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Big thistle eats the little thistle: does unidirectional introgressive hybridization endanger the conservation of O nopordum hinojense ?
Author(s) -
Balao Francisco,
CasimiroSoriguer Ramón,
GarcíaCastaño Juan Luis,
Terrab Anass,
Talavera Salvador
Publication year - 2015
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13156
Subject(s) - introgression , biology , hybrid , backcrossing , amplified fragment length polymorphism , evolutionary biology , gene pool , plant evolution , genome , genetics , zoology , botany , genetic diversity , population , gene , demography , sociology
Summary Hybridization is known to have a creative role in plant evolution. However, it can also have negative effects on parental species. O nopordum is a large genus whose species frequently hybridize. In the Southwest Iberian Peninsula, the rare O . hinojense co‐occurs with the widely distributed O . nervosum , and hybrids between these two taxa have been described as O . × onubense . In this study we determine the extinction risk in a hybrid zone, both for hybrids and parentals, using analyses of morphological and cytogenetic traits as well as genetic markers and demographic models. To investigate the introgression process we used amplified fragment length polymorphism ( AFLP ) markers, Bayesian analyses and genome scan methods. Morphology, genome size and molecular markers confirmed homoploid hybridization and also indicated unidirectional backcrossing of F 1 hybrids with O. nervosum , which is likely to swamp O. hinojense , the parental with lower pollen size and a very low fruit set (8%). Genome scan methods revealed several loci significantly deviating from neutrality. Finally, our demographic modeling indicated that the higher fitness of O. nervosum threats the survival of O . hinojense by demographic swamping. Our study provides strong new evidence for a scenario of rapid extinction by unidirectional introgression and demographic swamping. The multifaceted approach used here sheds new light on the role of introgression in plant extinctions.