Category: Environment

{Group mobbing behavior gives male birds the chance to impress potential mating partners.}

Dive bombing a much larger bird isn’t just a courageous act by often smaller bird species to keep predators at bay. It also gives male birds the chance to show off their physical qualities in order to impress females. This is according to a study in Springer’s journal Behavioral Ecology and Sociobiology on predator mobbing behavior of birds where potential prey approach and harass would-be predators such as owls. The study was led by Filipe Cunha of the University of Zurich in Switzerland and the Federal University of Ouro Preto in Brazil.

In birds, mobbing behavior includes calls, aerial swoops and even physical attacks. For a long time, researchers believed that this behavior mainly served as protection against predators, since most predators move away in response to mobbing.

As an added bonus, mobbing might give males the chance to advertise who has the best physical qualities, in an effort to impress potential mating partners. To investigate this further, Cunha and his fellow researchers studied what happened when replicas of two types of owls of similar size were presented to a bird community in south-eastern Brazil. The models were of a pygmy owl that regularly eats birds, and of a less threatening burrowing owl. The researchers measured the size of the mob that then assembled, the intensity by which individual members participated in the mock attacks, and whether things changed if females from the same species were present.

While 79 different bird species were seen to mob the models, data from only 19 sexually dimorphic species were included in the current study. In these species, males and females are easily distinguished from one another in the field.

These experiments showed that the mobbing was more intense when the less-threatening burrowing owl model was put out. This is in line with other findings that birds know whether there is a high or low risk associated with certain predators or behavior.

In most cases, the mobs were made up of males. The group size did not influence the intensity by which males participated in these anti-predatory activities. Males in the 19 species were, however, definitely more likely to up their game when more females from their own species were around.

Cunha explains, “Females may use these mobbing events to assess a male’s quality, for example their motor skills which allow them to escape from an attacking predator. This characteristic may provide clues about how well a male will be able to defend a nest or to forage.”

The findings highlight the importance of sexual selection and help to better understand the evolution of anti-predatory behavior. Moreover, they show that mobbing not only has a predator deterrence function.

“Recent studies showed that predator mobbing has other important social functions, such as to teach younger birds to distinguish friend from foe,” says Michael Griesser, co-author of the study.

Source:Science Daily

{Seagrass meadows — bountiful underwater gardens that nestle close to shore and are the most common coastal ecosystem on Earth — can reduce bacterial exposure for corals, other sea creatures and humans, according to new research published in Science Feb. 16.}

“The seagrass appear to combat bacteria, and this is the first research to assess whether that coastal ecosystem can alleviate disease associated with marine organisms,” said lead author Joleah Lamb of Cornell University’s Atkinson Center for a Sustainable Future, where she is a Nature Conservancy NatureNet fellow.

Senior author Drew Harvell, Cornell University professor of ecology and evolutionary biology and an Atkinson Center Fellow, had been running an international workshop and examining the health of underwater corals with colleagues near small islands at Spermonde Archipelago, Indonesia. But after a few days, the entire research team fell ill with dysentery, and one scientist contracted typhoid. “I experienced firsthand how threats to both human health and coral health were linked,” Harvell said.

Lamb returned with an international team armed to test the waters. On these small islands freshwater is sparse, surface soil is thin and just off shore the marine environment teems with solid waste, sewage and wastewater pollution. Generally, the islands — though filled with people — do not have septic systems.

The group used Enterococcus assays, the U.S. Environmental Protection Agency standard of health risk levels for wastewater pollution in recreational waters, to see whether seagrass meadows influenced bacterial levels. Water samples taken near the beaches exceeded exposure levels by a factor of 10. But, Lamb’s team found threefold lower levels of Enterococcus in seawater collected from within seagrass meadows.

“The genetic sequencing work pinpointed the kinds of bacteria — all in difficult, arduous conditions,” said Harvell. “It showed exactly what was in the water. The beautiful oceanside water looked blue-green, but truly it was filled with dangerous pollution — some really bad stuff in the water close to shore.”

While research is beginning to reveal the mechanisms driving bacterial-load reductions in these ecosystems, it is evident that an intact seagrass ecosystem — home to filter-feeders like bivalves, sponges, tunicates (marine invertebrates) — removes more bacteria from water.

As seagrass meadows and coral reefs are usually linked habitats, Lamb’s team examined more than 8,000 reef-building corals for disease. The researchers found lower levels — by twofold — of disease on reefs with adjacent seagrass beds than on reefs without nearby grasses. “Millions of people rely on healthy coral reefs for food, income and cultural value,” said Lamb.

Harvell, Lamb and their colleagues agree that these findings are key to conserving seagrass ecosystems. “Global loss of seagrass meadows is about 7 percent each year since 1990,” said Lamb. “Hopefully this research will provide a clear message about the benefits of seagrasses for human and marine health that will resonate globally.”

Regions around the world promote aquaculture to help feed populations, as diseases for many ocean-dwelling plants and animals increase, Harvell said, “Our goal is to stop measuring things dying and find solutions. Ecosystem services like seagrass meadow habitats are a solution to improve the health of people and the environment. Biodiversity is good for our health.”

Source:Science Daily

{New research suggests that a giant pterosaur — a toothless flying reptile with a 10 metre wingspan — may have been the dominant predator in ancient Romania.}

Palaeontologists examined the creature’s unusual gigantic neck vertebra and believe it was a formidable carnivore and major predator that terrorised dinosaurs and other prehistoric animals of Cretaceous-age Transylvania. It provides the first evidence of large predatory animals in the region at that time.

Dr Mark Witton, from the University of Portsmouth and Dr Darren Naish from University of Southampton, both in the UK, examined several fossilised remains of the creature, known as Hatzegopteryx, which belongs to the flying reptile group Azhdarchidae.

Usually this species’ tubular neck bones give them extremely long necks, over 2.5 metres in length in the largest species. However, the researchers suggest Hatzegopteryx had a considerably shorter and stronger neck, and with larger muscle masses. Other remains of Hatzegopteryx include a jaw joint indicative of a half-metre wide skull and reinforced limb bones. Dr Witton suggests that the proportions and structural reinforcement of all these elements are unlike those of any other azhdarchid species and would have made Hatzegopteryx a powerful and dominant predator.

He said: “The difference in structural properties between giant azhdarchid neck bones is remarkable — they’re in different biomechanical leagues, with Hatzegopteryx many times stronger than anything else on record. This, along with our calculations of neck length and muscle mass, suggests giant azhdarchids may have been radically different in appearance and behaviour.

“The large, reinforced skeleton and muscle power would have made it a formidable predator of other animals when stalking ancient prairies and woodlands. It may have even been capable of attacking animals too large or vigorous for other flying reptiles, even the other giants.”

Dr Witton said that Hatzegopteryx lived in a peculiar island ecosystem where many of the dinosaurs were dwarfed or belonged to relict lineages extinct in the rest of the Cretaceous world. “Ancient Transylvania was a strange place for a number of reasons, including the fact that we’ve yet to find evidence of large predatory animals that lived alongside Hatzegopteryx, such as giant carnivorous dinosaurs. This is despite centuries of sampling.”

The study thus potentially provides an answer to a mystery about life in Late Cretaceous Romania.

“Perhaps without large predators to challenge them, this island provided an opportunity for giant pterosaurs — already formidable animals — to become the dominant predators,” said Dr Witton.

“The finer details of ecology and lifestyle for Hatzegopteryx remain unknown because we’re still working from scraps of its skeleton, but the emerging picture of its lifestyle are fascinating. In some respects our unexpected findings highlight how little we actually know about these animals. We’ve had these scrappy remains for years, but we need to ask the right questions, and perform the right tests, to realise their significance. Future giant pterosaur research and discoveries.

Source:Science Daily

{Increasingly dangerous fire weather is forecast for Australia and the Mediterranean as the global footprint of extreme fires expands, according to the latest research.}

University of Tasmania Professor of Environmental Change Biology David Bowman led an international collaboration — including researchers from the University of Idaho and South Dakota State University — to compile a global satellite database of the intensity of 23 million landscape fires used to identify 478 of the most extreme wildfire events.

“Extreme fire events are a global and natural phenomenon, particularly in forested areas that have pronounced dry seasons,” Professor Bowman said.

“With the exception of land clearance, the research found that extremely intense fires are associated with anomalous weather — such as droughts, winds, or in desert regions, following particularly wet seasons.

“Of the top 478 events, we identified 144 economically and socially disastrous extreme fire events that were concentrated in regions where humans have built into flammable forested landscapes, such as areas surrounding cities in southern Australia and western North America.”

Using climate change model projections to investigate the likely consequences of climate change, the research found more extreme fires are predicted in the future for Australia’s east coast, including Brisbane, and the whole of the Mediterranean region — Portugal, Spain, France, Greece and Turkey.

“The projections suggest an increase in the days conducive to extreme wildfire events by 20 to 50 per cent in these disaster-prone landscapes, with sharper increases in the subtropical Southern Hemisphere, and the European Mediterranean Basin,” Professor Bowman said.

The research has been published in the scientific journal Nature Ecology and Evolution.

The research is released on the day the State remembers the impact of the 1967 bushfires in the city of Hobart and across the South, which claimed the lives of 62 people, left 900 injured and more than 7,000 homeless.

Source:Science Daily

{How old were the oldest dinosaurs? This question remains largely unanswered. The natural life span of these long-extinct giants is of interest to scientists, in combination with questions regarding how fast they could grow and how they could obtain sufficient nutrients from their habitat. Palaeontologists at the University of Bonn estimate by means of bone structures whether a particular dinosaur fossil is a young, adult or very old animal. The results have now been published in the journal Paleobiology.}

“Many animals show growth lines in their bones while they are growing — similar to annual rings in a tree trunk,” reports palaeontologist Jessica Mitchell from the Steinmann Institute of the University of Bonn. However, as bone ages, regular repair procedures are carried out to renew bone. These repair structures in the bone (osteons) are so small that they can only be detected with a microscope.

In adult dinosaurs, the bone is transformed such that the growth lines are completely destroyed. Instead, only the repair structures are visible in the bones, which eventually overlap each other. “We can see several generations of osteons in the bone of animals with advanced age,” says Jessica Mitchell. “Our research objective was to investigate whether these repair structures could be used as indicators of age.” The research team compared differently sized bones of 79 specimens of several long-necked dinosaurs, representing young to old individuals: the bones of an adolescent have a few repair structures, while bones of an older individual are completely rebuilt.

The researchers are able to roughly estimate whether the animals are young or adult in age. But is it possible to determine a higher age between two adult dinosaurs? This question can be answered by analysing the repair structures. For this, the researchers only need a small sample of the fossilized bone: a drill core is ground and polished until only a small, translucent plate remains. Under a light microscope, the bone plate can be examined and the structures of interest can be measured.

{{Bone reconstruction in dinosaurs is similar to humans}}

Despite the size difference, inside, the bones of aging dinosaurs are very similar to those of us humans: the repair processes in dinosaurs, humans and many vertebrate animals follow the same pattern. “This reconstruction process is continually taking place within us and ensures that we have a new skeleton more or less every ten years,” emphasizes the palaeontologist. In forensics and anthropology, bones are also examined to determine the age of humans. The bone structure analysis helped determine that “Ötzi” the 5,000-year-old ice man died roughly at the age of 45.

Although bones do not appear to be active organs, such as the heart or lungs, they are much more than just the solid structures inside our body. Bones contain blood vessels that supply nutrients and bone cells that signal to each other that a repair is necessary. The study showed that the number of osteon generations, which have gradually formed during the reconstruction of the bones, gives an important indication as to whether an animal is younger or older in a comparative study.

{{Great potential in extinct animals}}

“With this method an absolute value for age is not yet possible,” says Mitchell. Extending the study with more dinosaur bones could further improve the outcome. Another future approach is to compare the bone structures of dinosaurs with living vertebrate animals, the actual age of which can be known. This comparison might also allow for more specific ages for dinosaurs.

Source:Science Daily

{Analysis of tree rings reveals highly abnormal solar activity in the mid-Holocene.}

An international team led by researchers at Nagoya University, along with US and Swiss colleagues, has identified a new type of solar event and dated it to the year 5480 BC; they did this by measuring carbon-14 levels in tree rings, which reflect the effects of cosmic radiation on the atmosphere at the time. They have also proposed causes of this event, thereby extending knowledge of how the sun behaves.

When the activity of the sun changes, it has direct effects on the earth. For example, when the sun is relatively inactive, the amount of a type of carbon called carbon-14 increases in the earth’s atmosphere. Because carbon in the air is absorbed by trees, carbon-14 levels in tree rings actually reflect solar activity and unusual solar events in the past. The team took advantage of such a phenomenon by analyzing a specimen from a bristlecone pine tree, a species that can live for thousands of years, to look back deep into the history of the sun.

“We measured the 14C levels in the pine sample at three different laboratories in Japan, the US, and Switzerland, to ensure the reliability of our results,” A. J. Timothy Jull of the University of Arizona says. “We found a change in 14C that was more abrupt than any found previously, except for cosmic ray events in AD 775 and AD 994, and our use of annual data rather than data for each decade allowed us to pinpoint exactly when this occurred.”

The team attempted to develop an explanation for the anomalous solar activity data by comparing the features of the 14C change with those of other solar events known to have occurred over the last couple of millennia.

“Although this newly discovered event is more dramatic than others found to date, comparisons of the 14C data among them can help us to work out what happened to the sun at this time,” Fusa Miyake of Nagoya University says. She adds, “We think that a change in the magnetic activity of the sun along with a series of strong solar bursts, or a very weak sun, may have caused the unusual tree ring data.”

Although the poor understanding of the mechanisms behind unusual solar activity has hampered efforts to definitively explain the team’s findings, they hope that additional studies, such as telescopic findings of flares given off by other sun-like stars, could lead to an accurate explanation.

{For a plant, the evolutionary pathways to becoming a carnivore may be limited, researchers say.}

To the average plant-eating human, the thought of a plant turning the tables to feast on an animal might seem like a lurid novelty.

Now, science is showing just how remarkable these macabre traits really are.

A new study probes the origins of carnivory in several distantly related plants — including the Australian, Asian and American pitcher plants, which appear strikingly similar to the human (or insect) eye. Although each species developed carnivory independently, the research concludes that the biological machinery required for digesting insects evolved in a strikingly similar fashion in all three.

The findings hint that for a plant, the evolutionary routes to carnivory may be few and far between.

“It suggests that there are only limited pathways for becoming a carnivorous plant,” says University at Buffalo biologist Victor A. Albert. “These plants have a genetic tool kit, and they’re trying to come up with an answer to the problem of how to become carnivorous. And in the end, they all come up with the same solution.”

The research, “Genome of the pitcher plant Cephalotus reveals genetic changes associated with carnivory,” which will be published on Feb. 6, 2017 in Nature Ecology and Evolution. It was conducted by an international team led by Mitsuyasu Hasebe, PhD, of the National Institute for Basic Biology in Japan and SOKENDAI (The Graduate University for Advanced Studies) in Japan; Kenji Fukushima, PhD, of the same institutions and the University of Colorado School of Medicine; Shuaicheng Li, PhD, of BGI-Shenzhen in China; and Albert, PhD, a professor of biological sciences in UB’s College of Arts and Sciences.

How to become a pitcher plant: a narrow evolutionary road

Pitcher plants capture insects by luring them into a pitfall trap — a cupped leaf with a waxy, slippery interior that makes it difficult to climb out. A soup of digestive fluids sits at the bottom of this chamber and breaks down the flesh and exoskeletons of prey.

Australian, Asian and American pitcher plants possess these features despite having evolved independently to become carnivores, as Albert and colleagues discovered in a 1992 study published in the journal Science.

The new paper builds on this older work, conducting a deeper investigation into how unrelated pitcher plants came to share so much in common.

As it turns out, the path to carnivory was remarkably similar for the three species examined — Cephalotus follicularis (the Australian pitcher plant, related to starfruit), Nepenthes alata (an Asian pitcher plant related to buckweat) and Sarracenia purpurea (an American pitcher plant related to kiwifruit). A genetic analysis, which included sequencing the entire genome of Cephalotus, found strong evidence that during their evolution into carnivores, each of these plants co-opted many of the same ancient proteins to create enzymes for digesting prey.

Over time, in all three species, plant protein families that originally assisted in self-defense against disease and other stresses developed into the digestive enzymes we see today, genetic clues suggest. These enzymes include basic chitinase, which breaks down chitin — the major component of insects’ hard, exterior exoskeletons — and purple acid phosphatase, which enables plants to obtain phosphorus, a critical nutrient, from victims’ body parts.

Enzymes in a fourth carnivorous species, the sundew Drosera adelae, a relative of Nepenthes that is not a pitcher plant, also appeared to share this evolutionary road.

‘Constraints on the available routes’ to carnivory

The findings represent an example of convergent evolution, in which unrelated species evolve independently to acquire similar traits, say co-authors Hasebe and Fukushima.

“Such parallel development often points to a particularly valuable adaptation,” Hasebe says.

As Fukushima explains, “Carnivorous plants often live in nutrient-poor environments, so the ability to trap and digest animals can be indispensable given the dearth of other sources of nourishment.”

It’s striking that the plants studied took such a similar route to becoming predators, the co-authors say. Convergent evolution often works this way: For example, Albert and colleagues showed in a previous study that while coffee and chocolate plants developed caffeine independently, they co-opted closely related proteins to produce caffeine.

The new study’s results “imply constraints on the available routes to evolve plant carnivory,” the authors write in Nature Ecology and Evolution. This prospect is underscored by unusual commonalities between digestive enzymes in Cephalotus and Nepenthes plants.

During the course of evolution, building blocks of enzymes called amino acids are often swapped out and replaced by other amino acids. In C. follicularis and N. alata, basic chitinases and purple acid phosphatases share numerous identical or highly similar amino acid substitutions that don’t occur in non-carnivorous species, suggesting that these alterations may help these enzymes function in special, carnivorous ways.

Similarly, the enzyme RNase T2, which breaks down a material called RNA in insect cells to produce food for plants, had multiple evolutionarily convergent amino acid substitutions in C. follicularis and a common ancestor of N. alata and D. adelae.

{Nearly a decade after being logged, vegetation in forested areas severely burned by California’s Cone Fire in 2002 was relatively similar to areas untouched by logging equipment. The findings of a U.S. Forest Service study shed light on how vegetation responds to severe wildfire and whether further disturbances from logging affect regrowth.}

The study, “Response of understory vegetation to salvage logging following a high-severity wildfire,” reports a modest difference between logged and unlogged areas for some shrubs, but researchers with the agency’s Pacific Southwest Research Station conclude the diversity of plant species and their abundance, as a whole, differed little between logged and unlogged sites. Salvage logging refers to the practice of harvesting fire-killed trees (“salvage”) to extract economic value from them before the wood decays.

The differences observed within the shrub communities could stem from the plants’ reproduction cycle and timing of the logging operations.

“The three native shrub species that declined in abundance with logging (prostrate ceanothus, snowbrush ceanothus and greenleaf manzanita) have seeds triggered to germinate by heat or char from fire,” said Eric Knapp, a research ecologist with the Forest Service and study co-author. Logging occurred more than a year after the fire, which would have coincided with the seedling stage of the new shrubs, making them vulnerable to surface disturbances.

“It is possible that the effect on shrubs might have been avoided if logging had been done soon after the fire, prior to seeds germinating,” Knapp said.

{{Additional findings include:}}

Researchers did not find a difference in the abundance of native versus weedy non-native plants between logged and unlogged sites. A common concern in post-fire logging is that logging equipment may serve as a source or transport for unwanted plant species.

Researchers observed plant species which weren’t dependent on fire-stimulated germination to be less affected by post-fire logging. Many of these species emerge from deeply buried roots or bulbs, leading researchers to believe they were better protected from ground disturbances caused by logging machinery.

Researchers did observe, however, substantial changes in the plant community during the course of the six-year study. For example, the amount of weedy non-native plants across all research sites increased, suggesting that the plant community responded more strongly to environmental changes caused by high-intensity wildfire than disturbances from logging.

The relatively flat ground and rocky soil of the research sites within the Blacks Mountain Experimental Forest in California’s Lassen National Forest, where the Cone Fire burned, may have reduced negative effects associated with ground disturbance, leading researchers to caution applying their findings to areas where soil disturbance from logging is greater. However, the results do coincide with a growing body of evidence from other post-fire logging studies.

“Longer-term research is finding that understory vegetation might not be as substantially impacted by post-fire logging as originally feared,” said Martin Ritchie, Forest Service research forester and study co-author, “especially when care is taken to minimize soil impacts.”

Knowing that salvage logging doesn’t appear to significantly impact vegetation regrowth could allow researchers and land managers to instead focus attention on other aspects of post-fire logging that could benefit from further research.

“If future studies continue to not find strong longer-term salvage harvest effects on forest understory vegetation,” Knapp said, “the debates about pros and cons of post-fire management could then narrow to topics such as snag habitat and woody fuel levels that are unequivocally impacted by salvage harvest.”

{Shocking is one word Jill Pruetz uses to describe the behavior she witnessed after a chimp was killed at her research site in Fongoli, Senegal. The fact that chimps would kill a member of their own community is extremely rare — most aggression is between communities — but the abuse that followed was completely unexpected.}

“It was very difficult and quite gruesome to watch,” said Pruetz, a professor of anthropology at Iowa State University. “I couldn’t initially make sense of what was happening, and I didn’t expect them to be so aggressive with the body.”

Pruetz has witnessed many things since establishing her research site in 2001. She was the first to document chimps using tools to hunt prey. However, what she observed in 2013 was different. Pruetz and her research team documented the chimps’ behavior after discovering the body of Foudouko, a former leader of the Fongoli community, who was exiled from the group for five years. As Pruetz explains in the video above, the chimps — many of which Pruetz suspects killed Foudouko — abused and cannibalized his body for nearly four hours.

There is a lot of anecdotal information on how chimps grieve, but Pruetz says these chimps were not in mourning. The team’s reports and video, published in the International Journal of Primatology, build upon a 2014 study on lethal aggression. The younger adult male chimps were the most aggressive. Researchers noted that two of Foudouko’s former allies were the only ones that didn’t show any aggression. Pruetz says one of the two did yell at and hit the body, but it appeared to be an attempt to rouse Foudouko.

Few animals, other than humans, show such deadly aggression, and the field of primatology has been divided as to what causes this behavior among primates, Pruetz said. It is important to understand this deadly behavior because of the chimpanzee’s endangered status.

Pruetz has long thought that human-made environmental changes, which disrupt the chimp’s habitat, may contribute to the aggressive behavior researchers observed. She cannot say definitively if that was the case with Foudouko’s death. It’s likely that competition for a mate — there are more male than female chimps at Fongoli — and a power struggle with younger chimps were contributing factors.

The skewed gender balance at Fongoli may be linked to human factors. Pruetz says local residents have reported people hunting female chimps to get infants for the pet trade. Hunters capturing just one female chimp every few years would have a real impact on the community, because of their slow life history, she said.

Isolation and exile unique

The fact that Foudouko survived in isolation for several years is quite unusual. No one has ever recorded this happening for such a long period, Pruetz said. During the five years of his exile, Pruetz and her team observed Foudouko following the group from a distance, and privately interacting with some of his former allies, but these interactions were rare.

“It really struck us that Foudouko lived on the outskirts for so long,” Pruetz said. “Chimps are very social, so this type of isolation would be a huge stress, and it seemed Foudouko wanted to get back into the social group.”

Pruetz says Foudouko might have had a chance, if he had been more submissive. During the days before his death, researchers suspected he was in the area. Still, there was no indication or warning that the group would kill him, she said. As a leader, Foudouko was very dominant and feared by the other chimps. It’s possible the younger chimps were concerned he would try to regain a position of power, and decided to attack him, Pruetz said. The younger chimps outnumbered Foudouko and his allies, and they were in their physical prime, which gave them an advantage.

Even after the deadly attack, Pruetz says it was obvious the other chimps were still afraid of Foudouko. They showed signs of fear, especially when Foudouko’s body would jerk or move during the attacks. Once the chimps left the body, Pruetz and her team buried Foudouko. His bones will be exhumed for examination in the future.

Stacy Lindshield, an ISU lecturer in anthropology; Kelly Boyer Ontl, an ISU Ph.D. student; Elizabeth Cleaveland, a former ISU student now at the Ape Cognition and Conservation Initiative; Joshua Marshack, a lecturer at Colgate University; and Erin G. Wessling, a former ISU master’s student now at Max Planck Institute for Evolutionary Anthropology; all contributed to this study.