Patterns of hybridization and hybrid survival in the invasive alien Fallopia complex (Polygonaceae)

in Plant Ecology and Evolution (2011), 144(12-18),

Background -- Hybridization and polyploidization are considered important driving forces of invasive processes. In the invasive Fallopia spp. complex, hybridization between taxa of various ploidy levels ... [more ▼]

Background -- Hybridization and polyploidization are considered important driving forces of invasive processes. In the invasive Fallopia spp. complex, hybridization between taxa of various ploidy levels has been experimentally demonstrated. Extensive genetic variation has also been observed among hybrids in the field. However, what makes a certain hybridization event of evolutionary importance is still the subject of speculation considering the invasive potential of hybrid Fallopia. Aims -- The present study examined landscape scale patterns of interspecific hybridization within the alien invasive Fallopia complex, and tested whether cold winter might act as selective agent for hybrid survival. Methods -- Eighty seeds per clone were collected from four taxa (F. japonica, F. sachalinensis, F. aubertii, and F. xbohemica) and sown in greenhouse and outdoor conditions. Ploidy levels of the resulting seedlings were determined by flow cytometry at early stages of seedling growth and compared to those of mature clones present in the same landscapes. Key results -- The four studied taxa were involved in interspecific hybridization patterns. Seedlings resulting from hybridization had a large range of ploidy levels, including aneuploid and euploid progeny, and polyploid levels that were not observed in mature clones. Cold winter had a negative effect on germination success. However, a comparison of ploidy levels of seedlings that survived the cold winter with those grown under greenhouse conditions indicated that cold winter was not a significant selection agent for particular ploidy levels. Conclusions -- Our results stress the importance of interspecific hybridization and polyploidization events in generating invasive hybrids in the alien Fallopia spp complex. Cold winter represents a selection agent for the survival of early stages of progeny but does not explain the discrepancies in ploidy levels between produced seedlings and currently occurring mature clones. [less ▲]

Decline Of Endemic Oncocyclus Irises (Iridaceae) Of Lebanon: Survey And Conservation Needs

in Oryx (2009), 43(1), 91-96

Invasions biologiques: un peu de vocabulaire

in Silva Belgica (2009)

Les plantes exotiques envahissantes en Belgique ont-elles des impacts?

in Parcs & Réserves (2009), 64(4), 10-16

Contribution Of Delayed Autonomous Selfing To Reproductive Success In Kosteletzkya Virginica

in Belgian Journal of Botany (2008), 141(1), 3-13

Hybridisation efficiency in generating Hybridisation efficiency in generating invasive progeny in the alien Fallopia (Polygonaceae) complex

Poster (2007, November 16)

Hybridization And Sexual Reproduction In The Invasive Alien Fallopia (Polygonaceae) Complex In Belgium

in Annals of Botany (2007), 99(1), 193-203

† Background and Aims The knotweed complex, Fallopia spp. (Polygonaceae), belongs to the most troublesome invasive species in Europe and North America. Vegetative regeneration is widely recognized as the ... [more ▼]

† Background and Aims The knotweed complex, Fallopia spp. (Polygonaceae), belongs to the most troublesome invasive species in Europe and North America. Vegetative regeneration is widely recognized as the main mode of reproduction in the adventive regions. However, the contribution of sexual reproduction to the success of these invasive species has only been detailed for the British Isles. An examination was made as to how hybridization may influence the sexual reproduction of the complex in Belgium and to determine how it may contribute to the dispersal of the species. † Methods Studies were made of floral biology, reproductive success, seed rain, seed bank, germination capacity, seedling survival and dispersal capacity in order to characterize the reproductive biology of the species. Moreover, chromosome counts and flow cytometry were used to assess the hybrid status of seedlings produced by sexual reproduction. † Key Results In the area investigated, extensive sexual reproduction by hybridization within the complex, including one horticultural species, was demonstrated. A small percentage of seeds may be dispersed outside the maternal clone (.16 m) allowing the formation of genetically differentiated individuals. Seed germination was possible even after a winter cold period. †Conclusions The extensive sexual reproduction by hybridization could further contribute to the dramatic invasive success of knotweeds in Belgium and should not be underestimated when considering control and management measures. [less ▲]

Spatio-temporal demographic variation and reproductive strategy in rare endemic Oncocyclus irises (Iridaceae) of Lebanon

Poster (2006)

Hybridization and polyploidy: driving forces of evolutionary processes in the Fallopia spp complex

Conference (2006)

Hanging in there by a fall – The Oncocyclus of Lebanon

in British Iris Society Yearbook (2003)