Reciprocal invasions in East Asia and eastern North America: shared phylogeography and ecology, contrasting invasion pathways
John SILANDER, Jenica ALLEN
Univeristy of Connecticut, Storrs, CT, USA
East Asia and eastern North America share a large number of reciprocally introduced invasive plant species. Each region
views many of these species as the most invasive and problematic of their naturalized alien flora. However, this seeming
symmetry and the fact that both regions share strong phylogeographic linkages and are dominated by similar natural
community types, belie the striking differences in life histories and functional traits of the worst invaders in each
region. The most serious plant invaders in eastern North America tend to occur in and around forests and are perennial,
woody, bird-dispersed species with moderate levels of shade tolerance. In stark contrast, the invasive species in East
Asia originating from eastern North America are primarily short-lived herbaceous plants that colonize ruderal sites and
the edges of croplands. Why this asymmetry occurs is not well understood despite past attempts to synthesize data.
Using regional or county-wide databases of invasive alien species, we have been able to document and contrast
differences among countries and between regions in the groups of species that have become invasive and their functional
traits. We have supplemented this with remotely sensed data on land-use geometry and the history of introductions
across countries. We can explain many of the dissimilarities in the invasive alien floras between regions by striking
differences in: historical plant trade and associated international commerce, timing in alien plant introductions,
horticultural landscape and cultural aesthetics, and current and past land-use patterns and geometry.
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© 2012 Organizing Committee
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