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1 September 2016 Field Performance and Common-Garden Differentiation in Response to Resource Availability in Helianthus porteri (A. Gray) Pruski, a Granite-Outcrop Endemic
Alan W. Bowsher, Scott D. Gevaert, Lisa A. Donovan
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Abstract

Plant communities on granite outcrops are prone to water and nutrient limitations because of the shallow soils and high summer-temperatures characteristic of that habitat. Thus, resource availability is expected to influence plant performance on these sites. Here, we sought to determine if low resource-availability (water and nutrients) acts as a selective agent in natural populations of Helianthus porteri (Porter's Sunflower), a granite-outcrop endemic. We conducted field observations of growth and survival for 3 years in 3 populations spanning the species' range. We found that survival to flowering was correlated with soil-water availability (estimated by plant predawn water-potentials; Ψpd), and that drought severity (estimated by survival and Ψpd) differed among populations, suggesting the populations could be adaptively differentiated for resource-use traits. However, in a greenhouse common-garden experiment, the population that experienced the greatest drought severity in the field did not exhibit traits associated with greater drought resistance, and all 3 populations responded similarly to water and nutrient limitations. Thus, although drought influences survival in Porter's Sunflower, populations do not appear to be adaptively differentiated with respect to resource availability.

Alan W. Bowsher, Scott D. Gevaert, and Lisa A. Donovan "Field Performance and Common-Garden Differentiation in Response to Resource Availability in Helianthus porteri (A. Gray) Pruski, a Granite-Outcrop Endemic," Southeastern Naturalist 15(3), 467-487, (1 September 2016). https://doi.org/10.1656/058.015.0308
Published: 1 September 2016
JOURNAL ARTICLE
21 PAGES


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