Abstract Detail

Ecophysiology

Bowsher, Alan [1], Donovan, Lisa [1].

Evolution of fine root morphology and anatomy in Helianthus (sunflowers).

Recent work suggests the existence of a fundamental resource use trade-off governing plant form and function. Global analyses of leaf traits have identified sets of co-occurring traits that produce a spectrum of plant “strategies,” ranging from species that produce thin, short-lived leaves capable of rapid resource acquisition to those with tough, long-lived leaves better suited for resource conservation: a trade-off thought to reflect adaptation to resource-rich versus resource-poor environments, respectively. In comparison to leaf traits, however, our knowledge of belowground trait strategies across species and environments is limited. In this study, wild seed was collected from field sites of 15 species of North American Helianthus (sunflowers), and soil cores and climate data were collected from each site to characterize the native environment of each seed source. All 15 species were grown from seed in a common garden environment, and fine root characteristics (morphology and internal anatomy) were measured five weeks after sowing. In combination with knowledge of the source environment characteristics of each species, such a design allows identification of genetically-based differences in root traits among the species, and interpretation of how these differences might reflect adaptive differentiation across environments. Data will be analyzed by phylogenetically-independent contrasts to account for evolutionary relationships when testing for correlations between root traits and environmental characteristics. Preliminary results point towards a weak relationship between specific root length (root length per unit mass) and available phosphorus levels in the source environment of each species. Additional data on root internal anatomy (total xylem cross sectional area, mean xylem vessel cross sectional area, cortex width, etc.) will continue to be collected in summer 2013. The results of this study are expected to inform on the macroevolution of root traits in diverse environments, and provide evidence for the adaptive value of specific traits or trait combinations in specific environments, addressing a poorly understood area of plant ecology.

Broader Impacts:

1 - University of Georgia, Plant Biology, 2502 Miller Plant Sciences, Athens, GA, 30602, USA

Keywords:
roots
Helianthus
adaptation
trade-off
phylogenetically-independent contrasts.

Presentation Type: Oral Paper:Papers for Topics
Session: 27
Location: Elmwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 11:00 AM
Number: 27004
Abstract ID:408
Candidate for Awards:None