Thursday, May 28, 2026

New research helps scientists unlock evolution of gigantism in Scottish island wrens

Island birds could be the key for researchers to better understand the evolutionary paths that lead to ‘island syndromes’.

University of Birmingham

image:
A juvenile St Kilda Wren with colour-rings
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Credit: Craig Nisbet

A new study of British Wrens has provided new insights into the inner workings of ‘island syndromes’, according to research led by the University of Birmingham.

The paper, published in the Evolutionary Journal of the Linnean Society, reveals that different subspecies of island Wrens are evolving independently, with the team finding particularly strong evidence of ‘island gigantism’ in two of the studied populations.

Researchers examined four subspecies of island Wrens, each found on a specific island or archipelago in Scotland – Shetland, Fair Isle, the Outer Hebrides, and St Kilda. Each of these subspecies is geographically isolated (but exposed to broadly similar environments on different Scottish islands), and each differs significantly from the Wren subspecies found across mainland Great Britain and continental Europe.

Island gigantism is a biological phenomenon in which the size of an animal species isolated on an island increases dramatically in comparison to its mainland relative. This is most famously exemplified by the giant tortoises of the Galapagos, and the extinct Dodo of Mauritius; both of which far exceed the sizes of their continental ancestors.

Led by Dr Michał Jezierski, the study’s findings represent one of the most in-depth explorations of the population-level processes giving rise to island syndromes. These evolutionary phenomena, detected across disparate types of animals and plants across Earth’s islands, involve a suite of evolutionary changes in island species including; island gigantism, longer lifespans, slower rate of reproduction and, in birds, a tendency towards lower flight ability.

Key findings from the study include:

Wren populations on Shetland and St Kilda show minimal evidence of interbreeding with their cousins from mainland Britain.

These two subspecies have evolved spectacular island gigantism; a Wren from England will weigh 7-10g on average, whereas on St Kilda they range from 13-16g.

The largest St Kilda Wrens are more than twice the size of the smallest on mainland Great Britain, putting them within the top 25% of cases of island gigantism in birds worldwide.

Dr Michał Jezierski, from the School of Geography, Earth and Environmental Sciences and lead author of the study, said: “We found that all four Scottish Wren subspecies are genetically distinct from the Wrens of mainland Britain; with the Wrens of Shetland and St Kilda being especially distinct in both appearance and song. Their genetic distinctiveness is so high, that it is likely they are on their way to becoming new species.”

By comparing these four Scottish island subspecies with mainland Wrens, using body measurements, song recordings, and whole genome sequencing, researchers were able to explore the differences in biology between the different island populations in more detail than has previously been possible, allowing them to further investigate the ways in which island syndromes evolve.

Islands host 20-30% of species worldwide and are famous for their unusual wildlife – from Madagascan lemurs to Komodo Dragons. Similar conditions found across the world’s islands, including lower predation and competition than on adjacent mainlands, are driven by their inherent isolation. Although island syndromes may be found across much of our planet’s biodiversity, their underlying mechanisms are poorly understood.

Will Smith, from the University of Nottingham and a co-author of the study said: “Our research suggests that islands with similar environments can produce similar evolutionary outcomes using different genetic pathways. The Wrens of Scotland provide us with a powerful case study to understand the mechanisms by which island biodiversity is generated worldwide.”

Shared traits, different genetics

Whole genome comparisons showed that each island population is genetically distinct and largely isolated: while the Wrens of Shetland and St Kilda are physically similar, the regions of their genomes that show the most differences from mainland Wrens are largely independent from each other.

By contrast, Wrens from Fair Isle and the Outer Hebrides are more similar to those on the British mainland: highlighting that island evolution does not proceed in the same way, even within a relatively small geographic region, with each population representing a related, but largely independent, evolutionary unit.

Dr Jezierski added: “Our genomic data indicates that Shetland and St Kilda Wrens are genetically distinct from each other, despite their similarities in physical appearance. This means that their island gigantism is a case of ‘parallel evolution’, where a similar original population (probably colonists from the British mainland) made it to each island archipelago, and then independently evolved to become island giants. In the process, their songs also became very different from those of ‘mainland’ British birds.”

Understanding the ‘micro’ processes that lead to ‘macro’ patterns

The ‘giant’ size of the Wrens has evolved alongside other island associated traits, including distinctive songs and subtle differences in plumage and body proportions, supporting the idea that island environments consistently shape evolution in predictable directions.

The ‘why’ of island syndromes remains a mystery, and researchers do not yet fully know how changes in body size, or other island syndromes, represent adaptations to the special ecological conditions on islands. However, these latest findings amongst Wren populations may provide a great case study with which Birmingham researchers can further investigate this field of evolutionary science.

A Shetland Wren in hand in Kergord, Mainland, Shetland.

Credit

Michał T. Jezierski, University of Birmingham

Journal

Evolutionary Journal of the Linnean Society

DOI

10.1093/evolinnean/kzag008

Method of Research

Observational study

Subject of Research

Animals

Article Title

Parallel evolution of island syndromes coincides with limited parallel genetic differentiation in a passerine bird

Article Publication Date

28-May-2026

Simple training can save lives by keeping medical supplies on the shelves, UT San Antonio researcher finds

Low-cost training for frontline health workers can significantly reduce medical supply shortages, potentially saving thousands of lives in developing nations

University of Texas at San Antonio

Amir Karimi, UT San Antonio — image:
Amir Karimi, assistant professor of operations and analytics in the Carlos Alvarez College of Business at UT San Antonio.
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Credit: UT San Antonio

A recent study from The University of Texas at San Antonio reveals that low-cost training for frontline health workers can significantly reduce medical supply shortages, potentially saving thousands of lives in developing nations.

Amir Karimi, an assistant professor of operations and analytics in the Carlos Alvarez College of Business, evaluated a large-scale initiative in Indonesia designed to keep contraceptives on pharmacy shelves. The study recently accepted by Management Science, found that training nurses and midwives in basic inventory management reduced “stock-outs” — periods when a product is unavailable — by approximately 30%.

“We have the technology to manufacture these products, but when supply chains break, the consequences are just as devastating as if you couldn’t produce these medications at all,” Karimi said. “People are not going to have access, and it leads to adverse outcomes like unintended pregnancies, psychological distress and even death.”

A dual responsibility dilemma

In many low- and middle-income countries, frontline health workers are forced to balance a “dual role.” Though their focus is clinical care, such as administering medication or counseling patients, they are often tasked with managing inventory.

Because these workers are primarily trained for medical tasks, inventory management is often viewed as a secondary priority or handled ad hoc. This challenge is compounded by infrastructure issues such as poor roads and a lack of local manufacturing, which requires products to be imported and distributed across thousands of facilities

In Indonesia alone, approximately 17,000 health facilities must be replenished bimonthly. Along the way, medical supplies can encounter dozens of roadblocks, including complications in the import process, trucks breaking down, roads being closed due to flooding, or inventory being poorly managed on the shelves. When these systems fail, the results are stark: More than 95% of all maternal or newborn deaths globally occur in low- and middle-income countries.

On-the-job training yields high returns

Karimi’s team evaluated the MyChoice Project, which provided inventory management training to health workers across Indonesia. The study compared two delivery methods: “offsite” training in a traditional classroom and “onsite” training delivered on-the-job at health clinics.

The results showed that onsite training was not only more effective but also drastically cheaper. On-the-job sessions reduced stock-outs by up to 43%, compared to a much smaller impact from classroom-based learning.

“If training is delivered in the same setting where the work happens, it becomes more embedded,” Karimi explained. “It is experiential learning rather than a theoretical approach that is detached from their day-to-day tasks.”

The cost difference was equally significant. On-site training costs as little as $9.72 per facility, This is because trainers can visit multiple clinics on a single route, whereas off-site training requires paying for venue rentals, supplies and travel costs for all attendees.

Karimi’s analysis suggests that for every 100,000 women of reproductive age, this training prevents more than 800 unintended pregnancies and saves more than four maternal and newborn lives.

Expanding the reach

While the study focused on contraceptives in Indonesia, Karimi believes the model could be applied to other essential medicines and regions.

He has already conducted similar research in Senegal and is currently in discussions to design remote training programs. One of those includes a potential app that could further lower costs and expand the program’s reach.

“My ultimate goal is uncovering actionable insights that public health organizations and governments can use to address inequities on a global stage,” Karimi said.

Lanzhou Jiaotong University researchers develop sustainable wastewater-powered electricity generator system

Novel droplet-based energy harvesting technology converts secondary wastewater effluents into electricity while supporting pollutant removal

Editorial Office of Journal of Environmental Sciences

Droplet-based electricity generator system for harvesting wastewater energy — image:
Researchers develop a droplet-based electricity generator system capable of converting treated municipal wastewater into usable electrical energy for pollutant removal and electrocatalytic degradation applications.
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Credit: Thomas Hawk from Openverse Image Source Link: https://openverse.org/image/14cb8266-78f1-4a9d-ab0a-4fd476912d06?q=municipal+wastewater+treatment+plant&p=18

As cities worldwide face growing freshwater shortages and rising energy demands, it is important to develop new technologies that can simultaneously recover resources and reduce the environmental footprint of wastewater treatment. Considerable amounts of low-frequency and low-energy components have been found in secondary effluents in municipal wastewater that can be harvested by triboelectric nanogenerators (TENGs). While municipal wastewater treatment plants process enormous volumes of water every day, much of the residual mechanical and electrostatic energy contained in treated effluents is lost during discharge. In addition, there is limited research on harvesting energy from municipal wastewater using TENG.

To address this, a team of researchers led by Dr. Beidou Xi from the School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, China, and State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, China, has developed a novel droplet-based electricity generator (DEG) system that converts treated municipal wastewater into usable electrical energy. The study was made available online on May 10, 2025, and was published in Volume 161 of the Journal of Environmental Sciences on March 01, 2026.

“We fabricated several DEG devices using commercially available hydrophobic films, including perfluoroethylenepropylene copolymer (FEP), polytetrafluoroethylene, and polypropylene and investigated the effects of the droplets from various solutions on the output performance of DEGs,” says Dr. Xi.

The fabricated materials formed the contact layer of the generator system, where falling wastewater droplets generated electrical output through triboelectrification and electrostatic induction. Among the tested materials, FEP-based DEG devices demonstrated the strongest performance. A single DEG device achieved a maximum output voltage of 22.47 V, a current of 2.11 μA, and a peak power output of 15.18 μW when operating with secondary wastewater effluents. Remarkably, a single droplet impact was sufficient to illuminate 15 light emitting diodes (LEDs).

The researchers further scaled the technology into a DEG system consisting of multiple devices connected in parallel. After rectification, the system generated enhanced electrical output and efficiently charged capacitors. A six-device DEG system successfully powered an LED continuously without external electricity, demonstrating the technology’s practical energy harvesting capability. Importantly, the study showed that wastewater quality influenced electrical performance. Lower dissolved solids and lower ion concentrations improved electron transfer efficiency between droplets and the hydrophobic film surface, thereby increasing electrical output. However, the researchers found that once secondary effluents met China’s Grade I-A wastewater discharge standard, differences among wastewater treatment methods had little impact on generator performance.

Beyond energy harvesting, the DEG system was also used directly in wastewater treatment applications. For this, the harvested electricity was connected to stainless steel electrodes submerged in municipal wastewater. This configuration enabled electrochemical pollutant removal without relying on an external power source. The DEG-powered treatment system achieved ammonium nitrogen removal efficiencies of approximately 12% and chemical oxygen demand (COD) removal efficiencies exceeding 40%. The researchers observed that tiny bubbles generated during electrolysis promoted electro-flotation, allowing pollutants to attach to bubbles and separate more effectively from the water. Interestingly, alternating current generated by the DEG system appeared to reduce electrode passivation, improving treatment efficiency. Continuous polarity reversal helped prevent mineral accumulation on electrode surfaces, thereby maintaining electrochemical activity during wastewater treatment.

The researchers also explored the system’s capability for dye degradation using methyl orange (MO), a common model pollutant in wastewater treatment research. In experiments conducted without an external power supply, a six-device DEG system powered electrocatalytic degradation of MO solution over 54 hours. During the degradation process, the characteristic ultraviolet-visible absorption peaks associated with MO steadily diminished, indicating destruction of the dye’s aromatic ring and azo bond structures. The system achieved a COD removal efficiency of 91.31% and a decolorization rate of 96.08%, demonstrating strong electrocatalytic performance driven entirely by harvested wastewater energy.

Overall, the findings highlight the broader potential of TENG technology for sustainable environmental engineering applications. By recovering energy directly from treated wastewater streams, wastewater treatment facilities may be able to offset part of their operational energy demands while simultaneously supporting pollutant removal processes. Thus, DEG system may contribute to carbon reduction efforts in municipal wastewater treatment plants by transforming wastewater from an energy-consuming burden into a partially self-powered resource recovery platform.

“Our study demonstrates the application of TENG technology in energy harvesting from secondary effluents and introduces a novel approach to wastewater resource recovery, carbon reduction, and sustainable management,” concludes Dr. Xi.

Reference
DOI: https://doi.org/10.1016/j.jes.2025.05.020

About the Lanzhou Jiaotong University, China
Lanzhou Jiaotong University is located in Lanzhou, a city that lies along the Yellow River. Founded in 1958, the University adheres to the orientation of scientific research towards the frontiers of global science and technology, the main battlefield of the economy, the major needs of the country, and the health of the people. It continuously strengthens basic research and technological development, adheres to the cooperation among industry, academia, and research, and takes the initiative to serve the development of the country, the rail transit industry, and the local economy.

Website: https://en.lzjtu.edu.cn/

About Dr. Beidou Xi from Lanzhou Jiaotong University, China
Dr. Beidou Xi is affiliated to School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, China, and State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, China. He obtained his Bachelor of Engineering in June 1992 and his Master of Engineering in May 1999, both in the School of Environmental Engineering, from Lanzhou Jiaotong University. He earned his Ph.D. in Environmental Engineering from Tsinghua University in July 2002, after which he engaged in postdoctoral research in Canada.

Funding information
This work was supported by Gansu Province University Youth Doctoral Support Project (No. 2023QB-044), the Department of Education of Gansu Province: Major cultivation project of scientific research innovation platform in university (No. 2024CXPT-14), and the Science and Technology Program of Gansu Province (No. 24CXNA029).