[Cvetkoska] Differential assembly processes in time across the Mediterranean

German Title: Unterschiedliche Vergesellschaftungsprozesse über die Zeit in der Mittelmeerregion

Current Status: approved

Main Applicant:Dr. Alexandra Cvetkoska

Resources Recipient

Other Persons

Prof. Dr. Bernd Wagner

Conveyor Begin: 1 February, 2019
Conveyor End: 1 February, 2019
Conveyor Duration: 36
Year: 2019


The identity and relative abundance of co-occuring species within the ecological communities is shaped by distinct assembly processes. Only species with traits that match the local environment will be able to colonize particular site, but the interplay of its abiotic and biotic filters in the end defines the local community. The assembly processes are also affected by climate and environmental change, which if strong in magnitude may trigger shifts in assembly processes over time. Over the last decades, extensive research has been devoted to quantifying the relative importance of the assembly processes that shape communities over various spatial scales, experiments and simulations. Yet, their understanding as well as relative contribution in different ecosystems over geological time remains largely theoretical, partly due to limited:

  1. preservation of fossils;
  2. taxonomic accuracy;
  3. availability of phylogenetic and traitbased information; and
  4. availability of well-constrained geological records.

The high-quality sediment sequences recovered from lakes Ohrid and Prespa, the Fucino Basin and the Corinth Gulf provide exclusive potential to overcome these limitations. Their well-preserved diatom records can shed understanding on how the assembly rules might apply to the diatom communities in different ecosystems and at different climate boundary conditions. Based on our preliminary work, in this proposal I intend to use these sediment records from across the Mediterranean to study the processes driving community structure on a comprehensive time scale of the last ca. 400 ka. The main working hypothesis derived from the existing diatom analyses is that the relative importance of the deterministic assembly processes in shaping community structure over time depends on the ecosystem dynamics. The intensity of environmental filtering is expected to be greater in ecosystems with more frequent and pronounced climatically and/or environmentally triggered change in their physical and chemical properties.

To test this hypothesis, I will use paleontological and paleoecological information from Lake Ohrid, Lake Prespa, Lake Fucinus and the Gulf of Corinth to:

  1. infer the sequence of past climate and environmental change in the ecosystems by using geological data;
  2. obtain community time-series of relative species abundances from the sediment records;
  3. quantify the relative contribution of environmental filtering and species competition within and between the four ecosystems;
  4. identify the most important environmental/climate variables that influenced the assembly processes.

This project is valuable as, for the first time it combines sediment records recovered as part of the ICDP and IODP programme, in order to apply ecological theories to paleontological and paleoecological data to empirically test and improve our understanding about the role of community assembly processes in different ecosystems over long periods of geological time.