Abstract Detail

Reproductive biology

Steven, Janet C. [1], Franke, Morgan [2].

Environment-Dependent Sexual Dimorphism in Thalictrum pubescens.

Plant growth and reproductive investment are strongly dependent on the resource environment, and in dioecious species a difference between male and female plants in their response to resource availability has the potential to influence sexual dimorphism. For example, if males are larger than females in high-nutrient environments, but growth and flower production are more limited by nutrient availability in males due to the production of nutrient-rich pollen, low-nutrient environments may favor more growth in females and result in reduced or reversed dimorphism for size and flower number. We studied sexual dimorphism in the cryptically dioecious species Thalictrum pubescens in five natural populations and in a common garden experiment in which we manipulated nutrient and light availability. We found that sexual dimorphism in flower number and plant size was variable across natural populations, and influenced by both light and nutrient availability in the common garden. In two of the five natural populations, males produced significantly more flowers than females. In the common garden experiment, nutrient availability and sex were significant predictors of flower number. In the natural populations, males were significantly taller than females in one population, while females were significantly taller in two populations. In the common garden, males were larger only in the low light and high nutrient treatment, and light levels affected males and females differently. The variability in the presence and direction of sexual dimorphism in natural populations is potentially driven by differences in the resource environment and differing responses to resources in males and females. Sex-dependent responses to resource availability may have implications for the evolution of dioecy; specializing on one sex may increase fitness by allowing plants to avoid the resource constraints imposed by the opposite sex.

1 - Christopher Newport University, Department Of Organismal And Environmental Biology, 1 Avenue Of The Arts, Newport News, VA, 23606, USA
2 - Virginia Polytechnic Institute and State University, Department of Plant Pathology, Physiology, and Weed Science, 435 Old Glade Road, Blacksburg, VA, 24061, USA

Keywords:
sexual dimorphism
Thalictrum pubescens
dioecy
nutrient availability
light availability.

Presentation Type: Oral Paper:Papers for Topics
Session: 2
Location: Salon 1/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 8:45 AM
Number: 2004
Abstract ID:474
Candidate for Awards:None