Miller-Struttmann, Nicole .
Reproductive biology and stress-adaption in Ozark glade endemic plants reveals a counter-intuitive relationship between rarity and reproductive specialization .
The traditional stress-competition tradeoff in niche theory states that traits adaptive for high stress environments are maladaptive when competition for shared resources is high. Historically, this tradeoff has been conceptualized as competition for abiotic resources, but biotic interactions, such as competition for pollinator services, are also limiting in many habitats and could lead to the extinction of local populations via reduced reproductive success. In this study, I test the hypothesis that stress-adaptive traits (sensu Chapin's stress-resistance syndrome) reduce the competitive ability of locally-abundant, regionaly rare (LARR) Ozark glade plant in comparison to closely-related, common species (CC). Greenhouse and growth chamber experiments estimated the stress resistance of LARR taxa and their CC congeners to drought and high heat conditions. Individuals of each congeneric pair were exposed to a series of manipulated, abiotic conditions, in accordance with in situ field observations and optimized in the greenhouse, and their fitness responses were compared. A field observational study documented the degree of pollination specialization for LARR taxa and their CC congeners, and a field competition experiment explicitly tested the relative competitive abilities of the LARR and CC taxa for shared pollinators. Contrary to our predictions, LARR plants were not more resistant to high-stress condition, and they had higher pollination specialization scores and were better competitors for pollinators in comparison to their CC congeners. These results indicate that LARR plants are not locally adapted to heat or drought stress, and that reproductive specialization and competition for pollinators, not stress-adaptive traits, may be more important for the maintenance of populations in stressful environments.
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Presentation Type: Oral Paper:Papers for Sections
Location: Forsyth Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 11:30 AM