Sudler, K. Nicole .
The effect of competition and physiological integration on fitness-related traits: A two-year study of Viola blanda.
Physiological integration of physically connected ramets may increase fitness-related traits, such as plant size and reproduction. In contrast, competition among plants may reduce these traits. This study examined the interactive effect of competition and physiological integration on fitness-related traits over the 2001 and 2002 growing seasons. Ramet pairs (N=200) from two populations of Viola blanda in southeastern Kentucky were exposed to a competition treatment (with vs. without competitors) and an integration treatment (intact vs. severed ramet connections). Fitness measures included plant size (total leaf area), sexual reproduction (no. of seedpods) and clonal expansion (no. of stolons). Predictions of treatment effects were: 1) intact ramet pairs with competitors would be reduced in size and produce equivalent values of seedpods and stolons, 2) intact ramet pairs without competitors would produce the highest values of plant size, seedpods and stolons, 3) severed ramet pairs with competitors would be reduced in size and produce more seedpods than stolons, and 4) severed ramet pairs without competitors would also be reduced in size but produce fewer seedpods than stolons. Data from both the 2001 and 2002 growing season provided support for some predictions, while contradicting others. Significance of treatment effects was greatly dependent on population and year. Differences in environmental factors between the two populations included both quality and quantity of light, percent ground cover and soil moisture. The first population exhibited significant competitive and integrative treatment effects in all three fitness traits. However, the second population of V. blanda produced significantly less total leaf area and number of stolons and had very few significant treatment effects. These results suggest that site quality and seasonality may play an equally or more important role in plant fitness above that of competition and/or physiological integration.
1 - University of Kentucky, Department of Biology, 101 Morgan Bldg, Lexington, Kentucky, 40506, USA
Presentation Type: Paper
Location: Wasatch (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 4:00 PM