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Abstract Detail


Ecological Section

Hardiman, Nicole [1], Culley, Theresa M. [1].

Cultivar fitness and hybrid advantage in invasive Pyrus calleryana (Rosaceae).

There is increasing evidence of important evolutionary changes that occur as an introduced species becomes invasive. During this transition, some aspect of the population biology changes, which allows for an altered genetic background in introduced populations and a subsequent increase in invasive potential. Interspecific hybridization is a well-studied mechanism for increasing genetic diversity, subsequently releasing small, founder populations from genetic bottlenecks, and thus enhance invasive potential. Theoretical implications of hybridization also apply to intraspecific situations, where hybrids are formed between members of partially isolated and genetically distinct populations. Of the total genetic variance generated by hybridization, only a subset of genotypes may have an advantage in the new habitat. Additionally, later generation hybrids may have higher fitness over time compared to initial hybrids as selection favors traits that enhance survival and reproduction. Pyrus calleryana is an ornamental tree that has recently become invasive. Approximately 25 different cultivars are commercially available, and crossing between these genetically distinct cultivars has resulted in invasive populations across the United States. The goal of this research was to identify specific hybrid progeny that have an advantage for successful establishment and subsequent increased invasive potential. This was accomplished in two ways: 1) by examining reproductive output of cultivars and the subsequent success of early-generation hybrids and 2) by comparing the reproductive output of early-generation hybrids derived from cultivars and late-generation hybrids in wild populations. Measures of fitness included fruit weight, number of seeds per fruit, seed weight, percent germination, mortality, and relative growth rate. Significant differences indicated specific hybrid genotypes that were more fit than others. Coupled with successful exploitation of new conditions found in the introduced environment, hybridization can be implicated as a key mechanism to the evolution of invasive potential.


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1 - University of Cincinnati, Department of Biological Sciences, 614 Rieveschl Hall, Cincinnati, Ohio, 45221, USA

Keywords:
Pyrus calleryana
hybridization
intraspecific
cultivar
invasive.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P49025
Abstract ID:1945


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