The Great London [Search results for ecology

  • Natural Heritage: Sampling species' DNA trails is leading to better environmental monitoring

    Natural Heritage: Sampling species' DNA trails is leading to better environmental monitoring

    Using a technique that can tell if a species has passed by from just a sample of water, scientists are developing new ways to assess ecosystems.

    Sampling species' DNA trails is leading to better environmental monitoring
    Great crested newt [Credit: Imperial College London]

    All animals shed fragments of DNA as they go about their lives – in faeces, mucous, sperm and eggs, shed skin, hair and, eventually, their carcasses.

    These traces of genetic material can persist in the environment for some time – a matter of weeks in water and up to a few centuries in soil. With new, more sensitive DNA amplification and sequencing techniques, scientists can collect and analyse these fragments in water and soil samples and identify individual species that have passed by.

    One area where environmental DNA, or eDNA, is finding practical use is in environmental assessments, for example to check whether any protected species are present before construction works are carried out. Already, Defra in the UK have approved the use of eDNA sampling to assess the presence of protected great crested newts in ponds.

    Now, in a new partnership between Imperial College London and environmental ecology consultancy Thomson Ecology, scientists are hoping to expand the use of eDNA. They want to create protocols to assess whether different areas are home to key protected species, including crayfish, water voles, otters and reptiles.

    As well as looking at key protected species for conservation, the team want to use eDNA for biosecurity, by identifying invasive species. For example, as well as native crayfish, some UK waters have been occupied by invasive American Signal Crayfish, which outcompete the native species and damage the local environment. Early detection of invasive crayfish could mean they are dealt with sooner, and cause less damage.

    Ultimately, the researchers hope to be able to use eDNA to profile entire ecosystems, analysing water samples to get a snapshot of all the organisms present in the local environment that have shed some DNA.

    Victoria Priestley, who is taking on this task for her PhD thesis in the Department of Life Sciences at Imperial, said: "I think eDNA surveys represent a sea change in how we approach survey and monitoring of species.

    "There is a lot of effort going into eDNA research globally and once it becomes more established, we should be able to assess what species are present in an area much more quickly. Ultimately we should be able to use it to create a clearer and more detailed picture of global biodiversity."

    Efficient Environmental Assessments

    Currently, species are assessed based on intensive field surveys, requiring taxonomic expertise and often involving tagging animals and repeat visits to a site. However, Professor Vincent Savolainen, from the Department of Life Sciences at Imperial, is developing new protocols for various species.

    This is paving the way for much simpler and more cost-effective surveying for environmental assessments. Professor Savolainen said: "This research will contribute to developing new indices to meet goals of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), the body that assesses the state of biodiversity and of the ecosystem services it provides to society, in response to requests from decision makers."

    Although sequencing techniques have improved dramatically in the last few decades, challenges remain in analysing eDNA. The fragments degrade over time, a process enhanced by temperature, microbes, enzymes and salinity.

    The rate that eDNA is 'shed' from species to species and individual to individual also requires more research, as does the role of predators in moving eDNA between sites, and especially how eDNA is distributed in aquatic environments.

    However, Priestley is positive that eDNA surveys have a bright future: "There is still some way to go before whole-ecosystem eDNA monitoring is standard practice, but I believe that at least in the near future, eDNA will increasingly be one of the options in the survey toolkit, working alongside traditional methods to obtain the best ecological survey data in the most efficient way."

    Positive Partnership

    Professor Tom Welton, Dean of the Faculty of Natural Sciences, said partnerships like this one help translate research into real-world applications: "This exciting collaboration demonstrates that research across the whole breadth of natural sciences at Imperial, even on newts, has practical applications to real world problems.

    "Our partnership with Thomson Ecology will allow our research to have a positive impact on environmental protection and conservation."

    Author: Hayley Dunning | Source: Imperial College London [November 25, 2016]

  • Ecosystems: Immense species richness of bacterial-eating microorganisms discovered in soil

    Ecosystems: Immense species richness of bacterial-eating microorganisms discovered in soil

    Typically ignored, the millions of microorganisms that we tread upon daily play a major role in the decomposition of soil matter -- one that is of far greater significance than that of the whales and pandas that tend to steal our attention. A group of researchers has just shown that there is an enormous diversity among a group of bacteria-eating microorganisms known as Cercozoa. In four small soil samples, each consisting of a half gram of soil, they discovered more than 1000 different species per sample. The research suggests that a drier climate in the years ahead due to climate change will contribute to a shift in the number of soil microorganisms, and thus, a shift in the decomposition of soil matter, with as of yet to be known consequences.

    Immense species richness of bacterial-eating microorganisms discovered in soil
    The photo of a testate amoeba's shell (Euglypha) was taken using a scanning electron microscope. If the amoeba was alive, 
    it would protrude from the open end. The shell is approximately 0.04 mm long. Testate amoebae are large Cercozoa. 
    Small amoeba-like Cercozoa can be down to 0.003 mm long. testate amoebae appear to be sensitive to the type 
    of drier climate that we expect in the future [Credit: Clement Duckert, Neuchatel University, Switzerland]

    A team led by researchers from the Section for Terrestrial Ecology (Flemming Ekelund, Christopher B. Harder and Regin Ronn, at the Department of Biology, University of Copenhagen) has just published an article in the >ISME Journal. The group's studies show that there is enormous species diversity among an oft-overlooked group of organisms known as Cercozoa. In four small soil samples, each consisting of just a half gram of soil, the researchers discovered more than 1000 different species per sample. The research was conducted in collaboration with Section for Microbiology staff (Department of Biology, University of Copenhagen) and the eminent British scientist, David Bass (Natural History Museum, London), and is supported by national research councils and the Carlsberg Foundation.

    Associate Professor Flemming Ekelund of the Department of Biology explains, "Cercozoa are small bacteria-eating microorganisms that play a prominent role in soil ecology. Serious interest in these organisms began about 25-30 years ago, as people began to wonder what caused bacteria to disappear from soil. As interest took root, the number of known species increased sharply."

    The name Cercozoa is derived from the Greek word, kerkos (tail), as some of the species within the group have a tail like end, and zoon (animal), as these organisms were previously thought to be a type of animal.

    A single teaspoon of soil (a couple of grams) contains millions of microorganisms, so it is hopeless to create a species list by studying organisms one by one. Furthermore, many of these organisms belong to species unknown to science.

    "We took small soil samples (½-1 gram), from which we analysed DNA strands (genetic material) from hundreds of thousands of organisms" (deep sequencing), explains Christoffer Bugge Harder. "However, it's difficult to catalogue and systematise this huge amount of data. To do so, we used the Section of Microbiology's capacity to deploy specialized statistics tools. Our British colleague, David Bass, contributed precise DNA references for the species in the group that have already been thoroughly catalogued. For now, this remains at just under 1000."

    The studies were conducted in correlation with a climate experiment (Climate) that investigates the consequences of climate change in Denmark, as many climate researchers expect it to present itself, by 2075. Besides being able to report an enormous number of species in these samples, the research also demonstrated that a more arid climate, as expected in 2075, will probably lend to a shift in the occurrence of microorganism species; particularly within a group referred to as testate amoebae.

    Researchers already know that climate change will result in significant shifts in plant and animal frequency. But it can also lead to changed frequencies among microorganisms, which means that climate change could have an impact on the ecological processes at work in soil. More studies are needed for researchers to specify the impact of an offset and the amount of microorganisms found in soil as a result of global warming.

    Source: Faculty of Science - University of Copenhagen [June 21, 2016]

  • Forensics: Single strain of plague bacteria sparked multiple historical and modern pandemics

    Forensics: Single strain of plague bacteria sparked multiple historical and modern pandemics

    A single entry of the plague bacterium into Europe was responsible for the Black Plague of the mid-14th century. This same strain sparked recurrent outbreaks on the continent over the following four centuries before spreading to China, where it triggered the third plague pandemic in the late 19th century. The wave of plague that traveled to Asia later became the source population for modern-day epidemics around the globe. The bacterium's routes over time were revealed by genome analyses published in >Cell Host & Microbe.

    Single strain of plague bacteria sparked multiple historical and modern pandemics
    This is a photo of a mass burial site in Ellwangen, Germany 
    [Credit: Rainer Weiss]

    "Our study is the first to provide genetic support for plague's travel from Europe into Asia after the Black Death, and it establishes a link between the Black Death in the mid-14th century and modern plague," says first author Maria Spyrou of the Max Planck Institute for the Science of Human History.

    The plague bacterium, Yersinia pestis, is one of the deadliest pathogens in human history, sparking three major pandemics: the Plague of Justinian, which struck the Roman Empire during the 6th and 8th centuries; the second plague pandemic, which first erupted in Europe in the mid-14th-century Black Death and continued to strike the continent in recurrent outbreaks until the mid-18th century; and the third plague pandemic, which emerged in China during the late 19th century.

    Evidence based on ancient DNA samples and historical climate patterns has suggested that the recurrent outbreaks of the second pandemic were caused by multiple reintroductions of Yersinia pestis into Europe, most likely from Asia. Moreover, some scientists have recently suggested that the plague bacterium migrated from Europe to Asia after the Black Death, later giving rise to the third pandemic. But until now, genomic evidence to support this model was missing.

    To shed light on the origin and path of the second pandemic, Spyrou and co-senior study authors Alexander Herbig, Kirsten Bos, and Johannes Krause of the Max Planck Institute for the Science of Human History collected samples from plague-infected individuals buried in mass grave sites in Barcelona, Spain, and Ellwangen, Germany, as well as a single grave in Bolgar City, Russia.

    "The mass burials where our samples come from often represent events where hundreds of people died of plague during a single outbreak," Herbig says. "This gives us an impression about how significant the impact of this disease was during medieval times."

    The Bolgar City site was dated to the second half of the 14th century using coin artifacts known to have been minted after 1362. Radiocarbon dates from bone fragments and tooth roots were estimated at 1300-1420 for Barcelona, 1298-1388 for Bolgar City, and 1486-1627 for Ellwangen.

    Single strain of plague bacteria sparked multiple historical and modern pandemics
    This visual abstract depicts the findings of Spyrou et al., who sequenced historical Yersinia pestisgenomes 
    from victims of the Black Death and subsequent outbreaks in Europe. Their data suggest a connection between 
    the Black Death and the modern-day plague pandemic as well as the persistence of plague in Europe 
    between the 14th and 18th centuries [Credit: Spyrou et al./Cell Host & Microbe 2016]

    After analyzing DNA extracts from the teeth of 178 individuals, the researchers identified Y. pestis DNA in extracts from 32 individuals. Three individuals from Barcelona, Bolgar City, and Ellwangen had sufficient Y. pestis DNA for genome-level analysis. The researchers sequenced the genomes of these three ancient Y. pestis strains and compared them to 148 previously sequenced ancient and modern strains to reconstruct the Y. pestis phylogenetic tree.

    The phylogenetic analysis revealed no differences between their Black Death strain from Barcelona and previously genotyped strains from mid-14th-century London. The simultaneous presence of the same strain in both southern and northern Europe suggests that Y. pestis entered the continent in a single wave rather than through multiple pulses during the Black Death.

    These Black Death strains from London and Barcelona gave rise to a branch containing the Ellwangen strain and previously sequenced 18th-century strains from the Great Plague of Marseille in France. Moreover, all three newly reconstructed genomes and previously sequenced genomes from the second plague grouped together in the same branch on the phylogenetic tree. Taken together, these findings suggest that a single Y. pestis lineage was responsible for the Black Death and subsequent second pandemic outbreaks throughout Europe.

    Meanwhile, the Bolgar City strain shared similarities with the Black Death London strain as well as all modern strains. This finding supports the idea that one Y. pestis lineage traveled from Europe to Asia after the Black Death, later sparking the third pandemic and modern-day epidemics worldwide.

    "Our most significant finding revealed a link between the Black Death and modern plague," Krause says. "Though several plague lineages exist in China today, only the lineage that caused the Black Death several centuries earlier left Southeast Asia in the late 19th century pandemic and rapidly achieved a near worldwide distribution."

    In future studies, the researchers plan to gain additional insights into the entry and end points of the Black Death in Europe. They hope to expand their sample range and explore these regions further to better understand the route traveled by the disease, the evolutionary changes it acquired at different stages, and the toll it had on the human population.

    "We hope that our findings will highlight the importance for more extensive sampling and sequencing of both ancient and modern plague isolates around the world, and open up new research themes regarding the role played by Europe and West Asia in plague's evolution and ecology," Bos says.

    Source: Cell Press [June 09, 2016]

  • Fossils: New research reveals fires were more common 300 million years ago than today

    Fossils: New research reveals fires were more common 300 million years ago than today

    Scientists from the Department of Earth Sciences at Royal Holloway, University of London together with colleagues from the USA, Russia and China, have discovered that forest fires across the globe were more common between 300 and 250 million years ago than they are today. This is thought to be due to higher level of oxygen in the atmosphere at that time.

    New research reveals fires were more common 300 million years ago than today
    Forest fires across the globe were more common between 300 and 250 million years ago 
    than they are today, scientists have discovered. This is thought to be due to higher
     level of oxygen in the atmosphere at that time [Credit: NASA]

    The study which was published in the journal Frontiers in Plant Science, found that peats that were to become coal contained high levels of charcoal that could only be explained by the high levels of fire activity.

    The team used the data from charcoal in coal to propose that the development of fire systems through this interval was controlled predominantly by the elevated atmospheric oxygen concentration (p(O2)) that mass balance models predict prevailed. At higher levels of p(O2), increased fire activity would have rendered vegetation with high moisture contents more susceptible to ignition and would have facilitated continued combustion.

    In the study they examine the environmental and ecological factors that would have impacted fire activity and conclude that of these factors p(O2) played the largest role in promoting fires in Late Paleozoic peat-forming environments and, by inference, ecosystems generally, when compared with their prevalence in the modern world.

    Professor Andrew Scott, one of the lead authors, said: "High oxygen levels in the atmosphere at this time has been proposed for some time and may be why there were giant insects and arthropods at this time but our research indicates that there was a significant impact on the prevalence and scale of wildfires across the globe and this would have affected not only the ecology of the plants and animals but also their evolution."

    Professor Scott and his colleagues and students at Royal Holloway have pioneered the study of fire in Earth's deep past. Professor Scott, added: "We have been able to show that wildfire was an important element in Earth System many hundreds of millions of years before the arrival of humans."

    Source: University of Royal Holloway London [October 27, 2015]

  • Fossils: Stegosaurus bite strength revealed

    Fossils: Stegosaurus bite strength revealed

    The first detailed study of a Stegosaurus skull shows that the dinosaur had a stronger bite than suspected, enabling it to eat a wider range of plants than other plant-eating dinosaurs with similarly shaped skulls.

    Stegosaurus bite strength revealed
    1901 life restoration of S. ungulatus by Charles R. Knight with paired dorsal plates and eight tail spikes 
    [Credit: Public Domain]

    A team of scientists from Bristol, London, Manchester and University of Birmingham compared the skull of 'Sophie', the Natural History Museum's new Stegosaurus specimen, with two other dinosaurs, Plateosaurus and Erlikosaurus, which shared similar skull characteristics. Computer modelling at the University of Bristol showed that, despite looking very similar, the dinosaurs had different biting abilities.

    Although the three dinosaurs existed in different time periods and locations and had very differently shaped bodies, all three had similar-looking skulls: a large low snout, feeble peg-shaped teeth, and a scissor-like jaw action only capable of moving up and down. All three ate mainly or exclusively plants.

    Until now, it has been assumed that the dinosaurs probably had similar biting abilities and therefore ate similar types of plants. But the research reveals that it can be a trap to assume that because a set of dinosaurs shared a set of similar features, they all operated in the same way – function does not necessarily follow form.

    As Prof. Paul Barrett, Merit Researcher at The Natural History Museum explains: 'Our key finding really surprised us: we expected that many of these dinosaur herbivores would have skulls that worked in broadly similar ways. Instead we found that even though the skulls were fairly similar to each other in overall shape, the way they worked during biting was substantially different in each case.'

    Stegosaurus bite strength revealed
    Digital skull models of Erlikosaurus andrewsi, Stegosaurus stenops, and Plateosaurus engelhardti (from left to right) 
    [Credit: Stephan Lautenschlager]

    Stegosaurus lived around 150 million years ago and needed to eat a lot of plants to sustain its large size. As grasses did not exist then, it would have fed on plants such as ferns and horsetails. However the research indicates that it had a much higher bite force than anyone had suspected, enabling it to a wider range of plants than previously thought.

    As Barrett, leader of the research team, comments: 'Far from being feeble, as usually thought, Stegosaurus actually had a bite force within the range of living herbivorous mammals, such as sheep and cows.'

    This wider range of plants means that scientists need to reconsider how Stegosaurus fitted into its ecological niche. For example it may have had a role in spreading the seeds of cycads – woody ever green plants that were abundant in the time of the dinosaurs and whose seeds are contained in large cones.

    Dr David Button, from the University of Birmingham's School of Geography, Earth and Environmental Sciences, said: 'The extra information provided by computing modelling is invaluable. Although we can tell roughly what a dinosaur ate from the shape of its teeth and jaws, the differences highlighted by this study indicate that the biology and ecology of these animals is more complex than we previously thought. As we study the lives of dinosaurs in greater detail, they continue to surprise us.'

    Lead author Dr Stephan Lautenschlager, a post-doctoral researcher at the University of Bristol's School of Earth Sciences, employed digital models and computer simulations to analyse the dinosaurs' bites, using data from 3D scans of the skulls and lower jaws. He used engineering software to give the skulls the material properties that would match as closely as possible to the real thing, for example, using data on crocodile teeth to model those of the dinosaurs. By attaching muscles to the models, he was able to examine the forces that the jaws could produce and the subsequent stresses on the skulls.

    As computer power increases and software becomes more available, Lautenschlager thinks that we will see more modelling used in dinosaur research: 'Using computer modelling techniques, we were able to reconstruct muscle and bite forces very accurately for the different dinosaurs in our study. As a result, these methods give us new and detailed insights into dinosaur biology – something that would not have been several years ago.'

    The findings are published in >Nature Scientific Reports.

    Source: University of Birmingham [May 20, 2016]

  • Uganda: Conservationists 'on the fence' about barriers to protect wildlife in drylands

    Uganda: Conservationists 'on the fence' about barriers to protect wildlife in drylands

    To fence or not to fence? That is the question facing conservationists concerned with barriers that keep wildlife in and people out.

    Conservationists 'on the fence' about barriers to protect wildlife in drylands
    Conservationists 'on the fence' about barriers to protect wildlife such
     as cheetahs in drylands [Credit: Sarah Durant/ZSL]

    According to a new study by the Zoological Society of London (ZSL), Wildlife Conservation Society (WCS) and other groups, appearing in April 20 edition of the Journal of Applied Ecology, new policies must be developed before fences are erected -- particularly in dryland ecosystems where mobility is essential for both humans and wildlife.

    Some nations are considering fences as a means to protect remnant wildlife populations. For example, Uganda intends to fence all of its national parks to stem human-wildlife conflicts, while Rwanda recently erected a 120 km fence around Akagera National Park.

    But the study's authors caution that evidence is limited showing that fences are effective management tools, particularly in drylands.

    "Large-scale fencing can disrupt migration pathways and reduce access to key areas within drylands, such as seasonal foraging areas," said lead author Sarah Durant of ZSL. "This can lead to severe reductions in migratory wildlife populations and may prompt wider impacts on non-migratory species."

    The study says that policies are needed to evaluate whether fences should be erected and should be evaluated based on wildlife movement and distribution, climate change predictions, costs and benefits to local people, and other factors.

    Said co-author James Deutsch of WCS: "Fencing can initially appear to be an easy conservation solution. Yet, unless fencing strategies have local community support and financing for maintenance, there is a danger that they may generate more problems than they solve."

    The authors suggest that The United Nations Conventions on Migratory Species (CMS) and to Combat Desertification (UNCCD) are appropriate international agreements for leading to the development of policies and guidelines on fencing drylands.

    In response, the Scientific Council of CMS has proposed to form a Working Group on fencing problems and policies in dryland ecosystems.

    Said co-author Roseline Beudels-Jamar from the CMS Scientific Council: "CMS is concerned about the impact of human-wildlife conflict on both wildlife and on vulnerable livelihoods of marginalised people, and would like to better understand the impacts of fencing, or alternative methods, if used to mitigate such conflicts."

    Source: Wildlife Conservation Society [May 06, 2015]

  • Natural Heritage: Fate of turtles, tortoises affected more by habitat than temperature

    Natural Heritage: Fate of turtles, tortoises affected more by habitat than temperature

    Habitat degradation poses a greater risk to the survival of turtles and tortoises than rising global temperatures, according to new research.

    Fate of turtles, tortoises affected more by habitat than temperature
    Habitat degradation poses a greater risk to the survival of turtles and tortoises 
    than rising global temperatures [Credit: NHM, London]

    More than 60 per cent of the group are listed by the International Union for Conservation of Nature (IUCN) as vulnerable, endangered, or critically endangered, because they are being traded, collected for food and medicine and their habitats are being degraded. Understanding the additional impact of global warming and changes in rainfall patterns on their diversity and distributions is therefore paramount to their conservation.

    The team of researchers set out to test if long-term climate change poses a threat or opportunity to turtles and tortoises and how they might respond to increased global temperatures.

    As turtles live such long lives, it is impossible to conduct experiments to test for the impact of warming over several generations. The group used a novel combination of state of the art climate models and the deep time fossil record of turtles during warmer times.

    The Late Cretaceous fossil record (66-72 million years ago), dating from the time just before the demise of the dinosaurs, was investigated as a natural experiment to quantify differences between the ecology of living turtles and tortoises and those living in an earlier, warmer greenhouse world.

    The results of this study, funded by the Natural Environment Research Council (NERC) with support from The Royal Society, show that during periods with much warmer climates, turtles and tortoises were able to stand the heat in the warmer tropics -- as long as there was enough water to support those species living in rivers and lakes.

    Amy Waterson, PhD student and lead author from the University of Bristol, said: "Some groups of turtles have maintained similar niches over millions of years. They have withstood warmer climates in the past and their ability to adapt to the rate of environmental change happening today will be an important factor in their resilience to future climate change."

    Turtles and tortoises are highly sensitive to changes in temperature and rainfall, hence concerns about the impact of climate change on their distribution. Alongside overexploitation and habitat loss, climate change is a significant threat to their conservation status with growth, abundance and geographical ranges all predicted to decline under future climate change projections.

    In many species, temperature determines if the egg will develop into a male or female showing a direct impact of warming. As the group lives in ponds, rivers, on land and in the sea climate change can impact them via changes in temperature, rainfall, and major ocean currents.

    However, Professor Daniela Schmidt, an expert in palaeobiology from the University of Bristol's School of Earth Sciences, explained that the bigger question for the conservation of the group is not how warm it will be in the near future but how fast that warming will be: "The largest difference between the warm Cretaceous and today is that this earlier warming happened over tens of thousands of years, giving these animals a chance to adapt to these conditions, not in a century."

    Professor Paul Barrett from the Natural History Museum, London added: "Other conservation threats, such as humanmade habitat degradation and barriers to movement, might be as important in determining the fates of turtles in a warming world as the warming itself."

    The study is published in the >Royal Society of Proceedings B.

    Source: University of Bristol [September 22, 2016]

  • Breaking News: Natural selection, key to evolution, also can impede formation of new species

    Breaking News: Natural selection, key to evolution, also can impede formation of new species

    An intriguing study involving walking stick insects led by the University of Sheffield in England and the University of Colorado Boulder shows how natural selection, the engine of evolution, can also impede the formation of new species.

    Natural selection, key to evolution, also can impede formation of new species
    A new study involving CU-Boulder looks at the role of natural selection on
     three types of stick insect belonging to the species Timema cristinae. 
    The illustration shows how green, striped, and melanistic, or brown 
    varieties have evolved camouflaged appearances matching them 
    to certain areas on two separate species of shrub 
    [Credit: Rosa Marin]

    The team studied a plant-eating stick insect species from California called Timema cristinae known for its cryptic camouflage that allows it to hide from hungry birds, said CU-Boulder Assistant Professor Samuel Flaxman. T. cristinae comes in several different types -- one is green and blends in with the broad green leaves of a particular shrub species, while a second green variant sports a white, vertical stripe that helps disguise it on a different species of shrub with narrow, needle-like leaves.

    While Darwinian natural selection has begun pushing the two green forms of walking sticks down separate paths that could lead to the formation of two new species, the team found that a third melanistic, or brown variation of T. cristinae appears to be thwarting the process, said Flaxman. The brown version is known to successfully camouflage itself among the stems of both shrub species inhabited by its green brethren, he said.

    Using field investigations, laboratory genetics, modern genome sequencing and computer simulations, the team concluded the brown version of T. cristinae is shuttling enough genes between the green stick insects living on different shrubs to prevent strong divergent adaptation and speciation. The brown variant of the walking stick species also is favored by natural selection because it has a slight advantage in mate selection and a stronger resistance to fungal infections than its green counterparts.

    "This is one of the best demonstrations we know of regarding the counteractive effects of natural selection on speciation," said Flaxman of CU-Boulder's Department of Ecology and Evolutionary Biology, second author on the new study. "We show how the brown population essentially carries genes back and forth between the green populations, acting as a genetic bridge that causes a slowdown in divergence."

    A paper on the subject appeared in a recent issue of the journal Current Biology. Other study co-authors were from the University of Sheffield, Royal Holloway University of London, Utah State University, the University of Nevada, Reno and the University of Lausanne in Switzerland.

    "This movement of genes between environments slows down the genetic divergence of these stick insect populations, impeding the formation of new species," said Aaron Comeault, a former CU-Boulder graduate student and lead study author who conducted the research while at the University of Sheffield. Comeault is now a postdoctoral researcher at the University of North Carolina at Chapel Hill.

    The new results underscore how combining natural history and cutting-edge genetics can help researchers gain a better understanding of how evolution operates in nature. It also shows how natural selection can sometimes promote but other times hinder the formation of new species, according to the research team.

    Walking sticks are one of nature's oddest insect groups and range in size from the half-inch long T. cristinae to species in Borneo and Vietnam that are more than a foot long. Most walking sticks rely on plant mimicry to protect them from predators.

    Source: University of Colorado at Boulder [August 06, 2015]

  • Evolution: Size matters—the more DNA the better

    Evolution: Size matters—the more DNA the better

    A new study from researchers at Uppsala University shows that variation in genome size may be much more important than previously believed. It is clear that, at least sometimes, a large genome is a good genome.

    Size matters—the more DNA the better
    DNA double helix [Credit: WikiCommons]

    'Our study shows that females with larger genome lay more eggs and males with larger genome fertilize more eggs', says research leader Goran Arnqvist, Professor of Animal Ecology at Uppsala University.

    The amount of nuclear DNA per cell, or the size of the genome, varies by orders of magnitude across organisms. Our understanding of the evolutionary forces that are responsible for this variation is very limited. For unknown reasons, there are simple plants with a genome almost 50 times as large and grasshoppers with a genome 5 times as large as our own! In fact, the insects with the smallest and largest genomes differ by a factor of 200, yet they all look and act like typical insects.

    Biological explanations for these dramatic differences come in two flavours:

    The first suggests that variation in genome size is made up by "junk" DNA that has little bearing on organismal function and that random processes determine genome size.

    The second instead suggests that the amount of DNA matters and that natural selection shapes genome size. The study of seed beetles now present evidence suggesting that natural selection may be more important.

    The study is published in the scientific journal Proceedings of the Royal Society of London. Their results show that variation in genome size may be much more important than previously believed. It is clear that, at least sometimes, a large genome is a good genome.

    Source: Uppsala University [September 14, 2015]

  • Mongolia: First demonstration of sexual selection in dinosaurs identified

    Mongolia: First demonstration of sexual selection in dinosaurs identified

    Large ornamental structures in dinosaurs, such as horns and head crests are likely to have been used in sexual displays and to assert social dominance, according to a new analysis of Protoceratops carried out by scientists at Queen Mary University of London (QMUL). This is the first time scientists have linked the function of anatomy to sexual selection in dinosaurs.

    First demonstration of sexual selection in dinosaurs identified
    Life restoration of adult Protoceratops andrewsi in the foreground engaging 
    in speculative display postures. Non-mature animals can be seen 
    in the background [Credit: Rebecca Gelernter/QMUL]

    Protoceratops had a large bony frill that extended from the back of the head over the neck. Study of fossils aged from babies to adults revealed the adults to have disproportionately larger frills in relation to their size. The research, published in the journal >Palaeontologia Electronica, shows that the frill was absent in juveniles and suddenly increased in size as the animals reached maturity suggesting that its function is linked to sexual selection.

    This suggests the frill might have been used to attract suitable mates by showing off their best attributes or helping them assert the most dominant position in social interactions.

    First demonstration of sexual selection in dinosaurs identified
    Protoceratops ornamental structures were disproportionately large in mature animals, compared to younger specimens, 
    giving the scientists the first direct evidence linking the function of an anatomical feature to sexual selection 
    in dinosaurs [Credit: Richard T. Nowitz/Corbis]

    Dr David Hone, lecturer in Zoology from QMUL's School of Biological and Chemical Sciences, said: "Palaeontologists have long suspected that many of the strange features we see in dinosaurs were linked to sexual display and social dominance but this is very hard to show. The growth pattern we see in Protoceratops matches that seen for signalling structures in numerous different living species and forms a coherent pattern from very young animals right through to large adults."

    The researchers assessed the change in length and width of the frill over four life stages: hatchling babies, young animals, near-adults, and adults. Not only did the frill change in size but it also changed in shape, becoming proportionally wider as the dinosaur became older.

    First demonstration of sexual selection in dinosaurs identified
    Dr David Hone, a lecturer in zoology at Queen Mary University of London (QMUL), said the role of these elaborate 
    features in mating had long been suspected, but had been impossible to prove. Triceratops, a later beaked 
    dinosaur also had ornate facial features [Credit: Mark Stevenson/Stocktrek Images/Corbis]

    Dr Rob Knell, Reader in Evolutionary Ecology, also from QMUL's School of Biological and Chemical Sciences, said: "Biologists are increasingly realising that sexual selection is a massively important force in shaping biodiversity both now and in the past. Not only does sexual selection account for most of the stranger, prettier and more impressive features that we see in the animal kingdom, it also seems to play a part in determining how new species arise, and there is increasing evidence that it also has effects on extinction rates and on the ways by which animals are able to adapt to changing environments."

    The research formed part of current postgraduate student and QMUL graduate Dylan Wood's undergraduate thesis, which looked at sexual selection in extinct species.

    First demonstration of sexual selection in dinosaurs identified
    Protoceratops is a member of the ceratopisian group of beaked herbivorous dinosaurs, which includes the familiar and 
    much larger three-horned Triceratops[Credit: Kevin Schafer/Corbis]

    There are numerous, well-preserved specimens of ceratopisian dinosaurs of various sizes and ages making them a good groups to analyse. The researchers analysed 37 specimens of Protoceratops from fossils found in the Djadochta Formation in the Gobi desert and from previous published research. Protoceratops was a small-horned dinosaur that was similar in size to a sheep and was around 2m in total length from snout to tail tip.

    Source: Queen Mary, University of London [January 13, 2016]

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