In our recently published study in Molecular Ecology, Emanuel A. Fronhofer, Florian Altermatt, and me analyzed empirically observed genetic diversity of Gammarus fossarum metapopulations across the Rhine drainage area within Switzerland. We used microsatellite data and stochastic simulations to study the role of dispersal behaviour on observed genetic diversity. Allelic richness and observed heterozygosity were higher in more central nodes, unlike expected heterozygosity. Stochastic simulations suggest upstream movement probability and dispersal rate to be key factors explaining this finding. The study is open access. A huge thank you to Anja Westram and Jukka Jokela for support early on during analysis and providing data.
New groundwater amphipod discovered
Thanks to the collaboration with many water well managers, Nicole Bongni was able to describe a previously undocumented biological diversity in groundwater in her master’s thesis. The focus was on amphipods, in particular the genus Niphargus. Among the discoveries was a completely new species, which we have now described scientifically in Subterranean Biology. The name of the new species: Niphargus arolaensis, the Aare groundwater amphipod. The name is derived from the fact that we have only been able to detect the species at three sites in the Aare River basin. This research shows that we still understand the groundwater habitat far too poorly and therefore cannot protect it adequately. Thanks to the project AmphiWell we can continue basic research on this topic.
Biodiversity increases and decreases ecosystem stability
Experiments have shown that biodiversity may increase or decrease ecosystem stability. As part of a collaboration between Owen Petchey’s lab at University of Zurich and Florian Altermatt’s lab at Eawag, we performed a large experiment that showed that species richness can simultaneously increase and decrease ecological stability. This highlighed that one should consider multiple stability components and that this could provide new insights. The study was recently published in Nature (read article here) and I am proud to be part of this fruitful project. The story behind the paper can be read in this blog post by Frank Pennekamp.
Amphipod diversity in fluvial networks
In the recently published open-access article in Ecosphere we studied the influence of fluvial network topology on different measures of amphipod diversity. The scientific novelty is the distinction between native and non-native species within a single taxonomic group in a large and natural system. The study covers the 27,882-km2 drainage basin of the river Rhine in Switzerland and is based on a graph theory approach.
Patterns of native and non-native species in fluvial networks
As hypothesized, species richness increased along the network from headwaters to the outlet nodes. But native and non-native amphipod showed different patterns, with headwaters being refugia for native species and more downstream nodes being hotspots of biological invasions. Additionally, results from species turnover indicated a much lower dispersal limitation for non-native species. The amphipod community structure closely mirrored the topological modularity of the network.
Implications for conservation ecology
Our results highlight that connectivity plays an important role in community formation, also on a larger scale. Rivers and streams are essential in explaining biological invasions.