Abstract Detail

Conservation Biology

Knope, Matthew [1], Pender, Richard [2], Crawford, Daniel [3], Wieczorek, Ania [4].

Alien Congeners are Unlikely to Hybridize with Native Hawaiian Bidens (Asteraceae) .

One way by which invasive plant species may threaten native plants is genetic assimilation through hybridization. The risk is potentially heightened if the native populations are small relative to the alien species, a situation common on oceanic islands, where populations of native and endemic species may be small in size and number. A first step in assessing the potential threat of genetic assimilation of native species by hybridization with invasive plants is to determine whether they are cross compatible. The Hawaiian Islands flora may be particularly susceptible to the adverse affects of hybridization with invasive species. Approximately 89% of the angiosperm species native to Hawaii are endemic, and hybridization with alien congeners is known to occur. The genus Bidens (Asteraceae: Coreopsideae) is a large lineage in Hawaii, with 19 species and eight subspecies endemic to the archipelago. Two alien congeners in Hawaii are Bidens pilosa and B. alba, the former a cosmopolitan subtropical and tropical weed. Bidens pilosa would seem to pose a particular threat to the Hawaiian species because it has the same chromosome number (2n = 72) and it occurs as sister to the Hawaiian taxa in a large clade. Crosses between B. pilosa and nine endemic taxa, and crosses of B. alba with six Hawaiian endemics, failed to produce viable seed. While the two invasive species are cross compatible, seed set is low, presumably because of their different ploidal levels. Although B. alba is considered self incompatible in its native range, it sets self seed in Hawaii, as was also the case for introduced populations in Brazil. While the present data are not definitive evidence that elements of Bidens endemic to Hawaii and the two invasive congeners could never hybridize to produce viable hybrids, they do indicate that there are strong compatibility barriers between them, and the threat of genetic assimilation appears minimal.

Broader Impacts:

1 - Stanford University, Department of Geological and Environmental Sciences, 385 Serra Mall, Stanford, CA, 94305, USA
2 - University of Hawaii at Manoa, Botany Department, 3190 Maile Way, Honolulu, HI, 96822, USA
3 - University of Kansas, Department of Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, Haworth Hall, Lawrence, KS, 66045-7534, USA
4 - University of Hawaii at Manoa, Department of Tropical Plant and Soil Sciences, 3190 Maile Way, Honolulu, HI, 96822, USA

Keywords:
cross compatibility
Bidens
Hawaii
invasives.

Presentation Type: Oral Paper:Papers for Topics
Session: 20
Location: Marlborough A/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 9:00 AM
Number: 20003
Abstract ID:170
Candidate for Awards:None