The impact of human-made ecological changes on the genetic architecture of Daphnia species

1. Nora Brede^a,^b,¹,
2. Christoph Sandrock^a,²,
3. Dietmar Straile^c,
4. Piet Spaak^b,^d,
5. Thomas Jankowski^c,³,
6. Bruno Streit^a and
7. Klaus Schwenk^a,¹⁴

+Author Affiliations

1. ^aDepartment of Ecology and Evolution, Goethe-University Frankfurt am Main, Siesmayerstrasse 70, D-60054 Frankfurt am Main, Germany;
2. ^cLimnological Institute, University of Konstanz, D-75457 Konstanz, Germany;
3. ^bEawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland; and
4. ^dInstitute of Integrative Biology, ETH Zürich, CH-8092 Zürich, Switzerland

1. ↵¹N.B. and K.S. contributed equally to this work.

2. Edited by Nelson G. Hairston, Cornell University, Ithaca, NY, and accepted by the Editorial Board February 2, 2009 (received for review July 24, 2008)

Abstract

The overenrichment (eutrophication) of aquatic ecosystems with nutrients leading to algal blooms and anoxic conditions has been a persistent and widespread environmental problem. Although there are many studies on the ecological impact of elevated phosphorus (P) levels (e.g., decrease in biodiversity and water quality), little is known about the evolutionary consequences for animal species. We reconstructed the genetic architecture of a Daphnia species complex in 2 European lakes using diapausing eggs that were isolated from sediment layers covering the past 100 years. Changes in total P were clearly associated with a shift in species composition and the population structure of evolutionary lineages. Although environmental conditions were largely re-established after peak eutrophication during the 1970s and 1980s, original species composition and the genetic architecture of species were not restored but evolved along new evolutionary trajectories. Our data demonstrate that anthropogenically induced temporal alterations of habitats are associated with long-lasting changes in communities and species via interspecific hybridization and introgression.