Galloway Lab - University of Virginia

Biology Department
University of Virginia
Charlottesville, VA 22904

office 434-982-5010
lab 434-982-5599
fax 434-982-5626

Laura F. Galloway Plant Ecological Genetics

People in the lab
Laura F. Galloway
publications

post-doc:
Brian Barringer

graduate students:
Biology PhD:
Andrea Berardi
Ashley Dai
Lindsay Dierkes
Francis Kilkenny

undergraduates:
Campbell Grant
M. Brett Jones
A. Catherine Pham

Photos

For prospective graduate students

CURRENT RESEARCH PROJECTS

Maternal effects on life history
Laura Galloway
Parents may influence their offspring through genetic and environmental factors. We are using two approaches to evaluate intergenerational effects on life history evolution in the native wildflower Campanulastrum americanum (until recently Campanula americana). Our work focuses on the timing of seed germination because C. americanum seeds that germinate in the fall grow as annuals while those that germinate in the spring become biennials. Therefore maternal effects on germination timing will influence life span, fecundity and patterns of survivorship.

Parental Environmental Effects Campanula americana flower

with Julie Etterson (Univ. of Minnesota, Duluth)
Maternal and paternal environments may influence offspring characters. We found that parental light levels influence offspring germination and life history in Campanulastrum americanum. Offspring have three times greater fitness when grown in their maternal light environment than an alternate environment, indicating that maternal effects make a substantial contribution to adaptive evolution. We are currently evaluating maternal genetic effects on life history to provide a more holistic understanding of cross-generation effects.
Publications.

Effect of Maternal Phenology on Offspring Life History
with Kevin Burgess (Columbus State University)
Timing of flowering influences the timing of fruit maturation in C. americanum. Seeds from early season flowers ripen before those of later season flowers and have a greater potential to germinate in the fall as annuals. Therefore selection favoring the annual life history may act to either alter timing of seed germination or timing of flowering. We created early and late flowering individuals with artificial selection and environmental manipulation to determine the extent to which flowering time influences whether offspring grow as annuals or biennials.
Publications.

Evolution of Polyploids
Polyploidy, a doubling of the chromosome number, is a very common evolutionary change in plants. In particular autopolyploidy (within species chromosome doubling), results in changes in the amount, but not the type, of nuclear genetic material. Having twice as much genetic material may influence the evolution of polyploid species. For example, polyploids are predicted to have reduced levels of inbreeding depression relative to diploids because the probability of expressing recessive deleterious alleles is much lower if there are four alleles at a locus instead of the two present in diploids. Similarly, polyploids may accumulate genetic differentiation among populations more rapidly than diploids if either mutation accumulation increases with more loci or genetic changes in the "extra" gene copies are less likely to be removed by selection. We are conducting studies to address these ideas.

Polyploidy & Mating System
Campanulastrum americanum is insect-pollinated and self-compatible. Although there is a greater potential for selfing from within plant pollen movement in larger biennials, population-level selfing rates are negligible suggesting mating system does not differ between annuals and biennials. Inbreeding depression measured in three sequential cohorts in the field resulted in selfed offspring having only 6% of the fitness of outcross progeny. Cryptic self-incompatibility appears to maintain high outcrossing rates and inbreeding depression in this self-compatible species. High levels of inbreeding depression are surprising as theory predicts polyploids will have reduced inbreeding depression relative to diploids.
Publications.

Polyploidy & Population Differentiation
Populations in separate locations may differ from one another due to a combination of natural selection and genetic drift. In autotetraploid C. americanum first generation (F1) hybrids between nearby populations express hybrid vigor, outperforming their parents, while hybrid inferiority is expressed in crosses between more distant populations. F2 hybrids had greater outbreeding depression than F1 in some cases and less in others. Both cytoplasmic and nuclear genes contribute to this outbreeding depression. Outbreeding depression is unusual in first generation within-species hybrids. We currently gaining further insight into these unexpected results by expanding the spatial scale and complementing the phenotypic studies with genetic analyses. Previous work with Charles Fenster (Univ. of Maryland) found hybrid vigor in F1 crosses and hybrid breakdown in F3 hybrids for populations of diploid Chamaecrista fasciculata separated by 100m to 2000km. To determine whether differences in ploidy level may underlie the difference in outbreeding depression between these studies, we plan to initiate a project with Campanula rotundifolia, an autopolyploid series, with diploid, tetraploid and hexaploid populations.
Publications.

Graduate Student Research
Range expansion in Japanese Honeysuckle: Intraspecific hybridization?
Francis Kilkenny
I study the role of intraspecific hybridization in the North American

range expansion of the invasive vine Japanese honeysuckle (Lonicera japonica). If populations are genetically differentiated, hybridization between populations may generate evolutionary novelty and allow hybrid individuals to occupy niches separate from either parent. Enhanced performance in the hybrid generations may occur through heterosis or, in later generations, from the rise novel traits through genomic recombination. I am experimentally testing this hypothesis by constructing F1 and F2 hybrid generations from crosses between and among populations in the core and margin of the current range. Offspring will be planted in common gardens in the core, at the margin and beyond the range edge to compare the fitness of hybrid individuals and non-hybrid individuals. The role of hybridization in range expansion may depend on the population genetic structure within and at the edge of the range. Therefore I am also using population genetics approaches to determine how genetic variation is distributed within and between populations and regions, as well as the level of admixture between populations.

Integration of pollination and defense related traits
Lindsay Dierkes
Tradescantia ohiensis has considerable variation in flower color. I am interested in whether direct, pollinator-mediated selection maintains this variation in flower color or if it is a result of indirect selection via correlated traits. I am especially interested in traits that are correlated with flower color due to a common biosynthetic pathway, because such a correlation could pose a long term constraint to adaptation. Flower color in T. ohiensis is a result of anthocyanins, a terminal product of flavonoid synthesis. Other flavonoids influence herbivore defense and tolerance of extreme temperatures. Preliminary results suggest that both pollinator-mediated selection and abiotic factors such as soil nutrients, temperature and light contribute to variation in flower color. Check my web page for more information!

Selection for mate choice
Ashley Can Dai

I am interested in sexual selection in plants. Sexual selection has been studied extensively in animals but has received less attention in plants. This is partially because plants don't have active behavior making sexual selection unlikely to be analogous to animals, and most plants are hermaphroditic and it is difficult to tease the contribution of selection to male and female function apart. I am using the passion flower (Passiflora incarnata), which is functionally andromonoecious, to explore how sexual selection plays a role in floral trait evolution. In particular, which floral traits experience sexual selection? Is sexual selection important in maintaining andromonoecy? Does sexual selection change in pollen-limited environments?

Past lab members ....

Undergraduate Research
Current Projects:

Campbell Grant	My project addresses how invasive species spread using Japanese honeysuckle (Lonicera japonica) as a model organism. I am using DNA markers to determine whether the frequency of sexual reproduction and vegetative spread differ between the center and the edge of Lonicera‘s range
M. Brett Jones	C. americanum exhibits different life history schedules based upon the timing of germination, with individuals that germinate in the fall growing as annuals and those that germinate in spring becoming biennials. Furthermore, timing of flowering is strongly influenced by elevation. I am studying populations from different elevations to determine the relationship between maternal flowering phenology and offspring life history.
A. Catherine Pham	The invasive vine Japanese honeysuckle (Lonicera japonica) is believed to have been limited in its northward expansion by cold temperatures. However, continues to push its northern limits, so I am looking to see whether plants on the northern margin are evolving a tolerance to cold.
Past projects:
Deidra Jacobsen	Deidra explored how pollen limitation and herbivory influenced growth and reproductive success in Tradescantia ohioensis. She found that plants eaten by deer flowered first and had a similar number of flowers as uneaten plants whereas pollen limitation influence flower size. Deidra is from University of Nebraska and participated in Mountain Lake's REU program.
Susan Lin	Campanulastrum americanum is a favorite food of deer. Susan found that almost all plants growing in light gaps were eaten and subsequently died whereas fewer were browsed under the forest canopy and those that did recovered. Eaten plants bloomed later and were more likely to produce biennial offspring than uneaten plants. Susan participated in Mountain Lake's REU program; she graduated from Amherst College.

Contact Laura Galloway (lgalloway@virginia.edu) if you are interested in graduate studies or undergraduate research at UVA or Mountain Lake Biological Station

See also:
Evolution & Population Biology, University of Virginia
Biology Department, University of Virginia
Mountain Lake Biological Station