Molecular Ecology and Evolution
Green, Adam , Ramsey, Tara , Ramsey, Justin .
Invasion of ivies (Hedera spp, Araliaceae) in North American coastal forests.
Ivy (Hedera spp., Araliaceae) is a polyploid complex of 13 species characterized by a woody stem and a vine habit. Native to Eurasia and North Africa, ivy is cultivated worldwide and has become an aggressive invader of North American coastal forests. Naturalized populations form dense mats in forest understories and entomb trees with evergreen foliage, competing for sunlight and nutrients as well as increasing susceptibility to wind-fall and ice damage. Proper species identification is a critical first step in limiting recurrent introduction of invasive plants from horticultural sources. Unfortunately, identification of invasive ivy populations is difficult because of the subtle nature of morphological traits distinguishing natural Hedera species and also the incidence of cultivar types in forest habitats. To characterize the occurrence of Hedera species in North America, we assembled a comprehensive field collection consisting of 414 plants from 75 populations along the Atlantic Seaboard (Florida to New York) and the Pacific Northwest (Oregon and Washington). Chloroplast haplotypes recovered from invasive populations were identical or similar to those of European ivies (H. helix and H. hibernica) but distinct from those of Asian, Middle Eastern, and North African species. DNA content estimates revealed that diploid H. helix dominates the Atlantic Seaboard (144 of 182 sampled plants) while tetraploid H. hibernica is most abundant in the Pacific Northwest (232 of 283 sampled plants). Triploid genotypes – putative F1 hybrids between H. helix and H. hibernica – were also discovered (7 of 414 sampled plants). These results indicate differential invasion of Hedera species that presumably reflects either (1) unequal historic representation of taxa in gardens and urban landscaping; or (2) predisposition of some species to invade coastal forests of North America. Field transplant experiments are planned to critically evaluate survival and growth of Hedera species in eastern and western forests.
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1 - University of Rochester, Biology, 213 Hutchison Hall, River Campus, Rochester, NY, 14627, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Boulevard B/Hilton
Date: Wednesday, July 11th, 2007
Time: 8:15 AM