Forest elephants and whitetip sharks: PLOS ONE papers at CITES

Human activities and consumption pose constant threats to the environment and to wildlife but the scale of these threats can be hard to quantify. Accurate research to assess the status of threatened species is an essential first step to changing policies and human behavior that can ensure the survival of these species and habitats. The Convention on International Trade in Endangered Species or Wild Fauna and Flora (CITES) was organized to limit exploitation of international trade of wild animals and plants. Their latest meeting is currently underway in Bangkok, Thailand and two PLOS ONE papers provided evidence to support the enhanced protection of two threatened species – African forest elephants and oceanic whitetip sharks. These species were highlighted as facing intensified pressures that threaten their existence, calling for heightened regulations and  better enforcement of these regulations to prevent their extinction.

One of these recently published papers provided data on declining populations of African forest elephants. By surveying the forests of five East African countries primarily by foot, researchers were able to estimate that African forest elephant populations have declined by a devastating 62% between 2002 and 2011. The drivers of this decline are complex but hinge on a renewed international demand for ivory, especially sought after among China’s growing middle class. The study was covered by NPR, the New York Times and TIME magazine.

Another study tracked the movements of the severely threatened oceanic whitetip shark. Protecting sharks from overfishing poses a complex challenge as demand for shark fin and other products rises. To shed some light on just how far this species travels, researchers tagged 11 oceanic whitetip sharks and tracked their movements over 1,563 days. The tagged sharks spent the majority of their time in the protected waters of the Bahamas Exclusive Economic Zone (EEZ), where longlining and commercial trade of sharks is illegal. But the sharks ventured up to 1200 miles outside of this protected zone the rest of the time(see Figure 2 on the right). The tendency of these sharks to roam far and wide into these unprotected waters demonstrates the need for international cooperation if the species are to be protected. The study was covered by the BBC, NBC and Scientific American.

Continued research to quantify the threat facing these species and others is necessary to bolster support for regulations to be enacted and enforced internationally by bodies like CITES. Be sure to check out PLOS ONE for more research on conservation efforts for sharks and the plight of elephants.


Citations: Maisels F, Strindberg S, Blake S, Wittemyer G, Hart J, et al. (2013) Devastating Decline of Forest Elephants in Central Africa. PLoS ONE 8(3): e59469. doi:10.1371/journal.pone.0059469

Howey-Jordan LA, Brooks EJ, Abercrombie DL, Jordan LKB, Brooks A, et al. (2013) Complex Movements, Philopatry and Expanded Depth Range of a Severely Threatened Pelagic Shark, the Oceanic Whitetip (Carcharhinus longimanus) in the Western North Atlantic. PLoS ONE 8(2): e56588. doi:10.1371/journal.pone.0056588

Images: Shark photo credit: Lance Jordan, Microwave Telemetry, Inc.

Elephant photo copyright: Fiona Maisels of Wildlife Conservation Society.

Walk like a Camel (or a Giraffe)

It can be overwhelming to think of  the immense array of special shoes, insoles and orthotics available to relieve any manner of symptoms related to joint impact or stress. We have an entire industry designed to help the human species run and walk without injuries. Then consider the feet and joints of a more massive animal like the elephant or the giraffe, with no such industry to relieve their aches and pains.

A team of researchers studied how the feet and limbs of these animals handle the force of their weight as it hits the ground when they walk or run by analyzing a menagerie of videos.

Their results were published in PLOS ONE last week.

When you watch the plates shudder from the impact of the giraffe walking over the force platforms in the video below,  it seems a wonder that such small hooves manage to support such a massive animal without frequent injury. In view of how important these beasts of burden are for global welfare, understanding the dynamics of their foot design, locomotor behavior and impact forces is critical to ensuring their well-being. The study included elephants, pigs and alpacas as well as several other animals and found that the impact on the animals’ feet was proportional to their body size. But other aspects of the force of impact were distributed differently across their limbs to improve biomechanics and reduce injury. In previous research published in PLOS ONE, Dr. Hutchinson has analyzed locomotion in relation to limb and body dimensions in dinosaurs and cats.

Image Credit: 1 camel, 2 shadows by Sylvain Bourdos on Flickr

Citation: Warner SE, Pickering P, Panagiotopoulou O, Pfau T, Ren L, et al. (2013) Size-Related Changes in Foot Impact Mechanics in Hoofed Mammals. PLoS ONE 8(1): e54784. doi:10.1371/journal.pone.0054784

Citation: Hutchinson JR, Bates KT, Molnar J, Allen V, Makovicky PJ (2011) A Computational Analysis of Limb and Body Dimensions in Tyrannosaurus rex with Implications for Locomotion, Ontogeny, and Growth. PLoS ONE 6(10): e26037. doi:10.1371/journal.pone.0026037

Citation: Zhang KY, Wiktorowicz-Conroy A, Hutchinson JR, Doube M, Klosowski M, et al. (2012) 3D Morphometric and Posture Study of Felid Scapulae Using Statistical Shape Modelling. PLoS ONE 7(4): e34619. doi:10.1371/journal.pone.0034619

Targeting Drug Resistant Tumors

The vibrant colors in the image above show the levels of oxygen saturation in a breast tumor; note the prevalence of shades of dark and light blue, indicating very low oxygen saturation. These tumors are typically very difficult to treat with existing chemotherapy but new research published last week uses sickle cells to target and destroy these types of tumors.

The abnormal type of hemoglobin that causes sickle cell anemia alters the shape of red blood cells from circles to crescents (or sickles) making them less efficient at delivering oxygen to the body’s tissues. When there are low levels of oxygen in the environment, such as at high altitudes, these sickle cells clump together and rupture, damaging the blood vessels and surrounding cells. Honing in on this, researchers from the Jenomic Research Institute and Duke University were able to use this genetic mutation as a way to target tumors and promote a potent tumor-killing response.  Dr. Terman and his team found that they were able to quickly block blood supply to solid tumors with an injection of sickled blood cells along with a molecule that can release large amounts of oxygen. This is demonstrated in the first half of the video below which shows how an infusion of sickled blood cells slows and blocks the blood flow in hypoxic tumors, while the second half shows no noticeable slowing or blockage of blood vessels after infusion of normal cells. The sickled cells then clump together within the tumor blood vessels and when they rupture, the oxygen-releasing molecule kills many of the tumor cells and blood vessels.

This work offers an exciting new avenue for targeting and treating drug-resistant tumors and the video provides a fascinating window into the sickle cells in action.

Citation: Terman DS, Viglianti BL, Zennadi R, Fels D, Boruta RJ, et al. (2013) Sickle Erythrocytes Target Cytotoxics to Hypoxic Tumor Microvessels and Potentiate a Tumoricidal Response. PLoS ONE 8(1): e52543. doi:10.1371/journal.pone.0052543

PLOS ONE Papers of 2012

As we start off the New Year, we wanted to take a quick moment and highlight a few noteworthy papers published in 2012. Of the 23,468 papers published last year, five are already in the top 12 most viewed PLOS papers to date. Although they may not have gotten the press coverage of those listed in our 2012 Media Round-Up, Article Level Metrics reveal they’ve certainly received a lot of attention.

Published just over three months ago, a study showing that withdrawal symptoms of marijuana can be similar to those of tobacco is the third most highly viewed article published by any PLOS journal. With 227,928 total article views since publication on September 26, 2012 it’s only a few thousand views short of the top two articles published in 2008 and 2009. Other highly viewed ONE articles from 2012 include a study of genetic alterations in a line of flies reared in the dark (197,150 views since publication in March), the ecosystem implications of an invasive species (174,742 total article views, published September), an experiment depicted in Figure 3 to the right in immersive virtual reality between rats and humans (139,683 total article views, published in October), and a comparison of Westerners energetics with those of a hunter-gatherer society (102,167 total article views, published in July).

2012 also brought several papers describing new species, one of which was recognized as the “Best new species that was hiding in plain sight” by Jason G. Goldman of Scientific American. Other papers of note questioned beliefs about the limitations of alternative agriculture and challenged trusted measurements such as the Body Mass Index, commonly used to determine obesity rates.

Several more papers could even help support or inspire your New Year’s Resolutions. Whether it is to spend more time outdoors, watch what you eat, lose weight or conquer your fears, ONE has published research to help motivate those resolutions.

2012 was a year of growth and innovation for PLOS ONE, here’s looking forward to another great year!

Worth a Thousand Words: On Elephants, Literally

Ever wonder what purpose the sparse, coarse hairs covering an elephant’s skin serve? Authors from Princeton University wondered the same and recently published their findings in the paper “What Is the Use of Elephant Hair?” Body hair is typically thought of as an evolutionary advantage functioning mainly for insulation. Given that elephants typically inhabit warm climates and have a great need for heat loss due to their high body-volume to skin-surface ratio, insulation seems an unlikely explanation. We’ve all observed elephants using a variety of behavioral mechanisms to cool themselves down, (flapping their ears, bathing in dust, or spraying water and mud on themselves) but these alone are not sufficient in extreme heat conditions. It turns out that these little rough hairs are actually very important for keeping elephants cool.

From the Abstract:

The idea that low surface densities of hairs could be a heat loss mechanism is understood in engineering and has been postulated in some thermal studies of animals. However, its biological implications, both for thermoregulation as well as for the evolution of epidermal structures, have not yet been noted. Since early epidermal structures are poorly preserved in the fossil record, we study modern elephants to infer not only the heat transfer effect of present-day sparse hair, but also its potential evolutionary origins. Here we use a combination of theoretical and empirical approaches, and a range of hair densities determined from photographs, to test whether sparse hairs increase convective heat loss from elephant skin, thus serving an intentional evolutionary purpose. Our conclusion is that elephants are covered with hair that significantly enhances their thermoregulation ability by over 5% under all scenarios considered, and by up to 23% at low wind speeds where their thermoregulation needs are greatest. The broader biological significance of this finding suggests that maintaining a low-density hair cover can be evolutionary purposeful and beneficial, which is consistent with the fact that elephants have the greatest need for heat loss of any modern terrestrial animal because of their high body-volume to skin-surface ratio. Elephant hair is the first documented example in nature where increasing heat transfer due to a low hair density covering may be a desirable effect, and therefore raises the possibility of such a covering for similarly sized animals in the past. This elephant example dispels the widely-held assumption that in modern endotherms body hair functions exclusively as an insulator and could therefore be a first step to resolving the prior paradox of why hair was able to evolve in a world much warmer than our own.

And while on the topic of elephants, be sure to check out the videos accompanying the paper “Visualizing Sound Emission of Elephant Vocalizations: Evidence for Two Rumble Production Types” which capture the oral and nasal rumbles of elephants with an acoustic camera. The oral rumble of an elephant at 25 frames per second is below but you can watch the rest on our YouTube Channel here.


Citation: Myhrvold CL, Stone HA, Bou-Zeid E (2012) What Is the Use of Elephant Hair? PLoS ONE 7(10): e47018. doi:10.1371/journal.pone.0047018

Citation: Stoeger AS, Heilmann G, Zeppelzauer M, Ganswindt A, Hensman S, et al. (2012) Visualizing Sound Emission of Elephant Vocalizations: Evidence for Two Rumble Production Types. PLoS ONE 7(11): e48907. doi:10.1371/journal.pone.0048907

What Influences Voter Behavior?

The “worm” may be changing how voters vote (Figure 1. Davis et al.)

Although we’d like to believe that people determine how to vote based on relevant political issues, research has shown that countless subtle elements beyond just the candidate and party platform are at play in influencing voter decisions. In light of the upcoming election, let’s revisit some of this research published by PLOS ONE over the years that address some of these influences.

Impressions based on candidate age and gender, as well as subconscious judgments of competency, approachability and attractiveness, are likely to have played a role in informing voters’ choices as long as democracy has been practiced. Several studies have explored these notions. Among them, an investigation into the effects of voter and candidate gender on voting behavior, exploring voter biases toward older candidates in times of conflict and whether Democrats and Republicans can be identified as such by their facial appearance alone!

More recent developments in the media’s coverage of debates have incorporated social elements in broadcasting and may be biasing audiences in new ways. The “worm”, seen above, is one such innovation; this continuous response measure presents real time data from undecided voters in a streaming line presented during live coverage of a debate. The research of Davis et al. demonstrates how easily these innovations can sway the opinions of viewers and urges more investigation into the impacts of this and other social media additions to coverage of debates.

These and other studies show how many factors may be influencing our choices in elections. As the presidential election approaches in the United States, whatever determines your vote, we hope you all get to the polls on November 6th!


Citation: Chiao JY, Bowman NE, Gill H (2008) The Political Gender Gap: Gender Bias in Facial Inferences that Predict Voting Behavior. PLoS ONE 3(10): e3666. doi:10.1371/journal.pone.0003666

Citation: Spisak BR (2012) The General Age of Leadership: Older-Looking Presidential Candidates Win Elections during War. PLoS ONE 7(5): e36945. doi:10.1371/journal.pone.0036945

Citation: Rule NO, Ambady N (2010) Democrats and Republicans Can Be Differentiated from Their Faces. PLoS ONE 5(1): e8733. doi:10.1371/journal.pone.0008733

Citation: Davis CJ, Bowers JS, Memon A (2011) Social Influence in Televised Election Debates: A Potential Distortion of Democracy. PLoS ONE 6(3): e18154. doi:10.1371/journal.pone.0018154

Halloween Highlights: Carnivorous Plants

Plants may not generally be associated with the spooky sentiments of Halloween, but put the right Hitchcock soundtrack with the video below and it could have come straight out of a Hollywood horror film.

Carnivorous plants have inspired many creative minds over time, perhaps most memorably in the cult classic, Little Shop of Horrors which featured a fictitious new hybrid that thrived only on human blood. The real plants may not be so scary to us but for insects, they’re certainly something to be wary of.

The video above  shows the particularly dramatic “active” trapping mechanism employed by one carnivorous species the Drosera glanduligera, a sundew that feeds on insects. Even the abstract of the study Catapulting Tentacles in a Sticky Carnivorous Plant conjures cryptic images:

Prey animals walking near the edge of the sundew trigger a touch-sensitive snap-tentacle, which swiftly catapults them onto adjacent sticky glue-tentacles; the insects are then slowly drawn within the concave trap leaf by sticky tentacles.

“Passive” trapping mechanisms used by other carnivorous plants can be equally creepy when documented close up (and paired with the right soundtrack). Take a look at Video S1 and S3, below, of a paper published in 2007 investigating the digestive fluid of the Nepenthes rafflesian, a pitcher plant that relies on its unique shape and a pool of  highly viscoelastic fluid to trap insects for digestion. The first video shows how easily a fly can escape a pool of water, while the second video shows the distinct advantage the digestive fluid gives the plant. Both demonstrate the classic horror film qualities science can evoke!



Citation: Poppinga S, Hartmeyer SRH, Seidel R, Masselter T, Hartmeyer I, et al. (2012) Catapulting Tentacles in a Sticky Carnivorous Plant. PLoS ONE 7(9): e45735. doi:10.1371/journal.pone.0045735

Citation: Gaume L, Forterre Y (2007) A Viscoelastic Deadly Fluid in Carnivorous Pitcher Plants. PLoS ONE 2(11): e1185. doi:10.1371/journal.pone.0001185

Worth a Thousand Words: Handedness in Fish

If you look closely at the image above, you’ll see that the mouths of these cichlid fish, Perissodus microlepis, curve in opposite directions. Similar to left or right handedness in humans, many animals exhibit handedness in behavior or morphology. Whether handed behavior is expressed early in development and produces mouth asymmetry or the opposite, that mouth asymmetry produces handed behavior, however, is not well known. The authors of the study “Handed Foraging Behavior in Scale-Eating Cichlid Fish: Its Potential Role in Shaping Morphological Asymmetry” set out to investigate this question and more. The image above is Figure 1 of the article.


Scale-eating cichlid fish, Perissodus microlepis, from Lake Tanganyika display handed (lateralized) foraging behavior, where an asymmetric ‘left’ mouth morph preferentially feeds on the scales of the right side of its victim fish and a ‘right’ morph bites the scales of the left side. This species has therefore become a textbook example of the astonishing degree of ecological specialization and negative frequency-dependent selection. We investigated the strength of handedness of foraging behavior as well as its interaction with morphological mouth laterality in P. microlepis. In wild-caught adult fish we found that mouth laterality is, as expected, a strong predictor of their preferred attack orientation. Also laboratory-reared juvenile fish exhibited a strong laterality in behavioral preference to feed on scales, even at an early age, although the initial level of mouth asymmetry appeared to be small. This suggests that pronounced mouth asymmetry is not a prerequisite for handed foraging behavior in juvenile scale-eating cichlid fish and might suggest that behavioral preference to attack a particular side of the prey plays a role in facilitating morphological asymmetry of this species.


Citation: Lee HJ, Kusche H, Meyer A (2012) Handed Foraging Behavior in Scale-Eating Cichlid Fish: Its Potential Role in Shaping Morphological Asymmetry. PLoS ONE 7(9): e44670. doi:10.1371/journal.pone.0044670

The Advantage of Veins

Locust wing

Desert locusts are known to travel great distances, experiencing substantial mechanical stress along the way, however little is understood about their wings ability to resist damage during these long flights. Using a tensile test machine, Trinity College researchers Dr. Dirks and Dr. Taylor investigated the toughness of these insect’s extremely thin wings, specifically looking into the function of the network of veins running through the wing membrane, shown in Figure 1 above, as barriers to crack propagation. As the title, “Veins Improve Fracture Toughness of Insect Wings” suggests, the study found these veins increased the effective structural toughness of the wing significantly, causing cracks to slow or stop and helps explain how the insects manage to withstand damage incurred over long flights. Check out Video 1 of the article to see the veins impede cracks.


Image citation:

Dirks J-H, Taylor D (2012) Veins Improve Fracture Toughness of Insect Wings. PLoS ONE 7(8): e43411. doi:10.1371/journal.pone.0043411

PLOS ONE News and Media Roundup

Lesions found on coral trout.

Last month, the media covered PLOS ONE papers on germs in airports, skin cancer in fish, a potentially life extending pill, and more!

Research by a team at MIT identified New York City’s JFK, Los Angeles’s LAX and Honolulu’s HNL as the nation’s airports most likely to influence the spread of a major pandemic in the first few days of an emerging disease. The team used geographical information, traffic structure and individual mobility patterns to model contagious disease dynamics through the air transportation network. The study was covered by NPR, CNN, and Wired.

A recent study comparing a hunter-gatherer population with a modern Western population found that daily energy expenditure between the two populations is not all that different; challenging the view that obesity in Western society is largely due to a lack of exercise.  This research may encourage shifting the focus of this debate to the importance of calorie consumption and was covered by The Atlantic, Mother Nature Network and the BBC.

Dark patches found on fish in the Great Barrier Reef have been identified as a deadly form of skin cancer, melanoma. “Evidence of Melanoma in Wild Marine Fish Populations” is the first published study of melanoma in a wild fish population but it is unlikely the problem is new. The Great Barrier Reef sits under the largest hole in the ozone, exposing fish populations there to high levels of UV radiation. The image above is Figure 1 of the manuscript. The study was covered by Science, LA Times and Scientific American.

Autistic children may benefit from getting a pet. According to this study by a French research team, children who received a pet around the age of five showed improved social skills, including increased ability to share with and comfort others, compared to autistic children who either grew up with a pet or never had one. US News, Fox and Time all covered this study.

Findings from the study “Randomized Polypill Crossover Trial in People Aged 50 and Over” suggest that people over fifty may benefit from taking a once daily “polypill” comprised of three blood pressure-lowering drugs and a cholesterol-lowering statin. Read more at CBS, Reuters and ABC.

For more in-depth coverage on news and blog articles about PLOS ONE papers, please visit our Media Tracking Project.