Explore the latest insights from top science journals in the Muser Press daily roundup, featuring impactful research on climate change challenges.
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Scientists discover a genetic lifeline for the endangered shortfin mako shark
Shortfin makos are the fastest sharks in the sea, but they’re failing to outpace the scale of overfishing that is driving them to extinction. Global demand for their meat and lucrative fins has placed this predator on the International Union for Conservation of Nature’s (IUCN) endangered list and on Appendix II of the Convention on Trade in Endangered Species of Wild Fauna and Flora (CITES).
The situation for shortfin mako sharks in the Atlantic Ocean is particularly dire. Populations are currently managed as two assumed separate populations (or stocks), with fishery-based assessments indicating that Northern Atlantic mako sharks are overfished. Independent scientific surveys, using data from satellite tags deployed on shortfin makos, suggest that fishing mortality may be 10 times higher than estimates from previous fisheries models.
With extreme pressure on mako populations from international fisheries, the questions are: has the shortfin makos’ genetic health and potential to adapt been compromised; and is the current fisheries management strategy based on two populations backed by scientific evidence?
A team of scientists led by Dr Andrea Bernard and Professor Mahmood Shivji from the Save Our Seas Foundation Shark Research Center (SOSF-SRC), and Guy Harvey Institute at Nova Eastern University, USA, has published its answers in a paper in the journal Environmental Applications.
The scientists have for the first time sequenced entire genomes for mitochondrial DNA and conducted high-resolution scans across the nuclear genomes of shortfin makos from nearly the entire distribution of this species in the Atlantic Ocean.
These genomic assessments have discovered a potential lifeline that should add urgency to curbing overfishing. “Despite decades of fishing pressure, shortfin mako sharks in the Atlantic Ocean still show a (relatively) high level of genetic diversity,” explains Professor Shivji. “Genetic diversity in a population is what allows species to adapt to environmental change, or to survive catastrophes.”
While overfishing is the single greatest threat to sharks worldwide, many species remain vulnerable to complex and compounding additional threats like habitat loss, deep-sea mining, pollution and our changing climate.
“We were rather surprised, but also pleased, to see that the genetic health of shortfin makos does not appear to have been severely compromised – yet – by the population reductions caused by overfishing,” says Professor Shivji. “That means that if we can prevent further erosion of this genetic diversity in shortfin mako sharks by urgently curbing overfishing, we have more hope for this species to retain the resilience needed for its populations to adapt to our fast-changing climate and survive.”
He goes on to caution, “Typically, in most of the exploited shark species we study we see pretty low diversity.”
Such is the case for the critically endangered great hammerhead shark, another species being fished to the edge of existence, but whose vulnerability to being tipped into extinction is higher because it lacks the diversity to adapt to our rapidly changing climate.
The scientists also hypothesised that nomadic sharks like makos, which have been tracked making extraordinary journeys across oceans, would mix freely, hampered by few genetic barriers. And that is exactly what the research team found from the high-resolution scans made of shortfin mako nuclear DNA.
Nuclear DNA is inherited from both parents, and it suggests that male shortfin mako sharks are indeed ranging across the Atlantic and spreading their genes widely. “Female mako sharks, which get even larger than males, are quite capable of also making these large-scale journeys,” says Professor Shivji. “But when we look at the mitochondrial DNA – the genetic material inherited only from mothers – we see a contrasting picture.”
The mitochondrial genome sequences show matrilineal genetic structure for northern and southern hemisphere populations. That’s scientific-speak for the populations in each hemisphere being genetically distinct from each other. In fact, the results suggest that although female shortfin makos may well be as wide-ranging as their male counterparts, they return to key sites in one hemisphere to pup.
And if we’re to protect this important genetic diversity, the management of two distinct Atlantic populations – the northern Atlantic and southern Atlantic shortfin mako sharks – is now backed by this high-resolution genetic information.
Journal Reference:
Bernard, A.M., Mehlrose, M.R., Finnegan, K.A., Wetherbee, B.M. and Shivji, M.S., ‘Connections Across Open Water: A Bi-Organelle, Genomics-Scale Assessment of Atlantic-Wide Population Dynamics in a Pelagic, Endangered Apex Predator Shark (Isurus oxyrinchus)’, Evolutionary Applications 18: e70071 (2025). DOI: 10.1111/eva.70071
Article Source:
Press Release/Material by Save Our Seas Foundation
Tropical-extratropical interactions induce the end of the rainy (Baiu) season in Japan
Tsukuba, Japan — The end of the rainy (Baiu) season in the Kanto region and northern Japan is induced by a “convection jump,” known as the abrupt enhancement of convective activity (precipitation) over the northeast of the Philippines in late July.
The intrusion of cyclonic unstable airmass (high-potential-vorticity (PV) airmass) from the upper-tropospheric mid-latitude modulates the convective activity over the subtropical western North Pacific, including the northeast of the Philippines. However, the influence of extratropical upper-tropospheric variations on the convection jump has not been fully discussed.
In this study, researchers analyzed 20 typical convection jump years. When the convection jump occurs, the westerly winds meander largely over the east of Japan and the upper-tropospheric large-scale high-PV airmass intrudes around the occurrence region of the convection jump.
Using a method that can detect and track cyclonic circulation, the advection of the high-PV airmass is interpreted as the cutoff lows migrating from the upper-tropospheric planetary-scale trough. Furthermore, the intrusion of the high-PV airmass influences the enhancement of dynamical ascent and plays an encouraging role in the occurrence and maintenance of the convection jump.
These results, published in the Journal of Meteorological Society of Japan, show that the convection jump is influenced by the dynamical effects of the high-PV airmass intrusion from the upper-tropospheric mid-latitudes as well as the previously revealed coupled atmosphere-ocean system in the tropics related to the warm sea surface temperature.
Further investigation of the seasonal evolution from the rainy season to the mid-summer from the perspective of the interactions between the tropics and mid-latitudes will contribute to improving the accuracy of seasonal forecasts and our understanding of climate systems.
Journal Reference:
Ryouta NAKANISHI, Masaya KURAMOCHI, Hiroaki UEDA, ‘Summertime Convection Jump over the Subtropical Western North Pacific and its Relation to Rossby Wave Breaking near the Asian Jet Exit Region’, Journal of the Meteorological Society of Japan (Ser. II) 103, 1, 5-15 (2025). DOI: 10.2151/jmsj.2025-001
Article Source:
Press Release/Material by University of Tsukuba
Climate change reshuffles species like a deck of cards, new study finds
Santa Cruz, California | US – A new study led by an ecology and evolutionary biologist at UC Santa Cruz finds that temperature changes due to climate change have a doubly detrimental impact: Not only do they destabilize animal populations, but the impacts accelerate as temperatures change more rapidly.
In the study, published in Nature, the international team of researchers found that changing temperatures—either warming or cooling—drive changes in the composition of species in an ecosystem. The results also suggest that behavioral adaptation and changing species interactions are not enough to preserve species composition in the face of higher rates of temperature fluctuations.
“It’s like shuffling a deck of cards, and temperature change now is shuffling that deck faster and faster,” said lead author Malin Pinsky, associate professor of ecology and evolutionary biology at UC Santa Cruz. “The worry is that eventually you start to lose some cards.”
The study’s findings are unique because the impacts of temperature change have often not been clear on land or in freshwater ecosystems. While impacts on ocean species have been more overt, and therefore easier to measure, plants and animals on land adapt in subtler ways, the researchers said.
Unlike ocean animals, those on land can often move short distances to find new locations that better suit their temperature needs. Though this can mitigate the effects of temperature change a bit, this research finds that terrestrial creatures are still susceptible to destabilization and replacement due to temperature change.
In their paper, the researchers focus on the rates of species replacement, which refers to the loss and gain of species over time. While this happens naturally, they found that the rate of replacement is increasing due to faster temperature changes.
If that trend continues, species could be lost and ecosystems could begin to break down, the study concludes. The most effective ways to avoid these outcomes are to avoid further global warming, preserve landscapes with a diversity of temperatures, and reduce the alteration of natural environments. Benefits could include more abundant wildlife, clean water, and clean air.
“Temperature affects everything from how fast the heart beats to how flexible and porous our cell membranes are; from how much food animals eat to how fast plants grow,” said Pinsky. “Temperature is in many ways the metronome for life.”
Why diverse environments are important
In addition, the researchers found that species in ecosystems with less-varied habitats were more sensitive to temperature change than those with more diverse temperatures nearby. For example, if a person stood in an open field during summer and started to overheat, there would be nowhere cooler to hide. But if a forest were nearby, one could simply move into the shade of a tree to cool down. The paper concludes that plants and animals take advantage of habitat variation to buffer themselves against major temperature swings. Living near these temperature escapes allows organisms to move nearby for relief, rather than going extinct or being replaced entirely.
Whether due to natural conditions or human interference, not all environments have a diversity of temperatures to help protect the species that live in them. It is these animals that are most at risk due to faster temperature changes. Understanding the differing needs of species living in more or less varied environments can help society identify which ecosystems need the most attention and protection, the study concludes.
“Establishing this explicit link between rates of climate change and rates of species turnover allows us to better understand how changing temperatures can impact different ecosystems,” said senior author Shane Blowes, from Germany’s Centre for Integrative Biodiversity Research (iDiv) and Martin Luther University Halle-Wittenberg. “Pinpointing factors that impact the rate of local species replacement can help prioritise conservation actions.”
How human activity impacts turnover
Importantly, the researchers found that human impacts like land use, pollution, and introduction of invasive species exacerbate the impacts of temperature change on species replacement. This is possibly due to human activity reducing the diversity of landscapes and increasing stress on species that are already near their temperature limits.
To conserve ecosystems and their benefits to people, humans can help by “preserving more natural habitats, reducing pollution, and reducing the spread of invasive species,” Pinsky said. “In the ocean, factors like reduced fishing pressure and protecting habitats are important and helpful.”
The paper’s other authors include Helmut Hillebrand at the University of Oldenburg in Wilhelmshaven, Germany; Jonathan Chase, also from iDiv and Martin Luther University Halle-Wittenberg; and researchers from the Institute of Biodiversity at Friedrich Schiller University in Jena, Germany, the Research Centre for Ecological Change at the University of Helsinki, and the Scottish Association for Marine Science in the UK.
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Main funders for the study include the National Science Foundation, iDiv, and the Helmholtz Institute for Functional Marine Biodiversity.
Journal Reference:
Pinsky, M.L., Hillebrand, H., Chase, J.M. et al. ‘Warming and cooling catalyse widespread temporal turnover in biodiversity’, Nature (2025). DOI: 10.1038/s41586-024-08456-z
Article Source:
Press Release/Material by University of California – Santa Cruz
A window into the future of Amazonia
It’s a place where few living things can survive in the water.
Deep in the world’s largest rainforest, there is a boiling river. Found in eastern central Peru, it is a small tributary that eventually leads to the Amazon River.
Heated by cracks in the Earth’s crust, at its warmest spots, the water can reach 200 degrees Fahrenheit, an inhospitable environment with air temperatures hotter than anywhere else in the Amazon.
But the steamy river, known locally as “Shanay-Timpishka,” which translates as “boiled with the heat of the sun,” also offers an interesting perspective on what may happen to plant and tree communities as climate change pushes temperatures upward.
After visiting in 2021, a team of University of Miami biologists recognized that the boiling river could serve as a natural experiment.
“It really provides us a window into the future because the Amazon will get hotter whether we like it or not, so this allows us to understand what increases in temperature will do to the forest composition,” said Riley Fortier, lead author on a study of the site published in Global Change Biology, and a graduate student in professor Kenneth Feeley’s Jungle Biology lab. “It can tell us which species will be lost, and what the makeup of the forest might be like in the future.”
The team returned to Peru in 2022 and mapped the tropical plants and trees found in the area at 70 locations, starting upstream, where temperatures were cooler, down to the hottest part of the boiling river, where air temperatures often exceed 110 degrees Fahrenheit (approx. 43.3°C).
By examining forests for about a mile along the sweltering river and monitoring temperatures with onsite sensors, the team found several insights. They saw that plant diversity declined in the hottest parts of the river — with an 11 percent drop in tree diversity per each degree of warming — and that only plants suited for very warm tropical climates are able to thrive near the boiling river. Their results predict how tropical rainforests could look in the future Amazon as global warming continues.
“Overall, the tree community is less diverse, so we see fewer species in hotter spots,” Fortier said. “And forest composition was also more homogenous in the warmest locations, whereas in cooler forest plots, there was more plant diversity.”
One thing that surprised Fortier was how quickly the vegetation changed along the river.
“We saw a very directional change in composition, where the hottest part of the forest along the river had a greater representation of species that grow in hotter areas of the Amazon,” Fortier added. “Then, there was a drastic change in species as you moved away from the hottest part of the river. Usually, you wouldn’t see such a clear change in the species composition over such a short distance.”
For example, Fortier and Feeley saw that the hotter areas around the boiling river were drier and had more vines and scrubby vegetation. The trees were also smaller and less diverse, similar to a transition zone between a forest and a savanna ecosystem, but all within less than a mile of lush, green jungle.
“Over the course of dozens of miles, you might expect to see dramatic changes like that, but in the small sampling area that we had, you typically wouldn’t see such a clear change in composition,” Fortier added.
Feeley’s lab will continue its research of the boiling river, since it is such a unique place that could portend much about our natural world.
“You can’t heat a whole forest, at least not artificially, which is one of the coolest aspects of the boiling river,” Fortier added. “It’s a useful system because we can isolate temperature as having such an important effect on an entire plant community. At the boiling river, the rainfall, soil, and humidity are constant, but what we see is that as global warming happens, everything will change.”
Journal Reference:
Fortier, R., Kullberg, A., Soria Ahuanari, R., Coombs, L., Ruzo, A. and Feeley, K., ‘Hotter Temperatures Reduce the Diversity and Alter the Composition of Woody Plants in an Amazonian Forest’, Global Change Biology 30: e17555 (2024). DOI: 10.1111/gcb.17555
Article Source:
Press Release/Material by University of Miami
Featured image credit: Gerd Altmann | Pixabay
