Britton, Michael R. , Watkins, Jr., James (Eddie) .
Fertile-sterile leaf dimorphy in ferns: seasonal physiological responses and costs of reproduction.
Reproduction often results in significant costs for parent organisms. Organisms must carefully balance reproduction with growth and maintenance in order to maximize fecundity. Reproductive allocation is well studied in seed plants and bryophytes, but little is known of processes acting on ferns. These plants offer a unique model system to study reproductive allocation as, unlike flowering plants, ferns use the laminar surface as both the site of reproduction and carbon fixation. Such duality may result in unique patterns of allocation. Across the ferns, there is marked variation in the dedication of laminar surface to carbon gain and reproduction. For most species, there is little difference in the outward appearance between sterile and fertile fronds; however, there is an intriguing form of extreme leaf dimorphy in many taxa. The goal of this study is to examine the costs and benefits of varying degrees of dimorphy in ferns. The study was performed on Osmunda regalis, a hemidimorphic species, and Osmunda cinnamomea, a completely dimorphic fern. Photosynthetic rates along with % carbon and % nitrogen were measured from May to September, 2009. Data were recorded on the sterile and fertile fronds of O cinnamomea and the sterile sections of the fertile fronds of O. regalis. We found that fertile sections of the plants failed to exhibit positive carbon gain over the course of the summer and that %C and %N varied markedly between leaf types and over the growing season. This supports the hypothesis that dimorphy represents significant costs on the resources of a fern. Work on tracing carbon allocation over the season, within and between fertile/sterile sections, is ongoing.
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1 - Colgate University, Biology, 13 Oak Drive, Hamilton, NY, 13346, USA
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM