Systematics Section / ASPT
Mercure, Marjorie , Bruneau, Anne .
Hybridization between the escaped Rosa rugosa Thunb. and the native R. blanda Ait. along the St. Lawrence River estuary.
Rosa rugosa is an aggressive ornamental shrub introduced from Asia in the last century. It is commonly used in breeding for its great hardiness, vigour and long blooming period. Although of interest to horticulturists, these qualities also could have contributed to the escape from cultivation and subsequent establishment of R. rugosa in coastal northeastern North America. Dense colonies are found along the shores of the St. Lawrence River estuary where it shares common habitats with the native R. blanda. Preliminary morphological observations suggested frequent hybridization between these species. Nearly 200 individuals of parental species and putative hybrids were collected in pure and sympatric populations along R. rugosa’s naturalized range to evaluate the geographical, genetic and morphological extent of this hybridization. We developed allele-specific primers to assay highly diagnostic single nucleotide polymorphisms (SNPs) markers from one chloroplast and four nuclear introns. Our results confirm the abundant hybridization between these species and show that an uncommon bilateral introgression occurs in sympatric populations. Hybrids have been found in every sympatric population, showing the weakness of reproductive barriers between these species. Morphological data are concordant with molecular data and provide additional evidence for the presence of a few backcrosses. Morphological analyses yielded diagnostic characters for the field identification of hybrids and monitoring of the hybrid zone. This hybridization could ultimately lead to the localized genetic assimilation of R. blanda in the area of sympatry and to the formation of an invasive hybrid. This study supports the notion that introduced species are not only threatening native biodiversity by competing for habitats but that they also threaten, through introgression, the genetic integrity of native species.
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1 - Université de Montréal, Institut de recherche en biologie végétale, 4101 rue Sherbrooke est, Montréal, Québec, H1X 2B2, Canada
Rosa rugosa Thunb.
Rosa blanda Ait.
Low-copy Nuclear Markers
Presentation Type: Oral Paper:Papers for Sections
Location: International Ballroom South/Hilton
Date: Wednesday, July 11th, 2007
Time: 3:30 PM