Abstract Detail

Ecophysiology

Krieg, Christopher [1], Husby, Chad [2], Watkins, James E. [3].

Ecophysiological cost of reproduction in dioeciuos cycads.

Sexual reproduction can be a costly evolutionary strategy and remains a major topic of investigation in biology today. In dioecious plant species, where individuals are either male, or female, direct investments are made in the production of reproductive structures such as cones, pigments, nectar, pollen, thermogenesis of pheromones, etc. These investments are typically paid for with the carbon acquired from photosynthesis. Little attention has been paid to the cost of reproduction in cycads and so far has only focused on differences in morphology and leaf production. Specifically, we asked: What are the physiological costs of reproduction in dioecious cycads? To address this question, the Montgomery Botanical Center in Miami FL was chosen for its world renowned collection of cycads. The species studied were Cycas micronesia, Cycas rumphii, Zamia erosa, Zamia standleyii, and Zamia portoricensis. To compare photosynthetic physiology, a Licor 6400 photosynthetic system was used to obtain photosynthetic parameters of Amax (maximum photosynthetic rate), G_s (stomatal conductance), and R_d (dark respiration). Related measures of WUE (water use efficiency), SLA (specific leaf area), leaf nitrogen (¹⁵N) and carbon (¹³C) isotope discrimination were also examined. Morphological differences were addressed in measures such as leaf number, cone number, cone height and diameter, cone reproductive status, plant height, stomatal density, and leaf biomass. Preliminary findings support observations of differential morphology and leaf production between the sexes. Males have much smaller cones, compared to females, but produce many more cones relative to females. Additionally, males generally produced more leaves than females indicating a further investment in leaf biomass. How are males “paying” for these investments? We found that male photosynthetic physiology differed from females. This work is ongoing and aims to further reveal the ecophysiological costs of reproduction in several dioecious cycad species.

1 - University of Florida, 364 NW 48th Blvd, Gainesville, Florida, 32607, United States
2 - Fairchild Torpical Botanic Gardens, 10901 Old Cutler Road, Miami, Florida, 33156, USA
3 - Colgate University, Department Of Botany, 129 Ho Science Center, 13 Oak Drive, Hamilton, NY, 13346-1338, USA

Keywords:
cycads
dioecy
Ecophysiology.

Presentation Type: Poster
Session: P, Ecophysiology Poster Session
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PEP008
Abstract ID:541
Candidate for Awards:None