those that are evolved adaptations to current environments is not usually possible. We attempt to identify life history components that allow successful invasion by analysing the life history variables and ecological requirements of plant species that have successfully invaded the U.K. in recent years. The British flora is uniquely suited for this analysis because we have precise information on the dates of arrival, rates of spread and final spatial distribution of all our alien vascular plant species. Data on alien plants controls for evolution after invasion because there has been relatively little time for evolution to occur. We use modern phylogenetically-based comparative methods in an attempt to tease apart those components of life histories that have allowed successful invasion (large seeds, tall stature, protracted seed dormancy) from those that are irrelevant (dispersal syndrome, mating system, leaf shape).