Unearthing the Environmental Impact of Cambodia’s Ancient City, Mahendraparvata

Angkor from the air

 

From the 9th to the mid-14th century, the region of Angkor in modern-day northern Cambodia was the capital of Khmer Empire and the largest preindustrial city in the world. Home to possibly more than three quarters of a million people, several different urban plans and reservoir systems, and impressive monuments like the temple of Angkor Wat (pictured from a bird’s-eye-view above), Angkor was the core of the Khmer Empire, which dominated Southeast Asia by the 11th century CE. Like many modern, booming cities, Angkor was fed by water sourced from another city.

Mahendraparvata, a hill-top site in the mountain range of Phnom Kulen, is significant as the birthplace of the Khmer Kingdom and as the seat of Angkor’s water supply. In 802 CE, Jayavarman II proclaimed himself the universal king of the Angkor region on the top of Mahendraparvata. Jayavarman’s ascension to power marked the unification of the Angkor region and the foundation of the Khmer Empire.

Figure1_PLOS_Pennyetal

 

Until recently, however, little was known about the urban settlement of Mahendraparvata; a dense forest canopy obscures a great deal of the area’s archaeological landscape. To determine the extent of land use around Mahendraparvata, the authors of a recent PLOS ONE paper examined soil core samples taken from one of the Phnom Kulen region’s reservoirs.

As Angkor’s source of water, Phnom Kulen’s archaeological landscape is littered with hydraulic structures, like dams, dykes, and reservoirs (points A, B, and E on the remote sensing digital image shown below), meant to store and direct Angkor’s water sources strategically. The researchers focused on an ancient reservoir upstream of the main river running north to south, now a swamp, to find evidence of intensive land use.

Remote sensing

 

Core samples taken from the sediment of this ancient reservoir, point F on the image above, provided the researchers with chronological layers of earth containing organic materials, like wood, pollens, and spores, which could be assessed using radiocarbon dating.

By analyzing the sediment cores, researchers found that the reservoir was likely in use for about 400 years. Although the age of the reservoir itself remains inconclusive, sediment samples suggest that the valley was flooded in the mid-to-late 8th century CE, around the time Jayavarman II unified the area.

The authors found that medium-to-coarse sand deposition in the sediment samples beginning in the mid-9th century points to the presence of continual soil erosion, either from the surrounding hills or from the dyke itself, likely caused by deforestation in the area. By analyzing samples from the late 11th century, the authors found that the last and largest episode of erosion occurred, a possible result of intensive land use.

The researchers suggest that deforestation, as evidenced by soil erosion, implies that “settlement on Mahendraparvata was not only spatially extensive but temporally enduring.” In other words, the estimated extent of deforestation by continual sand deposits from the mid-9th century to the late-11th century in core samples indicates that Mahendraparvata was home to a large and thriving urban network in need of resources.

However, an increase in pollen spores dated to the 11th century, followed by the establishment of swamp forests in the early to mid-12th century in the reservoir, reflects that, by this time, the reservoir had fallen out of use, perhaps linked to changes in water management throughout the broader area, and possible population decline nearby. According to mid-16th century samples, the swamp flora around this time appears to have developed into the swamp flora seen today in the ruins of Mahendraparvata.

For some 400 years, the Phnom Kulen mountains acted as the main source of water for the Angkor region. The change of water management practices in the Phnom Kulen region has implications for the water supply to Angkor itself. In sum, by examining core samples drawn from one of Phnom Kulen’s ancient reservoirs, authors were able to explore an archaeological landscape that is still largely hidden and a history still mainly obscured by time. The potential link between the rise and fall of urban life in the Angkor region and the use of reservoirs like the one used in this study helps to unearth a little bit more about the the Khmer Kingdom and the marked environmental impact of Mahendraparvata.

Citation: Penny D, Chevance J-B, Tang D, De Greef S (2014) The Environmental Impact of Cambodia’s Ancient City of Mahendraparvata (Phnom Kulen). PLoS ONE 9(1): e84252. doi:10.1371/journal.pone.0084252

Image 1: Angkor Wat by Mark McElroy

Image 2: journal.pone.0084252

Image 3: journal.pone.0084252

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Watch Where I’m Going: Predicting Pedestrian Flow

Pedestrian traffic flow

Pedestrian traffic flow

At last check, the population of the world was around 7.1 billion and counting.  As we all know, the sheer number of people on the planet presents a host of new challenges and exacerbates existing ones.  The overarching population problem may seem daunting, but there’s still plenty we can do to make a crowded, urbanized world livable.  A new study in PLOS ONE focuses on the specific issue of pedestrian traffic and how to accurately model the flow of people through their environment.

Researchers with Siemens and the Munich University of Applied Sciences examined video recordings of commuters walking through a major German train station on a weekday, during both the morning and evening peak commute times. Scientists analyzed the videos to determine individual pedestrians’ paths and walking speeds, and used the resulting data to set the parameters for a simulation of pedestrian traffic flow.  According to the authors, this kind of calibration of theoretical models using real-world data is largely missing from the most pedestrian flow models, which are under-validated and imprecise.

Footage from train station

Footage from train station

The authors utilized a cellular automaton model to form the basis of this simulation. Cellular automatons are models in which cells in a grid evolve and change values through steps based on specific rules. In this instance, the authors used a hexagonal grid and a few simple rules about pedestrian movement:

  • Pedestrians know and will follow the shortest path to their destination unless pedestrians or other obstacles are in the way.
  • Pedestrians will walk at their own individual preferred speeds, so long as the path is unobstructed.
  • Individuals need personal space, which acts like a repelling force to other pedestrians and objects.
  • Walking speeds decrease as crowds get denser.
  • Factors like age and fitness are all captured by setting a range of individual walking speeds.
Pedestrian traffic flow model

Pedestrian traffic flow model (Settlers of Catan Pedestrian Expansion?)

This model also borrowed from electrostatics by treating people like electrons. As the authors write:

“Pedestrians are attracted by positive charges, such as exits, and repelled by negative charges, such as other pedestrians or obstacles.”

Add to this model rules about when and where pedestrians appear, the starting points and destinations, and the relative volume of traffic from each starting point to different destinations, and you’ve got a basic model of pedestrian traffic.

Next, the authors calibrated this model by setting parameters using real-world, observational data from the train station videos:  where people at each starting point were going, distance kept from walls, the distribution of walking speeds, and so on.  To test their model and parameters, the authors validated it by running predictive simulations and comparing it to real-world scenarios. Based on the results, the authors suggest that this kind of model, which includes parameters based on real-world observation, more accurately represents pedestrian flow than other models of walkers that do not incorporate observational data.

The authors also changed multiple parameters to determine which ones had the largest impact on the simulation. The parameter that had the largest effect when altered was the source-target distribution (the destinations of people coming from specific starting points), so the authors note that this is critical to measure accurately and precisely.

The ability to precisely predict the flow of traffic has many clear applications, from the design of buildings and public spaces to the prediction and prevention of unsafe crowd densities during large events or emergencies.

Next research question: when it’s crowded, does pushing really not make it go faster?

Related papers:

Citation: Davidich M, Köster G (2013) Predicting Pedestrian Flow: A Methodology and a Proof of Concept Based on Real-Life Data. PLoS ONE 8(12): e83355. doi:10.1371/journal.pone.0083355

Images: All images come from the manuscript

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Rainforest Fungi Find Home in Sloth Hair

Bradypus_variegatusMost of us have seen a cute sloth video or two on the Internet. Their squished faces, long claws, and scruffy fur make these slow-moving mammals irresistible, but our furry friends aren’t just amusing Internet sensations. Like most inhabitants of the rainforest, little is known about the role sloths play in the rainforest ecosystem.

Three-toed sloths live most of their lives in the trees of Central and South American rainforests. Rainforests are some of the most biodiverse ecosystems in the world and home to a wide variety of organisms, some of which can be found in rather unusual places.

Due to their vast biodiversity, rainforests have been the source for a wide variety of new medicines, and researchers of this PLOS ONE study sought to uncover whether sloth hair may also contain potential new sources of drugs that could one day treat vector-borne diseases, cancer, or bacterial infections. Why look in sloth fur? It turns out that sloths carry a wide variety of micro- and macro-organisms in their fur, which consists of two layers: an inner layer of fine, soft hair close to the skin, and a long outer layer of coarse hair with “cracks” across it where microbes make their homes. The most well-known inhabitant of sloth fur is green algae. In some cases, the green algae makes the sloth actually appear green, providing a rainforest camouflage.

In the study, seventy-four separate fungi were obtained from the surface of coarse outer hair that were clipped from the lower back of nine living three-toed sloths in Soberanía National Park, Panama, and were cultivated and tested for bioactivity in the lab.

Researchers found a broad range of in vitro activities of the fungi against bugs that cause malaria and Chagas disease, as well as against a specific type of human breast cancer cells. In addition, 20 fungal extracts were active in vitro against at least one bacterial strain. The results may provide for the first time an indication of the biodiversity and bioactivity of microorganisms in sloth hair.

Since sloths are moving around in one of the most diverse ecosystems in the world, it’s possible that they may pick up “hitchhikers,” so the researchers can’t be sure how these fungi came to live on the sloth fur. They may even have a symbiotic relationship with the green algae. However the fungi ended up in the fur, the authors suggest their presence in the ecosystem provides support for the role biodiversity plays both in the rainforest and potentially our daily lives.

Citation: Higginbotham S, Wong WR, Linington RG, Spadafora C, Iturrado L, et al. (2014) Sloth Hair as a Novel Source of Fungi with Potent Anti-Parasitic, Anti-Cancer and Anti-Bacterial Bioactivity. PLoS ONE 9(1): e84549. doi:10.1371/journal.pone.0084549

Image: Bradypus variegates by Christian Mehlführer

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Resolution Inspiration: What Will You Work on in 2014?

Resolutions 2012 - Flickr - Lori Ann

Though we are well into January, there is still time to set resolutions for 2014. What would you like to accomplish in the next twelve months? For some resolution inspiration, here’s a selection of PLOS ONE research articles to get you started:

Restaurant Bwyty sign by Dave GoodmanLearn a Language

Whether for work or pleasure, learning a new language can be a rewarding experience. It can also take a lot of time. Fear not—according to research published last year, you may be able to learn new words in a foreign language while performing other tasks. The key to this method of vocabulary building is exposure. In the study, participants were given a letter and tasked with finding the letter in a written Welsh word. As they looked for the letter, one group informally heard the word and saw an image of what it represented. Afterward, when participants were asked to determine whether a Welsh word matched an image, those who were exposed to corresponding images and audio scored higher than their counterparts in the control group.

 

Sing Along with Me (10 365) by John Liu

Get Vocal

For those of you with musical aspirations, take a nod from this study on vocal synchronization and rhythm. In it the researchers found that when participants read aloud together in real time, their speech patterns synchronized more readily than participants who read aloud with the recording of their partner’s voice. Though the study was primarily concerned with spoken rhythms, the researchers propose that the social component of rhythm, and the shared goal of synchronization, may be pertinent to music too. Musical rhythm, they suggest, may stem from social interaction rather than sexual selection.

 

smile by jessicahtamDe-stress

Under pressure? According to the authors of this next PLOS ONE paper, those who experience chronic stress may suffer from impaired problem-solving skills. To combat the deleterious effects of stress, they suggest performing a “self-affirmation” exercise before tackling a problem. In the study, the researchers asked underperforming and self-reportedly stressed college students to rank a series of values, such as creativity and friends/family, according to order of personal importance. They were then asked to write about why the top value was most important to them, or why one of the bottom values might be important to others. After completing the exercise, the students were given a word association test. Stressed-out students that wrote about their top value and its personal importance outperformed their peers. Talk about the power of positive thinking!

Whether you want to pick up a new language, reduce your stress, or get out and sing more karaoke this year, we hope you are inspired to try out a few resolutions. For even more inspiration, check out other posts in the PLOS Blogs network: Alessandro Demaio’s Translational Global Health and Peter Janiszewski’s post on Obesity Panacea.

 

Citations:

Bisson M-J, van Heuven WJB, Conklin K, Tunney RJ (2013) Incidental Acquisition of Foreign Language Vocabulary through Brief Multi-Modal Exposure. PLoS ONE 8(4): e60912. doi:10.1371/journal.pone.0060912

Bowling DL, Herbst CT, Fitch WT (2013) Social Origins of Rhythm? Synchrony and Temporal Regularity in Human Vocalization. PLoS ONE 8(11): e80402. doi:10.1371/journal.pone.0080402

Creswell JD, Dutcher JM, Klein WMP, Harris PR, Levine JM (2013) Self-Affirmation Improves Problem-Solving under Stress. PLoS ONE 8(5): e62593. doi:10.1371/journal.pone.0062593

 

Image: Resolutions 2012 by Lori Ann

Restaurant Bwyty sign by Dave Goodman

Sing Along with Me (10/365) by John Liu

Smile by jessicatam

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A Year in Review: 2013 PLOS ONE Papers in the Media

 

6647478555_f408a731f9_oImage Credit: Yutaka Tsutano

 

Tired of year-end lists? We know you’ve got room for at least one more. 2013 was a great year for PLOS ONE media coverage: We had over 5,000 news stories on over 1450 published articles.

The PLOS ONE press team poured tirelessly over the list to whittle down the papers that stood out the most. In celebration of the New Year, we’d like to share some of these titles with you.

Zipping back to January 2013 and moving forward from there, here they are:

 

1. Flowers Flowering Faster (Sooner)

journal.pone.0053788.g002_smallImage credit: PLOS ONE article

In “Record-Breaking Early Flowering in the Eastern United States,” US researchers used 161 years of historical reports—initiated by Henry David Thoreau and Aldo Leopold in 1935—to track spring flowering times. They discovered that exceptionally warm spring temperatures in Massachusetts and Wisconsin in 2010 and 2012 may have resulted in the earliest recorded spring in the eastern United States. Furthermore, scientists indicate that these advanced flowering times could be predicted based on the historical data. This research received media attention from the The New York Times, National Geographic, and NPR.

 

2. Lend an Ear?

journal.pone.0056506.g002Image credit: PLOS ONE article

US scientists 3D-printed a human ear using collagen hydrogels (a network of polymers that form a gel with water) derived from cow cartilage in the lab. They shared their results in “High-Fidelity Tissue Engineering of Patient-Specific Auricles for Reconstruction of Pediatric Microtia and Other Auricular Deformities.” The authors suggest that this advancement may be a significant first step toward creating patient-specific tissue implants for those who require ear prosthesis. Popular Science, Discovery News, and NPR covered this research.

 

3. Central African Elephants in Big Trouble

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African forest elephant populations may have declined by an alarming 62% in the last decade, according to the study “Devastating Decline of Forest Elephants in Central Africa.” The authors suggest that this dramatic drop is largely due to continuing illegal ivory trade and inadequate efforts to put a stop to it. ScienceNow, TIME, Slate, Smithsonian, and many others covered this article.

 

4. Wrapped up in a Book

moriza-300x300Image credit: moriza

For everyone who enjoys a good page-turner, researchers in the study “The Expression of Emotions in 20th Century Books” indicate that recent British and American books have fewer emotional “mood” words than they did in the earlier half of the 20th century. What’s more, the study’s authors provide evidence that American authors express more emotion than British authors, and that newer American books use more words conveying fear than older ones. This research was covered by the The New York Times Arts Beat, Jezebel, our EveryONE blog, and Nature.

 

5. Gaming for All Ages

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In the article “A Randomized Controlled Trial of Cognitive Training Using a Visual Speed of Processing Intervention in Middle Aged and Older Adults,” researchers from multiple institutions in Iowa discovered that when middle-aged and older adults played video games, they scored better on cognitive function tests. The authors hope that these results might help us slow cognitive decline in older individuals. This paper was covered by the The Wall Street Journal, Nature, and The Telegraph.

 

6. Seafood Watch for Arctic Foxes?

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In another saddening story of declining wild animal populations, researchers studying the “Correlates between Feeding Ecology and Mercury Levels in Historical and Modern Arctic Foxes (Vulpes lagopus)” found that mercury levels in seafood may be the culprit. They emphasize that overall direct exposure to toxic materials may not be as important as the feeding ecology and opportunities of predators, like the arctic fox, that have a very marine-based diet, which may contain these toxic substances. This research received media attention from Wired UK, Scientific American, and The Guardian.

 

7. Cancer in Neandertals

journal.pone.0064539.g001Image credit: PLOS ONE article

At least one Neandertal 120,000 years ago had a benign bone tumor in a rib, according to researchers in the study “Fibrous Dysplasia in a 120,000+ Year Old Neandertal from Krapina, Croatia.” The authors note, however, that they cannot comment on any health effects or the overall health condition of the individual without further evidence. This article received media attention from sources including the BBC, The New York Times, ScienceNOW, and Gizmodo.

 

8. Who Needs Rows of Teeth When You’ve Got a Tail to Slap Sardines?

journal.pone.0067380.g004

Image credit: PLOS ONE article

Thresher Sharks Use Tail-Slaps as a Hunting Strategy” contains the first video evidence of long-tailed sharks tail-slapping to stun their sardine prey. The authors suggest that this method may be effective when hunting prey that swim in schools. A Scientific American podcast, National Geographic’s Phenomena blogs, and NBC News were some of the media outlets that covered this research.

 

9. Contagious Yawning in Dogs and Chimps

Video credit: PLOS ONE article

Yawning animals were the focus of more than one PLOS ONE article in 2013. In one study, “Familiarity Bias and Physiological Responses in Contagious Yawning by Dogs Support Link to Empathy,” Japanese researchers found that dogs yawn more often in response to their owners’ yawns rather than a stranger’s, and received media coverage from The Guardian, CBS News, and The Telegraph. The authors of another research article “Chimpanzees Show a Developmental Increase in Susceptibility to Contagious Yawning: A Test of the Effect of Ontogeny and Emotional Closeness on Yawn Contagion” showed that chimpanzees appear to develop a contagion for yawning as they get older, just as humans do, and this article received media attention from The New York Times Science Takes, Los Angeles Times, and Scientific American Blogs.

 

10. What, the Cat? Oh, He’s Harml…

1091487059_7d9e530e28_oImage credit: Denis Defreyne

Our favorite parasite Toxoplasma gondii strikes again. Mice are normally terrified of cats, and rightly so, but Berkeley researchers (including a PLOS founder Mike Eisen) in “Mice Infected with Low-Virulence Strains of Toxoplasma gondii Lose Their Innate Aversion to Cat Urine, Even after Extensive Parasite Clearance” show that mouse exposure to the parasite, carried in cat feces, may alter the mouse’s brain, causing the mouse to permanently lose its fear of cats. The story received coverage from several news outlets, including a CNN segment by Charlie Rose, and coverage by BBC, National Geographic Phenomena, and Nature.

 

11. Just in Time for the Movie: Jurassic Park is Fake

740px-Spider_in_amber_(1)Image credit: Wikipedia

Sorry in advance for the disheartening news: Jurassic Park will likely remain a work of fiction. In “Absence of Ancient DNA in Sub-Fossil Insect Inclusions Preserved in ‘Anthropocene’ Colombian Copal,” UK researchers were unable to find any evidence of ancient DNA in specimens of prehistoric insects fossilized in hardened tree sap. Conveniently, the article published right when the newest Jurassic Park film series was announced, and was covered by San Francisco Chronicle, The Telegraph, The Conversation, and others.

 

12. Not Now, Honey – The Pressure Just Dropped

journal.pone.0075004.g001Image credit: PLOS ONE article

Insects avoid sex when a drop in atmospheric pressure occurs, which usually precedes rain, according to researchers in the study “Weather Forecasting by Insects: Modified Sexual Behaviour in Response to Atmospheric Pressure Changes.” Injury from rain can be deadly for some insect species, so the authors suggest that the insects modified their behavior to enhance survival (good choice!). The article has received attention from nearly 20 news outlets, including Nature, Los Angeles Times, Scientific American, and ScienceNOW.

 

13. Dinos with Squishy Joints and Tiny Arms

 

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Image credit: PLOS ONE article

Dinosaurs were a popular item in PLOS ONE in 2013, especially with the launch of PLOS ONE’s New Sauropod Gigantism Collection. The most popular article was a simulation of how the largest dinosaur, the Argentinosaurus, might have walked in “March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs,” which was covered in Washington Post and The Guardian. Another group of researchers showed that squishy joints were a major factor in the massiveness of saurischian dinosaurs in “What Lies Beneath: Sub-Articular Long Bone Shape Scaling in Eutherian Mammals and Saurischian Dinosaurs Suggests Different Locomotor Adaptations for Gigantism.” The article was covered by Gizmodo, Inside Science, and Discovery. Finally, a new super-predator larger than T. rex lived 80 million years ago and was described in “Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans” and covered by BBC, Nature, and Discovery.

 

14. Huh?

journal.pone.0078273.g001Image credit: PLOS ONE article

The title of this next study says it all: “Is “Huh?” a Universal Word? Conversational Infrastructure and the Convergent Evolution of Linguistic Items.” The authors of this article suggest that it is, and that at least ten countries use a variation of this word to verbally express confusion. The article was featured in NPR, The New York Times, and LA Times.

 

15. Little Red Riding Hood: The Evolution of a Folk Tale

journal.pone.0078871.g004Image credit: PLOS ONE article

Little Red Riding Hood has very deep roots, as the authors of “The Phylogeny of Little Red Riding Hood” show in their article. It has made its way across China to Europe and back again, but where did it begin? The authors indicate that phylogenetic methods (like the branched chart above) may be a new way to analyze cultural relationships among folk tales and oral narratives. This article received coverage in ScienceNOW, National Geographic, and Nature.

Thank you to all of our Academic Editors, reviewers, and authors for making these articles a reality. Needless to say, PLOS ONE staff cannot wait to see what lies ahead in 2014!

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New Year, New Species

rock lizards.0080563.g006

Rock lizards, pigment producing fungus, eagle rays, ant garden parasites, and Antarctic sea anemones: new species are discovered all the time and there are likely still millions that we simply haven’t yet discovered or assessed. Species are identified by researchers using a range of criteria including DNA, appearance, and habitat. PLOS ONE typically publishes several new species articles every month, and below we are pleased to help introduce five that were discovered in 2013.

rock lizards.0080563.g005

Iranian Rock Lizards

Thought previously to consist of only three species, this group of lizards are now seven distinct species. They appear very similar to one another, making it difficult to tell which characteristics define different species, and which are just variations present in the same species. They also have a variety of habitats, from trees to rocky outcrops, and the genus is widespread. Iranian, German, and Portuguese scientists used genetic variation and habitat to help describe four new species of Iranian rock lizards, Darevskia caspica, D. Kamii, D. kopetdaghica, and D. schaekeli. These techniques, in addition to analysis of the the lizards’ physical features, as in the photo of the four new species’ heads at the top of this page, helped to identify them definitively.

 

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Pigment producing fungus

Found in soil, indoor environments, and fruit, Talaromyces atroroseus produces a red pigment that might be good for manufacturing purposes, especially in food. Some other species of this type of fungus produce red pigments, but they are not always as useful because they can also produce toxins. T. atroroseus produces a stable red pigment with no known toxins, making it safer for human use, according to the Dutch and Danish researchers who identified it.

 

 

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Naru eagle ray

Fish, like rays and sharks, are at high risk for extinction as a group, but as rare as they are, they can be plentiful enough in some locations to make them undesirable to locals. The discovery of the Naru eagle ray, Aetobatus narutobiei, splits a previously defined species, A. flagellum, that, due to its shellfish-eating habits, is considered a pest and culled in southern Japan. The discovery by Australian and Japanese scientists that this species is actually two species prompted the authors to encourage a reassessment of the conservation status of the rays.

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 0082265_Figure_S2

Fungal parasites in ant gardens

In the Brazilian rainforest of Minas Gerais, leafcutter ants cultivate fungus, their primary source of food, on harvested leaf clippings. But scientists from Brazil, United Kingdom, and The Netherlands have discovered that their food source is threatened by four newly identified mycoparasites, Escovopsis lentecrescens, E. microspora, E. moellieri, and Escovopsioides nivea. The parasites grow like weeds in the ants’ gardens, crowding out more desirable fungus used for food. Unfortunately for the ants, researchers expect there are many similar unidentified species yet to be discovered.

Escovopsis moelleri.0082265.g002

 

 

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Antarctic sea anemone

Living on the previously undocumented ecosystem of the underside of the Ross Ice Shelf in Antarctica, American researchers discovered the first species of sea anemone known to live in ice, Edwardsiella andrillae. Fields of anemone were discovered using a scientist-driven remote-controlled submersible. The anemone burrows and lives within the ice and dangles a tentacle into the water beneath, almost as if it is dipping a toe in the water to test the chilly temperature.

 

edwardsiella.0083476.g003 edwardsiella.0083476.g004

Look here to read more about new species.

 

Citations

Ahmadzadeh F, Flecks M, Carretero MA, Mozaffari O, Böhme W, et al. (2013) Cryptic Speciation Patterns in Iranian Rock Lizards Uncovered by Integrative Taxonomy. PLoS ONE 8(12): e80563. doi:10.1371/journal.pone.0080563

Frisvad JC, Yilmaz N, Thrane U, Rasmussen KB, Houbraken J, et al. (2013)Talaromyces atroroseus, a New Species Efficiently Producing Industrially Relevant Red Pigments. PLoS ONE 8(12): e84102. doi:10.1371/journal.pone.0084102

White WT, Furumitsu K, Yamaguchi A (2013) A New Species of Eagle RayAetobatus narutobiei from the Northwest Pacific: An Example of the Critical Role Taxonomy Plays in Fisheries and Ecological Sciences. PLoS ONE 8(12): e83785. doi:10.1371/journal.pone.0083785

Augustin JO, Groenewald JZ, Nascimento RJ, Mizubuti ESG, Barreto RW, et al. (2013) Yet More “Weeds” in the Garden: Fungal Novelties from Nests of Leaf-Cutting Ants. PLoS ONE 8(12): e82265. doi:10.1371/journal.pone.0082265

Daly M, Rack F, Zook R (2013) Edwardsiella andrillae, a New Species of Sea Anemone from Antarctic Ice. PLoS ONE 8(12): e83476. doi:10.1371/journal.pone.0083476

Figures are all from their respective articles.

 

 

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Thanking Our Peer Reviewers

In 2013 PLOS ONE published 31,500 articles, nearly 8,000 more than in 2012. In reaching this milestone, we would like to take a moment to recognize the hard work and dedication of our peer reviewers. Without their critical insight, support, and hard work, we couldn’t do what we do.

Last year we had over 78,000 unique reviewers from 172 countries. The top 20 institutions that contributed nearly 4,000 reviews are represented below (find the interactive version here).Reviewer word cloud

We would like to send a sincere thank you to all of our amazing peer reviewers. We are enormously grateful for your contributions and look forward to working with you in the New Year!

In addition to PLOS ONE’s record-breaking year, PLOS has just announced the publication of its 100,000th article, so we also  extend our thanks for the hard work of the peer reviewers contributing to all of the PLOS journals.

Best wishes in the New Year!

PLOS ONE Team

Image: http://tagul.com

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Underwater Compositions: Song Sharing Between Southern Ocean Humpback Whales

Whale Tail

Imagine a world where sight is limited by the extreme scattering of photons and smell is ineffective due to lethargic diffusion of molecules slowed by the density of water. In these conditions both sight and smell are limited. These conditions characterize, among other things, the ocean, where large sea mammals rely mostly on sound to communicate. The speed of sound is four times greater in water than in air at sea level. Male humpback whales have been observed communicating via ever-changing patterns of vocalization, which scientists have termed ‘song’. These whales compose their songs for the purposes of breeding, learning new songs as they come in contact with fellow crooners. Exactly how and when humpback whales learn these songs, however, remains a larger mystery.

To dive more deeply into the nebulous realms of humpback whale song sharing, researchers of a recent PLOS ONE study recorded instances of humpback whale song in the Southern Ocean.

Humpback whale song is identifiable because of its intricate pattern of structure. Songs are composed of multiple sound types, for example, as these researchers suggest, ‘ascending cry,’ ‘moan,’ and ‘purr’. When units come together to form a pattern, these units form a phrase. Phrases repeated become a theme, and themes sung in a particular order compose a song. Researchers recorded these compositions by deploying radio-linked sonobuoys, which transmit underwater sound, and then digitized the recordings.

Here is an example of song recorded off the coast of New Caledonia in 2010: 

Recordings, like the one above, reveal a possible link between three distinct breeding populations (marked D, E, and F on the map below) off the shores of eastern Australia and the island to the east of New Caledonia with a shared feeding ground in Antarctica (Area V).

journal.pone.0079422.g001 map

 

In early 2010, the researchers identified four songs near Antarctica that matched themes from eastern Australia in 2009. By July, 2010, all four songs were then also identified in the group from New Caledonia. The themes recognized in New Caledonia in 2010 were entirely different than the themes of 2009, suggesting a movement of new songs eastward from eastern Australia to New Caledonia.

Consequently, the shared feeding grounds in Antarctica used by both the eastern Australia and New Caledonia groups in early 2010 may be the point at which these populations’ songs diverged.

By capturing sonobuoy recordings near feeding grounds off the Balleny Islands, researchers recorded the first instances of humpback whale song in Area V of Antarctica.

Sonobuoy recording

 

In addition, the inclusion of feeding grounds into the dynamic pattern of humpback whale song sharing helps shed new light on overall patterns of song learning and transmission from one breeding group to another.

Sound recording off the Balleny Islands near Antarctica, however, is challenging, and the sample of whale singers from this area remains relatively small. Regardless, the song documented here suggests Antarctica (Area V) as an emerging location for future study, and highlights the importance of feeding grounds in the transmission of humpback whale song. Through a better understanding of how and where these dynamic compositions radiate across the Southern Ocean, we can begin to understand humpback whale population connectivity and one of the best examples of non-human, large-scale learning demonstrated throughout the Southern Hemisphere.

To listen to more of the whale song recorded by these researchers, check out the Supporting Information of their article. For more on humpback whales, check out these PLOS ONE papers.

Citation: Garland EC, Gedamke J, Rekdahl ML, Noad MJ, Garrigue C, et al. (2013) Humpback Whale Song on the Southern Ocean Feeding Grounds: Implications for Cultural Transmission. PLoS ONE 8(11): e79422. doi:10.1371/journal.pone.0079422

Images and Acoustic Files:

Image 1: Humpback Whale Tail by Natalie Tapson

Acoustic File: doi:10.1371/journal.pone.0079422

Image 2: doi:10.1371/journal.pone.0079422

Image 3: doi:10.1371/journal.pone.0079422

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Fish Beware – A New Species of Parasite is Discovered

Drawing of  Lethacotyle vera.

Drawing of Lethacotyle vera.

The world is full of creepy crawlers; some are harmless bugs while others are blood sucking parasites. Adding to the list of parasites this month is one identified in a recent PLOS ONE article, Lethacotyle vera n. sp, a new species of fish parasite, found in the South Pacific. Lethacotyle vera is part of the class Polyopisthocotylean monogenean, which are tiny (less than 1-cm long), parasitic flatworms that live on fish gills.

For any type of ectoparasite (parasites that live outside their host’s body) staying attached to their host is an important ability. One of the most notable features of Polyopisthocotylea is their multiple sucking clamps that allow them to keep their position on the fish. These clamps are found on the haptor, a body part developed specifically for attaching. Some parasites in this group can have hundreds of clamps as part of their haptor. In fact, Polyopisthocotylea literally translates to ‘many sucker-cups at the rear’. Thank goodness they only like fish!

However, there is one rare species discovered 60 years ago, Lethacotyle fijiensis, that appears to be clamp-less. The only available specimen for study is the one shown in the picture below.

The only available specimen of L. fijiensis

The only available specimen of L. fijiensis.

 

This close up below shows you what L. fijiensis actually looks like. The clamp-less haptor is the oblong protrusion on the very left end.

 

Close up of L. fijiensis

Because only four specimens of L. fijiensis have ever been found, and because having clamps is a major distinguishing feature of monogeneans, many researchers have assumed that L. fijiensis was incorrectly identified as clamp-less, and that these specimens probably lost their clamps through mishandling of the specimens by people.

In an attempt to verify the true nature of L. fijiensis, the authors went in search of additional specimens in the Pacific, where it was originally discovered. While they were unable to find any, they instead unearthed a hereto-undiscovered close relative, which they named Lethacotyle vera (vera is Latin for true, meaning that the genus Lethacotyle, is indeed real).

Haptor and Hooks

As it turns out L. vera is also a monogenean without clamps. The main physical difference between L. vera and L. fjiensis is the length in the male reproductive organ. The authors noted that L. vera has flaps on its haptor that are covered in many ridges, as well as hooks. A drawing of the haptor with its ridges and hooks can be seen in part F in the image to the right.

 

The authors sequenced the DNA from two of the eighteen specimens. The extracted DNA showed that the genetic information in L. vera is unique from all other known monogeneans. Then, in an effort to determine why L. fijiensis and L. vera don’t have the typical clamps of their family, they compared the ratio of clamp-to-body surface area in 120 different monogenean species. They found that members of the monogenean family to which L. vera and L. fijiensis belong, protomicrocotylids, had consistently the smallest clamp-to-body ratio. Additionally, many other species of polyopisthocotylean monogeneans had lateral flaps with ridges on their haptors.

From this observation, the authors concluded that in the family protomicrocotylids, their clamps are in fact slowly disappearing, and that in the specific case of L. fijiensis, the clamps have completely disappeared. The authors suggest that flaps can also hold onto the host, and that this process is assisted by the ridges and hooks along the flaps.

The discovery of a new species is always exciting, and as the case of L. vera shows us, can lead to insights about the larger family of related organisms. Read more about new species at PLOS ONE, such as this orchid or this Indonesian owl.

Citation: Justine J-L, Rahmouni C, Gey D, Schoelinck C, Hoberg EP (2013) The Monogenean Which Lost Its Clamps. PLoS ONE 8(11): e79155. doi:10.1371/journal.pone.0079155

Image 1 Credit: doi:10.1371/journal.pone.0079155.g001

Image 2 Credit: doi:10.1371/journal.pone.0079155.g002

Image 3 Credit: doi:10.1371/journal.pone.0079155.g007

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Awkward Silences: Technical Delays Can Diminish Feelings of Unity and Belonging

France_in_XXI_Century._Correspondance_cinema

Smooth social interaction is fundamental to a sense of togetherness. We’ve all experienced disrupted conversations—some caused by human awkwardness and others by breakdowns in technology. The content of our interactions does influence our connection to each other, but the form and process of communication also play a role.  Technical delays that occur below our conscious detection can still make us feel like we don’t quite click with the person we are trying to communicate with. The authors of a recently published PLOS ONE article, funded by a Google Research Award, investigated how delays introduced into technologically mediated conversations affected participants’ sense of solidarity with each other, defined as unity, belongingness, and shared reality.

For this research, conducted at University of Groningen, The Netherlands, participants in three sets of experiments sat in cubicles with headsets connected to computers (conditions that many of us with desk jobs can relate to) and were asked to talk about holidays for five minutes with an assigned partner. Some conversations were uninterrupted. Others were manipulated by introducing a one-second auditory delay. Some pairs knew about the delay and others did not. Afterward, the conversationalists completed a questionnaire about their sense of unity, belonging, understanding, and agreement with their partners.

journal.pone.0078363.s001

Researchers found that those participants whose conversations were interrupted expressed significantly diminished feelings of unity and belonging. Awareness of technical problems had no apparent effect on perceived solidarity.  Even acquaintances stated that they felt a disconnect, though to a lesser degree, than participants who did not know each other. Despite participants expressing that they felt less unity and belongingness with their partner even when they had the opportunity to attribute it to technical problems, technology did not get a free pass on the delayed signal. Those with an interrupted connection also expressed less satisfaction with the technology. Points may have been lost for both relationships and telecommunications.

In a world where our interactions are increasingly mediated by computers and mobile phones with less than perfect signals, the authors suggest that this research provides insight into how our daily interactions may be affected. The method of communication we choose may influence our personal and business relationships, especially among strangers. The authors also posit that technology meant to improve long distance communication by imitating face-to-face interaction may not measure up to expectations if it is not executed without interruptions or delays. Perhaps this is something to consider during your next awkward phone call or video conference— though your awareness of technology as a possible barrier ultimately may not make a difference in how you perceive the person on the other end of the line.

Citation: Koudenburg N, Postmes T, Gordijn EH (2013) Conversational Flow Promotes Solidarity. PLoS ONE 8(11): e78363. doi:10.1371/journal.pone.0078363

Images: First image by Villemard is in the public domain. Second image is Supplemetary Figure 1 from the article.

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