Abstract Detail

Biogeography

Green, Adam F [1], Ramsey, Tara [2], Ramsey, Justin [2].

Polyploidy and the invasion of ivy (Hedera spp., Araliaceae) in North America.

Polyploidy is a common feature of agricultural weeds and natural area invaders. There are few studies comparing related diploid and polyploid exotics, however, and it is unclear what ecological and genetic factors favor the establishment and spread of polyploid taxa. We investigated the geographic distribution, size, and reproductive characteristics of diploid Hedera helix and tetraploid H. hibernica, sister species that are invading North American coastal forests. Although these species are virtually indistinguishable in field conditions, analysis via flow cytometry demonstrated consistent differences in DNA content. Diploid H. helix was dominant on the U.S. east coast (78.5% of sampled plants) while tetraploid H. hibernica was dominant on the U.S. west coast (72.2% of sampled plants). Nearly 5% of sampled plants were triploids, putative F1 hybrids (H. helix × hibernica), which heretofore were unknown from natural populations. Local co-occurrence of H. helix and H. hibernica in Washington state enabled us to compare the species while growing in sympatry. We found tetraploid H. hibernica to be the principle invader of forests despite cultivation of diploid H. helix in suburban neighborhoods. Moreover, individuals of H. hibernica were substantially larger and more frequently reproductive than individuals of H. helix. Because the ecogeographic distribution of H. helix and H. hibernica in North America mirrors that found in Europe, we hypothesize that cytotype invasion is mediated primarily by physiological adaptation to alternative environmental conditions rather than the genetic attributes of polyploidy per se.

Broader Impacts:

1 - University of Rochester, Biology, 213 Hutchison Hall, River Campus, Rochester, NY, 14627, USA
2 - University of Rochester, Department of Biology, 213 Hutchison Hall, River Campus, Rochester, NY, 14627, USA

Keywords:
polyploidy
plant invasion
Hedera
hybridization.

Presentation Type: Oral Paper:Papers for Topics
Session: 28
Location: 552B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 9:45 AM
Number: 28008
Abstract ID:522