Abteilung Fischökologie & Evolution

31. Mai 2019

«Copy-Paste» eines Gens ermöglichte Stichlingen, Süssgewässer zu besiedeln

Stichlinge haben es seit der letzten Eiszeit geschafft, vom Meer aus zahlreiche Süssgewässer zu besiedeln. Genanalysen von Forschenden der Eawag, der Universität Bern und vom National Institute of Genetics in Shizuoka (Japan) zeigen nun, dass ihnen dies aufgrund zusätzlicher Genkopien eines Stoffwechsel-Gens gelungen ist. Weiterlesen

Originalpublikation

30. Mai 2019

Ecological Consequences of Animal Migration: Prey Partial Migration Affects Predator Ecology and Prey Communities

Patterns of animal migration and the ecological forces that shape them have been studied for centuries. Yet ecological impacts caused by the migration, such as altered predator–prey interactions and effects on community structure, remain poorly understood. This is to a large extent due to the scarcity of naturally replicated migration systems with negative controls, that is, ecosystems without migration. In this study, we tested whether partial migration of certain species within the overall prey community affects foraging ecology of top predators and thereby alters energy pathways in food webs. We carried out the study in independent replicated freshwater lake systems, four with and four without opportunity for prey migration. Specifically, we compared predator foraging mode in lakes where cyprinid prey fish perform seasonal partial migrations into connected streams with lakes lacking migratory opportunities for prey fish. We found clear seasonal bottom-up effects of prey migration on predators, including changes in size structure and total biomass of ingested prey, size-specific changes in littoral versus pelagic origin of diet, and a higher degree of feast-and-famine for predators in systems with migratory prey. Our analyses further showed that partially migratory prey species constitute a larger part of the prey community in systems that allow migration. Hence, prey migrations have important implications for predator foraging ecology and may cause seasonal shifts in the importance of their supporting energy pathways. We suggest that such bottom-up effects of partial migration may be a widespread phenomenon both in aquatic and in terrestrial ecosystems. Weiterlesen

17. Mai 2019
Sinergia project "20'000 years of evolution" has started

Our new SNF Sinergia project entitled "20'000 years of evolution and ecosystem dynamics in the world's largest tropical lake reconstructed from sediment cores, fossils and ancient DNA" has started!

10. Mai 2019

Vision using multiple distinct rod opsins in deep-sea fishes

Vertebrate vision is accomplished through light-sensitive photopigments consisting of an opsin protein bound to a chromophore. In dim light, vertebrates generally rely on a single rod opsin [rhodopsin 1 (RH1)] for obtaining visual information. By inspecting 101 fish genomes, we found that three deep-sea teleost lineages have independently expanded their RH1 gene repertoires. Among these, the silver spinyfin (Diretmus argenteus) stands out as having the highest number of visual opsins in vertebrates (two cone opsins and 38 rod opsins). Spinyfins express up to 14 RH1s (including the most blueshifted rod photopigments known), which cover the range of the residual daylight as well as the bioluminescence spectrum present in the deep sea. Our findings present molecular and functional evidence for the recurrent evolution of multiple rod opsin–based vision in vertebrates.

Originalpublikation

17. April 2019

Bedrohte Fischvielfalt in Bächen wird erfasst

Mit der systematischen Befischung der Schweizer Fliessgewässer hat das «Progetto Fiumi» über 40 Fisch-Arten dokumentiert. Eine zuvor nur ansatzweise erfasste Vielfalt hat das Eawag-Team zudem innerhalb der Arten gefunden. Damit liefert das Projekt Grundlagen für den Schutz dieser genetischen und ökologischen Vielfalt.

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