Sunday, November 15, 2026

Survival in a patchwork landscape: City life leaves subtle genetic traces in Berlin squirrels

Leibniz Institute for Zoo and Wildlife Research (IZW)

image:
Eurasian red squirrel (Sciurus vulgaris) in Berlin (photo by Stephanie Kramer-Schadt/Leibniz-IZW)
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Credit: photo by Stephanie Kramer-Schadt/Leibniz-IZW

Roads, buildings and other infrastructure can restrict the movements of wildlife in cities. As a result, urban wildlife from different areas encounter one another less frequently, potentially resulting in reduced genetic diversity. Scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) and the Technische Universität Berlin (TUB) investigated whether these effects are also evident in squirrels in Berlin. While genetic differences between the populations studied were generally small, subtle differences between locations were already evident. These suggest that the exchange of genetic variations (alleles) within the city may be limited. However, this does not yet have a significant impact on survival probability. The study has been published in the journal Ecology and Evolution.

Eurasian red squirrels (Sciurus vulgaris) are well adapted to life in cities. They adjust their diurnal activities very flexibly to humans, pets and wildlife in the city, actively avoiding predators such as cats, martens and dogs. They readily make use of human food sources and generally thrive in gardens and parks. Nevertheless, frequent sightings should not obscure the fact that their habitats are small and fragmented, and thus are more reminiscent of a patchwork quilt. A new study by the Leibniz-IZW has now investigated whether this habitat fragmentation is already detectable in the genomes of red squirrels from different locations in Berlin, and whether these differences have an impact on the animals’ probability of survival.

141 squirrels, three locations, two genetic groups

To this end, the team studied squirrels at three locations in Berlin from autumn 2021 to spring 2025: an inner-city cemetery, a large city park and a woodland area on the outskirts of the city. The areas differ significantly in terms of development, infrastructure and human activity. The three sites were specifically selected because, despite generally providing suitable habitats for squirrels, they represent varying degrees of urbanisation and different levels of integration into the urban landscape: ranging from a contiguous woodland area to a city park heavily surrounded by urban infrastructure. A total of 141 squirrels were captured and individually marked. For the genetic analyses, 135 individual genetic profiles were generated. This enabled the scientists to investigate how genetically diverse the populations are and to what extent they differ from one another. In a well-connected urban landscape, it is to be expected that populations are more genetically intermixed and therefore differ less from one another.

“Genetic diversity was high at all three sites. If one considered only the geographical location, one would have expected the populations in the city park and the cemetery – which are just a few kilometres apart – to be genetically similar, whilst the forest population, which is significantly further away, would stand out more,” explains lead author Sinah Drenske from the Leibniz-IZW. However, the genetic analyses revealed a different pattern: Whilst the squirrels from the woodland and the cemetery were predominantly assigned to a single genetic group, the animals from the city park differed more markedly from the other two. “We do not see any highly isolated populations,” says Drenske. “But we are already detecting subtle genetic differences that suggest that squirrels cannot move completely freely through the city.”

Subtle genetic differences, but no clear differences in survival

The team also investigated whether these genetic differences were already having an impact on the animals, using catch-recapture data collected over several years. The estimated probability of survival over a six-month period was similar across the three sites. Although it was slightly lower in the heavily urbanised city park, the statistical uncertainty was too great to conclude that urbanisation had a clear negative effect.

Stephanie Kramer-Schadt from the Leibniz Institute for Zoo and Wildlife Research (IZW) and the Technische Universität Berlin (TUB) explains: “The results show that Berlin’s squirrels exhibit a high level of genetic diversity and that there is currently no evidence of significant inbreeding or advanced isolation. Should connectivity between urban habitats continue to decline in future, this could also lead to a further reduction in genetic exchange.” For squirrels and other species that depend on tree-rich habitats, green spaces and tree-lined corridors could therefore play an important role in maintaining exchange between populations. Wildlife-friendly urban planning should take this into account.

Journal

Ecology and Evolution

DOI

10.1002/ece3.74273

Method of Research

Data/statistical analysis

Subject of Research

Animals

Article Title

Urbanisation Leaves a Genetic Signature but No Detectable Demographic Effects in a Small Mammal Population

Eurasian red squirrel (Sciurus vulgaris) in Berlin

(photo by Stephanie Kramer-Schadt/Leibniz-IZW)

Eurasian red squirrel (Sciurus vulgaris) in Berlin (photo by Stephanie Kramer-Schadt/Leibniz-IZW)

ERC Synergy Grant of €10 million awarded to Hebrew University and international partners to study judges’ role in defending democracy

The Hebrew University of Jerusalem

Prof. Keren Weinshall joins researchers from the University of Copenhagen, Washington University in St. Louis and the University of Oslo in a six-year collaboration examining 48 supreme and constitutional courts.

The Hebrew University of Jerusalem proudly announces that Prof. Keren Weinshall of its Faculty of Law, together with three international research partners, has been selected to receive a European Research Council (ERC) Synergy Grant, one of the Council’s most prestigious and competitive funding awards. With a success rate of approximately 5%, the grant will support an ambitious six-year project with a total budget of approximately €10 million.

The research project, JUSTGOV, is jointly led by Prof. Weinshall; Prof. Urška Šadl of the University of Copenhagen; Prof. Lee Epstein of Washington University in St. Louis; and Prof. Daniel Naurin of the University of Oslo.

JUSTGOV seeks to transform how scholars understand the role of courts in safeguarding democracy. Rather than treating supreme courts as single, unified institutions and assessing their decisions solely by whether they favor or oppose those in power, the project places individual judges at the center of the analysis. It will examine judges as actors operating within complex social, institutional, and political environments.

The international research team will undertake an unprecedented comparative study of 48 supreme and constitutional courts in OECD countries and candidate countries, including Israel. The researchers aim to map how judges act as agents of democracy during periods of democratic stability, under threats to democratic governance, and throughout processes of institutional recovery.

At a time when democracies around the world face mounting institutional challenges, the project will offer a new comparative perspective on the choices judges make and the conditions that shape their capacity to defend democratic institutions.

“Understanding what enables democratic institutions to withstand pressure is a vital challenge for research today,” said Prof. Tamir Sheafer, President of the Hebrew University of Jerusalem. “Prof. Keren Weinshall and her international partners are bringing exceptional expertise to a question that matters deeply across societies: how individual judges help sustain democracy when its institutions are tested. This ERC Synergy Grant recognizes both their scholarly ambition and the power of international collaboration to advance knowledge on questions of shared public importance. We are proud of Prof. Weinshall and the Hebrew University’s role in this important undertaking.”

ERC Synergy Grants support ambitious research projects that bring together leading investigators whose complementary expertise can address complex scientific questions. The award recognizes both the promise of the JUSTGOV collaboration and the Hebrew University’s contribution to internationally significant research on law, courts, and democracy.

New project takes a closer look at Antarctic glaciers

University of Gothenburg

image:
Anna Wåhlin, Professor of Oceanography at the University of Gothenburg.
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Credit: Johan Wingborg

Antarctica’s glaciers are deteriorating at different rates. Now, a research project led by the University of Gothenburg aims to find out why. A new underwater vehicle, purchased to replace Ran after it disappeared beneath a floating glacier in 2024, could provide answers.

On the surface, two glaciers in Antarctica may look identical. But while one is wasting away due to global warming, the other may remain almost intact. The European Research Council has awarded €14 million to polar researchers from four European universities to find out why.

The focus of the research project is the 400-kilometre-long Riiser-Larsen Ice Shelf in East Antarctica. An ice shelf is the outermost part of a glacier that has extended from the land into the sea, where it floats on the seawater – a floating glacier.

Rising sea levels

The ice shelf acts as a protective barrier, preventing the glacier behind it from sliding into the sea too quickly.

“Despite their enormous importance, we still don’t fully understand what affects the stability of these vast ice shelves. Without this knowledge, we cannot make reliable predictions about future sea-level rise,” says Anna Wåhlin, Professor of Oceanography at the University of Gothenburg and corresponding principal investigator of the research project.

The researchers will therefore study processes beneath, on top of and within the ice – and how these processes interact. Warm seawater flows into cavities beneath the ice, melting the ice and weakening it from below. Increasing snowfall makes the ice heavier, possibly leading to more melting and weakening it from above. Cracks, channels and shearing weaken the ice from within.

The data collected during the project will also be important for assessing the future of other glaciers in Antarctica, such as Thwaites Glacier, also known as the Doomsday Glacier. Thwaites Glacier is enormous, and its collapse could have major consequences for sea levels.

New underwater robot go beneath the ice

“Our hypothesis is that the hidden structure within the ice shelves determines how external influences from the ocean and atmosphere cause them to break down. Hopefully, the data we collect will give us a better understanding of this,” says Anna Wåhlin.

Anna Wåhlin will be using the underwater robot Ran II, a replacement for Ran, which disappeared beneath the Dotson Ice Shelf in January 2024. Like its predecessor, Ran II will be sent beneath the ice shelf to map its underside and investigate how ocean currents affect melting.

“From the outside, it might seem completely crazy to send another extremely expensive robot beneath several hundred metres of thick ice. But it is the only way to collect the data we need on how ocean currents affect melting. The alternative would be to stop doing this research because it is too expensive and risky. Fortunately, there are organisations that fund high-risk research,” says Anna Wåhlin.

Bringing together different areas of expertise

The researchers will make several expeditions to Antarctica over the six years of the project. The first expedition is scheduled for early 2028.

“That is why large European grants like this are so important. Existing observations and models cannot capture these interacting processes. We are therefore putting together an entirely new team with expertise in different fields, including oceanography, meteorology, glaciology, satellite data and modelling,” says Anna Wåhlin, who is now planning her ninth expedition to Antarctica.

Facts: Research project Stability and Known Unknowns of Antarctic ice shelves (SKUA)

ERC Synergy is one of the EU’s larger funding schemes for fundamental science research. Its aim is to bring together researchers with different areas of expertise to tackle complex problems that no individual researcher or institution could solve alone. All prinicipal investigators must be among the best in their respective fields.

Principal investigators (PI):

Anna Wåhlin, University of Gothenburg, Sweden
Ruth Mottram, Danish Meteorological Institute, Denmark
Roderik Van de Wal, The Royal Netherlands Meteorological Institute, Netherlands
Peter Davis, British Antarctic Survey, United Kingdom

The focus of the research project is the 400-kilometre-long Riiser-Larsen Ice Shelf in East Antarctica. An ice shelf is the outermost part of a glacier that has extended from the land into the sea, where it floats on the seawater – a floating glacier.

Credit

Anna Wåhlin

Underwater robot Ran disappeared beneath the Dotson Ice Shelf in January 2024. Like its predecessor, Ran II will be sent beneath the ice shelf to map its underside and investigate how ocean currents affect melting.

Credit

Filip Stedt

Anna Wåhlin got funding to replace the missing Ran with a new under water robot; Ran II.

"From the outside, it might seem completely crazy to send another extremely expensive robot beneath several hundred metres of thick ice. But it is the only way to collect the data we need on how ocean currents affect melting."

Credit

Olof Lönnehed

Hanyang University ERICA researchers reported how a warming ocean is changing the base of the marine food web 

Researchers investigate regional copepod diet differences to investigate effects of climate change on marine food webs

Hanyang University Research Strategy Planning Team

How Calanus spp. diet varies geographically in a warming ocean — image:
The diet of Calanus spp. has significant geographical variations, with nitrogen fixing and heterotrophic bacteria being dominant sources in tropical and subtropical Pacific and dinoflagellates in the Pacific Arctic Ocean.
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Credit: Professor Kyung-Hoon Shin from Hanyang University, South Korea

Climate change is causing warming in the oceans, which can have significant effects on marine food webs. Rising ocean temperatures can intensify seawater stratification, a process in which ocean water forms layers of different densities that mix less readily. This can reduce the supply of nutrients to surface waters and favor smaller phytoplankton species that are better adapted to low-nutrient conditions. Phytoplankton support zooplankton, which in turn transfer energy to fish and other animals. Changes in phytoplankton communities can therefore lead to cascading effects in marine food webs.

In the western North Pacific, changes in ocean temperatures, circulation patterns, and sea-ice cover are causing changes in phytoplankton ecosystem structure. However, how contributions of different microscopic food sources to zooplankton vary across these regions, remain poorly understood.

To address this gap, a research team led by Professor Kyung-Hoon Shin from the Department of Marine Science and Convergent Technology at Hanyang University in South Korea analyzed the cosmopolitan calanoid copepod Calanus spp., a zooplankton that is a key source of food for fishes and sea birds, making it an ideal indicator of basal resource composition and nitrogen pathways. “Our objective was to quantify how nutrient sources and primary-producer communities shape zooplankton diets and nitrogen transfer pathways across the dynamic western north Pacific,” explains Prof. Shin. “To this end, we utilized a new dual-isotope approach for estimating the diet of Calanus.” Their study was made available online in Volume 12, Issue 38 of Science Advances on September 18, 2026.

The researchers sampled Calanus across the western North Pacific during summer and autumn, covering a broad region from tropical and subtropical waters, the subarctic Pacific, to the Bering Strait and southern Chukchi Sea in the Pacific Arctic Ocean. They analyzed carbon and nitrogen isotope ratios in essential amino acids from Calanus spp. tissue. These chemical signatures helped them estimate the contributions of different basal food sources and investigate the nitrogen sources supporting microalgae.

The results revealed notable geographical variations in basal diets of the copepods. In tropical and subtropical Pacific, which have strong surface stratification and low phytoplankton amounts, N2-fixing bacteria and heterotrophic bacteria accounted for 19.6 ± 5.8% and 30.6 ± 5.3%, respectively, of the basal diet. Further north, in regions of the subarctic Pacific, the contribution of N2-fixing bacteria and heterotrophic bacteria decreased, while those of eukaryotic microalgae, such as diatoms and dinoflagellates, increased. Notably, in the Bering Strait and Chukchi Sea, dinoflagellates made up more than half (54.4 ± 10.5%) of the basal diet, while the total eukaryotic microalgae contribution rose to approximately 80%.

The researchers also found that the estimated contribution of dinoflagellates was strongly correlated with the protist contribution inferred from nitrogen isotope ratios. N2 sources supporting microalgae also varied regionally: biologically fixed N2 was more dominant in the tropical Pacific, accounting for 29.2 ± 7.9% of the nitrogen source, while nitrates were the primary source in the Pacific Arctic Ocean, accounting for an estimated 91.4 ± 2.3%.

“Our results demonstrate that combining carbon and nitrogen isotope ratios in Calanus spp. is a robust framework for understanding dietary records,” remarks Prof. Shin. “Importantly, our study shows how warming-driven changes in stratification and nutrient dynamics are reshaping planktonic food webs. This will have cascading consequences for marine biodiversity, biogeochemical cycling, and ecosystem resilience.”

In summary, this study offers an innovative method to track dietary sources of zooplankton, establishing a foundation for investigating how climate change may affect marine food webs.

***

Reference
DOI: 10.1126/sciadv.aed3966

About Hanyang University ERICA
Hanyang University ERICA (Education Research Industry Cluster at Ansan) is a prominent research-focused campus established in 1979 in Ansan, South Korea. ERICA offers undergraduate and graduate programs. ERICA is renowned for its active industry-university cooperation, offering students hands-on experience through partnerships with various industries. This ensures that graduates are well-prepared to meet societal needs and excel in their respective fields. With state-of-the-art facilities and a supportive learning environment, Hanyang University ERICA empowers students to pursue their passions and contribute meaningfully to society, staying true to the university's founding philosophy of "Love in Deed and Truth."
Website: https://www.hanyang.ac.kr/web/eng/erica-campus1

About the Author
Prof. Kyung-Hoon Shin is currently a Professor at the Department of Marine Science and Convergence Engineering and a Director of the Global Science Research Center for Marine Material Cycle Processes at Hanyang University. His research group is developing approaches to assess organic biogeochemical cycles and marine food web structure through compound-specific isotope technology for advanced ocean science and environmental ecology. Prof. Shin’s group is also developing lipid biomarker analytical skills and their applications for carbon cycle and nitrogen source identification in marine and environmental science. Prof. Shin has served as Vice President of the Korean Academy of Marine Science and has been a Distinguished Fellow of the Academy since 2021.