Graduate Thesis Or Dissertation
 

Fingerprinting, reproductive behavior and pollinator dynamics of Buddleja davidii and interspecific hybrids

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/4j03d724r

Descriptions

Attribute NameValues
Creator
Abstract
  • Buddleja davidii (butterfly bush) is a highly adaptable landscape plant known for pollinator attraction. Unfortunately, it is also regarded as an invasive plant in highly disturbed environments across the globe. It is an invasive species in Oregon, officially classified as a class B noxious weed in 2004. Currently the state only allows sale of B. davidii that are reported to represent a 98% reduction in fertility by the breeder or any interspecific hybrid proven by pedigree. The breeding projects aimed at reducing invasive potential generally include interspecific crosses between tetraploid B. davidii and several diploid to tetraploid crossing partners. This has resulted in a proliferation of cultivars, increasing the chance of cultivar misidentification. The efficacy of these interspecific crosses in reducing fertility, and the actual effect that the crossing has on genome size of the hybrids has yet to be studied. Additionally it is unclear that reducing fertility alone will be useful in reducing invasive potential, as there are many other lifestages in the woody perennial lifecycle to consider. Finally the effect of selling and growing only low fertility cultivars of a plant known to attract pollinators on pollinator populations is worth considering. Will the new cultivars be as attractive to pollinators as fully fertile invasive cultivars? Potential missteps in cultivar identification were addressed through identifying and applying cross-transferrable microsatellite markers designed for B. davidii and closely related species. A subset of markers (Bud_03, Bud_10, and Bud_13) successfully amplified loci across B. davidii cultivars in the study as well as several classes of interspecific hybrids, involving B. alternifolia, B. globosa, B. fallowiana and B. lindleyana. The marker set should be of use in cultivar identification, intellectual property protection and possibly further developed to detect traces of interspecific hybridization in naturalized B. davidii stands. Relative fecundity of all cultivars was analyzed several ways: counting of open pollinated seedlings generated in the study field, counting of seedlings through controlled crossing, and counting of seedlings produced by an open pollinated (OP) population collected from the study field. Both study years in the field saw significant differences in cultivars for seedling production (Kruskal-Wallis tests p= 2.2e-16 in 2020 and 2021). Top three most fertile hybrids when considering how many seedlings a plant in the field could produce (seedlings counted from a single inflorescence * number of inflorescences produced by that plant) included interspecific hybrids in both years. In 2021, the most fecund cultivar in the field was Blaze Pink™, calculated to produce a mean of 5,698,664.3 seedlings per year. Lowest fecund cultivars in the field were all either interspecific cultivars or cultivars with unknown pedigree, showing that interspecific hybridization is a means of reducing fecundity. Controlled crossing experiments generally showed similar patterns to field crossing for female fecundity. Male fecundity was also assessed using greenhouse crossing. Several cultivars that constantly exhibited a reduction in fecundity by 98% across trials showed elevated male fecundity, including ‘Purple Haze’(15.4% relative male fecundity), Flutterby Petite ® Tutti-Fruitti (11.1% relative male fecundity), and Flutterby Petite® Blue Heaven (29.0% relative male fecundity). Sowing of OP population and subsequent seedling counts revealed few upticks in fecundity amongst low fecundity cultivars- many of which did not produce seedlings for analysis. A matrix modelling procedure was conducted to generate asymptomatic growth rates (λ) values for three fecundity levels. We performed elasticity analysis to identify lifestages to target for reducing λ. Population modelling conducted on three select cultivars ‘Purple Haze’(λ=5.74), ‘Grand Cascade’(λ=66.15), and ‘Royal Red’(λ=65.45) confirmed the efficacy of reducing fecundity as a means for reducing population growth according to elasticity analysis of several lifestages. Flow cytometry conducted on cultivars did not show high rates of successful interploidy crossing. Many cultivars that could be triploid by parentage instead appear to be tetraploid, though chromosome counts are still needed to confirm. Additionally genome size measurements of five previously uncharacterized Buddleja species is reported. There were significant differences between cultivars in terms of pollinator attraction including and excluding honey bees in 2020 (Kruskal-Wallis tests, P= 1.75 e-08 and P=.0001 respectively) and 2021 (Kruskal-Wallis tests P=1.23 e-08 and P= 7.27 e-11 respectively). Pearson’s correlation coefficient identified no strong correlation between fecundity and pollinator attraction (including honey bees) for either year (Pearson correlation coefficient, P= .09 in 2020,P =.67 in 2021). Factor Analysis of Mixed Data identified pollen presence/absence, inflorescence count, and color as significant contributors to overall variation in the population of Buddleja plants in both study years. These may be good traits to target in future studies designed to better understand which floral resources are most attractive to pollinators in Buddleja.
License
Resource Type
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Rights Statement
Funding Statement (additional comments about funding)
  • Funded by the Horticultural Research Institute and the Oregon Specialty Crop Block Grant.
Publisher
Peer Reviewed
Language

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details StillCaraM2023.pdf 2023-03-27 Public Download