SUDLER, K. NICOLE. School of Biological Sciences, University of Kentucky, 101 T.H. Morgan Bldg., Lexington, KY 40506. - Phenotypic selection on sexual reproduction vs. clonal expansion in five populations of Viola blanda.
Viola blanda is a common forest understory plant that produces
new individuals both sexually and vegetatively, via stolons. The goal
of this research was to evaluate the relative importance of plant size
on sexual reproduction and clonal expansion in five different
populations. Plant size was estimated using leaf number and leaf size.
Number of fruit capsules and number of stolons were employed as sexual
and clonal fitness measures, respectively. Phenotypic selection on
leaf number and leaf size was found to differ in both magnitude and
direction on several levels: 1) within fitness measures, among
populations, and 2) within populations, between sexual and clonal
fitness. There is some suggestion that different growth strategies are
being utilized in different populations. The interaction between leaf
traits and population (site) were significant for two of the five
populations in relation to sexual fitness and four out of five
populations relative to clonal fitness. The five populations are known
to differ in their distribution of light, soil type and understory
density. Selection differences on leaf number and leaf size may be in
response to local environmental conditions. No clear tradeoffs were
found between sexual reproduction and clonal expansion. However,
within some populations, selection on a given leaf characteristic was
found to be in opposite directions when assessing sexual vs. clonal
fitness.
Key words: clonal growth, selection, sexual reproduction, tradeoffs, Viola blanda