Evidence of hybridization between Lythrum salicaria and L. alatum in North America
Although Lythrum salicaria (Lythraceae) was introduced into North America from Europe in the early 1800s, it did not become invasive until the 1930s. Whether hybridization with L. alatum could have played a role in its ultimate spread was tested. Evidence indicated that L. salicaria may have hybridized with L. alatum, but if so, only a small fraction of L. alatum genes have been retained in the genome of L. salicaria. This is unlikely to have led to a dramatic adaptative shift unless the introgression of a few key genes into L. salicaria stimulated a genomic reorganization. It is more likely that crossing among genotypes of L. salicaria from multiple introductions provided the necessary variability for new adaptations to arise.
Houghton-Thompson J, Prince HH, Smith JJ, Hancock J (2005) Evidence of hybridization between Lythrum salicaria (Purple Loosestrife) and L. alatum (Winged Loosestrife). Annals of Botany 96, 877-885.
Available online at www.aob.oxfordjournals.org