Gammon, Melinda , Kesseli, Rick .
A comparison of vegetative and reproductive success of the invasive species Fallopia japonica, Fallopia sachalinensis and Fallopia X bohemica (Polygonaceae) in a common garden experiment.
The Asian perennials Fallopia japonica (Japanese Knotweed), Fallopia sachalinensis (Giant Knotweed), and their hybrid Fallopia X bohemica, are aggressive invaders well established in Europe and the U.S. In Europe, where the genetic diversity and ecology of these taxa have been studied for over a decade, hybrids have been shown to be spreading faster than either parent species. However, the reproductive dynamics and relative success of entities in U.S. swarms are not well understood. Our observations of variation in taxon frequency, morphology, fertility, ploidy, and genetic diversity have raised questions about hybrid vegetative and sexual reproductive contributions, and suggest the U.S. introduction history of knotweeds is unique. In 2005 and 2006, over 200 greenhouse created and field collected seeds were germinated and planted in a common garden, with six cross types and 15 families represented. Eleven factors of ecological success were measured. In nearly all cases, hybrids were either equivalent to one or both parental species for a given variable, or demonstrated hybrid vigor. All hybrid types showed higher photosynthetic rates, while F1 hybrids also had higher leaf N concentrations. F1 progeny and those resulting from backcrosses to F. sachalinensis demonstrated higher vegetative biomass. Reproductively, F1 hybrids had higher seed mass and number, but decreased germination success. F2 plants had the lowest female investment and fertility, yet had pollen viability equivalent to parentals. Only backcrosses to F. japonica showed significantly lower pollen fertility. This powerful combination of vegetative and reproductive capabilities may be responsible for the spread of hybrids in the U.S., and could lead to increased adaptability of the complex. While extensive vegetative spread in F. japonica has in the past been the main focus of management, we propose a greater focus on F. sachalinensis and swarms as a whole, as well as the prevention of flowering and seed set.
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1 - University of Massachusetts Boston, Biology, 100 Morrissey Boulevard, Boston, MA, 02171, USA
2 - University of Massachusetts Boston, Biology, 100 Morrissey Boulevard, Boston, MA, 02125, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Ontario/Hilton
Date: Monday, July 9th, 2007
Time: 2:00 PM