Chemical ecology and phenotype in lichens: examining some environmental factors that influence variability, species assemblages and chemical compounds

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Date
2018-12-17
Authors
Zraik, Mohanad
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Abstract
The general goal of this thesis was to explore the chemical ecology and macromorphological variability in lichens that colonize soils in five locations in Manitoba with respect to the carbon-nutrient balance hypothesis (CNBH). The CNB hypothesize states that when a plant or lichen is growing in nutrient-poor conditions, the excess carbon may be shunted into biosynthesis of carbon-based secondary metabolites such as polyketides. Three specific goals were further examined in four chapters to investigate:1) the distribution of secondary metabolites and species assemblages with respect to soil characteristics (Ch. 2), which resulted in 2) a report on Cladonia magyarica and C. humilis in Manitoba, describing the habitat, and providing morphological and chemical comparisons to distinguish five species (Ch. 3), 3) the phenotype in lichen species showing plasticity with respect to soil type, temperature and precipitation (Ch. 4), and 4) the effect of temperature and moisture on the quantity of three secondary metabolites (atranorin, fumarprotocetraric acid, and usnic acid) produced by three lichen species (Ch. 5). Field collections of lichens, soil features and environmental data were made in five locations. Secondary metabolites were determined using Thin Layer Chromatography (TLC) and High-Performance Liquid Chromatography (HPLC). Morphological and fecundity characteristics were podetium height, cup diameter, squamule diameter, apothecium diameter, number of apothecia on cup and presence of apothecia. Soil characteristics were pH, organic matter, sand content, and sand grain shapes. The results showed that usnic acid and atranorin supported the CNB hypothesis. Species as Cladonia magyarica and C. humulis were reported for the first time in Manitoba. The CNB hypothesis was not supported for all lichen species, which may have been complicated by variability in biotic and abiotic conditions. Temperature and moisture affected the stability of secondary metabolites and partial degradation occurred. This thesis forms a foundation for further studies on the relationship between secondary metabolites with biotic and abiotic factors.
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Carbon, Cladonia, HPLC, TLC, Morphology, atranorin, usnic acid
Citation
Zraik, M., Booth, T., and Piercey-Normore, M.D. 2016. Reports of Cladonia magyarica and C. humilis in Manitoba. Evansia 33(3): 136–144
Zraik, M., Booth, T., and Piercey-Normore, M.D. 2018. Relationship between lichen species assemblages, secondary metabolites and soil characteristics in Manitoba. Botany 96: 267–279