When domesticated rabbits go feral, new morphologies emerge

University of Adelaide

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When domesticated rabbit breeds return to the wild and feralise, they do not simply revert to their wild form – they experience distinct, novel anatomical changes.

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Credit: Michael SY Lee.

Originally bred for meat and fur, the European rabbit has become a successful invader worldwide. When domesticated breeds return to the wild and feralise, the rabbits do not simply revert to their wild form – they experience distinct, novel anatomical changes.

Associate Professor Emma Sherratt, from the University of Adelaide’s School of Biological Sciences, led a team of international experts to assess the body sizes and skull shapes of 912 wild, feral and domesticated rabbits to determine how feralisation affects the animal.

“Feralisation is the process by which domestic animals become established in an environment without purposeful assistance from humans,” says Associate Professor Sherratt, whose study was published in Proceedings of the Royal Society.

“While you might expect that a feral animal would revert to body types seen in wild populations, we found that feral rabbits’ body-size and skull-shape range is somewhere between wild and domestic rabbits, but also overlaps with them in large parts.

“Because the range is so variable and sometimes like neither wild nor domestic, feralisation in rabbits is not morphologically predictable if extrapolated from the wild or the domestic stock.”

Associate Professor Sherratt, who performed this study as part of her ARC Future Fellowship, says the greater diversity seen in the skull shape of feral rabbit populations could be related to changes in evolutionary pressures.

“Exposure to different environments and predators in introduced ranges may drive rabbit populations to evolve different traits that help them survive in novel environments, as has been shown in other species.

“Alternatively, rabbits may be able to express more trait plasticity in environments with fewer evolutionary pressures.

“In particular, relaxed functional demands in habitats that are free of large predators, such as Australia and New Zealand, might drive body size variation, which we know drives cranial shape variation in introduced rabbits.” she says.

Associate Professor Sherratt plans to follow up this research by looking into what environmental factors drive the observed variation in body size and skull shape of Australia’s feral rabbits.

“We found Australian feral rabbits are quite a lot larger than European rabbits. We intend to find out why,” she says.

“And we focus on skull shape because it tells us how animals interact with their environment, from feeding, sensing and even how they move.

“Understanding how animals change when they become feral and invade new habitats helps us to predict what effect other invasive animals will have on our environment, and how we may mitigate their success.”

The University of Adelaide and the University of South Australia are joining forces to become Australia’s new major university – Adelaide University. Building on the strengths, legacies and resources of two leading universities, Adelaide University will deliver globally relevant research at scale, innovative, industry-informed teaching and an outstanding student experience. Adelaide University will open its doors in January 2026. Find out more on the Adelaide University website.

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DOI

10.1098/rspb.2025.1150 

 

Rain events could cause major failure of Waikīkī storm drainage by 2050

University of Hawaii at Manoa

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Ala Wai Canal at high tide. 

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Credit: Matthew Gosner; Courtesy Hawai‘i Sea Grant King Tides Project.

Existing sea level rise models for coastal cities often overlook the impacts of rainfall on infrastructure. Researchers at the University of Hawai‘i at Mānoa discovered that by 2050, large rain events combined with sea level rise could cause flooding severe enough to disrupt transportation and contaminate stormwater inlets across 70% of Waikīkī on O‘ahu, Hawai‘i, due to interactions with water in the Ala Wai Canal. Their study was published recently in Scientific Reports.

“We’ve known that sea level rise will reduce the capacity for our drainage system to handle surface runoff, however, including rainfall events in our models showed that Waikīkī’s drainage infrastructure could fail sooner than we anticipated,” said Chloe Obara, lead author of the study who was a graduate student in the Department of Earth Sciences at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST) at the time of this research. “This study highlights the importance of incorporating rainfall and drainage infrastructure into coastal flood models to better understand how drivers of coastal flooding change over time.”

“The many factors affecting flooding should be included in risk assessments and resiliency planning for Waikīkī and other coastal urban areas. Only with accurate information can we strategically mitigate urban flood risks in Honolulu’s tourism hub and other coastal areas,” said Chip Fletcher, study co-author, director of the Coastal Research Collaborative, and Dean of SOEST.

SOEST researchers developed a computer model of the Waikīkī storm drainage system. They also installed ten sensors throughout the storm drainage system—including at street-level inlets and canal or oceanside outfalls—which recorded water depth during two rain events to calibrate and validate their model. They simulated various scenarios of sea level rise and rainfall to determine where and under what conditions the storm drainage system will experience failure.

They determined rainfall is the dominant driver of drainage backflow currently and until sea level rises two feet. Once four feet of sea-level rise is reached, the dominant driver of drainage backflow was determined to be high tidal levels. 

“Management practices aimed at reducing rainfall runoff will help minimize compound flooding in the short-term, but management to reduce tidal backflow, such as pumped drainage, is also urgent, as storm drains are presently impacted by high sea levels and will continue to fail as sea level rises,” said Obara.

Over 75% of the storm drainage system in Waikīkī is connected to the Ala Wai Canal, which is known to be heavily contaminated. Accounting for precipitation, the new study determined that 100% of the outfalls of the Waikīkī storm drainage system will fail by 2050, causing backflow of potentially contaminated water. 

“This research contributes to the growing body of knowledge warning of present and near future climate challenges that will affect transportation, recreation, and accessibility in Waikīkī,” said Obara. “Additionally, it raises awareness of the potential health hazard posed by the presence of drainage backflow containing highly contaminated water from the Ala Wai Canal.”

With this research, the team aims to inform and prepare planners and managers so they can be better positioned to take action to allow Honolulu to continue serving the people of Hawai‘i.

A storm drain in Waikīkī is nearly full of water during a king tide. In this state, the drainage system has limited capacity to drain storm water out of the streets.

Credit

Hawai’i and Pacific Islands King Tides Project, University of Hawai’i Sea Grant

Journal

Scientific Reports

DOI

10.1038/s41598-025-07332-8 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Drainage failure and associated urban impacts under combined sea-level rise and precipitation scenarios

Article Publication Date

2-Jul-2025

 

Development of a quality design method for real-time videos from uncrewed aerial vehicles UAV

University of Tsukuba

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Tsukuba, Japan—Uncrewed aerial vehicle (UAV) video surveillance systems equipped with computers can monitor real-time images of areas that are not easily accessible to humans. However, a high-quality, reliable video surveillance system that properly integrates computers, UAVs, networks, and surveillance software is difficult to design. During the early design phase, before the system is implemented on-site, valuating the quality and considering uncertain factors that might affect the system performance are complicated tasks. This study introduces SPADE, which creates a virtual environment closely resembling the actual operating environment of a UAV video surveillance system. Using video data of a UAV flying in this virtual environment, SPADE enables detailed quality evaluations without real-world manipulations.

SPADE collects virtual images using a UAV flight simulator. The recorded images are processed by an actual computer, which measures the processing accuracy, performance, and power consumption of the UAV. These data are introduced to a state transition model of the system for quality evaluation and trade-off analysis. The SPADE method can evaluate the effects of resolution differences among the input images on the quality of the system for real-time object detection by a UAV.

Various UAV video surveillance systems can be designed through this approach. Future research will develop methods that efficiently design complex, large-scale systems involving multiple UAVs working in coordination.

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This work was supported in part by the grant of the Telecommunications Advancement Foundation.

 

Original Paper

Title of original paper:
SPADE: Simulator-assisted Performability Design for UAV-based Monitoring Systems

Journal:
Future Generation Computer Systems

DOI:
10.1016/j.future.2025.107967

Correspondence

Associate Professor MACHIDA, Fumio
Institute of Systems and Information Engineering, University of Tsukuba

Qingyang Zhang
Doctoral Program in Computer Science, Degree Programs in Systems and Information Engineering, Graduate School of Science and Technology, University of Tsukuba

Related Link

Institute of Systems and Information Engineering

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Journal

Future Generation Computer Systems

DOI

10.1016/j.future.2025.107967 

Article Title

SPADE: Simulator-assisted Performability Design for UAV-based monitoring systems

 

New “bone-digesting” cell type discovered in pythons

Society for Experimental Biology

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Research into the intestinal cells of Burmese pythons has revealed the existence of a previously unknown cell type, responsible for completely absorbing the skeletons of their prey.

Most carnivores eat only the flesh of their prey and avoid eating the bones or pass them undigested, but many snakes and reptiles often consume their prey whole, including the bones. The cellular mechanisms that enable them to do this have remained mysterious until now.

Snakes that are fed on boneless prey suffer from calcium deficiencies, and so bones are a required part of their diet. However, absorbing all the available calcium from a skeleton could result in too much calcium entering their bloodstream. “We wanted to identify how they were able to process and limit this huge absorption of calcium through the intestinal wall,” says Dr Jehan-Hervé Lignot, a Professor at the University of Montpellier.

Dr Lignot and his team analysed the enterocytes, or intestinal lining cells, of Burmese pythons (Python bivittatus) using both light and electron microscopy alongside blood calcium and hormone measurements. This study revealed the presence of a new type of cell along the intestine that is involved in the production of large particles made from calcium, phosphorus and iron.

“A morphological analysis of the python epithelium revealed specific particles that I’d never seen in other vertebrates,” says Dr Lignot. These particles were found inside the internal “crypt” of specialised cells that differed from traditional intestinal cells. “Unlike normal absorbing enterocytes, these cells are very narrow, have short microvilli, and have an apical fold that forms a crypt,” adds Dr Lignot.

To assess the function of these new cells, the intestinal cells of pythons were analysed after they had been fed on three different diets: a normal diet of whole rodents, a low-calcium diet of “boneless prey” and a calcium-rich diet of boneless rodents supplemented with injections of calcium.

The researchers found that when fed with boneless prey, these calcium and phosphorus-rich particles were not produced, but when fed with either a whole rodent or the calcium-supplemented diet, the cell’s crypt filled with large particles of calcium, phosphorus and iron. No bone fragments were found in the python’s faeces, confirming that skeletons were always entirely dissolved inside the body.

This new specialised bone-digesting cell has now been identified in several python and boa species, as well as the Gila monster, a venomous lizard native to the Southwestern United States and Mexico.

However, bone-filled diets aren’t limited to reptiles and there are many other carnivores that eat bony animals whole. “Marine predators that eat bony fish or aquatic mammals must face the same problem,” says Dr Lignot. “Birds that eat mostly bones, such as the bearded vulture, would be fascinating candidates too.”

This research is being presented at the Society for Experimental Biology Annual Conference in Antwerp, Belgium on the 9th July 2025.

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Journal

Journal of Experimental Biology

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Diet-dependent production of calcium- and phosphorus-rich ‘spheroids’ along the intestine of Burmese pythons: identification of a new cell type?

Article Publication Date

25-Jun-2025

 

New study points to Skagerrak as nursery area for the enigmatic Greenland shark

A new international study shows that Skagerrak probably serves as a nursery area for young Greenland sharks

University of Copenhagen - Faculty of Science

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Small Greenland shark measuring approx. 120 cm from Vågsfjorden in northern Norway, released with a tag so that it can be recognized if recaptured. Photo: Martin Nielsen

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Credit: Martin Nielsen

The Greenland shark – the world's longest-living vertebrate – is most often associated with cold Arctic waters. However, a new international study led by researchers from the Greenland Institute of Natural Resources and the University of Copenhagen shows that Skagerrak probably serves as a nursery area for young Greenland sharks. The study also points out that Greenland sharks are not born in Greenland or anywhere else in the Arctic.

It can live for several centuries and, measuring at least 5.5 meters from snout to tail tip, is one of the world's largest carnivorous sharks. The Greenland shark is usually associated with the cold deep waters of the Arctic, where it lives a slow life shrouded in mystery, with a white worm-like parasite dangling from each eye.  

A new study led by researchers from the Greenland Institute of Natural Resources and the Natural History Museum of Denmark presents important new pieces of the puzzle surrounding the mysterious life of the Greenland shark. Among other things, the study shows that the Greenland shark is found much closer to Denmark than most people imagine.

The researchers have examined catch data from over 1,600 Greenland sharks across the North Atlantic, and here the Skagerrak—between Denmark, Norway, and Sweden—stands out as the area with the highest proportion of young sharks between 90 and 200 centimeters.

“We consider the deepest areas of the Skagerrak to be a potentially important feeding ground for ‘teenage Greenland sharks’, and in fact, the study is the first to systematically examine the occurrence of Greenland sharks in the Skagerrak,” says Associate Professor and marine biologist Peter Rask Møller from the Natural History Museum of Denmark.

The mystery of shark birth

One of the biggest mysteries surrounding the Greenland shark's way of life has been where it gives birth to its (presumably) hundreds of pups per pregnancy. Newborn Greenland sharks measure approximately 40 centimeters at birth, and the new study concludes that this is unlikely to take place in fjords or on the continental shelf in the waters around Canada, Greenland, Iceland, Norway, or Russia. This is because neither pregnant females nor newborn pups have ever been recorded in any of these areas.

However, through a thorough review of Danish, Norwegian, and German museum collections, as well as unpublished scientific databases from Iceland, Norway, and Russia, the researchers have managed to find observations of newborn Greenland sharks—all recorded near the Mid-Atlantic Ridge and the Irminger Sea south of Iceland.

“Future targeted studies will most likely confirm that the Greenland shark gives birth to its many pups in undisturbed parts of the deep sea near the Mid-Atlantic Ridge in deep waters , where there is little activity from commercial fisheries,” says the study's lead author Julius Nielsen, a visiting researcher at the Natural History Museum of Denmark and former employee of the Greenland Institute of Natural Resources.

Denmark's deepest sea area plays a role

The Greenland shark is listed as ‘vulnerable’ on the International Red List of Threatened Species and is currently exposed to significant bycatch, not least in trawl, gillnet, and longline fisheries for halibut and cod in deep water. 

Therefore, the new knowledge that the study brings to light about the geographical distribution and distribution of different life stages is important in relation to protecting the Greenland shark across national borders in the North Atlantic.

 “The study breathes new life into the story of the Greenland shark throughout the North Atlantic—and, among other things, provides an understanding of how Denmark's deepest sea area also plays a role in the species' life history,” says Peter Rask Møller, adding that individual Greenland sharks are very likely to travel across large parts of the North Atlantic during their very long lives.

This means that even though the birth area is the Mid-Atlantic Ridge, the teenage years may well be spent in the Skagerrak, and later in life the adult shark may reside in South Greenland or Iceland, for example. However, much more knowledge from, for example, tagging studies is needed to understand exactly how the different areas are used.

150 years of observations and Swedish anglers

Historical data from Denmark also supports the conclusion that Skagerrak is a special place for Greenland sharks. The study corresponds well with the strandings and bycatches that have occurred over the last 150 years in Denmark, which have been collected and reviewed by the Fish Atlas at the Natural History Museum of Denmark.

In the new research article, the researchers have also drawn on a newer and somewhat special data source to study Greenland sharks in the Skagerrak. The catches come primarily from Swedish recreational fishermen who fish in the deep waters of the Skagerrak and often catch the juvenile sharks. This contribution has been crucial in documenting the common presence of Greenland sharks in the Skagerrak – a presence that is otherwise best known from sporadic strandings or bycatches over time.

Unlike many of the other areas studied in the 1610 Greenland shark study across the North Atlantic, the Skagerrak is also notable for the fact that adult individuals are very rare.

“This does not mean that large females cannot be found in the Skagerrak, but the probability of catching a large female is very small there,” says Julius Nielsen.

The large adult females, which typically measure over four meters in length and are over 100 years old, are most frequently found in Subarctic areas where warm Atlantic water also flows. For example, Southwest Greenland, Iceland, and southern Arctic Canada have been identified as regions where the largest females are most frequently found.

The study has been published in the scientific journal Ecology and Evolution: https://onlinelibrary.wiley.com/doi/epdf/10.1002/ece3.71564 

  

Greenland shark from NV released after being caught on a longline.

Credit

Foto Julius Nielsen

Greenland shark from NW approx. 2.5 m caught and released from the Greenland Institute of Natural Resources' research vessel RV Sanna in the area around Uummannaq, NW Greenland. Photo: Julius Nielsen

Credit

Julius Nielsen

Journal

Ecology and Evolution

DOI

10.1002/ece3.71564 

Article Title

Spatial Distribution of Greenland Shark Somniosus microcephalus (Bloch & Schneider, 1801) Life Stages Across the Northern North Atlantic