title: Dispersal pathways and genetic differentiation among worldwide populations of the invasive weed Centaurea solstitialis L. (Asteraceae).
abstract: The natural history of introduced species is often unclear due to a lack of historical records. Even when historical information is readily available, important factors of the invasions such as genetic bottlenecks, hybridization, historical relationships among populations and adaptive changes are left unknown. In this study, we developed a set of nuclear, simple sequence repeat markers and used these to characterize the genetic diversity and population structure among native (Eurasian) and non-native (North and South American) populations of Centaurea solstitialis L., (yellow starthistle). We used these data to test hypotheses about the invasion pathways of the species that were based on historical and geographical records, and we make inferences about historical relationships among populations and demographic processes following invasion. We confirm that the center of diversity and the native range of the species is likely the eastern Mediterranean region in the vicinity of Turkey. From this region, the species likely proceeded to colonize other parts of Europe and Asia via a slow, stepwise range expansion. Spanish populations were the primary source of seed to invade South America via human-mediated events, as was evident from historical records, but populations from the eastern Mediterranean region were also important. North American populations were largely derived from South America, but had secondary contributors. We suggest that the introduction history of non-native populations from disparate parts of the native range have allowed not just one, but multiple opportunities first in South America then again in North America for the creation of novel genotypes via intraspecific hybridization. We propose that multiple intraspecific hybridization events may have created especially potent conditions for the selection of a noxious invader, and may explain differences in genetic patterns among North and South America populations, inferred differences in demographic processes, as well as morphological differences previously reported from common garden experiments.
authors.affiliation: Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, United States of America.
authors.forename: Renée L
authors.initials: RL
authors.lastname: Eriksen
authors.affiliation: Instituto de Ciencias de la Tierra y Ambientales de La Pampa (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de La Pampa), Santa Rosa, La Pampa, Argentina.
authors.forename: José L
authors.initials: JL
authors.lastname: Hierro
authors.affiliation: Biyoloji Bölümü, Fen-Edebiyat Fakültesi, Adnan Menderes Üniversitesi, Aydın, Turkey.
authors.forename: Özkan
authors.initials: Ö
authors.lastname: Eren
authors.affiliation: Environmental Studies Department, De Anza College, Cupertino, California, United States of America.
authors.forename: Krikor
authors.initials: K
authors.lastname: Andonian
authors.affiliation: Centre for Ecological Research (MTA ÖK), Vácrátót, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Török
authors.affiliation: Departamento de Ecosistemas y Medio Ambiente, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Pablo I
authors.initials: PI
authors.lastname: Becerra
authors.affiliation: Centre for Functional Ecology, Departamento de Ciências da Vida, Faculdade de Ciência e Tecnologia da Universidade de Coimbra, Coimbra, Portugal.
authors.forename: Daniel
authors.initials: D
authors.lastname: Montesinos
authors.affiliation: Institute of Botany, Ilia State University, Tbilisi, Georgia.
authors.forename: Liana
authors.initials: L
authors.lastname: Khetsuriani
authors.affiliation: Institute of Biological Research, Biological Control Laboratory, Iasi, Romania.
authors.forename: Alecu
authors.initials: A
authors.lastname: Diaconu
authors.affiliation: Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, United States of America.
authors.forename: Rick
authors.initials: R
authors.lastname: Kesseli
mesh_terms: D031179:Centaurea / Q000235:genetics* / Q000502:physiology*; D030541:Databases, Genetic; D020224:Expressed Sequence Tags / Q000378:metabolism; D005787:Gene Frequency; D056426:Genetic Loci / Q000235:genetics; D014644:Genetic Variation; D058865:Introduced Species; D018895:Microsatellite Repeats / Q000235:genetics; D063148:Plant Dispersal; D057685:Plant Weeds / Q000235:genetics* / Q000502:physiology*