Hybridization as a stimulus for the evolution of invasiveness in plants? |
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Authors: | Norman C Ellstrand Kristina A Schierenbeck |
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Institution: | (1) Department of Botany and Plant Sciences and Center for Conservation Biology, University of California, Riverside, CA 92521-0124, USA;(2) Department of Biology, California State University, Chico, CA 93740, USA |
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Abstract: | Summary Invasive species are of great interest to evolutionary biologists and ecologists because they represent historical examples
of dramatic evolutionary and ecological change. Likewise, they are increasingly important economically and environmentally
as pests. Obtaining generalizations about the tiny fraction of immigrant taxa that become successful invaders has been frustrated
by two enigmatic phenomena. Many of those species that become successful only do so (i) after an unusually long lag time after
initial arrival, and/or (ii) after multiple introductions. We propose an evolutionary mechanism that may account for these
observations. Hybridization between species or between disparate source populations may serve as a stimulus for the evolution
of invasiveness. We present and review a remarkable number of cases in which hybridization preceded the emergence of successful
invasive populations. Progeny with a history of hybridization may enjoy one or more potential genetic benefits relative to
their progenitors. The observed lag times and multiple introductions that seem a prerequisite for certain species to evolve
invasiveness may be a correlate of the time necessary for previously isolated populations to come into contact and for hybridization
to occur. Our examples demonstrate that invasiveness can evolve. Our model does not represent the only evolutionary pathway
to invasiveness, but is clearly an underappreciated mechanism worthy of more consideration in explaining the evolution of
invasiveness in plants.
This paper was presented at the National Academy of Sciences colloquium “Variation and Evolution in Plants and Microorganisms:
Toward a New Synthesis 50 Years After Stebbins,” held January 27–29, 2000, at the Arnold and Mabel Beckman Center in Irvine,
CA.
Reprinted from PNAS 97(13): 7043–7050 (2000). |
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Keywords: | evolution gene flow hybrid species hybridization invasive plants weeds |
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