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DFG Priority Program 1704 DynaTrait

Flexibility matters: Interplay between trait diversity and ecological dynamics using aquatic communities as model systems

PI: Prof. Dr. Ursula Gaedke Department of Ecology and Ecosystem Modelling, University of Potsdam

Human activities increase the frequency and intensity of environmental changes (e.g. climate and land-use change) and biodiversity is declining as are ecological functions and services at high speed. The negative consequences of these processes on ecological systems such as individuals, clones, populations, communities and food webs meanwhile threatening economies and human well-being at a global scale and may reinforce each other: Environmental change can speed up biodiversity loss and a reduced biodiversity may increase the sensitivity of ecological systems to environmental changes. We aim to improve our understanding of this extremely important but severely understudied feedback loop by accounting for the biodiversity-related flexibility of ecological systems to adjust to altered abiotic and biotic conditions. Depending on the different facets of biodiversity (e.g. phenotypic, genetic and species diversity) individuals, clones and populations can change their properties to adjust to ambient conditions to improve their fitness. This influences their dynamics and those of the entire food web. For example, enhanced herbivory may lead to a higher share of less edible plants which reduces herbivory. This, in turn, dampens the reduction of plant biomass which likely feeds back on the herbivore biomass and community composition, e.g. the share of herbivorous species able to exploit less edible plants may increase. As a result, the advantage of less-edible plants compared to edible ones is reduced and promotes the coexistence of different plant types and hence biodiversity. Given such feedback loops, the responses of large, nonlinear and intricately interconnected ecological networks such as food webs to altered conditions are yet very difficult to understand and to predict, but of outstanding importance for fundamental and applied ecology. To overcome these limitations, the present proposal moves away from the classical static species-based approach (where rigid properties are assigned to each organism or species independent of ambient conditions), to an innovative flexible trait-based approach. It explicitly considers functional traits which are measureable properties (e.g. edibility of prey, selectivity of consumers) that may change over time depending on the prevailing conditions. We intend a mutually stimulating interplay between experimental approaches, field measurements and mathematical modelling using mostly aquatic microbial communities (plankton and biofilms) as empirical model systems. They comprise multiple trophic levels with internal feedbacks and their small size and short generation times allow to quantify their dynamics for many generations, to measure and manipulate trait variations and to estimate the major trade-off(s) among traits. We want to broaden our very limited quantitative knowledge and predictive power on how biodiversity affects ecological dynamics and responses to environmental changes. In particular, we want to quantitatively test the hypotheses:

  1. The potential of ecological systems to adjust to altered abiotic and biotic conditions depends on their biodiversity;
  2. These adjustments influence their dynamics and response to environmental change; and
  3. The altered dynamics feed back on the maintenance of biodiversity and thus the potential to adjust to future perturbations.

Our aims are to advance ecological theory providing a basis to improve management practices to mitigate the consequences of environmental change and biodiversity loss, and to stimulate other disciplines such as social science, cell biology and transportation that make also use of network science. A priority programme is optimally suited to support the proposed research at the highest international level as it demands the combined interdisciplinary skills of numerous scientists from all over Germany.