It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Sunday, January 19, 2020
As superbugs spread, WHO raises alarm over lack of new antibiotics
JANUARY 17, 2020
Credit: CC0 Public Domain
The World Health Organization warned Friday that a dire lack of new antibiotics was threatening efforts to curb the spread of drug-resistant bacteria, which kill tens of thousands of people each year.
The UN health agency published two new reports revealing that there are few new effective antibiotics in the pipeline, meaning that the world is running out of options for fighting so-called superbugs.
"Never has the threat of antimicrobial resistance been more immediate and the need for solutions more urgent," WHO chief Tedros Adhanom Ghebreyesus said in a statement.
"Numerous initiatives are underway to reduce resistance, but we also need countries and the pharmaceutical industry to step up and contribute with sustainable funding and innovative new medicines," he said.
Antibiotic resistance happens when bugs become immune to existing drugs, rendering minor injuries and common infections potentially deadly.
An estimated 33,000 people die in Europe every year from such drug-resistant bacteria, according to EU data, while the US estimates the death toll there is around 35,000.
"We see that this is spreading and we are running actually out of antibiotics that are effective against these resistant bacteria," Peter Beyer, of WHO's essential medicines division, told reporters in Geneva.
"This is one of the biggest health threats that we have identified," he said.
Discovered in the 1920s, antibiotics have saved tens of millions of lives by defeating bacterial diseases such as pneumonia, tuberculosis and meningitis.
But over the decades, bacteria have learned to fight back, building resistance to the same drugs that once reliably vanquished them—turning into so-called "superbugs".
To counter bacteria's ability to become resistant to known drugs, a steady stream of new antibiotics is needed, but for pharmaceutical companies, developing competitive new products in this field is complicated, costly, and not seen as very profitable.
According to the WHO, the 60 new products currently in development—50 antibiotics and 10 biologics—"bring little benefit over existing treatments and only two target the most critical resistant bacteria", the so-called Gram-negative bacteria.
A range of other drugs still in pre-clinical testing are more innovative, WHO said, but warned it will take years before they reach the market.
Of the 252 such drugs still in very early-stage testing, the two to five first products could become available in about 10 years, according to an optimistic scenario, WHO said.
"It's important to focus public and private investment on the development of treatments that are effective against the highly resistant bacteria," Hanan Balkhy, WHO Assistant Director-General for Antimicrobial Resistance, said in the statement.
The fMRI machine located in the IDOR imaging suite. fMRI is used to indirectly detect increased neuronal activity in an area of the brain by measuring higher levels of oxygenated to deoxygenated blood. Credit: Andressa Dias Lemos, IDOR
Attention-deficit hyperactivity disorder (ADHD) is a neurobiological disorder characterized by symptoms of hyperactivity, inattention and impulsivity. People with the condition are often prescribed a stimulant drug called methylphenidate, which treats these symptoms. However, scientists do not fully understand how the drug works.
Now, researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) have identified how certain areas of the human brain respond to methylphenidate. The work may help researchers understand the precise mechanism of the drug and ultimately develop more targeted medicines for the condition.
Previous research suggests that people with ADHD have different brain responses when anticipating and receiving rewards, compared to individuals without ADHD. Scientists at OIST have proposed that in those with ADHD, neurons in the brain release less dopamine—a 'feel-good' neurotransmitter involved in reward-motivated behavior—when a reward is expected, with dopamine neurons firing more when a reward is given.
"In practice, what this means is that children, or even young adults, with ADHD may have difficulty engaging in behavior that doesn't result in an immediate positive outcome. For example, children may struggle to focus on schoolwork, as it may not be rewarding at the time, even though it could ultimately lead to better grades. Instead, they get distracted by external stimuli that are novel and interesting, such as a classmate talking or traffic noises," said Dr. Emi Furukawa, first author of the study and a researcher in the OIST Human Developmental Neurobiology Unit, led by Professor Gail Tripp.
Scientists believe that methylphenidate helps people with ADHD maintain focus by influencing dopamine availability in the brain. Therefore, Dr. Furukawa and her colleagues set out to examine how the drug affects a brain region called the ventral striatum, which is a vital component of the reward system and where dopamine is predominantly released.
"We wanted to take a look at how methylphenidate affects the ventral striatum's responses to reward cues and delivery," said Furukawa.
The study, which was recently published in the journal Neuropharmacology, was jointly conducted with scientists at D'Or Institute for Research and Education (IDOR) in Rio de Janeiro, Brazil. The collaboration allowed the researchers to combine expertise across multiple disciplines and provided access to IDOR's functional magnetic resonance imaging (fMRI) facility.
When the slot machine showed Cue A – the Japanese character み (mi) – participants received money 66% of the time. When the slot machine showed Cue B – the Japanese character そ (so) – the participants did not receive any money. Credit: OIST
Delving into the brain
The researchers used fMRI to measure brain activity in young adults with and without ADHD as they played a computer game that simulated a slot machine. The researchers scanned individuals in the ADHD group on two separate occasions—once when they took methylphenidate and another time when they took a placebo pill. Each time the reels of the slot machine spun, the computer also showed one of two cues, either the Japanese character み (mi) or そ (so). While familiarizing themselves with the game before being scanned, the participants quickly learned that when the slot machine showed み, they often won money, but when the slot machine showed そ, they didn't. The symbol み therefore acted as a reward-predicting cue, whereas そ acted as a non-reward-predicting cue.
The researchers found that when individuals with ADHD took the placebo, neuronal activity in the ventral striatum was similar in response to both the reward predicting and non-reward predicting cue. However, when they took methylphenidate, activity in the ventral striatum increased only in response to the reward cue, showing that they were now able to more easily discriminate between the two cues.
The researchers also explored how neuronal activity in the striatum correlated with neuronal activity in the medial prefrontal cortex—a brain region involved in decision-making that receives information from the outside world and communicates with many parts of the brain, including the striatum.
When the individuals with ADHD took placebo instead of methylphenidate, neuronal activity in the striatum correlated strongly with activity in the prefrontal cortex at the exact moment the reward was delivered, and the participants received money from the slot machine game. Therefore, the researchers believe that in people with ADHD, the striatum and the prefrontal cortex communicate more actively, which may underline their increased sensitivity to rewarding external stimuli. In participants who took methylphenidate, this correlation was low, as it was in people without ADHD.
The results implicate a second neurotransmitter, norepinephrine, in the therapeutic effects of methylphenidate. Norepinephrine is released by a subset of neurons common in the prefrontal cortex. Researchers speculate that methylphenidate might boost levels of norepinephrine in the prefrontal cortex, which in turn regulates dopamine firing in the striatum when rewards are delivered.
"It's becoming clear to us that the mechanism by which methylphenidate modulates the reward response is very complex," said Furukawa.
The red points show the regions examined in the striatum. The researchers calculated correlations between these striatal regions and the medial prefrontal cortex regions shown as blue points. Credit: OIST
Tailoring New Therapies for ADHD
Despite the complexity, the scientists believe that further research could elucidate methylphenidate's mechanism of action, which could benefit millions of people worldwide.
Pinning down how methylphenidate works may help scientists develop better therapies for ADHD, said Furukawa. "Methylphenidate is effective but has some side effects, so some people are hesitant to take the medication or give it to their children," she explained. "If we can understand what part of the mechanism results in therapeutic effects, we could potentially develop drugs that are more targeted."
Furukawa also hopes that understanding how methylphenidate impacts the brain could help with behavioral interventions. For example, by keeping in mind the difference in brain responses when children with ADHD anticipate and receive rewards, parents and teachers could instead help children with ADHD stay focused by praising them frequently and reducing the amount of distracting stimuli in the environment
Clinical trials suggest treatment that involves psychedelics can be more effective than psychotherapy alone. More than three million people in the United States are diagnosed each year with post-traumatic stress disorder, whose symptoms include nightmares or unwanted memories of trauma, heightened reactions, anxieties, and depression—and can last months, or even years.
People with PTSD—difficulty recovering from experiencing or witnessing a traumatic event—have traditionally been treated with a combination of trauma-focused psychotherapy and a regimen of medications. Many sufferers have not responded well to that treatment, but new research to be presented by the Medical University of South Carolina's Dr. Michael Mithoefer and colleagues, at the annual meeting of the American College of Neuropsychopharmacology, suggests that the combination of some psychedelic drugs and traditional psychotherapy holds promise.
Psychedelic substances are often found in nature and have been used in various cultures over thousands of years. Formal medical research into their medicinal uses starting in the 1950s produced promising results published in major journals but was largely halted in the 1970s for political rather than medical or scientific reasons. More recent studies argue that, when administered in a controlled clinical setting, MDMA (more commonly known as ecstasy) and psilocybin (the active ingredient in "magic mushrooms") have acceptable risk profiles —and patients who experienced temporary adverse reactions did not require additional medical intervention.
In the past few years the FDA has granted both MDMA and psilocybin Breakthrough Therapy Designations for PTSD and depression respectively, acknowledging they may improve upon existing therapies, and agreeing to expedite their development and review.
The research by Dr. Mithoefer and his team includes six Phase 2 clinical trials conducted by independent investigators in four countries. In the trials, one group of patients was administered MDMA during their psychotherapy sessions, while the other group was administered a placebo or low dose comparator in conjunction with the same psychotherapy. The overall conclusion from these studies was that MDMA-assisted psychotherapy was significantly more effective at treating patients with persistent PTSD than unassisted psychotherapy.
The researchers aim to both review the successes that have been seen in the use of psychedelic drugs to treat trauma-related disorders and depression, as well as address several of the outstanding questions the medical community may still have concerning the safety, efficacy, and neurobiological functions of these novel treatment options.
More information: The findings were presented at the 58th Annual Meeting of The American College of Neuropsychopharmacology (ACNP) in Orlando, FL, December 8-11, 2019.
Research shows real risks associated with cannabis exposure during pregnancy
A new study from researchers at Western University and Queen's University definitively shows that regular exposure to THC, the main psychoactive ingredient in cannabis, during pregnancy has significant impact on placental and fetal development. With more than a year since the legalization of recreational cannabis in Canada, the effects of its use during pregnancy are only now beginning to be understood.
The study, published today in Scientific Reports, uses a rat model and human placental cells to show that maternal exposure to THC during pregnancy has a measurable impact on both the development of the organs of the fetus and the gene expression that is essential to placental function.
The researchers demonstrated in a rat model that regular exposure to a low-dose of THC that mimics daily use of cannabis during pregnancy led to a reduction in birth weight of 8 per cent and decreased brain and liver growth by more than 20 per cent.
"This data supports clinical studies that suggest cannabis use during pregnancy it is associated with low birth weight babies. Clinical data is complicated because it is confounded by other factors such as socioeconomic status," said Dan Hardy, Ph.D., Associate Professor at Western's Schulich School of Medicine & Dentistry and co-author on the paper. "This is the first study to definitively support the fact that THC alone has a direct impact on placental and fetal growth."
The research team was also able to characterize how THC prevents oxygen and nutrients from crossing the placenta into the developing fetus. By studying human placental cells, the researchers found that exposure to THC caused a decrease in a glucose transporter called GLUT-1. This indicates that the THC is preventing the placental transfer of glucose, a key nutrient, from the mother to the fetus. They also found a reduction in placental vasculature in the rat model suggesting reduced blood flow from the mother to the fetus.
The researchers say both of those factors are likely contributing to the growth restriction that they observed in the offspring.
The researchers point out that there are currently no clear guidelines from Health Canada on the use of cannabis in pregnancy and some studies have shown that up to one in five women are using cannabis during pregnancy to prevent morning sickness, for anxiety or for social reasons.
"Marjiuana has been legalized in Canada and in many states in the US, however, its use during pregnancy has not been well studied up until this point. This study is important to support clinicians in communicating the very real risks associated with cannabis use during pregnancy," said David Natale, Ph.D., Associate Professor at Queen's and co-author on the paper.
More information: Bryony V. Natale et al, Δ9-tetrahydrocannabinol exposure during rat pregnancy leads to symmetrical fetal growth restriction and labyrinth-specific vascular defects in the placenta, Scientific Reports (2020). DOI: 10.1038/s41598-019-57318-6
Experts warn over scale of China virus as US airports start screening
JANUARY 18, 2020The outbreak centred around a seafood market in the central city of Wuhan
The true scale of the outbreak of a mysterious SARS-like virus in China is likely far bigger than officially reported, scientists have warned, as countries ramp up measures to prevent the disease from spreading.
Fears that the virus will spread are growing ahead of the Lunar New Year holiday, when hundreds of millions of Chinese move around the country and many others host or visit extended family members living overseas.
Authorities in China say two people have died and at least 45 have been infected, with the outbreak centred around a seafood market in the central city of Wuhan, a city of 11 million inhabitants that serves as a major transport hub.
But a paper published Friday by scientists with the MRC Centre for Global Infectious Disease Analysis at Imperial College in London said the number of cases in the city was likely closer to 1,700.
The researchers said their estimate was largely based on the fact that cases had been reported overseas –- two in Thailand and one in Japan.
The virus—a new strain of coronavirus that humans can contract—has caused alarm because of its connection to SARS (Severe Acute Respiratory Syndrome), which killed nearly 650 people across mainland China and Hong Kong in 2002-2003.
China has not announced any travel restrictions, but authorities in Hong Kong have already stepped up detection measures, including rigorous temperature checkpoints for inbound travellers from the Chinese mainland.
The US said from Friday it would begin screening flights arriving from Wuhan at San Francisco airport and New York's JFK—which both receive direct flights—as well as Los Angeles, where many flights connect.
And Thailand said it was already screening passengers arriving in Bangkok, Chiang Mai and Phuket and would soon introduce similar controls in the beach resort of Krabi.
Two deaths
No human-to-human transmission has been confirmed so far, but Wuhan's health commission has said the possibility "cannot be excluded".
A World Health Organization doctor said it would not be surprising if there was "some limited human-to-human transmission, especially among families who have close contact with one another".
Scientists with the MRC Centre for Global Infectious Disease Analysis—which advises bodies including the World Health Organization—said they estimated a "total of 1,723" people in Wuhan would have been infected as of January 12.
"For Wuhan to have exported three cases to other countries would imply there would have to be many more cases than have been reported," Professor Neil Ferguson, one of the authors of the report, told the BBC.
"I am substantially more concerned than I was a week ago," he said, while adding that it was "too early to be alarmist".
"People should be considering the possibility of substantial human-to-human transmission more seriously than they have so far," he continued, saying it was "unlikely" that animal exposure was the sole source of infection.
Local authorities in Wuhan said a 69-year-old man died on Wednesday, becoming the second fatal case, with the disease causing pulmonary tuberculosis and damage to multiple organ functions.
After the death was reported, online discussion spread in China over the severity of the Wuhan coronavirus—and how much information the government may be hiding from the public.
Several complained about censorship of online posts, while others made comparisons to 2003, when Beijing drew criticism from the WHO for underreporting the number of SARS cases.
"It's so strange," wrote a web user on the social media platform Weibo, citing the overseas cases in Japan and Thailand. "They all have Wuhan pneumonia cases but (in China) we don't have any infections outside of Wuhan—is that scientific?"
JANUARY 17, 2020
Thais find second case linked to China mystery virus
Thailand detected its second case of a mysterious SARS-linked virus in a visitor from China, health officials said Friday, as authorities ramp up airport screenings ahead of an expected surge in arrivals for Chinese New Year.
The 74-year-old Chinese woman is being treated at hospital after presenting with symptoms at Thailand's biggest airport Suvarnabhumi on January 13, according to the health ministry.
She was diagnosed with pneumonia linked to the new coronavirus, which has stirred alarm after killing two in China and hospitalising dozens. It has also been detected in Japan.
"People don't have to panic as there is no spread of the virus in Thailand," the ministry said in its statement.
The woman, whose condition is improving, arrived from the central Chinese city of Wuhan—believed to be at the epicentre of the outbreak.
It came after Thai doctors diagnosed another Chinese traveller with mild pneumonia on January 8, later confirmed to have been caused by the new virus.
The World Health Organisation has said "much remains to be understood" about the coronavirus from the same family as SARS (Severe Acute Respiratory Syndrome), which claimed hundreds of lives more than a decade ago.
During the upcoming holiday period, more than 1,300 passengers are expected to arrive in Thailand daily from Wuhan alone.
First author Dr. Kayla Dadgar. Credit: Kayla Dadgar
Scurvy, the debilitating condition remembered as a disease of pirates, is still found in Canada.
The disease, which is caused by a vitamin C deficiency, can result in bruising, weakness, anemia, gum disease, hemorrhage, tooth loss, and even death if undiagnosed and untreated.
McMaster University researchers surveyed the data of patients of Hamilton's two hospital systems over nine years and found 52 with low Vitamin C levels. This included 13 patients who could be diagnosed as having scurvy, and an additional 39 who tested positive for scurvy but did not have documented symptoms.
Among those with scurvy, some were related to alcohol use disorder or to bariatric surgery but the majority were related to other causes of malnutrition such as persistent vomiting, purposeful dietary restrictions, mental illness, social isolation and dependence on others for food.
"Scurvy is seen as a disease irrelevant to the modern world, but it still exists, and clinicians caring for at-risk patients should be aware of it and know how to diagnose it," said John Neary, associate professor of medicine at McMaster and the senior author of the study published this month in the Journal of General Internal Medicine.
First author Kayla Dadgar, who did the research as a medical student at McMaster, said: "Scurvy should be a 'never event' in a healthy society. That it still occurs in Canada in our time indicates that we are not supporting vulnerable people as we should."
The patients with scurvy who were given Vitamin C had a rapid recovery of their symptoms.
More information: Kayla Dadgar et al, Clinical Profile of Scurvy in Hamilton Since 2009: a Cohort Study, Journal of General Internal Medicine (2020). DOI: 10.1007/s11606-020-05636-1
Using waste carbon dioxide to separate metals from ores
by Bob Yirka , Phys.org JANUARY 17, 2020
a, First level: carbamation, dC. Reversible carbamate N–CO2 bond formation (eq. 1) and hydrolysis (eq. 2) deliver the subsystem of organic species. b, Second level: ligation, dL. Binding of nucleophilic species such as amines (eq. 3), carbamates and amines (eq. 4), carbamates and halides (eq. 5) or carbamates exclusively (eq. 6) in the first coordination sphere of the metal deliver the subsystem of complexes. c, Third level: ion pairing, dIP. Salt bridge formation between species of opposite charge including halides, ammonium carbamates and ligated metal are exemplified by metal–ammine adducts paired with carbamate counter-ions (eq. 7) and carbamato–metal adducts paired with metal–ammine complexes (eq. 8). Credit: Nature Chemistry (2020). DOI: 10.1038/s41557-019-0388-5
A combined team of researchers from the University of Lyon and the University of Turin has developed a way to use waste CO2 to separate metals used in products. In their paper published in the journal Nature Chemistry, the group describes their process and why they believe it can be used as a global warming mitigation tool.
Scientists have promoted the idea of using carbon capture and storage (CCS) as a way to reduce the amount of CO2 emitted into the atmosphere. CCS involves capturing the exhaust from a car or a factory, removing the CO2 and then storing it until scientists develop a use for it.
Unfortunately, CCS has proven to be too expensive for commercial use. In this new effort, the researchers developed a way to use waste CO2 to create ligands for separating metals from ores. The recovered metals can then be sold for use in making products such as smartphone components. Their idea is to recoup the cost of capturing CO2 (or make it profitable) so that businesses will find it more economically viable. The researchers claim their approach is the first to use two waste streams as part of a process that yields multiple purified compounds in a single pot.
In their process, the CO2 serves as a type of bonding agent—it takes advantage of the attraction of ligands for metals using temperature and pressure. The team injected 2,2'-Iminodi(ethylamine) solution into a mix of LaCl3 and NiCl2 to demonstrate how their approach works. They then bubbled CO2 from car exhaust through the mix. Doing so resulted in 2,2'-Iminodi(ethylamine) capturing carbon dioxide and producing ligands that bound with lanthanum.
After a few minutes, crystals containing lanthanum formed, and the nickel that was bound to unreacted diethylenetriamine remained in the solution. Both metals were then recovered using a centrifuge—testing showed both were 99 percent pure. A second test involved separating useful metals from an electrode taken from a nearly dead battery—it yielded cobalt, nickel and lanthanum. The researchers claim a secondary benefit of their approach is that it is a greener way to separate metals from ores than standard methods.
More information: Jean Septavaux et al. Simultaneous CO2 capture and metal purification from waste streams using triple-level dynamic combinatorial chemistry, Nature Chemistry (2020). DOI: 10.1038/s41557-019-0388-5
Using machine learning to fine-tune views of the ancient past
by Bob Yirka , Phys.org JANUARY 17, 2020
Credit: Nanjing University
A team of researchers affiliated with several institutions in China and two in the U.S. has developed a way to use machine learning to get a better look at the past. In their paper published in the journal Science, the group describes how they used machine learning to analyze records of the past.
Scientists use fossils to date rocks because they have no way to test the age of rock directly. Prior research has shown that most species only exist for a certain amount of time. If scientists determine the time when a given dinosaur lived in a given area, they can use that information to date the local rocks using the fossils embedded within them. A drawback to this method of dating rocks is that it does not give scientists a very fine filter when attempting to create a timeline of historical events such as mass extinctions.
A decade ago, a group of mathematicians developed a statistical approach to creating a biodiversity timeline based on analyzing hundreds of thousands of records of marine and land fossils. Their method would have allowed scientists to divide the past several hundred million years into small spans of time. This would have provided a finer view of what has transpired. Unfortunately, it took dozens of months to run the programs—too long for practical use. In this new effort, the researchers have resurrected the work by the mathematicians by applying machine learning to the data and then analyzing the results on a Tianhe-2 supercomputer.
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Paleontologists use big data and supercomputers to recover marine paleobiodiversity. Credit: Nanjing University, We Video
The researchers entered data covering approximately 300 million years—from the beginning of the Cambrian period, approximately 540 million years ago, until shortly after the Triassic period began, approximately 240 million years ago. The computer returned results for periods of time as short as 26,000 years. They compared the difference in resolution to looking at six months of people living during a given time period versus a century.
The researchers found the timeline produced by the computer differed in some ways from the timeline produced using longer periods of time. For example, one of the five great mass extinctions believed to have happened did not actually happen—it was more of a slow change in biodiversity.
More information: Jun-xuan Fan et al. A high-resolution summary of Cambrian to Early Triassic marine invertebrate biodiversity, Science (2020). DOI: 10.1126/science.aax4953
Climate may play a bigger role than deforestation in rainforest biodiversity
JANUARY 17, 2020By measuring characteristics like ear, foot, and tail size in species like Euryoryzomys russatus, researchers can quantify functional diversity in large rainforests. Credit: Ricardo S. Bovendorp
"Save the rainforests" is a snappy slogan, but it doesn't tell the full story of how complicated it is to do just that. Before conservationists can even begin restoring habitats and advocating for laws that protect land from poachers and loggers, scientists need to figure out what's living, what's dying, and which patterns explain why. Tackling these questions—in other words, finding out what drives a region's biodiversity—is no small task.
The better we measure what's in these rainforests, the more likely we are to find patterns that inform conservation efforts. A new study in Biotropica, for instance, crunched numbers on a behemoth dataset on small mammals in South America and found something surprising in the process: that climate may affect biodiversity in rainforests even more than deforestation does.
Noé de la Sancha, a scientist at the Field Museum in Chicago, professor at Chicago State University, and the paper's lead author, stresses that changing how we measure biodiversity can uncover patterns like these.
"When we think about biodiversity, we usually think about the number of species in a particular place—what we call taxonomic diversity," says de la Sancha. "This paper aims to incorporate better measures of biodiversity that include functional and phylogenetic diversity."
Functional diversity looks at biodiversity based on the roles organisms play in their respective ecosystems. Rather than simply counting the species in an area, scientists can use categories—"Do these mammals primarily eat insects, or do they primarily eat seeds?" and "Do they only live on the forest floor, or do they live in trees?" as well as quantitative characters like weight and ear, foot, and tail size, for instance—to determine and quantify how many different ecological roles a habitat can sustain.
Meanwhile, phylogenetic diversity looks at how many branches of the animal family tree are represented in a given area. By this measure, a patch of land consisting almost entirely of closely-related rodents would be considered far less diverse than another that was home to a wide genetic range of rodents, marsupials, and more—even if the two patches of land had the same number of species.
The Atlantic Forest is the second largest and second most biodiverse forest system in South America. Credit: Noé de la Sancha
By applying these approaches to data on all known small mammal species and all those species' characteristics, scientists are able to see the forest from the trees, uncovering patterns they wouldn't have using any single dimension of diversity alone.
This is how de la Sancha and his co-authors found, based on functional and phylogenetic measures, that while deforestation causes local extinctions, climate-related variables had more of an effect on small mammal biodiversity patterns across the entire forest system.
In other words, if a section of rainforest was cut down, some of the animals living there might disappear from that area, while the same species living in intact patches of rainforest could survive. And, the researchers found, even if a species disappears from one area, different species that play a similar role in the ecosystem tend to replace them in other forest patches and other parts of the forest system. Meanwhile, changes to the climate may have big, sweeping effects on a whole rainforest system. This study found that BIO9, a bioclimatic variable measuring mean temperature of the driest quarter—more simply put, how hot the forest is in its least rainy season—affects biodiversity across the whole forest system.
Knowing these climate variables play a role in rainforest health can be concerning. This study and others provide strong evidence of climate change's effects on large ecosystems, underlining the urgency of studying and protecting habitats like the Atlantic Forest, the South American forest system at the center of the study.
"We still have so much that we don't know about so many of these species, which underlines the necessity for more fieldwork," de la Sancha says. "Once we have more specimens, we can improve how we quantify functional diversity and our understanding of why these small mammals evolved the way they did. From there, we can keep better track of biodiversity in these areas, leading to improved models and conservation strategies down the line."
Still, with only 9-16 percent of the Atlantic Forest's original habitat space remaining, this study lends a silver lining to an otherwise grim narrative about the effects of human activity on rainforests.
"I think this gives us a little bit of hope. As long as we have forest—and we need to have forest still—we can maintain biodiversity on a large scale," de la Sancha says. "As long as we don't wipe it all out, there's good evidence to show that we can maintain biodiversity, at least for small mammals, and the ecosystem services these critters provide."
More information: Noe U. de la Sancha et al. Disentangling drivers of small mammal diversity in a highly fragmented forest system, Biotropica (2020). DOI: 10.1111/btp.12745
