31 mai 2019

Le « copier-coller » d’un gène permet aux épinoches de peupler les eaux douces.

Depuis la dernière période glaciaire, les épinoches ont réussi à coloniser depuis la mer de nombreuses eaux douces. Des analyses génétiques effectuées par des chercheurs de l’Eawag, de l’université de Berne et du National Institute of Genetics à Shizuoka (Japon) montrent qu’elles y sont parvenues grâce à des copies supplémentaires d’un gène du métabolisme. En savoir plus

Publication originale

mai 30, 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. En savoir plus

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.

publication originale

17 avril 2019

Une biodiversité étonnante dans les cours d'eau suisses

Grâce à un recensement systématique de la faune piscicole des cours d'eau, le « Progetto Fiumi » a permis d'inventorier plus de quarante espèces de poissons. L'équipe de l'Eawag a par ailleurs observé une diversité encore mal cernée jusque là au sein même des espèces. Le projet livre donc de nouvelles bases pour la protection de la diversité écologique et génétique des poissons. En savoir plus