Plant trait variation and evolution in the biodiversity-ecosystem functioning context

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The role of evolutionary processes for plant species responses to plant community diversity, plant history and soil history is discussed as a possible mechanism explaining the maintenance of biodiversity and the strengthening of biodiversity effects on ecosystem functioning over time. However, so far the potential of evolutionary processes for increased biodiversity effects has barely been studied in long-term experiments. In this subproject we will focus on evolutionary responses of plant species, which should be measurable in the phenotype and at the molecular level to pursue the following objectives: (1) We will test if phenotypic responses are heritable and adaptive to local plant community diversity, plant and soil history, or if they reflect adaptive phenotypic plasticity due to differences in the actual growth environment. (2) We will analyze how within-species variation in phenotypic trait expression is related to genetic and epigenetic differences. (3) We will assess whether epigenetic variation is mainly under genetic control or to what extent patterns of epigenetic differentiation are reversible under different environmental conditions or result from heritable epigenetic differentiation. First, we will conduct a phytometer experiment with eight plant species to test for adaptive phenotypic responses to plant community diversity, plant history and soil history. We will transplant the offspring of seed families collected in the 17-year old plant communities of the Field Experiment to their origin environments "with plant history, with soil history" and in environments "without plant history, with soil history" and "without plant history, without soil history" of the same plot. Second, we will use genotypes of the model species Plantago lanceolata with a selection history in low- and high-diversity communities over nine years as phytometers in the Ecotron Experiment. We will test if genotypes show adaptive phenotypic plasticity and epigenetic variation in response to the actual environment (with different plant community diversity, plant and soil history). Third, we will quantify evolutionary changes in response to plant diversity at the genetic, epigenetic and phenotypic level using the apomictic model species Taraxacum officinale. In a common garden, we will grow offspring of seed families collected after 17 years selection history and after five years of selection history in the Field Experiment as well as offspring from the seeds used for the initial sowing of the Jena Experiment in 2002 (no selection history). We will assess genetic and epigenetic variation and measure phenotypic traits of the offspring as well as of the mother individuals in the Field Experiment. Together, these experiments will contribute to a more thorough understanding of how biodiversity influences evolutionary processes.