Can recycled pacemakers from the U.S. save lives overseas? Study seeks to find out

Investigators hope to formalize the process and increase pacemaker access and implantation in low- and middle-income countries through an innovative trial

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MICHIGAN MEDICINE - UNIVERSITY OF MICHIGAN

 

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ERIC PUROLL WORKING ON RECONDITIONING SEVERAL PACEMAKERS AT WORLD MEDICAL RELIEF. 

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CREDIT: BRYAN MCCULLOUGH, MICHIGAN MEDICINE

From inside an operating room in Barquisimeto, Venezuela, electrophysiologist Maria Milagros Arends, M.D., threads wires from a pacemaker through the veins and into the heart muscle of a patient. 

This pacemaker, which regulates the heartbeat and can be lifesaving, was once in the body of another person. It has been recycled, or “reconditioned”— donated, tested, sterilized and shipped from the United States to the South American country for implantation. 

“We have a waiting list of around 300 people who could potentially lose their lives in less than a month,” said cardiologist Bartolome Finizola, M.D., founder and director of ASCARDIO, a nonprofit health care organization founded in 1976 that performs over 100,000 diagnostic and therapeutic procedures each year in Venezuela. 

“Almost nine out of every 10 patients live in poverty conditions and are therefore unable to easily access a pacemaker implant," he said. "Implanting these reconditioned devices has been our solution and around one in seven that we do comes from our partnership with the University of Michigan.”

The process of servicing medical devices for reimplantation in life-threatening cases with no alternative, known as compassionate use, is not new. Pacemakers, however, are considered single-use devices in the U.S. and cannot be reimplanted in such situations. 

Researchers and clinicians at the U-M Health Frankel Cardiovascular Center began sending reconditioned pacemakers to low- and middle-income countries for compassionate use cases in 2010 through the “My Heart Your Heart” program. The project offers the chance for American patients who are preparing to have their pacemaker removed for a new device, and the survivors of a person who died with a pacemaker in place, to consent to donate the device.

Surgeons have since reimplanted approximately 150 of these compassionate use devices in South America, Africa, Asia and Europe.

And the U-M team is leading a clinical trial in low- and middle-income countries that is testing the impact of sending reconditioned pacemakers abroad for standard use. If successful, the trial could greatly increase access to pacemaker treatment for patients who otherwise would not receive it.

“I don’t believe that there’s any other effort on this scale in the world that’s trying to create a blueprint for how to safely recondition pacemakers and offer them to patients at no cost,” said the study’s principal investigator Thomas C. Crawford, M.D., a cardiac electrophysiologist at the Frankel Cardiovascular Center and medical director of the program.

Landmark clinical trial

The international, randomized clinical trial of post-mortem pacemaker utilization, which is still enrolling patients, began in October of 2018, with sites in countries including Venezuela, Kenya and Nigeria. 

“We’ve been met with a lot of enthusiasm from different countries,” Crawford said. “After overcoming the regulatory obstacles, we’ve been able to provide devices to physicians who really know what to do with them, and we’ve helped to train many of them.”

As a part of the clinical trial, patients are either given new pacemakers or those that have been reconditioned in the U.S. Pacemaker recipients are individuals who are unable to pay for a new device and for whom all other methods for acquiring one are exhausted. 

SEE ALSO: U-M Health performs its first heart transplant after cardiac death

The main method of determining if the reconditioned pacemakers are successful is whether recipients have infections related to the device implantation, as well as any software or hardware malfunctions. 

Over 200 patients have already enrolled in the trial, with more than 100 coming from ASCARDIO in Venezuela. 

“Proof of the safety of these devices would give us the opportunity to win time for even more of our patients,” said Vicente Finizola, M.D., interventional cardiologist at ASCARDIO and board member of the Venezuelan Society of Cardiology.

“It could shorten the long waiting list we already have.”

Investigators have a goal of 260 patients and hope to complete it by October 2025. 

“If the trial shows positive results, we could scale this up and create a self-sustaining operation to allow for large-scale pacemaker reconditioning and donations to low-income countries,” Crawford said. 

“Reconditioning” a pacemaker

The program got its start more than a decade ago when the spouse of a recently deceased patient called Timir S. Baman, M.D., who was then a cardiology fellow.

The caller's wife died soon after receiving a pacemaker implantation, and they did not want the device to go to waste. Pacemakers can remain in the body for around 15 years.

“It got us looking into the possibility of reconditioning these pacemakers,” Crawford said. “We looked at the literature, and it set us on the path to where we are today.”

The chance encounter sparked a multidisciplinary partnership; an assembly line of charitable people and organizations dedicated to providing the devices at no cost. 

Anchoring the line is Eric Puroll, the program’s project manager, who splits his time between the university and a lab donated by World Medical Relief, a non-governmental organization in Southfield, Mich. 

“This requires a lot of hard work and some tedious work,” Puroll said. “But it’s a labor of love and time.”

When a person who has indicated their wish to donate a pacemaker dies, the funeral home handling their preparations request a prepaid shipping envelope from Ann Arbor, as well as a consent form for the deceased person's family to sign and a biohazard bag for the pacemaker. 

Although the majority of their devices initially came from Michigan funeral homes, the project now receives pacemakers from all 50 states. Individuals who have a pacemaker but are scheduled to get a new one implanted can also consent to donate the one being removed from them. 

“For years, most of the pacemakers that are explanted from decedents would either end up in medical waste bins or trash,” said Kiki Rodgers, licensed funeral director at Nie Family Funeral & Cremation Service in Ann Arbor. 

“It is truly a wasted resource otherwise. But if you can do something additional and it is a lifesaving measure for someone else, why not be involved?”

If a device has more than four years of remaining battery life, the process moves forward. Those deemed unusable are sent to Implant Recycling in Sterling Heights, Mich.

Puroll and his team of volunteers then remove the pacemaker’s patient health information and ship it to Northeast Scientific, Inc., a Connecticut-based company that specializes in remanufactured medical devices. 

“They clean and decontaminate the device, as well as remove the set screw in the screw cap,” Puroll said. 

“They ship the device back to us, and we electrically test the device to make sure all the parameters are met. We dip the device in silicone solution and send it back to Northeast Scientific to bathe the pacemaker in ethylene oxide. Then, the device is ready for reimplantation.”

Changing lives abroad

In Venezuela, the team at ASCARDIO implanted more than 135 reconditioned pacemakers in 2023. Of those, over 100 came from Ann Arbor.

The partnership did not start by Finizola contacting U-M or the other way around. Much like the genesis of My Heart Your Heart, it began with a patient’s concerned family member.

“In 2020, I was looking for a replacement pacemaker battery for my mom,” said Azorena Aponte, a New York City resident whose mother lives in Barquisimeto, Venezuela.

“I decided to reach out to a few places, NGOs and so on. One that popped up was this program, My Heart Your Heart. No one answered me except for Eric Puroll. He quickly sent me two devices, in case one of them was faulty.”

Aponte shipped the pacemakers to Venezuela, and her mother’s reimplantation was successful.

A few weeks later, Crawford called Aponte looking for help to find a partner for the program in Latin America. From the east coast, she connected U-M and ASCARDIO, and the two organizations formalized the partnership with approval from Venezuela’s ministry of health.

“This is something I felt like God kind of threw at us,” Aponte said. “I took the opportunity and ran with it. There are a lot of people involved in this process.”

While pacemakers are mostly a treatment for older adults, and the clinical trial is limited to people over the age of 18, several compassionate use re-implantations have saved younger patients, even one as young as 12 years old.

“We had one patient under 20 years old who was functionally very limited before receiving her pacemaker,” Finizola said. “Now, she is healthy and gave us good news that she is expecting a baby.”

While there have been few adverse events after implantation over the last 10 years, as would be expected with any kind of pacemaker surgery, no devices have been reported as faulty. During his visits, Crawford follows up with patients who received implants. 

The impact, he says, can be immediate.

“We see their quality of life improve; many of them are able to breath normally and exercise, to a degree, again,” Crawford said. 

“Many times, patients who are having dizzy spells, who were not able to walk across a room, can function almost normally. It’s very rewarding to see that.”

The future of My Heart Your Heart

In Michigan, the notes, photos and videos of patients with their new pacemakers, Puroll says, keeps him and the volunteers motivated. 

“Seeing patients receive the devices that we put our blood, sweat and tears into, it means everything,” he said. 

“To be able to give back to people who can’t afford the same care that we can — that we often take for granted — pushes me to continue this work for as long as possible.”

As the trial continues, the team at the Frankel Cardiovascular Center aren’t limiting the project’s scope to pacemakers. 

“I see unlimited growth for My Heart Your Heart,” said Kim Eagle, M.D., founder of the program and a director of the Frankel Cardiovascular Center.

“Beyond this trial, we could one day test the safety and efficacy of other implantable devices, specifically biventricular pacemakers, defibrillators and implantable cardioverter-defibrillators. This program represents exactly what we stand for at U-M. We will continue to push forward in a way that improves lives across the globe.”

My Heart Your Heart has unlimited appreciation for our partners at funeral homes, World Medical Relief, Northeast Scientific, Inc., and Implant Recycling. The program is funded entirely by donors, foundations and the U-M Health Frankel Cardiovascular Center. 

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METHOD OF RESEARCH

Randomized controlled/clinical trial

SUBJECT OF RESEARCH

People

Dogs are not always frustrated when they get kibble instead of liver for their work

dogs are not as sensitive to such replacement as other mammalian species.

Peer-Reviewed Publication

EÖTVÖS LORÁND UNIVERSITY

 

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EXPLORING HOW CHANGING REWARDS AFFECTS DOG’S BEHAVIOR

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CREDIT: PHOTO: ENIKŐ KUBINYI

In animals, and often in humans too, performance is significantly impaired when the value of the reward for work is reduced. Argentinian and Hungarian researchers have studied what happens when family dogs are forced to switch from a cooked liver reward snack to dry food. The results show that dogs are not as sensitive to such replacement as other mammalian species.

It's easy to imagine the feelings of an employee who, through no fault of his own, has his salary cut because of the company's difficulties or a child whose teacher gives him a C instead of an A for the same performance. The result is frustration, disillusionment, lack of motivation and poor performance. This can also happen to animals that struggle to get a valuable, tasty snack and then are unexpectedly given low-calorie, tasteless junk.

This negative behavioural response is scientifically known as "successive negative contrast". Research into this phenomenon highlights the importance of expectations and the emotional impact of reward changes. It is important not only for animal trainers but also for people to understand how expectations influence emotions and, through them, performance. But while it is possible to explain to humans why they are rewarded less for the same performance, it is not possible to do this with animals, so particular attention needs to be paid to changing expectations gradually and not abruptly.

“We applied two behavioural tests in family dogs to investigate how a sudden reduction in the value of a reward changes performance. We used cooked beef liver as a high-value reward and dry dog food as a low-value reward”, explains Mariana Bentosela, head of the Grupo de Investigación del Comportamiento en Cánidos in Argentina. In the first behavioural test, the dog was rewarded if it followed the experimenter's pointing gesture to choose a particular dish and not another one. In the second test, rewards had to be extracted from a commercially available 'smart' dog toy by removing small lids. So, the main difference between the two tests was that one was a social situation, and the reward could be obtained with the help of the experimenter, whereas in the other test, the dogs worked independently.

The researchers divided the participating dogs into two groups. In the control group, the dogs were given the same dry dog food throughout. In the experimental group, they were given liver first and then dry dog food. Then, at the end of the test, they were given liver again to see if they had already had enough to eat and, therefore, stopped working.

The results, published in the Journal of Veterinary Behavior, showed that in the pointing test, the dogs in the experimental group were slower and more reluctant to go to the bowls when the liver pieces were changed to kibble. In the control group, there was no such change.

However, in the ‘dog toy’ test, the behaviour of the experimental and the control groups did not differ, suggesting that the dogs were not disturbed by the change in the reward value.

"It seems that dogs react negatively to the deterioration in the quality of the reward in certain situations but not in others. There may be methodological reasons for this, for example, the difference between cooked liver and dry food is not as great for the dogs as we imagined. It is also possible that family dogs might become accustomed to the frequent changes in reward value, especially when receiving small bites between meals," said Enikő Kubinyi, head of the MTA-ELTE Lendület Companion Animals Research Group in Hungary. The study confirmed that, compared to other animals, dogs are unique in that the quality of the treats used for motivation typically does not have a strong impact on their performance.

Two behavioural tests were applied in family dogs to investigate how a sudden reduction in the value of a reward changes performance. The researchers used cooked beef liver as a high-value reward and dry dog food as a low-value reward

CREDIT

The first part of the picture is provided by Mariana Bentosela, Grupo de Investigación del Comportamiento en Cánidos in Argentinaand; the second part is made by: Enikő Kubinyi / Eötvös Loránd University

In animals, and often in humans too, performance is significantly impaired when the value of the reward for work is reduced. Argentinian and Hungarian researchers have studied what happens when family dogs are forced to switch from a cooked liver reward snack to dry food. The results show that dogs are not as sensitive to such replacement as other mammalian species.

CREDIT

Photo: Enikő Kubinyi

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JOURNAL

Journal of Veterinary Behavior

DOI

10.1016/j.jveb.2023.12.009 

ARTICLE TITLE

What if the reward is not as yummy? Study of the effects of Successive Negative Contrast in domestic dogs in two different tasks

 

Tiny AI-based bio-loggers revealing the interesting bits of a bird’s day

Researchers from Osaka University find a way that, without supervision by researchers, automatically captures video of rare animal behavior over the long term in extreme environments using a light-weight AI controller to preserve bio-logger battery power

Peer-Reviewed Publication

OSAKA UNIVERSITY

 

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FINDING AND RECORDING RARE BEHAVIORS OF WILDLIFE BY AI

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CREDIT: TAKUYA MAEKAWA, OSAKA UNIVERSITY

Osaka, Japan – Have you ever wondered what wildlife animals do all day? Documentaries offer a glimpse into their lives, but animals under the watchful eye do not do anything interesting. The true essence of their behaviors remains elusive. Now, researchers from Japan have developed a camera that allows us to capture these behaviors.

In a study recently published in PNAS Nexus, researchers from Osaka University have created a small sensor-based data logger (called a bio-logger) that automatically detects and records video of infrequent behaviors in wild seabirds without supervision by researchers.

Infrequent behaviors, such as diving into the water for food, can lead to new insights or even new directions in research. But observing enough of these behaviors to infer any results is difficult, especially when these behaviors take place in an environment that is not hospitable to humans, such as the open ocean. As a result, the detailed behaviors of these animals remain largely unknown.

“Video cameras attached to the animal are an excellent way to observe behavior,” says Kei Tanigaki, lead author of the study. However, video cameras are very power hungry, and this leads to a trade-off. “Either the video only records until the battery runs out, in which case you might miss the rare behavior, or you use a larger, heavier battery, which is not suitable for the animal.”

To avoid having to make this choice for the wild seabirds under study, the team use low-power sensors, such as accelerometers, to determine when an unusual behavior is taking place. The camera is then turned on, the behavior is recorded, and the camera powers off until the next time. This bio-logger is the first to use artificial intelligence to do this task.

“We use a method called an isolation forest,” says Takuya Maekawa, senior author. “This method detects outlier events well, but like many other artificial intelligence algorithms, it is computationally complex. This means, like the video cameras, it is power hungry.” For the bio-loggers, the researchers needed a light-weight algorithm, so they trained the original isolation forest on their data and then used it as a “teacher” to train a smaller “student” outlier detector installed on the bio-logger.

The final bio-logger is 23 g, which is less than 5% of the body weight of the Streaked Shearwater birds under study. Eighteen bio-loggers were deployed, a total of 205 hours of low-power sensor data were collected, and 76 5-min videos were collected. The researchers were able to collect enough data to reveal novel aspects of head-shaking and foraging behaviors of the birds.

This approach, which overcomes the battery-life limitation of most bio-loggers, will help us understand the behaviors of wildlife that venture into human-inhabited areas. It will also enable animals in extreme environments inaccessible to humans to be observed. This means that many other rare behaviors — from sweet-potato washing by Japanese monkeys to penguins feeding on jellyfish — can now be studied in the future.

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The article, “Automatic recording of rare behaviors of wild animals using video bio-loggers with on-board light-weight outlier detector,” was published in PNAS Nexus at DOI: 10.1093/pnasnexus/pgad447

AI-enabled device and videos automatically recorded by the device

CREDIT

Takuya Maekawa, Osaka University

Introduction of AI-enabled bio-logger for finding rare behaviors (VIDEO)

About Osaka University
Osaka University was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world, being named Japan's most innovative university in 2015 (Reuters 2015 Top 100) and one of the most innovative institutions in the world in 2017 (Innovative Universities and the Nature Index Innovation 2017). Now, Osaka University is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.
Website: https://resou.osaka-u.ac.jp/e

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JOURNAL

PNAS Nexus

DOI

10.1093/pnasnexus/pgad447 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Automatic recording of rare behaviors of wild animals using video bio-loggers with on-board light-weight outlier detector

ARTICLE PUBLICATION DATE

16-Jan-2024

AI naturalists record rare bird behavior

Peer-Reviewed Publication

PNAS NEXUS

 

VIDEO: 

RARE BEHAVIORS RECORDED BY AI-ENABLED BIO-LOGGERS AFFIXED TO STREAKED SHEARWATERS.

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CREDIT: TANIGAKI ET AL, OSAKA UNIVERSITY

For centuries, naturalists have braved trackless forests, windy clifftops, and the cramped confines of blinds and submarines, hoping to capture rare behaviors that might reveal important aspects of animal biology and ecology. Takuya Maekawa and colleagues sought to deploy wearable trackers, which have become common in animal biology, to capture rare behaviors for study. As animal-borne video loggers can only capture a few hours of video due to battery limitations, a key challenge is deciding when to record. The authors created an on-device AI program capable of “unsupervised learning” to automatically find and record rare behaviors without supervision by human naturalists. First, an outlier detector program was trained on unlabeled accelerometer and water-depth data from seabirds to automatically determine when an unusual behavior is taking place. This outlier detector program was used to create streamlined outlier detectors—one for accelerometer data and one for water-depth data—that fit on a low-energy micro control unit on a logger with limited memory and computational power. These detectors turn on a video camera of the logger when a rare behavior occurs in real time. The final AI-enabled bio-logger includes a video camera, three-axis acceleration sensor, GPS unit, water pressure sensor, thermometer, magnetometer, and illuminometer, which was then affixed to a streaked shearwater (Calonectris leucomelas). The bio-logger weighs 23 g, less than 5% the weight of a shearwater. In field trials in 2022, the authors attached the bio-loggers to 18 birds. The acceleration-based rare-behavior detectors recorded videos of vigorous head shaking near the beginning of flight that the authors hypothesize may function to remove nasal salt gland fluids and other external materials to increase subsequent flight efficiency. The depth-based rare behavior detectors captured 50 minutes of active foraging for fish—including preliminary below-water peeks before diving—behavior rarely caught on camera. According to the authors, AI-enabled bio-loggers can be used on a range of species to capture many kinds of seldom-seen moments, including deep-sea mating rituals, the hunting strategies used for rare prey items, and the causes of death of wild animals.

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JOURNAL

PNAS Nexus

ARTICLE TITLE

Automatic recording of rare behaviors of wild animals using video bio-loggers with on-board light-weight outlier detector

ARTICLE PUBLICATION DATE

16-Jan-2024

 

Agriculture: Changing animal feed reduces consumption of natural resources such as soil and water

A study published on the cover of Nature Food opens up new scenarios for sustainability in agri-food systems

Peer-Reviewed Publication

POLITECNICO DI MILANO

 

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GLOBAL DISTRIBUTION OF PROTEIN PRODUCTION, INCLUDING MEAT AND DAIRY PRODUCTS, ADAPTED FROM FAO, COMBINED WITH RESULTS ON REGION-SPECIFIC LAND AND WATER USE FOR ENERGY-RICH LIVESTOCK FEED PRODUCTION AND THE POTENTIAL SAVINGS ACHIEVABLE BY REPLACING FEED WITH AGRICULTURAL BY-PRODUCTS

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CREDIT: POLITECNICO DI MILANO

Milan, 16 January 2024 - A study published on the cover of Nature Food, the result of a collaboration between Politecnico di Milano and the University of Milan, highlights how the increased use of by-products in the feed sector in a circular perspective can lead to significant savings in the use of land and water resources and thus to more sustainable agri-food systems.

 

Underlying the work signed by Camilla Govoni and Maria Cristina Rulli (Politecnico di Milano), Paolo D'Odorico (University of California at Berkeley) and Luciano Pinotti (University of Milan), there is a thorough analysis of the competition for natural resources between animal and human food production and a search for strategies to reduce both this competition and the unsustainable use of natural resources that can result from it.

 

The study shows that an 11-16% substitution of energy-intensive crops currently used as animal feed (eg cereals) with agricultural by-products would save approximately between 15.4 and 27.8 million hectares of soil, between 3 and 19.6 km3 and between 74.2 and 137.8 km3 of irrigation and rainwater. This saving of natural resources is an appropriate strategy for reducing the unsustainable use of natural resources both locally and globally, ie through virtual trade in land and water.

 

Agricultural by-products are defined as secondary products derived from the processing of primary crops such as cereals and sugar. Included in the study are cereal bran, sugar beet pulp, molasses, distillery residues and citrus pulp.

 

Food of animal origin is an important source of protein in human diets and contributes on average 16% of global food requirements, while using 1/3 of the resources used in agriculture and up to 3/4 of all agricultural land for their production.

Animal production can therefore compete directly or indirectly with plant food production.

 

 

‘Not only does the use of agricultural by-products in animal diets decrease competition between sectors and pressure on resources, but it would also increase the availability of calories that can be directly earmarked for the human diet (eg cereals); if the saved resources are used for other purposes, including the production of plant foods lacking in current diets, it would improve food security in several countries, with healthier as well as more sustainable food choices’ - comments Camilla Govoni, researcher at Politecnico di Milano.

 

 ‘The use of alternative ingredients in animal diets would lead to increased sustainability and reduced environmental impact not only locally, where the company raises and produces meat and animal products, but also over large distances. Indeed, a decrease in demand for feed could lead to less importation of feed with both economic and socio-environmental benefits. The production of certain feed products actually corresponds to over-pressure on water resources and deforestation, with consequent effects on the concentration of greenhouse gases in the atmosphere, loss of biodiversity and so on.’ - explains Maria Cristina Rulli, Professor of Hydrology and Coordinator of the Glob3ScienCE Lab (Global Studies on Sustainable Security in a Changing Environment) of Politecnico di Milano - ‘The inter-sectoral decrease in the demand for cereals is of particular relevance at a time when the supply of these crops is facing serious shortages due to the combination of the ongoing war between Russia and Ukraine, the residual effects on the food supply of the Covid-19 pandemic, and a drop in harvests caused by increasingly frequent extreme events such as floods, droughts and heat waves induced by climate change.’

 

 ‘By converting fodder and agricultural by-products into high value-added products and services, animal production makes a fundamental contribution to the modern bio-economy. Alongside this, livestock farming is often held responsible for a significant global environmental impact, which is why it is essential to rethink animal nutrition in particular, as it is one of the main reasons for competition for resources’ - concludes Luciano Pinotti, Professor of Nutrition and Food at the University of Milan. ‘The approach must be to develop “smart animal nutrition”, where research must come up with solutions to increase animal protein production without increasing the environmental footprint of animal protein. Hence the importance of studying animal nutrition not only in terms of competition, but also in terms of synergies and complementarity with human nutrition, so as to optimise the utilisation of nutrients in the food chain. The main challenge is thus to explore innovative feeds which may work as an alternative to conventional ones, possibly do not compete with human nutrition, are part of a circular economy and are intended with a view to 'one nutrition'.

Link to the study: Preserving global land and water resources through the replacement of livestock feed crops with agricultural by-products | Nature Food

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JOURNAL

Nature Food

DOI

10.1038/s43016-023-00884-w 

METHOD OF RESEARCH

Data/statistical analysis

 

Most biodiversity is found in rainy regions

Researchers from Tel Aviv University led the most comprehensive study to this date on species richness of land vertebrates:

Peer-Reviewed Publication

TEL-AVIV UNIVERSITY

 

IMAGE: 

SPATIAL VARIANCE IN THE IMPORTANCE OF ENVIRONMENTAL PREDICTORS ON TETRAPOD SPECIES RICHNESS.

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CREDIT: TEL AVIV UNIVERSITY

An international research group led by Tel Aviv University and Ben-Gurion University of the Negev tried to answer the centuries long question: why there are more animal and plant species in the tropics? In the most comprehensive study to this date on species richness of land vertebrates, the researchers explored patterns in the number of species – all across the world – using comprehensive data for tens of thousands of species of amphibians, birds, mammals, and reptiles. The researchers highlighted again the dominance of tropical regions, close to the equator, as centers of high biodiversity. When investigating the reasons behind these patterns, they found that the combination of climate and topography was key in explaining them. However, while larger amounts of rainfall contribute to higher richness for amphibians, birds, and mammals, more reptiles are found in warmer regions, regardless of rainfall. Patterns are even more complex as species numbers increase with rainfall almost everywhere in the world – but in cold regions temperature has a more dominant effect.

The research was led by PhD student Tal Raz and Prof. Shai Meiri from Tel Aviv University’s School of Zoology at the Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History, along with Prof. Uri Roll from the Mitrani Department of Desert Ecology at Ben-Gurion University of the Negev. The research encompassed 5,983 amphibian, 9,630 avian, 5,004 mammal and 8,939 reptile species and was published in the Journal of Zoology.

"Until recently, we didn't have enough data on where land vertebrates are found and thus on how many species are actually found in different areas of the world. Now, we have detailed data for reptiles, which we made available, along with publicly available data for other land vertebrate groups. This allows us to accurately study global patterns and how they relate to the environment. The relationship between temperature, precipitation, and topography in shaping ecosystems is fascinating. In regions where environmental factors are diverse, they tend to have a more pronounced influence on the number of species. In Africa, for instance—where temperatures are quite high all over, the varying rainfall plays a crucial role in determining the number of species. In Eurasia, both temperature and rainfall are highly diverse, making them both influential for species richness. But with all that, amphibians never forget their connection to rainfall, and reptiles hold onto their affinity for warmth”, said Tal Raz.

The researchers found that reptiles have a slightly different species-richness pattern that is more influenced by temperature and less by rainfall. Prof. Shai Meiri from Tel Aviv University explained that “reptiles can do with very little water, because their metabolism is much slower compared to birds and mammals and because, unlike amphibians, they have highly efficient mechanisms to prevent water loss. But reptiles are highly sensitive to temperatures and cannot readily function in cold regions. Therefore, we see relatively high numbers of reptiles in deserts worldwide, where mammals, birds and, especially, amphibians, are scarce.” Prof. Meiri added “in recent years we have made tremendous efforts to map the global distributions of about 12,000 species of reptiles (as part of the Global Assessment of Reptile Distributions). Such efforts enable us to ask such broad-scale fundamental questions regarding the ecology and evolution of life on our planet”.

Prof. Roll: “We live in an age of the biodiversity crisis! If trends continue as they are, many of the plants and animals that share the Earth with us will not be here by the end of the 21st century due to destruction of their habitats, climate change, and other human effects. A better understanding of where biodiversity is found, and why we find it there, is fundamental for our efforts to conserve it. Moreover, works such as this highlight how life on Earth is a truly miraculous phenomenon, and should serve as a call to action to everyone to protect it.”

Which environmental factor explains most of the variation in the number of species?

Here you can see (Image 2 of Map) whether rainfall, temperature, or height determines the number of species in different places in the world. The size of the circle depicts the importance of the factor. The two most important factors are presented for each animal group. The dragon represents all land vertebrates together (birds, mammals, amphibians, and reptiles combined). For example, temperature explains most of the variation in the number of species in North America for all animal groups, while rainfall and range of heights are the most important in South-East Asia.

Species-richness patterns and latitudinal diversity gradient of terrestrial tetrapods.

CREDIT

Tel Aviv University

Patterns of the number of species worldwide. Red means many species, yellow means an intermediate number, and blue means few species. The top map (a) represents all land vertebrates together (birds, mammals, amphibians, and reptiles combined). The bottom maps (c-e) are species-richness patterns of each group individually. For example, for all animal groups there are many species in the Amazon Forest, and few species in the Sahara Desert. You can also see some differences among group like in Australia – where there are many reptile species but few amphibians and mammals.

Link to the article:

https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/jzo.13130

 

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DOI

10.1111/jzo.13130