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)
Friday, July 02, 2021
Good food in a nice setting: wild bees need diverse agricultural landscapes
Research team investigates influence of different mass-flowering crops on pollinators
IMAGE: SOLITARY WILD BEE ON AN OILSEED RAPE FLOWER view more
CREDIT: N BEYER
Mass-flowering crops such as oilseed rape or faba bean (also known as broad bean) provide valuable sources of food for bees, which, in turn, contribute to the pollination of both the crops and nearby wild plants when they visit. But not every arable crop that produces flowers is visited by the same bees. A team from the University of Göttingen and the Julius Kühn Institute (JKI) in Braunschweig has investigated how the habitat diversity of the agricultural landscape and the cultivation of different mass-flowering crops affect wild bees. The research shows that diverse agricultural landscapes increase the species richness of wild bees. Flowering arable crops with different flower shapes support different wild bee species. The results of the study have been published in Landscape Ecology.
The research team recorded wild bees in flower-rich, semi-natural habitats such as hedgerows and flower strips in a total of 30 different agricultural landscapes, each covering one square kilometre, near Göttingen, Itzehoe and Leipzig. Researchers counted the number of bees along standardised sections and used a hand net to catch them and identify the species. The landscapes used in the study differed in their diversity and in the proportion of land covered by rapeseed and faba beans.
"The shape of the flower is an important criterion for determining which wild bee species will collect nectar from its flowers," says PhD student Felix Kirsch from the University of Göttingen, who conducted the study as part of his Master's thesis. "For example, the shape of the flower must fit the bee's body size and the length of its tongue. Nectar is easily accessible from rapeseed flowers, while the nectar of faba bean is hidden deep inside the flowers."
CAPTION
Long-tongued bumblebee on a faba bean flower
CREDIT
N Beyer
"Our study shows that faba beans promote social wild bees, especially long-tongued bumblebees," explains Dr Doreen Gabriel from the JKI in Braunschweig. A different picture emerged in landscapes with large amounts of oilseed rape: here, the study found that the proportion of solitary wild bees, which often have a smaller body size, was higher. "The cultivation of a certain mass-flowering crop is not sufficient to maintain diverse bee communities, which in turn ensure the pollination success of many flowering arable crops and wild plants," says first author Nicole Beyer, a postdoctoral researcher in the Functional Agrobiodiversity Department at Göttingen University. The head of the department, Professor Catrin Westphal, concludes: "Our results show convincingly that diverse, flowering arable crops and especially diverse semi-natural habitats in the agricultural landscape are necessary to support a broad range of wild bee species."
Original publication: Beyer, N. et al. Identity of mass-flowering crops moderates functional trait composition of pollinator communities. Landscape Ecology 2021. https://doi.org/10.1007/s10980-021-01261-3
Striking a balance: Trade-offs shape flower diversity
An international research team led by a researcher from the University of Tsukuba proposes that catering to different visitors has influenced flower evolution
IMAGE: FLOWER GENERALIZATION HAS OFTEN BEEN VIEWED AS A SUBOPTIMAL SOLUTION TO MANAGING THE NEEDS OF DIFFERENT VISITORS. RESEARCHERS FROM THE UNIVERSITY OF TSUKUBA HAVE DEVELOPED A FRAMEWORK TO EXAMINE FLOWER-ANIMAL... view more
CREDIT: UNIVERSITY OF TSUKUBA
Ibaraki, Japan - Flowers come in a multitude of shapes and colors. Now, an international research team led by a researcher from Japan has proposed the novel hypothesis that trade-offs caused by different visitors may play an important role in shaping this floral diversity.
In a study published last month, the team explored how the close associations between flowers and the animals that visit them influence flower evolution.
Visitors to flowers may be beneficial, like pollinators, or detrimental, like pollen thieves. All of these visitors interact with flowers in different ways and exert different selection pressures on flower traits such as color and scent. For example, a scent that attracts one pollinator may deter other potential pollinators. In this case, the flower would be expected to cater to the best pollinator.
"On the basis of this theory, you'd expect that flowers would mostly be visited by one particular group of pollinators," says lead author of the study, Professor Kazuharu Ohashi. "But flowers often host many different visitors at the same time and flowers appear to meet the needs of multiple visitors. The question we wanted to answer is how this happens in nature."
Balancing the demands of multiple visitors involves trade-offs. For example, diurnal bees and nocturnal moths can both pollinate goat willow but prefer different smells. A floral scent adapted to only one of these animals would mean missed opportunities for pollination by the other. To see how these types of visitor-mediated trade-offs affect the evolution of flowers, the researchers developed a conceptual framework to examine the different types of trade-offs and how flowers might adapt. They then looked at previous studies of flower-animal interactions to see whether the research supported the proposed framework.
What they found was a variety of strategies for mitigating trade-offs. In the case of goat willow, flowers produce different scents during the day and night, and therefore attract both types of pollinator. Another example is floral color change as a strategy to attract both bees and flies. Retaining old flowers could attract opportunistic foragers like flies, while repelling smart foragers like bees. The color change in flowers as they age could reduce this trade-off by allowing bees to select young, rewarding flowers. Many other strategies were noted, all of which involved acquiring novel combinations of traits to attract, or exclude, different visitors.
"Most flowers are ecologically generalized and the assumption to date has been that this is a suboptimal solution," explains Professor Ohashi. "But our findings suggest that interactions with multiple animals can actually be optimized by minimizing trade-offs in various ways, and such evolutionary processes may have enriched the diversity of flowers."
The discrepancy between observed flower visitors and those predicted on the basis of a flower's traits has long been a topic of debate. Taking visitor-mediated trade-offs into account in future studies of flower evolution may help settle that argument.
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The article, "Trade-off mitigation: a conceptual framework for understanding floral adaptation in multispecies interactions," was published in Biological Reviews at DOI:10.1111/brv.12754
New approach can add diversity to crop species without breeding GMOs
Genetic technique edits every chloroplast in a plant, but does not change nuclear DNA of offspring
IMAGE: RESEARCHERS IN JAPAN HAVE DESIGNED A TECHNIQUE THAT CAN MAKE POINT MUTATIONS TO THE DNA OF PLANT CHLOROPLASTS WITHOUT LEAVING ANY OF THE GENETIC ENGINEERING TECHNOLOGY BEHIND TO BE INHERITED... view more
CREDIT: IMAGE BY HIROKO UCHIDA CC BY-SA 4.0, HTTP://UCHIDAHIROKO.COM/WORKS-S.HTML
Breeding better crops through genetic engineering has been possible for decades, but the use of genetically modified plants has been limited by technical challenges and popular controversies. A new approach potentially solves both of those problems by modifying the energy-producing parts of plant cells and then removing the DNA editing tool so it cannot be inherited by future seeds. The technique was recently demonstrated through proof-of-concept experiments published in the journal Nature Plants by geneticists at the University of Tokyo.
"Now we've got a way to modify chloroplast genes specifically and measure their potential to make a good plant," said Associate Professor Shin-ichi Arimura, who leads the group that performed the research.
Chloroplasts, the parts of plant cells that convert carbon dioxide and sunlight into sugar, possess their own circular DNA that is made of the same ATGC-code as the double helix DNA in the nucleus of the cell. However, chloroplast DNA is maintained and inherited completely separately from nuclear DNA. Every cell can contain multiple chloroplasts, each with many identical copies of the chloroplast DNA. The same change must be made in every copy of chloroplast DNA if any genome editing is to have a noticeable effect that can be inherited by the plant's offspring.
In the 1990s, experts invented a technique to insert new DNA fragments into chloroplast genomes, but it also inserts extra genetic tags or markers.
The goal of Arimura and his colleagues is to make uniform, inheritable modifications to only specific parts of chloroplast DNA without leaving genome editing tools behind or permanently altering nuclear DNA. They started with an existing tool known as TALENs. The original TALENs use a large protein that recognizes specific short DNA sequences and cuts that DNA with an enzyme. In recent years, other research groups have improved TALEN technology: the DNA recognition sequences can be customized and the DNA cutting enzyme can be replaced with an enzyme that changes GC pairs in the DNA code into AT pairs.
These GC to AT changes are subtle -- just changing one point of the DNA code to another, rather than inserting or deleting whole genes. However, point mutations can have major effects depending on their location.
Arimura's team combined these TALEN improvements and added an extra "chloroplast-targeting" component, calling their finalized version ptpTALECDs. For every genome edit that researchers wanted to make, they needed to build a matching left and right pair of ptpTALECDs in bacteria. The design process is complicated because the pairs of large TALENs proteins and the chloroplast-targeting signals must be expressed simultaneously as a single unit from the nuclear DNA.
"Building the ptpTALECDs was an extremely laborious process, but we have a very dedicated master's degree student who did almost all the work, Issei Nakazato," said Arimura. Nakazato is the first author of the research publication.
After designing the ptpTALECDs DNA sequence, researchers then inserted it into Arabidopsis thaliana plants, a species of thale cress common in research laboratories. The UTokyo researchers are confident that after building them, the ptpTALECDs could be inserted into many crop species because that part of the process is a straightforward and standard procedure in agriculture and botany labs.
The ptpTALECDs enter the plants' nuclei and then the cells produce ptpTALECDs in the same way they produce any other protein. The chloroplast-targeting sequence ensures that the finished ptpTALECD proteins are shuttled out of the nucleus into the chloroplasts where they then are expected to edit every chloroplast genome they encounter.
This first generation plants are considered genetically modified organisms (GMOs) because their nuclear DNA has been permanently altered to contain the ptpTALECD sequence.
When these genetically modified plants reproduce with themselves through self-fertilization or with nonmodified (wild-type) plants, the next generation of plants inherits nuclear DNA in the normal way, meaning genes are mixed and matched between the ovules and pollen. Some seeds inherit the ptpTALECD sequence and other seeds do not.
However, plants always inherit their chloroplasts whole and intact through their "mothers," the ovules. So regardless of what nuclear DNA the next generation of plants inherits, if their female parent plant had modified chloroplasts, the next generation will always inherit modified chloroplasts.
Researchers then search the offspring to find plants that did not inherit edited nuclear DNA, but did inherit modified chloroplasts. These members of the second generation of plants and any of their future offspring can be considered non-GMO end products because their nuclear DNA contains none of the ptpTALECDs' genetic engineering machinery.
Legal definitions vary, but broadly speaking, countries either assess the end product or the process when deciding to label an organism as a GMO. By end-product definitions used in Japan and the U.S., plants produced with this technique are not GMOs. However, the same plants are GMOs under process based-definitions used in the European Union.
So far, Arimura's team proved their system works by editing three chloroplast genes and observing the expected effects in the offspring plants.
"Chloroplast DNA encodes less than 1% of the total genetic material in a plant, but it has a very important effect on photosynthesis, and therefore the health of the plant. Hopefully, this method will be useful in fundamental research and applied agriculture," said Arimura.
Researchers are optimistic that the fact that none of the genetic engineering tools are inherited by future generations and that the method only makes point mutations will ensure that the method will be used to breed better crops that are accepted by farmers and consumers.
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Research Publication
Issei Nakazato, Miki Okuno, Hiroshi Yamamoto, Yoshiko Tamura, Takehiko Itoh, Toshiharu Shikanai, Hideki Takanashi, Nobuhiro Tsutsumi, Shin-ichi Arimura. 1 July 2021. Targeted base editing in the plastid genome of Arabidopsis thaliana. Nature Plants. DOI: 10.1038/s41477-021-00954-6 https://www.nature.com/articles/s41477-021-00954-6
Associate Professor Shin-ichi Arimura Laboratory of Plant Molecular Genetics, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657
About the University of Tokyo
The University of Tokyo is Japan's leading university and one of the world's top research universities. The vast research output of some 6,000 researchers is published in the world's top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at http://www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.
Funders
This research was supported partly from the University of Tokyo GAP fund program and from the Japan Society for the Promotion of Science (Grant Numbers 20H00417, 16H06279, 19H02927 and 19KK0391).
From meadow to plate: The cultured meat that replaces animals with grass
An affordable lab system that uses grass blades to turn cells into cultured meat has been developed at the University of Bath in the UK
IMAGE: ALIGNED MYOTUBES (CYLINDRICAL CELLS FOUND IN MUSCLE FIBER) GROWING ON GRASS. view more
CREDIT: ALLAN SCOTT
An affordable lab system that uses grass blades to turn cells into cultured meat has been developed at the University of Bath in the UK.
Researchers have successfully taken grass from the university's campus and used it to create a scaffold that animal cells can attach to and grow on. The resulting tissue has the potential to be used both as lab-made meat and as human muscle tissue to repair or replace tissue which has been damaged or lost through injury or disease.
The study, by Dr Paul De Bank (Department of Pharmacy & Pharmacology), Professor Marianne Ellis (Department of Chemical Engineering) and Scott Allan (a PhD researcher in the Department of Chemical Engineering), is published in this month's Journal of Biomedical Materials Research - Part A.
The first step in the new bioengineering process involves emptying grass blades of their native cells in a process known as decellularisation. The decellularised blades are then seeded with a set of cells derived from a mouse cell line (these cells would eventually be replaced by bovine stem cells). The introduced cells stick to the scaffold's surface, multiply and form links with neighbouring cells, eventually growing as a cell mass to form new 3D tissue.
There are several challenges researchers must overcome when looking for a suitable scaffold on which to engineer new muscle tissue. First, the scaffold must be one cells can readily attach to the surface. It must then allow these cells to proliferate and align in a way that precisely mimics the fibres of the natural tissue they are replicating (with muscle fibres, for instance, all the cells need to contract and relax in tandem). Second, for scale-up, the scaffold must be cost-effective and straightforward to manufacture. For lab-grown meat, there is a third challenge: the scaffold must be edible to humans, even if not highly digestible (as is the case for grass).
The Bath project shows grass blades fulfil all criteria.
Dr Paul De Bank, who led the research, said: "When we were looking for a scaffold for our cells, we wanted to find something that was both sustainable and edible. I thought along the lines of a decellularised natural material because cellulose (which grass is largely made of) is edible, but also because grass has aligned grooves that I hoped would allow the cells to line up together to make the fibres we needed - and it worked!"
He added: "When we eat beef, we're partly eating the grass the cows have grazed on in their lifetime. What's neat about our study is that it shows that we can directly replace the animals with the grass they eat. Our system needs to be scaled up but I'm hopeful that sooner rather than later, we could have a meat product on the market based on grass."
The adhesion of the animal stem cells to the grass surface was found to be around 35%, which is considered a good result. "Often, decellularised plant scaffolds need to be chemically modified to get cells to grow on them. The great thing we've found with grass is that we get significant adhesion without further processing steps." said Dr De Bank, adding: "We are, however, hoping to find a way to increase this adhesion - we have a new PhD student who will be working on this, exploring ways to optimise cell attachment and growth.
The next big challenge will be scaling up this process to generate sufficient quantities of both cells and scaffold material in order to produce a significant quantity of muscle tissue. If this is successful then - one day - consumers may be able to buy grass-reared meat with a clear conscience, free from the environmental and animal-welfare concerns many are wrestling with today.
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Global climate dynamics drove the decline of mastodonts and elephants, new study suggests
IMAGE: DUSK FALLS ON EAST AFRICA'S TURKANA BASIN 4 MILLION YEARS AGO, WHERE OUR EARLY UPRIGHT-WALKING APE ANCESTORS, AUSTRALOPITHECUS ANAMENSIS (FOREGROUND), SHARED THEIR HABITAT WITH SEVERAL COEXISTING PROBOSCIDEAN SPECIES, AS PART... view more
CREDIT: JULIUS CSOTONYI
Elephants and their forebears were pushed into wipeout by waves of extreme global environmental change, rather than overhunting by early humans, according to new research.
The study, published today in Nature Ecology & Evolution, challenges claims that early human hunters slaughtered prehistoric elephants, mammoths and mastodonts to extinction over millennia. Instead, its findings indicate the extinction of the last mammoths and mastodonts at the end of the last Ice Age marked the end of progressive climate-driven global decline among elephants over millions of years.
Although elephants today are restricted to just three endangered species in the African and Asian tropics, these are survivors of a once far more diverse and widespread group of giant herbivores, known as the proboscideans, which also include the now completely extinct mastodonts, stegodonts and deinotheres. Only 700,000 years ago, England was home to three types of elephants: two giant species of mammoths and the equally prodigious straight-tusked elephant.
An international group of palaeontologists from the universities of Alcalá, Bristol, and Helsinki, piloted the most detailed analysis to date on the rise and fall of elephants and their predecessors, which examined how 185 different species adapted, spanning 60 million years of evolution that began in North Africa. To probe into this rich evolutionary history, the team surveyed museum fossil collections across the globe, from London's Natural History Museum to Moscow's Paleontological Institute. By investigating traits such as body size, skull shape and the chewing surface of their teeth, the team discovered that all proboscideans fell within one of eight sets of adaptive strategies.
"Remarkably for 30 million years, the entire first half of proboscidean evolution, only two of the eight groups evolved," said Dr Zhang Hanwen, study coauthor and Honorary Research Associate at the University of Bristol's School of Earth Sciences.
"Most proboscideans over this time were nondescript herbivores ranging from the size of a pug to that of a boar. A few species got as big as a hippo, yet these lineages were evolutionary dead-ends. They all bore little resemblance to elephants."
The course of proboscidean evolution changed dramatically some 20 million years ago, as the Afro-Arabian plate collided into the Eurasian continent. Arabia provided crucial migration corridor for the diversifying mastodont-grade species to explore new habitats in Eurasia, and then into North America via the Bering Land Bridge.
CAPTION
A scene from northern Italy 2 million years ago - the primitive southern mammoths Mammuthus meridionalis (right-hand side) sharing their watering hole with the mastodont-grade Anancus arvernensis (left-hand side), the last of its kind. Other animals that brought an 'East African air' to Tuscany included rhinos, hippos and zebra-like wild horses.
CREDIT
Tamura Shuhei
"The immediate impact of proboscidean dispersals beyond Africa was quantified for the very first time in our study," said lead author Dr Juan Cantalapiedra, Senior Research Fellow at the University of Alcalá in Spain.
"Those archaic North African species were slow-evolving with little diversification, yet we calculated that once out of Africa proboscideans evolved 25 times faster, giving rise to a myriad of disparate forms, whose specialisations permitted niche partition between several proboscidean species in the same habitats. One case in point being the massive, flattened lower tusks of the 'shovel-tuskers'. Such coexistence of giant herbivores was unlike anything in today's ecosystems."
Dr Zhang added: "The aim of the game in this boom period of proboscidean evolution was 'adapt or die'. Habitat perturbations were relentless, pertained to the ever-changing global climate, continuously promoting new adaptive solutions while proboscideans that didn't keep up were literally, left for dead. The once greatly diverse and widespread mastodonts were eventually reduced to less than a handful of species in the Americas, including the familiar Ice Age American mastodon."
By 3 million years ago the elephants and stegodonts of Africa and eastern Asia seemingly emerged victorious in this unremitting evolutionary ratchet. However, environmental disruption connected to the coming Ice Ages hit them hard, with surviving species forced to adapt to the new, more austere habitats. The most extreme example was the woolly mammoth, with thick, shaggy hair and big tusks for retrieving vegetation covered under thick snow.
The team's analyses identified final proboscidean extinction peaks starting at around 2.4 million years ago, 160,000 and 75,000 years ago for Africa, Eurasia and the Americas, respectively.
"It is important to note that these ages do not demarcate the precise timing of extinctions, but rather indicate the points in time at which proboscideans on the respective continents became subject to higher extinction risk," said Dr Cantalapiedra.
Unexpectedly, the results do not correlate with the expansion of early humans and their enhanced capabilities to hunt down megaherbivores.
"We didn't foresee this result. It appears as if the broad global pattern of proboscidean extinctions in recent geological history could be reproduced without accounting for impacts of early human diasporas. Conservatively, our data refutes some recent claims regarding the role of archaic humans in wiping out prehistoric elephants, ever since big game hunting became a crucial part of our ancestors' subsistence strategy around 1.5 million years ago," said Dr Zhang.
"Although this isn't to say we conclusively disproved any human involvement. In our scenario, modern humans settled on each landmass after proboscidean extinction risk had already escalated. An ingenious, highly adaptable social predator like our species could be the perfect black swan occurrence to deliver the coup de grâce."
CAPTION
Highly complete fossil skull of a typical mid Miocene 'shovel-tusker', Platybelodon grangeri, roamed in large herds across Central Asia 13 million years ago. The specimen is display mounted at the Hezheng Paleozoological Museum, Gansu Province, China.
CREDIT
Zhang Hanwen
Paper
'The rise and fall of proboscidean ecological diversity' by Cantalapiedra, J.L. et al. in Nature Ecology & Evolution.
Notes to editors
Dr Zhang Hanwen (Steven) is available for interview. To schedule this please email hz1646@bristol.ac.uk and Victoria Tagg, Media & PR Manager (Research) at the University of Bristol: victoria.tagg@bristol.ac.uk
Caption: Dusk falls on East Africa's Turkana Basin 4 million years ago, where our early upright-walking ape ancestors, Australopithecus anamensis (foreground), shared their habitat with several coexisting proboscidean species, as part of a spectacular herbivore community containing some progenitors of today's charismatic East African animals. Background (left to right): Anancus ultimus, last of the African mastodonts; Deinotherium bozasi, colossal herbivore as tall as a giraffe; Loxodonta adaurora, gigantic extinct cousin of modern African elephants, alongside the closely-related, smaller L. exoptata. Middle ground (left to right): Eurygnathohippus turkanense, zebra-sized three-hoofed horse; Tragelaphus kyaloae, a forerunner of the nyala and kudu antelopes; Diceros praecox - ancestor of the modern black rhino.
Caption: Highly complete fossil skull of a typical mid Miocene 'shovel-tusker', Platybelodon grangeri, roamed in large herds across Central Asia 13 million years ago. The specimen is display mounted at the Hezheng Paleozoological Museum, Gansu Province, China.
Image Credit: Zhang Hanwen
Image 3
Prehistoric Safari : Pliocene Southern Europe by Jagroar on DeviantArt
Caption: A scene from northern Italy 2 million years ago - the primitive southern mammoths Mammuthus meridionalis (right-hand side) sharing their watering hole with the mastodont-grade Anancus arvernensis (left-hand side), the last of its kind. Other animals that brought an 'East African air' to Tuscany included rhinos, hippos and zebra-like wild horses.
Caption: Disparity of proboscidean forms through 60 million years of evolution. Early proboscideans like Moeritherium (far left) were nondescript herbivores typically the size of a pig. But subsequent evolution of this lineage was almost consistently dominated by gigantic species, many considerably larger than today's elephants (e.g. Deinotherium 2nd left; Palaeoloxodon furthest right). A key factor of proboscidean evolutionary innovation lies with disparities in tooth morphology.
Image credit: Óscar Sanisidro
The rise and fall of elephants
MUSEUM FÜR NATURKUNDE, LEIBNIZ INSTITUT FÜR EVOLUTIONS- UND BIODIVERSITÄTSFORSCHUNG
IMAGE: ABOUT 4 MILLION YEARS AGO, AN AUSTRALOPITHECUS ANAMENSIS OBSERVED THE RICHNESS OF PROBOSCIDEANS IN WHAT IS NOW TURKANA, KENYA. FROM LEFT TO RIGHT ANANCUS ULTIMUS, DEINOTHERIUM BOZASI, LOXODONTA ADAURORA... view more
CREDIT: ILLUSTRATION BY JULIUS CSOTONYI
Based on fossil finds, we know that the vast majority of species that once inhabited the earth have become extinct. For example, there are about 5,500 mammal species living on the planet today, but we know of at least 160,000 fossil species, so for every mammal species living today, there are at least 30 extinct ones. We therefore know with great certainty that the lineages of living things come and go along immense time scales. But what factors cause these lineages to come into being and disappear is still an unsolved question.
To investigate this problem more closely, the research team focused on a charismatic group: the proboscideans, which include today's elephants, but also the extinct mammoths, mastodons and dinotheria. The history of the proboscideans is one of glory and decline. Although today there are only three species of elephants left in Asia and Africa, we know fossil more than 180 species of these animals, which also inhabited Europe, South America and North America. "In the past, more than 30 species of these giants lived on the planet at the same time, and many ecosystems were so productive and ecologically complex that it was not uncommon for three or more species of proboscideans to live together in the same ecosystem," explains Juan López Cantalapiedra, a researcher at the University of Alcalá in Spain and lead author of the new study.
However, as the researchers were able to show, proboscideans were not always so diverse. In the first 30 million years of their history, the group was limited to Africa and Arabia, which together formed an isolated continent that was not connected to Asia as it is today. Until then, the evolution of these animals was quite slow and the few existing species were ecologically quite similar. But about 22 million years ago, Afro-Arabia connected with Eurasia and the proboscideans spread all over the world. The new challenges faced by the lineages scattered outside Afro-Arabia caused the ecology of the group to multiply. Species emerged with different, highly diverse tooth shapes, including strange, shovel-shaped tusks. "This ecological diversity reduced competition between species and allowed several of them to live together in the same ecosystem at the same time," points out Fernando Blanco, a researcher at the Museum für Naturkunde Berlin. This marked the beginning of the golden age of proboscideans. "If the link between Afro-Arabia and Eurasia had not happened, or had happened at a different time, the evolutionary history of proboscideans would have been radically different," Blanco adds.
The new study also revealed the factors that determined the group's ultimate decline. Seven million years ago, modern savannah ecosystems spread across all continents, and because of this change, many proboscideans adapted to life in forested areas disappeared. At the same time, however, new forms appeared that were able to feed on less nutritious plant material such as wood and especially grass, which is typical of savannas. Today's elephants are among these evolutionary newcomers.
About 3 million years ago, the rules of the game changed again with the onset of the ice ages. In Eurasia and Africa, the extinction rate quintupled. But as the researchers were able to show, the extinction rate rose even further in Eurasia and America 160,000 and 75,000 years ago, respectively. Were humans responsible for this debacle? "At that time, Homo sapiens had not yet made it to these continents," Cantalapiedra explains. The analyses showed that the different phases of extinction were linked to the decline and rapid fluctuations in global temperatures as a result of the ice ages. "The impact of our ancestors probably contributed to the extinction of the few surviving species, such as the woolly mammoth, a little later."
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Publication: Cantalapiedra JL, Sanisidro O, Zhang H, Alberdi MT, Prado JL, Blanco F, Saarinen J (2021) The rise and fall of proboscidean ecological diversity. Nature Ecology & Evolution. doi: 10.1038/s41559-021-01498-w
RUDN University chemists synthesize biodiesel from jatropha curcas plant
IMAGE: RUDN UNIVERSITY CHEMISTS HAVE PROPOSED A NEW METHOD OF PRODUCING FUEL FROM JATROPHA CURCAS, A POISONOUS TROPICAL PLANT. NATURAL MINERALS AND A NON-TOXIC ADDITIVE FROM VEGETABLE RAW MATERIALS ARE USED... view more
CREDIT: RUDN UNIVERSITY
RUDN University chemists have proposed a new method of producing fuel from Jatropha Curcas, a poisonous tropical plant. Natural minerals and a non-toxic additive from vegetable raw materials are used for that. The reaction efficiency is 85%. The fuel can be used in diesel internal combustion engines. The results are published in the International Journal of Green Energy.
Jatropha Curcas is a common plant in many tropical regions. Its seeds contain lots of oil, but they cannot be used agriculture because the oil contains toxins that are dangerous for people and animals. But the composition of jatropha oil is suitable for the manufacture of biodiesel. One of challenge of the processing the plant raw materials is to select sufficiently effective and safe catalysts. RUDN University chemists found a suitable catalyst and selected the optimal additive-a substance that improves the useful properties of the fuel.
"Mineral catalysts with a complex chemical composition, for example, zeolites -- calcium and sodium silicates, have performed well in biodiesel production from vegetable and animal fats. They are quite active, eco-friendly and can be reused. But biodiesel, like hydrocarbons, cannot be used without improving additives", Ezeldin Osman, PhD student at RUDN University.
RUDN University chemists decided to use furfural as an additive for diesel biodiesel. It is obtained from plant waste, such as sawdust or straw, it improves the characteristics of diesel fuel, in particular, its cetane number is an indicator of flammability.
As a first step, the researchers obtained biodiesel from Jatropha Curcas oil. To do this, they mixed the oil with three times as much methanol and added a catalyst -- minerals from the zeolite group, mainly thomsonite. The catalyst amount was 5 times lower than the oil. RUDN University chemists also tested other reaction settings, but the highest yield of biodiesels (up to 85% in the composition of the reaction products) was obtained at this ratio of reagents and a temperature of 75°C.
The main part of the experiment was the selection of the optimal amount of furfural to improve the characteristics of biodiesel. RUDN University chemists mixed biodiesel and the additive in equal quantities, in other variants they used twice as much additive as fuel, and vice versa. It turned out that the highest cetane number (64.1) is in fuel containing 66.6% of furfural. This is 4.3 units higher than that of biodiesels without furfural. In this ratio, the additive removes all compounds that impair flammability from the biodiesel, such as alcohols and carbonyl compounds. The achieved characteristics of biodiesel from jatropha kurkas allow it to be used in internal combustion engines in the future.
"The additive reduced the content of aluminum, sodium, magnesium, potassium, iron and other substances in biodiesel that form ash -- a non-combustible solid residue of fuel. This not only improves fuel performance, but also reduces the risk of engine wear. At the same time, furfural is a stable additive at high temperatures, environmentally friendly in production and application. We will continue experiments to improve diesel fuel with this substance", Tatiana Sheshko, PhD, the head of the Adsorption and Catalysis Laboratory at RUDN University.
Catalyzing the conversion of biomass to biofuel
Water in zeolites saves energy in the conversion of biomass into biofuel
IMAGE: PROF. LERCHER IN HIS LABORATORY AT THE DEPARTMENT OF CHEMISTRY AT THE TECHNICAL UNIVERSITY OF MUNICH. view more
CREDIT: ANDREAS HEDDERGOTT / TUM
Zeolites are extremely porous materials: Ten grams can have an internal surface area the size of a soccer field. Their cavities make them useful in catalyzing chemical reactions and thus saving energy. An international research team has now made new findings regarding the role of water molecules in these processes. One important application is the conversion of biomass into biofuel.
Fuel made from biomass is considered to be climate-neutral, although energy is still needed to produce it: The desired chemical reactions require high levels of temperature and pressure.
"If we are to do without fossil energy sources in the future and make efficient large-scale use of biomass, we will also have to find ways to reduce the energy required for processing the biomass," says Johannes Lercher, professor for Chemical Technology at the Technical University of Munich (TUM) and Director of the Institute for Integrated Catalysis at the Pacific Northwest National Laboratory in Richland, Washington (USA).
Working together with an international research team, Lercher has taken a closer look at the role of water molecules in reactions inside the zeolite's pores, which are less than one nanometer in size.
It all starts with acids
One characteristic of an acid is that it easily donates protons. Thus, when added to water, hydrochloric acid splits into negatively charged chloride anions, like those found in table salt crystals, and positively charged protons which attach themselves to the water molecules. This results in a positively charged hydronium ion, which looks to further pass on this proton, for example to an organic molecule.
When the organic molecule is "forced" to accept a proton, it tries to stabilize itself. Thus, an alcohol can give rise to a molecule with a double bond - a typical reaction step on the path from biomass to biofuel. The zeolite walls stabilize transitional states occurring during conversion and, thus, help to minimize the amount of energy required by the reaction to occur.
Zeolites acting as acids
Zeolites contain oxygen atoms in their crystal structure which already carry a proton. Like molecular acids they form hydronium ions through the interactions with water.
However, while hydronium ions disperse in water, they remain closely associated with the zeolite. Chemical pre-treatment can vary the number of these active centers and, thus, establish a certain density of hydronium ions in the pores of the zeolite.
The ideal zeolite for every reaction
By systematically varying the size of the cavities, the density of the active sites and the amount of water, the research team was able to elucidate the pore sizes and concentrations of water which best catalyzed selected example reactions.
"In general, it's possible to increase the reaction rate by making the pores smaller and raising the charge density," Johannes Lercher explains. "However, this increase has its limits: When things get too crowded and the charges are too close to one another, the reaction rate drops again. This makes it possible to find the optimum conditions for every reaction."
"Zeolites are generally suitable as nanoreactors for all chemical reactions whose reaction partners fit into the pores and in which an acid is used as a catalyst," emphasizes Lercher. "We are at the very beginning of a development with the potential to increase the reactivity of molecules even at low temperatures and, thus, to save considerable amounts of energy in the production of fuels or chemicals."
Participants in the research included the Catalysis Research Center at the Technical University of Munich, the US Institute for Integrated Catalysis at the Pacific Northwest National Laboratory, the Swiss Paul Scherrer Institute as well as the University of Yangzhou and the Qingdao Institute of Bioenergy and Bioprocess Technology in China. The work was funded by the Technical University of Munich and the US Department of Energy, Office of Science.
