Spixia alvarezii

Scientists have long wondered how microbes growing in the deepest parts of the oceans can survive with no sunlight. Now, a team of researchers led by <a href="https://www.monash.edu/">Monash University</a> in Australia has shown that a distinct process called “chemosynthesis” (growth using inorganic compounds) fuels these microbes. More specifically, two common gases – hydrogen and carbon monoxide – serve as fuel for the trillions of microbes living in the depths of the <a href="https://www.earth.com/video/how-the-ocean-and-climate-influence-each-other/">oceans</a> from the tropics to the poles.



Until recently, most scientists believed that ocean microbial life is also driven by photosynthesis (growth by using light energy). "But what about those regions so deep that light can’t penetrate or so nutrient-poor that algae can’t thrive? We showed in this study that instead chemosynthesis is dominant in these regions,” said study senior author Chris Greening, an expert in Microbiology at Monash. 



“Hydrogen and carbon monoxide in fact “fed” microbes in all regions we’ve looked at: from urban bays to around tropical islands to hundreds of meters below the surface. Some can even be found beneath Antarctica’s ice shelves.”



The researchers combined chemical measurements during ocean voyages with lab-based characterization of microbial cultures, as well as metagenomic sequencing (a method providing the genetic blueprints of all the microbes present in a specific region in the ocean).&nbsp;



“We found the genes that enable hydrogen consumption across eight distantly related types of microbes, known as phyla, and this survival strategy becomes more common the deeper they live,” reported lead author Racheal Lappan, a research fellow in Microbiology at Monash.



The study was inspired by previous work on soil bacteria which revealed that most of these terrestrial microorganisms can thrive by consuming hydrogen and carbon monoxide from the atmosphere.&nbsp;



“The surface layers of the world’s oceans generally contain high levels of dissolved hydrogen and carbon monoxide gases due to various geological and biological processes. So it made sense that oceanic bacteria used the same gases as their terrestrial cousins,” Lappan explained.



The findings provide novel insights into how life on Earth evolved. “The first life probably emerged in deep-sea vents using hydrogen, not sunlight, as the energy source. It’s incredible that, 3.7 billion years later, so many microbes in the oceans are still using this high-energy gas and we’ve completely overlooked this until now,” Greening concluded.



The study is published in the journal <a href="http://dx.doi.org/10.1038/s41564-023-01322-0">Nature Microbiology</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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How can deep ocean microbes survive without sunlight?

Scientists have long wondered how microbes growing in the deepest...

The number of unprovoked <a href="https://www.earth.com/news/shark-populations-are-rebounding-in-the-northwest-atlantic/">shark</a> attacks in oceans around the world was at a 10-year low during 2022, with a total of 57. This number is on a par with the attacks recorded during 2020, when the Covid-19 pandemic kept tourists and locals off beaches and out of coastal waters. According to the latest annual report of the University of Florida’s&nbsp;<a href="https://www.floridamuseum.ufl.edu/shark-attacks/">International Shark Attack File</a> (ISAF), most of the 2022 attacks occurred in the United States and Australia. Of these, five attacks were fatal, down from nine deaths in 2021 and 10 the year before.



The ISAF is the world’s only scientifically documented, comprehensive database of all known shark attacks. It was initiated in 1958 and is housed at the Florida Museum of Natural History. Currently, the list documents 6,800 shark attack cases during the period from the early 1500s to the present. This annual report focuses particularly on unprovoked shark attacks, defined as “incidents in which a bite on a live human occurs in the shark’s natural&nbsp;habitat with no human provocation of the shark.”



According to the latest statistics, there have been an average of 74 unprovoked bites per year since 2013. Therefore, the bites recorded during 2022 mark a significant decrease. According to scientists, this overall reduction in the number of last year’s bites may reflect the&nbsp;<a href="https://www.nature.com/articles/s41586-020-03173-9">documented global decline</a>&nbsp;of shark populations.&nbsp;



“Generally speaking, the number of sharks in the world’s oceans has decreased, which may have contributed to recent lulls” said Gavin Naylor, director of the Florida Museum of Natural History’s&nbsp;<a href="https://www.floridamuseum.ufl.edu/sharks/">Florida Program for Shark Research</a>. “It’s likely that fatalities are down because some areas have recently implemented rigorous beach safety protocols, especially in Australia.”



Analysis of the geographic distribution of shark attacks in the 2022 Annual Report shows that the U.S. recorded the highest number of shark bites, and that Florida, in particular, had more bites than anywhere else on Earth. However, none of Florida’s 16 unprovoked bites was fatal, but two – likely from bull sharks (Carcharhinus leucas) – required medical treatment resulting in amputations. Only one of the unprovoked shark attacks in U.S. waters resulted in a fatality, which occurred late in the year when a snorkeler went missing along Keawakapu Beach in Maui, Hawaii.



In contrast, Australia had nine confirmed unprovoked bites, and single bites occurred in New Zealand, Thailand and Brazil. Two fatal attacks occurred on the same day in Egypt’s Red Sea, where shark encounters are considered rare. South Africa, which averages a few bites a year, had two unprovoked attacks in 2022, both of which were fatal and likely caused by great white sharks (Carcharodon carcharias).



Although there were fewer bites in the U.S. last year, there were spikes in certain hotspot regions that have caused concern from residents and government officials in these areas. For example, New York had a record eight bites in 2022, compared with a total of only 12 reported unprovoked bites in the State before this time.



In 2016, researchers discovered that juvenile sand tiger sharks (<a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharias-taurus/">Carcharias taurus</a>) had taken up residence in Great South Bay, between Long Island and Fire Island. The sharks continue to use the sheltered bay as a nursery, where they’re better protected from predation than they’d otherwise be in the open ocean. According to Naylor, the majority of bites in Long Island were likely from sand tiger sharks that were drawn into the surf zone by an influx of baitfish.



“The Gulf Stream’s eddies ebb and flow each year. Sometimes they can come very close to shore, bringing nutrients and fish with them. The juvenile sand tigers will follow the fish, which in some cases leads to an uptick in encounters with people,” he said. “But local perceptions of shark bites rarely map to global statistics. If you zoom out, these eddies unpredictably break off from oceanic currents all over the world in haphazard ways.”



For as long as records have been kept, there have been no reported fatalities from sand tiger attacks, but juveniles have often been implicated in non-lethal bites.



“Juveniles tend to be more experimental and will try things that an adult shark wouldn’t,” Naylor said. “If fish are especially dense where people are swimming and visibility is poor, then it is more likely that young sharks, which lack the experience of older animals, will mistake a swimmer’s foot for their intended prey.”



Another noteworthy record in the 2022 Annual Report comes from the Red Sea off the coast of Egypt. On January 8, 2022, two attacks occurred less than a mile from each other and both were fatal. It is possible that the attacks were perpetrated by the same individual shark, most likely considered to be a tiger shark (<a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/galeocerdo-cuvier/">Galeocerdo cuvier</a>).&nbsp;



Shark attacks are relatively rare in the Red Sea, but when they do occur, they’re often fatal, Naylor said. This is due primarily to the unique topography of the region. The Red Sea began forming roughly 50 million years ago as the tectonic plates underlying Africa and Arabia began pulling apart, creating a steep gorge between them.



“It’s a very unusual marine system because the seafloor drops so precipitously, as much as 1,000 feet in 100 yards in some places,” noted Naylor.



In regions like eastern North America, where the continental shelf slopes gradually, large pelagic sharks often forage far from the coast. In the Red Sea, however, they’re mere meters from the shore, Naylor explained. “Open oceans are often pretty bleak, and the pelagic sharks that live in them make their living by opportunism. Whatever potential food source they find, they’ll sample.”



The authors of the report emphasize that the chances of being bitten by a shark remain incredibly low. According to the World Health Organization, drowning is the&nbsp;<a href="https://www.who.int/news-room/fact-sheets/detail/drowning">third leading cause of accidental death</a>&nbsp;worldwide, and coastal features like rip tides and strong currents pose a greater risk to beachgoers than do sharks.&nbsp;



Despite this, the ISAF provides recommendations for reducing the risk of a shark bite for those who swim in the oceans. These include removing shiny jewelry before entering the water, not swimming at dawn or dusk, and avoiding areas where there are active fishermen or shoals of fish. For more resources, including the full 2022 report, you can visit the&nbsp;<a href="https://www.floridamuseum.ufl.edu/shark-attacks/">International Shark Attack File’s website</a>. &nbsp;



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Shark attacks decreased in 2022, but spiked in local hotspots

The number of unprovoked shark attacks in oceans around the...

Most of the research on skin coloration and patterning in vertebrates has been conducted on laboratory mice. However, since mice don’t share all of the same kinds of color-producing cells (known as chromatophores) with other vertebrates, there are limits to what mice can tell us about coloration in reptiles such as <a href="https://www.earth.com/news/modern-snakes-evolved-from-just-a-few-surviving-species/">snakes</a>, for instance.&nbsp;



Now, by combining techniques such as whole gene sequencing, gene-editing, and electron microscopy, a team of researchers from <a href="https://www.mcgill.ca/">McGill University</a> in Canada has examined color variations and patterning in the skin shed by ball pythons (Python regius) bred in captivity. The analysis revealed that a particular gene (tfec) plays a crucial role these snakes’ pigmentation, more specifically in a classic color variant found across vertebrates and distinguished by blotches of white (the so-called “piebald coloration”).



The captive-bred reptile industry is currently booming, with over 4.5 million households in the U.S. alone keeping reptiles. Due to the spectacular color variations produced through captive breeding, a single ball python can now sell for tens of thousands of dollars.



“Ball pythons show incredible variation in skin coloring and patterning, which is part of their appeal for hobbyists, but also makes them really useful for researchers who want to understand the genetic basis of coloration,” said study senior author Rowan Barrett, an expert in Biodiversity Science at McGill.



“The pet trade has created a huge pool of color variation that would not have existed otherwise. This provides a catalogue for us to figure out the many ways that genes produce the amazing diversity of colors, spots, and stripes we see across different animals.”



In order to identify the genes responsible for particular traits, scientists usually examine genetic variants that are present in the animals that have the traits, and absent in those that don’t have them. By using shed skin samples collected from snake breeders, the researchers discovered that piebald snakes carried the same mutation in a gene called tfec.



However, since finding a correlation between a specific gene and a particular trait does not necessarily imply causation, the scientists used the genetic-editing technique CRISPR to modify this gene in a different species of reptile, the brown anole lizard. This intervention revealed that genetically modified lizards do indeed show altered coloration, thus proving that mutations to tfec cause changes to color-producing cells.



“Our research advances knowledge of the genetics of vertebrate coloration generally and particularly of the development of iridescent cells, which haven’t been studied as much as other color pathways,” said study lead author Alan Garcia-Elfring, a PhD student in Biology at McGill.



“It also highlights the potential benefits of working with non-academic communities like ball python breeders to accelerate discoveries in fundamental science. Our job, at this point, is to figure out what other mutations underlie all this variation seen in captivity, and how these mutations interact. It’s an exciting time for both researchers and reptile hobbyists.”



The study is published in the journal <a href="http://dx.doi.org/10.1016/j.cub.2023.01.004">Current Biology</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Ball pythons shed new light on reptile coloration

Most of the research on skin coloration and patterning in...

Howling is a characteristic form of communication in wolves that helps them send messages across long distances, mark territory boundaries, and identify the position of other wolves. Among <a href="https://www.earth.com/news/dog-ancestry-traced-to-two-populations-of-ancient-wolves/">dogs</a> - the wolves’ domestic relatives - the situation is more complicated. While some breeds, such as wolf-like sled dogs, howl frequently, even in “reply” to irrelevant sounds like bells, sirens, or music, other types of dogs never engage in such behavior.



Now, a team of ethologists from the <a href="https://www.elte.hu/en/">Eötvös Loránd University</a> (ELTE) in Hungary has examined the phenomenon of dog howling by testing the reaction of 68 purebred family dogs to recorded wolf howls. To test the effect of a dog's breed, the experts measured its genetic similarity to wolves.



“According to our results, breeds which are genetically more similar to wolves (“ancient breeds”), are more prone to reply with their own howls to wolf howl playbacks. On the other hand, breeds more distantly related to wolves (“modern breeds”) typically reacted with barking instead of howls. It seems that although howling is present in most breeds’ repertoire, it lost its functionality due to the changed social environment, thus, modern breeds do not use it in adequate situations,” reported study lead author Fanni Lehoczki, a postdoctoral researcher in Neuroethology at ELTE. “Additionally, we found that breeds which howl more also show more stress-related behaviors in this situation.”



“We assume that more ancient breeds, which are genetically closer to wolves, can process the information encoded in wolf howls better than modern breeds. Thus, ancient breeds of our study might become stressed by intruding on a pack’s territory and use howling for the sake of avoidance, just as wolves do,” added study lead author&nbsp;Tamás Faragó, a postdoctoral fellow in Ethology at the same university.



“Interestingly,&nbsp;this genetic effect on howling occurs only among older dogs (&gt;5 years), for which an experience- or some age-related personality effect can be a plausible explanation. It is possible that - in line with our hypothesis, that howling appearing with a higher level of stress is a fear reaction - older dogs are more fearful, which was already suggested by previous studies, but these speculations require further investigation.”



Besides the breed and age of the dogs, the scientists also tested the effect of other features such as sex or reproductive status. The analysis revealed that, while there was no difference between intact and spayed females, intact dogs behaved differently from neutered ones.&nbsp;



“Neutered males, which are in lack of testosterone, howl more in response to the playbacks. As neutered males are suggested to be more fearful, this result can be in line with our findings about responsiveness and more stressed behavior. Thus, the dog howl may mean ‘I am scared, don't come closer,’” Lehoczki explained.



These findings support the hypothesis that domestication and selective breeding by humans significantly changed dogs’ vocal repertoire, including the perception and production of howls.



The study is published in the journal <a href="http://dx.doi.org/10.1038/s42003-023-04450-9">Nature Communications Biology</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Why do some dogs howl, but others don't?

Howling is a characteristic form of communication in wolves that...

A fungus that can cause deadly <a href="https://www.earth.com/news/covid-disrupts-gut-health-increasing-risk-of-other-infections/">infection</a> in salamanders and newts has a secret weapon that makes it more dangerous, according to a study led by the <a href="https://www.exeter.ac.uk/">University of Exeter</a>. The experts report that a fungus called Batrachochytrium salamandrivorans (Bsal) contains multiple copies of “jumping genes," which can essentially duplicate themselves.&nbsp;



Jumping genes, known by scientists as transposons, are DNA sequences that move from one location on the genome to another. While possessing repeated parts of DNA can be harmful to an organism, the researchers have found a possible evolutionary advantage of jumping genes in Bsal.



The team found different versions of jumping genes repeated multiple times in the genome of Bsal. Furthermore, the transposons appear to have duplicated another group of genes that play a role in the severity of an infection.&nbsp;



“Bsal and related fungal species infect amphibians worldwide, and have been responsible for more than 90 extinctions,” explained study first author Theresa Wacker.&nbsp;



“Bsal infects the skin of salamanders and newts and causes severe wounds. It emerged in Asia, where many newts and salamanders have some tolerance, but it has spread to Europe and is causing European salamander populations to decline."



“Using new sequencing technologies, we found that Bsal has undergone a genome expansion compared to related species - that is to say, it now has a bigger genome with more genes and also more of these ‘jumping gene’ transposons.”



The experts determined that the ability of jumping genes to "copy and paste" themselves has contributed to the expansion of the Bsal genome.



“If you think of an organism’s genome as a blueprint, transposons are like having many identical pages,” said Wacker. “And sometimes, during the process of copying and pasting, other parts of the book are also copied.”



"It appears that this copying and pasting caused by repetitive jumping gene transposons has also amplified some skin-destroying genes. Having more of these skin-destruction genes allow the fungus to destroy the skin of salamanders more quickly, making it more deadly.”



Study senior author Dr. Rhys Farrer noted that this kind of gene repetition is probably more widespread in nature than we currently realize. “If, as appears to be the case, it confers an evolutionary advantage for the pathogen by making it more virulent, it’s not clear why this isn’t much more common.”



The study is published in the journal <a href="http://dx.doi.org/10.1073/pnas.2212633120">Proceedings of the National Academy of Sciences</a>.



Image Credit: Jaime Bosch



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By <a href="mailto:csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Editor



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A fungus has become more deadly thanks to jumping genes

A fungus that can cause deadly infection in salamanders and...

A recent study published in the journal <a href="http://dx.doi.org/10.1111/brv.12931">Biological Reviews</a> has found that over one in six bird eggs fail to <a href="https://www.earth.com/news/neon-gobies-decide-when-to-hatch-their-embryos/">hatch</a>, and hatching failure increases as bird species decline. Moreover, the experts discovered that hatching failure is a much bigger problem in the case of captive threatened species, with nearly half of their eggs failing to hatch. These findings provide evidence that conservation managers could use in their decision making for creating the best possible outcomes for endangered bird species recovery.



By assessing 241 bird species across 231 previous studies to examine hatching failure, the researchers discovered that almost 17 percent of bird eggs fail to hatch, which is nearly double than the number reported four decades ago. These values are even more worrisome in the case of endangered species, with 43 percent of eggs from threatened species bred in captivity being unsuccessful in hatching.



“Around 13 percent of bird species globally are currently threatened with extinction, and things are getting worse instead of better. Species on the verge of extinction have much higher levels of hatching failure compared to non-threatened species, and breeding birds in captivity appears to be having a negative impact,” said study co-author Nicola Hemmings, an expert in Biosciences at the <a href="https://www.sheffield.ac.uk/">University of Sheffield</a>.



“There are important considerations that we need to make - does the benefit of captivity and other interventions outweigh the reduced reproduction of these species? For many species, these practices are absolutely vital for species survival, so we need to carefully weigh up the pros and cons of different approaches to ensure that we are doing everything that we can to protect birds from extinction.”



The scientists outlined four different conservation practices associated with lower hatching rates, including keeping birds in captivity, hatching eggs in artificial incubators, feeding the birds supplementary foods, and providing them with artificial nest boxes or sites. However, despite their potentially negative impact of hatching, some of these measures may still prove important to birds’ survival and reproduction. For instance, the eggs of some ground-nesting birds are at such a high risk of predation that leaving them in the wild would most likely result in their destruction.



“With this work we hope to provide vital evidence needed to understand how effective different management practices are at improving hatching success and aid population recovery,” said study senior author Patricia Brekke, a researcher at the <a href="https://www.zsl.org/science/users/patricia-brekke">Zoological Society of London</a> (ZSL).&nbsp;



“Conservation managers are doing an amazing job of preventing species decline, but they have an incredibly difficult job of making decisions when species are at the brink of extinction, on what tools to implement, and when. This kind of work provides the evidence necessary to improve decision making and hopefully improve recovery,” she concluded.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Hatching failure rates increase as bird species decline

A recent study published in the journal Biological Reviews has...

A team of researchers led by the <a href="https://www.uc.edu/">University of Cincinnati</a> (UC) has recently discovered a new species of frog in Tanzania’s Ukaguru Mountains. The Ukaguru spiny-throated reed frog (Hyperolius ukaguruensis) has a distinct feature: it is among the few species of <a href="https://www.earth.com/news/why-do-frogs-have-fused-forearms/">frogs</a> in the world that do not vocalize at all. Belonging to a group of “spiny throated” reed frogs, it is characterized by the presence of tiny spines on the male’s throat, which the frogs use to recognize other members of their species.



“It’s a very odd group of frogs,” said study lead author Lucinda Lawson, a conservation biologist at UC. “The male frogs don’t call like most other frogs do. We think they may use the spine as something like Braille for species recognition. “Without a call, they need some other way to recognize each other.”



H. ukaguruensis belongs to a family of nearly 200 species in the genus Hyperolius. According to the experts though, it may be significantly different from other species from this genus. “With any Hyperolius, I can probably tell by looking at it whether it’s new or potentially new,” Lawson explained. “Immediately it was clear that it was a spiny-throated reed frog. But this one was a golden, greenish brown instead of the green color found in the other species. Sometimes color variation doesn’t mean anything, but it might here.”



A combination of genetic and genomic analyses confirmed that this frog was distinct from other members of Hyperolius, while measurements shown that it had unique body proportions, with smaller eyes in relation to its head than other spiny-throated reed frogs.



As many of its relatives, H. ukaguruensis is a critically endangered species and should thus be considered of high conservation concern, particularly since amphibians are highly susceptible to human impacts, such as deforestation. “If a bird’s habitat is destroyed, they sometimes can fly to a new forest. But that’s hard for amphibians,” Lawson said.&nbsp;



Conservation measures are highly important because having a diversity of species is crucial to maintain healthy ecosystems. “We think about this question a lot: why does one species matter?” Lawson said.&nbsp;“If this one species goes extinct, nothing much happens. We just lose one more strand in the fabric of the ecosystem. But if you keep pulling out strands, the ecosystem becomes destabilized and the fabric unravels,” she concluded.



The study is published in the journal <a href="http://dx.doi.org/10.1371/journal.pone.0277535">PLoS ONE</a>.&nbsp;&nbsp;



Image Credit: Christoph Liedtke



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Voiceless frog recently discovered in Africa

A team of researchers led by the University of Cincinnati...

Spixia alvarezii

Taxonomic tree: