Category: Environment

{Hunting is a major threat to wildlife particularly in tropical regions, but a systematic large-scale estimate of hunting-induced declines of animal numbers was lacking so far. A study published in Science on April 14 fills this gap. An international team of ecologists and environmental scientists found that bird and mammal populations were reduced within 7 and 40 km of hunters’ access points, such as roads and settlements.}

Within these impact zones, mammal populations declined on average by 83% and bird populations by 58%. Additionally, the team found that commercial hunting had a higher impact than hunting for family food, and that hunting pressure was higher in areas with better accessibility to major towns where wild meat could be traded. The impact of hunting was found to be larger than the team expected. ‘Thanks to this study, we estimate that only 17 percent of the original mammal abundance and 42 percent of the birds remain in hunted areas.’

The researchers synthesised 176 studies to quantify hunting-induced declines of mammal and bird populations across the tropics of Central and South America, Africa and Asia. The study was led by Ana Benítez-López, who works at the department of Environmental Science at Radboud University in Nijmegen, the Netherlands. She cooperated with researchers from the Netherlands Environmental Assessment Agency (PBL), the universities of Wageningen and Utrecht in the Netherlands and a colleague from the School of Life Sciences, University of Sussex.

{{Higher hunting pressure around villages and roads}}

‘There are several drivers of animal decline in tropical landscapes: habitat destruction, overhunting, fragmentation etcetera. While deforestation and habitat loss can be monitored using remote sensing, hunting can only be tracked on the ground. We wanted to find a systematic and consistent way to estimate the impact of hunting across the tropics. As a starting point, we used the hypothesis that humans gather resources in a circle around their village and in the proximity of roads. As such, hunting pressure is higher in the proximity of villages and other access points. From there the densities of species increase up to a distance where no effect of hunting is observed. We called this species depletion distances which we quantified in our analysis. This allowed us to map hunting-induced declines across the tropics for the first time,’ Benítez-López explains.

{{Not only the big cuddly species
}}

The main novelty of the current study is that it combined the evidence across many local studies, thus for the first time providing an overarching picture of the magnitude of the impact across a large number of species. The study takes all animals into account — not only the big cuddly species, but birds and rodents as well. Benítez-López explains the difference in impact between birds and mammals: ‘Mammals are more sought after because they’re bigger and provide more food. They are worth a longer trip. The bigger the mammal, the further a hunter would walk to catch it.’ With increasing wild meat demand for rural and urban supply, hunters have harvested the larger species almost to extinction in the proximity of the villages and they must travel further distances to hunt. Besides, for commercially interesting species such as elephants and gorillas, hunting distances are much larger because the returns are higher.

{{Protected areas are no safe haven}}

Another interesting finding of this study is that mammal populations have also been reduced by hunting even within protected areas. ‘Strategies to sustainably manage wild meat hunting in both protected and unprotected tropical ecosystems are urgently needed to avoid further defaunation,’ she says. ‘This includes monitoring hunting activities by increasing anti-poaching patrols and controlling overexploitation via law enforcement’.

Source:Science Daily

{Paleobiologist’s latest discovery of Teleocrater rhadinus has overturned popular predictions}

For decades, scientists have wondered what the earliest dinosaur relatives looked like. Most assumed that they would look like miniature dinosaurs, be about the size of a chicken, and walk on two legs.

A Virginia Tech paleobiologist’s latest discovery of Teleocrater rhadinus, however, has overturned popular predictions. This carnivorous creature, unearthed in southern Tanzania, was approximately seven to 10 feet long, with a long neck and tail, and instead of walking on two legs, it walked on four crocodylian-like legs.

The finding, published in the journal Nature April 12, fills a critical gap in the fossil record. Teleocrater, living more than 245 million years ago during the Triassic Period, pre-dated dinosaurs. It shows up in the fossil record right after a large group of reptiles known as archosaurs split into a bird branch (leading to dinosaurs and eventually birds) and a crocodile branch (eventually leading to today’s alligators and crocodiles). Teleocrater and its kin are the earliest known members of the bird branch of the archosaurs.

“The discovery of such an important new species is a once-in-a-lifetime experience,” said Sterling Nesbitt, an assistant professor of geosciences in the College of Science.

He and Michelle Stocker, a co-author and also an assistant professor of geosciences in the College of Science, will give a free public talk with the fossils at 7 p.m. Thursday, April 13, 2017 at the Virginia Tech Museum of Geosciences on the second floor of Derring Hall.

Teleocrater fossils were first discovered in Tanzania in 1933 by paleontologist F. Rex Parrington, and the specimens were first studied by Alan J. Charig, former Curator of Fossil Reptiles, Amphibians and Birds at the Natural History Museum of London, in the 1950s.

Largely because the first specimen lacked crucial bones, such as the ankle bones, Charig could not determine whether Teleocrater was more closely related to crocodylians or to dinosaurs. Unfortunately, he died before he was able to complete his studies. The new specimens of Teleocrater, found in 2015, clear those questions up. The intact ankle bones and other parts of the skeleton helped scientists determine that the species is one of the oldest members of the archosaur tree and had a crocodylian look.

Nesbitt and co-authors chose to honor Charig’s original work by using the name he picked out for the animal, Teleocrater rhadinus, which means “slender complete basin” and refers to the animal’s lean build and closed hip socket.

“The discovery of Teleocrater fundamentally changes our ideas about the earliest history of dinosaur relatives,” said Nesbitt. “It also raises far more questions than it answers.”

“This research sheds light on the distribution and diversity of the ancestors of crocodiles, birds, and dinosaurs,” says Judy Skog, program director in the National Science Foundation’s Division of Earth Sciences, “and indicates that dinosaur origins should be re-examined now that we know more about the complex history and traits of these early ancestors.”

Teleocrater and other recently discovered dinosaur cousins show that these animals were widespread during the Triassic Period and lived in modern day Russia, India, and Brazil. Furthermore, these cousins existed and went extinct before dinosaurs even appeared in the fossil record.

The team’s next steps are to go back to southern Tanzania this May to find more remains and missing parts of the Teleocrater skeleton. They will also continue to clean the bones of Teleocrater and other animals from the dig site in the paleontology preparation lab in Derring Hall.

“It’s so exciting to solve puzzles like Teleocrater, where we can finally tease apart some of these tricky mixed assemblages of fossils and shed some light on broader anatomical and biogeographic trends in an iconic group of animals,” said Stocker.

Stocker and Nesbitt are both researchers with the Global Change Center at Virginia Tech. Other co-authors on the paper include: Richard J. Butler with the University of Birmingham; Martin D. Ezcurra with Museo Argentino de Ciencias Naturales; Paul M. Barrett with the Natural History Museum of London; Kenneth D. Angielczyk with the Field Museum of Natural History; Roger M. H. Smith with the University of the Witwatersrand and Iziko South African Museum; Christian A. Sidor with the University of Washington; Grzegorz Niedzwiedzki with Uppsala University; Andrey G. Sennikov with Borissiak Paleontological Institute and Kazan Federal Univeristy; and Charig.

The research was funded by the National Science Foundation, National Geographic Society, a Marie Curie Career Integration Grant, a National Geographic Society for Young Explorers grant, and the Russian Government Program of Competitive Growth of Kazan Federal University.

Source:Science Daily

{Researchers at the University of Alberta have demystified the way that polar bears search for their typical prey of ringed seals. The answer, it turns out, is simple: they follow their nose using the power of wind.}

Using satellite telemetry data collected from 123 adult polar bears in Canada’s Hudson Bay over 11 years, the researchers merged the movements of polar bears with wind patterns to explore how they looked for seals.

They hypothesized that when a bear smells prey, it moves up-wind to find it. But what is a bear to do before it smells anything at all?

“Predators search for prey using odours in the air, and their success depends on how they move relative to the wind,” explained Ron Togunov, University of Alberta alumnus and lead author on the study. “Travelling crosswind gives the bears a steady supply of new air streams and maximizes the area they can sense through smell.”

While this phenomenon had been suspected in many animals, it had not been quantified in mammals until now.

The best conditions for olfactory hunting, explained UAlberta professor Andrew Derocher, co-author and polar bear expert, takes place at night during the winter.

“Crosswind search was most frequent when winds were slow, when is is easier to localize the source of a certain smell, and at night when bears are relatively active and when vision is less effective, so bears rely more heavily on their sense of smell.”

The findings also raise questions about the implications of climate change.

“Wind speeds in the Arctic are projected to increase, potentially making olfaction more difficult,” explained Togunov. “It is important to understand how polar bear hunting success will be affected by these changing conditions.”

The study, “Windscapes and olfactory foraging in a large carnivore,” was published in Scientific Reports in April 2017.

Source:Science Daily

{Large predators are reoccupying former ranges, where they often rely on newly available human foods}

On landscapes around the world, environmental change is bringing people and large carnivores together — but the union is not without its problems. Human-wildlife conflict is on the rise as development continues unabated and apex predators begin to reoccupy their former ranges. Further complicating matters, many of these species are now reliant on anthropogenic, or human, foods, including livestock, livestock and other ungulate carcasses, and garbage.

Writing in BioScience, Thomas Newsome, of Deakin University and the University of Sydney, and his colleagues use gray wolves and other large predators as case studies to explore the effects of anthropogenic foods. They find numerous instances of species’ changing their social structures, movements, and behavior to acquire human-provisioned resources. For instance, in central Iran, gray wolves’ diets consist almost entirely of farmed chickens, domestic goats, and trash.

Other instances of these phenomena abound. In a similar case in Australia, dingoes gained access to anthropogenic foods from a waste facility. The result, according to the authors, was “decreased home-range areas and movements, larger group sizes, and altered dietary preferences to the extent that they filled a similar dietary niche to domestic dogs.” Moreover, wrote the authors, “the population of subsidized dingoes was a genetically distinct cluster,” which may portend future speciation events. Hybridization among similar predator species may also contribute to evolutionary divergence: “Anthropogenic resources in human-modified environments could increase the probability of non-aggressive contact” between species. According to the authors, “If extant wolves continue to increase their reliance on anthropogenic foods, we should expect to observe evidence of dietary niche differentiation and, over time, the development of genetic structure that could signal incipient speciation.”

Wolves’ use of anthropogenic food could have serious implications for wider conservation efforts, as well. In particular, Newsome and his colleagues raise concerns about whether wolf reintroduction and recolonisation programs will meet ecosystem-restoration goals in human-modified systems. Managers will need to consider “how broadly insights into the role played by wolves gleaned from protected areas such as Yellowstone can be applied in areas that have been greatly modified by humans,” say the authors.

Newsome and his colleagues call for further research — in particular, “studies showing the niche characteristics and population structure of wolves in areas where human influence is pervasive and heavy reliance on human foods has been documented.” Through such studies, they argue that “we might be able to ask whether heavy reliance of anthropogenic subsidies can act as a driver of evolutionary divergence and, potentially, provide the makings of a new dog.”

Source:Science Daily

{Researchers from the CNRS have discovered that mandrills use their sense of smell to avoid contamination by intestinal protozoans through contact with infected members of their group. Their work, published in Science Advances, shows that parasites shape the social behavior of these primates, leading them to develop a strategy of parasite avoidance through smell.}

The Mandrillus Project was launched in 2012, in southern Gabon, to study the ecology of the world’s sole population of wild mandrills habituated to human presence. Frequent grooming among these mandrills is undoubtedly a means of eliminating ectoparasites[1], but it also plays a major role in social cohesion — helping to soothe tensions after conflict, for example.

Mustering data from five years of field observation, the researchers demonstrated that mandrills harboring parasitic protozoans in their digestive tracts were less frequently groomed by their conspecifics than were healthy mandrills. Groomers especially avoided the perianal zone, which poses a high risk of contagion.

To pursue their investigations, the scientists conducted an experiment using antiparasitics. They captured infected mandrills, administered the antiparasitic drug, and returned the treated mandrills to their group. Now free of parasites, these primates once again enjoyed frequent grooming.

The research team next sought to determine whether olfactory communication could explain avoidance of infected conspecifics. First, chemical analyses showed that fecal odors differed between infected and healthy mandrills. Next the team conducted behavioral experiments under controlled conditions on 16 captive mandrills at a Gabonese research institute. The researchers collected fecal matter from mandrills at different times — while parasitized and when free of parasites — and rubbed it onto bamboo shoots. These shoots were then presented to captive mandrills. Curiously, the scientists noticed that the captive primates sniffed the bamboo set before them but actively avoided those shoots rubbed with infected feces. Such selective shunning elegantly demonstrates how olfactory communication may play a role in the behavioral and social avoidance of parasitic infection.

This research suggests that parasites, similarly to kinship ties and social rank, influence mandrill behavior by shaping social dynamics in their group. This study of the evolution of antiparasitic behavior is currently focused on the influence of parasites spread merely by contact. But it could expand its scope to include other mandrill pathogens with different routes of transmission, such as nematodes spread through contact with the environment or retroviruses spread from male to male by biting.

This research involves scientists from the Centre d’écologie fonctionnelle et évolutive (CNRS / University of Montpellier / Paul Valéry University / EPHE) and the Institut des sciences de l’évolution de Montpellier (CNRS / University of Montpellier / IRD / EPHE) participating in the Mandrillus Project — based at the INEE Station d’étude en écologie globale in Lékédi Park, Gabon — working in cooperation with the Evo-Eco-Paleo laboratory (CNRS / Lille University), the CIRMF Centre de primatologie in Franceville, Gabon, and the German Primate Center (DPZ) in Göttingen, Germany.

[1] An ectoparasite is an external parasite — that is, one that lives on the surface of a living being.

Source:Science Daily

{An American who fell in love with both the Great Barrier Reef and his wife via The University of Queensland has led a breakthrough discovery that could protect one of the Seven Natural Wonders. Husband-and-wife Professor Bernard Degnan and Associate Professor Sandie Degnan, believe they, along with research colleagues, can use the powers of attraction to decimate one of the reef’s fiercest enemies.}

In the journal Nature, the international research team has revealed crown-of-thorns starfish gather en masse due to a release of pheromones — a scent they’ve decoded so the prickly pests can be lured to their capture.

“For an already struggling Great Barrier Reef, and indeed any reefs across the Indo-Pacific region, these starfish pose an enormous threat due to the ability of a single female to produce up to 120 million offspring in one spawning season,” Professor Bernard Degnan said.

“They feast on the coral and leave it bleached white and vulnerable to destruction in heavy storms.

“Millions of dollars have been spent over many years on a variety of ways to capture crown-of-thorns starfish, whether it be via diver collection, injections or robotics.

“Now we’ve found the genes the starfish use to communicate, we can begin fabricating environmentally safe baits that trick them into gathering in one place, making it easier to remove reproductively-primed animals.”

The Degnans worked alongside a team of UQ researchers, and long-standing colleagues at the Australian Institute of Marine Science (AIMS), the Okinawa Institute of Science and Technology (OIST) and University of the Sunshine Coast (USC). The painstaking process of sequencing the of crown-of-thorns genome and its pheromones was completed 30 years after Professor Degnan moved from his hometown of New York to Brisbane to study as one of UQ’s first international exchange students.

A graduate in Marine Biology and Molecular Biology, Professor Degnan developed an early fascination with the biodiversity of Queensland’s Great Barrier Reef in his formative years, and while at UQ’s Heron Island Research Station he met his future wife.

“I guess there is a nice story there about the reef bringing us together and now we’re working hard to develop novel ways to understand and preserve it,” Professor Bernard Degnan said.

“But beyond us, there’s personal history with some of the other researchers, like Mike Hall at AIMS who is one of our oldest colleagues and who came up with the original genome concept.

“Nori Satoh at OIST could be considered the grandfather of marine genomics and has been a very supportive friend, as has Scott Cummins of USC, who was a former research fellow in my lab.”

“What I like most is that we’re finding a solution to a problem, not merely documenting it.”

Beyond the role their genomics breakthrough brings to controlling the crown-of-thorns, the Degnans believe it could have other environmental and economical benefits.

They say a similar approach could be used to combat invasions of sea snails and other marine pests throughout the world.

For fishermen and coastal communities, that’s a win on several fronts.

“I expect for local economies there could be some positive cash flow from the fishermen that collect and remove the crown-of-thorns.,” Professor Bernard Degnan said.

“Furthermore, as the reef becomes healthier, the benefits to a raft of industries from tourism to fisheries quickly follow.”

Source:Science Daily

{New research led by the University of Southampton suggests that, over the next 100 to 200 years, carbon dioxide concentrations in Earth’s atmosphere will head towards values not seen since the Triassic period, 200 million years ago. Furthermore, by the 23rd century, the climate could reach a warmth not seen in 420 million years.}

The study, published in Nature Communications, compiled over 1200 estimates of ancient atmospheric carbon dioxide (CO2) concentrations to produce a continuous record dating back nearly half a billion years. It concludes that if humanity burns all available fossil fuels in the future, the levels of CO2 contained in the atmosphere may have no geologically-preserved equivalent during this 420 million year period.

The researchers examined published data on fossilised plants, the isotopic composition of carbon in soils and the oceans, and the boron isotopic composition of fossil shells. Gavin Foster, lead author and Professor of Isotope Geochemistry at the University of Southampton, explains: “We cannot directly measure CO2 concentrations from millions of years ago. Instead we rely on indirect ‘proxies’ in the rock record. In this study, we compiled all the available published data from several different types of proxy to produce a continuous record of ancient CO2 levels.”

This wealth of data shows that CO2 concentrations have naturally fluctuated on multi-million year timescales over this period, from around 200-400 parts per million (ppm) during cold ‘icehouse’ periods to up to 3000 ppm during intervening warm ‘greenhouse’ periods. Although evidence tells us our climate has fluctuated greatly in the past (with Earth currently in a colder period), it also shows the current speed of climate change is highly unusual.

Carbon dioxide is a potent greenhouse gas and in the last 150 years humanity’s fossil fuel use has increased its atmospheric concentration from 280 ppm in the pre-industrialisation era to nearly 405 ppm in 2016. However, it’s not just CO2 that determines the climate of our planet, ultimately it is both the strength of the greenhouse effect and the amount of incoming sunlight that is important. Changes in either parameter are able to force climate change.

“Due to nuclear reactions in stars, like our sun, over time they become brighter,” adds co-author Dan Lunt, Professor of Climate Science at the University of Bristol. “This means that, although carbon dioxide concentrations were high hundreds of millions of years ago, the net warming effect of CO2 and sunlight was less. Our new CO2 compilation appears on average to have gradually declined over time by about 3-4 ppm per million years. This may not sound like much, but it is actually just about enough to cancel out the warming effect caused by the sun brightening through time, so in the long-term it appears the net effect of both was pretty much constant on average.”

This interplay between carbon dioxide and the sun’s brightness has fascinating implications for the history of life on Earth. Co-author Professor Dana Royer, from Wesleyan University in the US, explains: “Up until now it’s been a bit of a puzzle as to why, despite the sun’s output having increased slowly over time, scant evidence exists for any similar long-term warming of the climate. Our finding of little change in the net climate forcing offers an explanation for why Earth’s climate has remained relatively stable, and within the bounds suitable for life for all this time.”

This long-term view also offers a valuable perspective on future climate change. It is well recognised that the climate today is changing at rates well above the geological norm. If humanity fails to tackle rising CO2 and burns all the readily available fossil fuel, by AD 2250 CO2 will be at around 2000 ppm — levels not seen since 200 million years ago.

Professor Foster adds: “However, because the Sun was dimmer back then, the net climate forcing 200 million years ago was lower than we would experience in such a high CO2 future. So not only will the resultant climate change be faster than anything Earth has seen for millions of years, the climate that will exist is likely to have no natural counterpart, as far as we can tell, in at least the last 420 million years.”

This collaborative study involves the University of Southampton (UK), University of Bristol (UK), and Wesleyan University (US) and is an output from ‘Descent into the Ice House’, one of the four research projects under the umbrella programme ‘The Long-term Co-Evolution of Life and the Planet’ funded the by the National Environment Research Council (NERC).

Source:Science Daily

{According to the latest research results of a German-Mexican team of geoscientists, the gradual decline of the dinosaurs and pterosaurs presumably came before the impact of the Chicxulub asteroid and the global mass extinction at the end of the Cretaceous Period. Studies under the direction of Prof. Dr Wolfgang Stinnesbeck of Heidelberg University and Prof. Dr Eberhard Frey of the State Museum of Natural History Karlsruhe also indicate that bird species spread and diversified at the same time the dinosaurs disappeared. Their results were published in the journal Geological Society of America Bulletin.}

While conducting paleontological research in northeastern Mexico, the scientists came upon sedimentary rock deposited toward the end of the Cretaceous Period that evidenced an enormous diversity of fossils, including the tracks of birds, dinosaurs and pterosaurs. “Most of the imprints come from at least five different species of birds; dinosaur tracks, however, are rare. Only a single footprint comes from a predatory dinosaur,” explains Prof. Stinnesbeck. The finds therefore indicate a gradual decline of the dinosaurs with a simultaneous increase in the diversity of birds even before the end of the Cretaceous Period. “Until now, it was generally assumed that the dinosaurs died out first and bird species diversified afterward,” states the researcher. “Our data, however, substantiate the theory that birds ascended before dinosaurs became extinct.”

Fossil analysis also showed that the decline of the dinosaurs occurred gradually, with probably only a few species surviving until the end of the Cretaceous Period. The extinction of the dinosaurs is therefore not — as science frequently assumes — due to the impact of the Chicxulub asteroid that struck Earth more than 65 million years ago.

“For most of the dinosaurs and pterosaurs, this strike no longer had any effect,” explains Prof. Stinnesbeck. Even the group of cephalopods, the so-called ammonites, was not annihilated by the asteroid strike at the end of the Cretaceous Period.

According to Prof. Stinnesbeck, fossil finds of the Sphenodiscus pleurisepta ammonite show their successive decline beyond the Cretaceous Period. “The effects of the Chicxulub impact were therefore not the cause of a global mass extinction, which probably came about considerably less catastrophically than previously assumed,” states the Heidelberg researcher.

Source:Science Daily