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Reproductive success of cultivated Pyrus calleryana (Rosaceae) and establishment ability of invasive, hybrid progeny
Author(s) -
Hardiman Nicole A.,
Culley Theresa M.
Publication year - 2010
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1000113
Subject(s) - biology , intraspecific competition , hybrid , cultivar , invasive species , botany , zoology
• Premise of the study : Pyrus calleryana Decne., an ornamental tree species introduced from China, is a relatively new invasive that has only recently begun to spread across the United States after intraspecific hybridization between cultivars. The function of such hybridization in the evolution of invasiveness is still relatively understudied, especially with respect to the initial establishment and persistence of invasive genotypes. Multiple introductions of genetically divergent populations or cultivars may benefit from new genetic combinations created during hybridization events and/or release from Allee effects in founder populations. • Methods : We quantified the outcome of intraspecific hybridization between cultivars of P. calleryana in a common garden. Measures of the reproductive success and establishment ability of their early‐ and advanced‐generation hybrid offspring were collected to assess the likelihood of particular cultivar genotypes to establish in invasive populations. These traits also were compared between cultivated and invasive parents to identify any generational differences in invasive potential. • Key results : Differences were detected in measures of reproductive ability, but no group emerged as consistently more fecund. Advanced‐generation hybrids also had significantly less biomass, indicating a reduction in hybrid performance relative to that of the cultivated progeny. • Conclusion : Ultimately, this study indicates that increased spread of P. calleryana has been initiated by introduction of multiple cultivar types and subsequent widespread planting and is not the result of an inherent fitness advantage of hybrid progeny.