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Phenotypic plasticity and selection on Elymus athericus

Souiljee, T. (2000) Phenotypic plasticity and selection on Elymus athericus. Master's Thesis / Essay, Biology.

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Elymus athericus is a clonal grass dominating the high salt marshes. The last years it has started to invade the low salt marshes as well. The dominance of a few species such as E. at/zericus decreases the species diversity. Management regimes are applied on nature areas to conserve or to increase species diversity. The success of Elymus athericus can have two alternative explanations. Either this species has a high phenotypic plasticity or it can genetically adapt to the conditions in the new habitat. In a situation of global change it becomes more important whether a species can cope with changing conditions, because it will disappear if it cannot. On Schiermonnikoog, an experiment is running during 30 years. The vegetation were grazed, mown or untreated on different sites at the salt marshes. These treatments created a 'changing environment' compared to the untreated parts. Applications of these treatments created new strong selection pressures comparable to changes occurring through global change. In spite of the phenotypic differences of the plants, which appeared between these management regimes in the field, it does not necessarily mean that the differences were genetic adaptations. By using a common garden experiment, phenotypic and fitness-related traits where analysed for Elymus athericus. 300 plants were used, originated from the different sites and treatments of the experiment. During growing in a common environment, differences in these traits were found between the treatments. This supposes the fixation of various traits between the management regimes. Main result was that the grazed and mown treatments are different from the control plants. Selection occurred on shoot length, above-ground biomass and the total leaf area. The plants reacted to this selection by producing small shoots, less biomass and less total leaf area, if they were grazed or mown. On the opposite, E. athericus from the grazed and mown areas produced more ramets. Within ecological time scale the plants thus adapted to a new environment and showed a rapid evolution.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Biology
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:31
Last Modified: 15 Feb 2018 07:31

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