Science – Page 4 – The Speaker News Journal

Girls Who Have Sex Lose Both Female And Male Friendships, Study Finds; For Males, It’s The Opposite

August 24, 2015 by The Speaker Editors

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Early adolescent males gain friends when they have sex while females lose them, a new study has found. Not only that, males who make out without having sex lose popularity, while females who do the same gain.

The findings of the study will be presented at the 110th Annual Meeting of the American Sociological Association (ASA).

“In our sample of early adolescents, girls’ friendship networks shrink significantly after they have sex, whereas boys’ friendship networks expand significantly,” said Derek A. Kreager, the lead author of the study and an associate professor of sociology and criminology at Pennsylvania State University.

“But what really surprised us was that ‘making out’ showed a pattern consistent with a strong reverse sexual double standard, such that girls who ‘make out’ without having sex see significant increases in friendships, and boys who engage in the same behavior see significant decreases in friendships.”

The study was based on information gathered from 921 students in 28 rural communities in Iowa and Pennsylvania states. Data was gathered from students over grades six through nine.

When asked to select their best or closest friend in their grade, students showed a high degree of preference for males who had sex but didn’t just make out and for females who made out but didn’t have sex.

Girls who had sex experienced a 45 percent decrease in peer acceptance. Boys who had sex had an 88 percent increase. Girls who just made out, however, had a 25 percent increase in peer acceptance while boys experienced a 29 percent decrease.

“Our results are consistent with traditional gender scripts,” Kreager said. “Men and boys are expected to act on innate or strong sex drives to initiate heterosexual contacts for the purpose of sex rather than romance and pursue multiple sexual partnerships.

“In contrast, women and girls are expected to desire romance over sex, value monogamy, and ‘gatekeep’ male sexual advances within committed relationships. A sexual double standard then arises because women and girls who violate traditional sexual scripts and have casual and/or multiple sexual partnerships are socially stigmatized, whereas men and boys performing similar behaviors are rewarded for achieving masculine ideals.”

Kreager thinks boys and girls reinforce traditional gender scripts at school.

“[The] pattern suggests that other boys are the peers that police social norms when it comes to masculinity, whereas girls receive strong messages about gender-appropriate sexual behavior from boys and girls,” Kreager explained. “It is not surprising that girls do not punish boys for ‘making out,’ as this behavior is rewarding for girls both socially and physically.

“However, there is somewhat of a paradox for boys stigmatizing girls who have sex because these boys are punishing girls for behavior that benefits boys both socially and sexually. We believe one reason for this is that only a small minority of boys have such sexual access, so those who do not have sex negatively define the girls who are having sex.”

“During early adolescence,” Kreager noted, “peer evaluations of initial sexual behaviors and virginity loss are likely to have large and lasting impacts on later sexual adjustment.”

By Cheryl Bretton

Quasicrystal Growth Observed For First Time Under Microscope

January 26, 2021August 11, 2015 by The Speaker Editors

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Quasicrystals in the act of growing have for the first time been recorded by Japanese researchers using high-resolution transmission electron microscopy, answering a mechanical dilemma of chemistry with an “error-and-correction” observation.

“For the first time, we succeeded in observing the quasicrystal growth directly,” University of Tokyo’s Dr. Keiichi Edagawa told The Speaker. “By the direct observation, we obtained [a] picture of formation.”

The researchers heated a two-dimensional quasicrystal sample of aluminum, nickel, and cobalt (Al70.8Ni19.7Co9.5) at temperatures between 1123 and 1183 Kelvins.

Using HRTEM, the researchers put together a series of images of the sample as the quasicrystals transformed under heat.

The composite video illustrates the researchers’ main finding:
Quasicrystals, at least in the decagonal phase observed, grow according to an “error-and-correction” pattern.

The team observed a quasicrystal grain growing into the space left by another shrinking quasicrystal grain.

The action takes place in the middle of the growing and shrinking grains — a region known as the “growth front.” There, atomic clusters appear as a row of tiles being flipped, breaking the long-range quasiperiodic order of the lattice and resulting in disorder.

However, as more rearrangements take place over time, the disordered clusters correct, sometimes after several rows have grown incorrectly.

Dr. Keichi Edagawa — Dr. Keiichi Edagawa

“Quasicrystals grow with frequent error-and-repair, where the repair process corresponds to the relaxation of so-called phason strain,” Edagawa told us. “No strict local growth rules are at work, which is somewhat different from the ideal growth models previously proposed theoretically.”

What drives the errors and corrections during growth is still not known. Also unknown remains whether the phenomena observed also takes place in other quasicrystal phases.

https://www.youtube.com/watch?v=brnrZv5o_A0

The report, “Experimental Observation of Quasicrystal Growth,” was completed by University of Tokyo and Tohoku University researchers Drs. Keisuke Nagao, Tomoaki Inuzuka, Kazue Nishimoto, and Keiichi Edagawa, and was published online in APS Physics.

Fruit Fly Larva Brain Activity Caught On Camera

August 11, 2015 by Robbie Carney

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Scientists in Virginia used light-sheet microscopy to video the goings-on of the larva’s nervous system

ASHBURN, Va. – Scientists at the Howard Hughes Medical Institute have imaged motor neuron activity in a millimetre-long larva.

Their paper was published today in the open-access journal Nature Communications. Photographs were taken of the neurons of the larva, Drosophila melanogaster, five times per second, using penetrative lasers as part of a cutting edge technique called light-sheet microscopy.

The footage has been made available on YouTube l, and provides a fascinating insight into one of nature’s great miracles. Only the larva’s nervous system is shown, and areas of activity glow orange-red. The nerves are being artificially stimulated, as if the larva were crawling around.

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Philipp Keller, a participating scientist, said: “By imaging different parts of the nervous system at the same time, we can see how behaviours are controlled and then build models of how it all works.”

The study builds on research which involved even smaller organisms like nematode worms. By imaging not just the brain, but also the nerve cord, scientists can better see how the two work together. The team has now moved on to adult flies, zebrafish, and mouse embryos.

By Robbie Carney

Selfies Are Linked To Narcissism In Men, But Not In Women, New Research Finds

August 6, 2015 by The Speaker Editors

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According to new research, selfies are linked to narcissism in men, but not in women. The research, undertaken by Polish psychologist, went further, providing an understanding about which aspects of narcissism were associated with selfie-taking for each gender.

Research, though still scant, is emerging about who posts selfies and why.

According to the new Polish study, which examined three types of selfies — solo selfies, selfies with a romantic partner, and group selfies — and examined almost 1300 Polish men and women — not just American men, the subject of the recent popular news report on selfies and narcissism — men and women vary in exhibiting selfie behavior.

The researchers tried two things: they asked one group of men and women to self-report how many selfies of each of the three types they posted to Facebook and other social media. Then they obtained access to the social media accounts of a second group to count the selfies.

Women post more selfies than men do on social media, the researchers found.

But the researchers also wanted to get an understanding of the relationship between selfie posting and narcissism. They tested participants for narcissistic traits — four separate traits: Exhibitionism, Admiration Demand, Leadership and Self-Sufficiency.

When they compared their narcissism test results with the selfie posting numbers, they found that selfie posting by males was positively correlated with Exhibitionism, Admiration Demand and Leadership, but not Self-Sufficiency. For men, these relationships existed for all types of selfie pictures.

For women, only a correlation between selfie posting and Admiration Demand was found, and only for solo selfies in the first study and romantic partners in the second.

However, the researchers concluded that narcissism only explains a small part of self-posting, because the correlations were all quite modest.

The study, “Selfie posting behaviors are associated with narcissism among men,” was completed by Sorokowski, P., Sorokowska, A., Oleszkiewicz, A., Frackowiak, T., Huk, A., & Pisanski, K. and was published in Personality and Individual Differences.

By Cheryl Bretton

The brain and music: McGill team graphs regions of the brain responsible for music training and individual skill

July 29, 2015 by The Speaker Editors

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Nature and nurture in music has now been mapped by McGill neurologists who have recorded the activity and changes in the brains of young adults over the course of a six-week piano training session. Among the results of the research is a greater understanding of how natural disposition factors into skills like music.

“I would venture to say that new skills probably change almost the entire brain in some way or another,” Dr. Robert Zatorre, Professor of Neurology and Neurosurgery at McGill’s Montreal Neurological Institute and lead author of the work, told The Speaker.

“What we try to do in our experiments is to isolate specific components of these changes so that we can characterize them accurately.”

In their recent work, the Neuro team sought to display and map the brain’s response to learning music. They also sought for differences in how individuals learn and respond to musical training.

The team provided six weeks of piano training for 15 young adults who had little or no background in music.

“We measured the entire brain simultaneously using functional MRI,” Zatorre told us, “and then searched the whole brain to find the areas that changed after training, and to distinguish them from those areas which were predictive of learning success.”

The brains of all of the young adults changed as they learned the motor skills involved with playing simple piano pieces, but the team found that the brain activity of some students predicted how quickly they would become skilled.

“The areas that changed most after training were in the premotor cortex and in the parietal cortex, regions concerned with coordinating movements and mapping actions to sounds; the areas that were predictive of subsequent learning were totally different from these and involved the auditory cortex and the hippocampus, the latter of course a structure involved in the formation of memories.”

Zatorre commented on the important role of individual predisposition in learning a skill like music.

“We think that those people who are better at initially encoding sound properties will subsequently have an edge when it comes to learning how to move their fingers to produce that same sound pattern,” Zatorre said.

And the findings do not apply only to music, but are an example of how the brain responds to any skill, according to the neurologists.

“We see it in the context of other research looking at skills such as learning the sounds of a foreign language, or skilled sports activities. In each of these cases there are distinct neural circuits that have to be “trained up” so the specific brain regions involved might differ. But we think the same principle may apply, that is, that some brain circuits are changed by training, but others may be indicative of the predisposition to learn a specific skill.”

The report, “Dissociation of Neural Networks for Predisposition and for Training-Related Plasticity in Auditory-Motor Learning,” was completed by Sibylle C. Herholz, Emily B.J. Coffey, Christo Pantev, and Robert J. Zatorre, and was published in Cerebral Cortex.

By Sid Douglas

Images 3 and 4 from the report of the Neuro team

A Face Can Mean Life Or Death

January 26, 2021July 25, 2015 by Justin Munce

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In the US, 72 people were sentenced to death last year, and according to new research the faces of those tried in court may have had something to do with their sentence. An “alarming bias” in the criminal justice system, U of T researchers found, results from the prejudice attached to people’s appearance.

The researchers conducted two studies based on real world sentences, unlike past hypothetical experiments.

In the first study, they found that the trustworthiness of a person predicted whether they received death sentences. Two-hundred and eight American adults judged photos of the faces of 226 murder convicts on a trustworthiness scale of 1 to 8. The photos didn’t show that the faces were those of prison inmates. Of the faces of people convicted of first degree murder, some were sentenced to death and some were sentenced to life in prison — a less severe penalty. The faces of those who had received the lesser sentence were also the faces people perceived to be more trustworthy. The less trustworthy a face, the more likely the person behind it was to receive the death sentence.

Then in the second study, the researchers found that even for innocent people who had been exonerated after being falsely sentenced to death, the link of perceived trustworthiness and death sentence remained, demonstrating, the researchers concluded, that it wasn’t just that real criminals had meaner faces, but that anyone who had an untrustworthy-seeming face faced stiffer penalties.

The researchers surmised that the results show that people want to punish those who appear less trustworthy.

The researcher pointed to a lesson that could be learned from their study: since we know we are biased, we can police our thoughts to some degree.

The report, “Facial Trustworthiness Predicts Extreme Criminal-Sentencing Outcomes,” was completed by Drs. John Paul Wilson and Nicholas Rule of the University of Toronto and was funded by the Social Sciences and Humanities Research Council of Canada. It was published in Psychological Science.

The study material is publicly available.

Sea change based on evidence: warmer waters may mean LESS fish due to unexpected factors

July 23, 2015 by The Speaker Editors

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Warmer waters in the north mean less overwinter death and increased growth for cold-blooded fish, so they will benefit from global warming… or so the theory went. New research says that these species may actually suffer more than they benefit, and global warming will end up reducing their populations.

“Even if summer conditions are better for growth under a warmer climate, this may mean little if the number of offspring produced has already been limited by short, warm winters,” Auburn University’s Dr. Troy Farmer told The Speaker.

The research team studied a particular species of northern fish, yellow perch, in Lake Erie, one of North America’s Great Lakes shared between the United States and Canada.

The reason for the yellow perch population reduction, the team found, had to do in large part with reproduction and early development.

“Our results suggest that climate warming during winter may negatively affect yellow perch populations by reducing reproductive success,” Farmer told us.

A shorter winter, the researchers found, results in a spawn that takes place within warm waters. A warm water spawn is different from a cold water spawn for yellow perch: smaller eggs are produced that hatch at lower rates and produce smaller larvae.

“Our research also offers an explanation for observed trends in Lake Erie yellow perch populations. Specifically, it indicates that reduced reproductive success may be responsible for lower juvenile abundance following short, warm winters. Ultimately, we also found that years of low juvenile abundance led to lower adult abundances in future years.”

This makes for a new picture of the future cold water fish species, according to Farmer:

“Climate change will likely affect northern fish species in many different ways. As winters get shorter, longer summer growing seasons may benefit some fishes. However, shorter winters may also have negative effects on reproduction, as our study indicates. Understanding which species thrive and which species decline in a warmer climate will require a more complete understanding of how warmer temperatures during both summer and winter influence all aspects of survival, growth, and reproduction. For some fishes, such as our study species, yellow perch, the negative effects of short winters on reproduction may outweigh any positive benefits from a longer growing season.”

“Prior to our research, scientists speculated that cool-water fish species like yellow perch would benefit from warmer temperatures associated with climate change. Warmer temperatures would equate to a longer growing season, which could lead to larger fish that survive the winter better or that could produce more eggs or better quality larvae. But, few studies have speculated on how reproduction might be affected by a change in winter severity or temperature.

“When we looked at long-term monitoring data for yellow perch in Lake Erie, however, we saw just the opposite: short, warm winters were followed by fewer juveniles the following year. The largest cohorts of juvenile fish came after long, cold winters.

“Yellow perch females spawn (or lay their eggs) during the spring, which means any effect of winter temperatures on juvenile production were likely the result of temperature effects on adults during the egg development phase. This phase occurs during winter.

“One potential explanation for this pattern was suggested by previous laboratory research, conducted in the 1970s, which suggested that yellow perch require a certain number of cold days to successfully develop their eggs – but the reasons for this were unknown.”

The teams research involved a simple comparison; they studied yellow perch in both warm and cold water conditions and recorded how the two groups fared.

“We conducted a laboratory experiment in which we exposed half of a group of adult female yellow perch to a short winter and the other half to a long winter. Females exposed to the short winter produced smaller eggs that hatched at lower rates and produced smaller larvae than females exposed to a long winter. This is important because large larvae grow and survive better than small larvae during their first months of life in Lake Erie. These results help explain why short winters were associated with poor years of yellow perch production in Lake Erie.

Farmer also touched upon the complexity of the cold water ecosystem of Lake Erie, and how the diet of fish species like yellow perch might also be affected by warmer waters.

“We also observed another negative effect of warm winters on yellow perch reproduction. When spring arrival was extraordinarily early, yellow perch did not shift their spawning time. Instead, females spawned at the normal time when temperatures were already too warm. Unfortunately, zooplankton (the prey of the yellow perch larvae) might grow in response to warming temperatures, appearing earlier in years with an early spring. Thus, short winters may cause a mismatch in timing between yellow perch larvae and their prey.”

What can we expect then, for ectotherms if their environments continue to suddenly heat up?

“Most temperate ectotherms have highly evolved lifecycles that are tightly coupled to seasonal temperature cycles,” Farmer told us. “As summers grow longer and the duration of cold winter temperatures shrink, this may disrupt the highly evolved lifecycles of ectotherms. In our study species, yellow perch (a cool-water fish), we saw that shorter winters negatively affected egg development and altered the timing of spawning, leading to lower reproductive success.”

The report, “Short winters threaten temperate fish populations,” was completed by Troy M. Farmer, Elizabeth A. Marschall, Konrad Dabrowski & Stuart A. Ludsin, and was published on Nature Communications.

By Sid Douglas

Images 4 and 5 from Ohio State University’s Aquatic Ecology Laboratory

Couchsurfing toddlers get bullied more as kids

July 17, 2015July 17, 2015 by Cheryl Bretton

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Are your rugrats babysat by the TV? Dr. Linda Pagani of the University of Montreal, who just completed an extensive study of the long-term effects of toddler TV viewing, says they might suffer for it later.

“Basically, too much time in front of the telly creates a time-debt for other enriching activities,” Pagani told The Speaker. “In early childhood children need live interaction to help their brains develop and to maximize their emotional intelligence. It is like IQ, we are born with a potential, but need interactions with people and objects in the environment to fully develop it. More television time means less time for play and less time in active social exchanges of ideas and information.”

In their most recent research, Pagani and her team surveyed the experience of almost 2,000 Canadian children and their parents, and found that kids were likely to be bullied in sixth grade an extra 11% for every 53 minutes of daily TV viewing at 29 months of age.

Not only were kids more likely to be bullied, but early television viewing was also found to be associated with deficits in problem solving ability, emotional control, peer play competence, social contact ability, and eye-contact — which is important for friendship and self-affirmation in relationships.

“Watching the telly is not an effortful activity, and thus it fosters lifestyle habits that are less energetic and there is less of a tolerance for more demanding interactions on a social level. It also does not hone shared eye contact, for which we are wired at birth. Therefore, less effortful interactions mean less activities that foster and reinforce shared eye contact. Eye contact is the most powerful mode of information exchange apart from talking and one reinforces the other.”

So how should a child’s day be broken up? Pagani referred to the recommendations of the American Academy of Pediatrics, a professional association dedicated to the health and well-being of infants, children, adolescents and young adults. Half of the 24 hours of their day should be spent sleeping, eating, and tending to hygiene, according to the AAP, which leaves 12 hours to fill. Of those 12 hours children should get no more than 1 to 2 hours of television per day. She pointed out, though, that the recommendations relate particularly to quality TV viewing time.

“Assuming the content is of quality not more than two hours per day for over age 2,” Pagani advised, “and try to favor other pastimes that involve interaction between the child and others, and add some creative play to that too.”

Pagani had a simple suggestion for busy parents who wanted to mitigate the negative effects of occupying their toddlers with television: “Lots of social interaction.”

Pagani also offered some broader context for understanding the role of television in the lives of children:

“Television is effortless — is this the kind of natural habit we want our children to develop? The brain is like a muscle and social, cognitive, and motor sedentariness (effortlessness) is detrimental to its architecture.

“Our previous research has shown that excessive televiewing has a long-term negative influence on children’s bio-psycho-social well-being,” Pagani told us, referring to a wealth of past research she and her team had completed, “therefore the AAP guidelines which discourage any viewing prior to age 2 and not more than two hours beyond age 2 are there to favor conditions for brain development and (intellectual, social, and physical) non-sedentary lifestyle habits.”

“Too Much Television? Prospective Associations Between Early Childhood Televiewing and Later Self-Reports of Victimization By Sixth Grade Classmates” was published in the Journal of Developmental & Behavioral Pediatrics.

By Cheryl Bretton

Below-zero fluid viscosity achieved by “doping” bacteria

July 9, 2015 by Sid Douglas

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New rheological research has created fluid viscosity in which the viscous resistance to shear disappears. Researchers at University Paris-Sud in France employed swimming bacteria and organized them to push past the dissipative effects of viscous loss to create a “superfluidlike” suspension.

The collectively organized “pusher swimmers” may be harvested to power tiny mechanical devices such as microfluid pumps, the researchers believe.

Paris-Sud’s Hector Lopez and his team studied fluid-bacteria mixtures, measuring their viscosity within a container that applied shear stress with a rotating outer wall.

They found that the use of swimming E. coli bacteria reduced the viscosity for low to moderate stress values. But when the team energized the E. coli with extra nutrients — “doping” them, as the researchers referred to it — the E. coli’s heightened swimming activity created below-zero viscosity similar to the viscosity of superfluids like liquid helium.

The secret to this swimming success is in the organization of organisms that force fluid to flow out from their tails. When their efforts are aligned collectively, their bulk “push” contributes to the velocity gradient of their liquid environment.

The report, “Turning Bacteria Suspensions into Superfluids,” was completed by Dr. Héctor Matías López, Jérémie Gachelin, Carine Douarche, Harold Auradou, and Eric Clément and published in Physical Review Letters.

By Sid Douglas

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Antimatter created by thunderstorms — NHU physicists — mystery continues

June 17, 2015May 17, 2015 by The Speaker Editors

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Large amounts of antimatter have been detected in the midst of thunderclouds, according to University of New Hampshire physicists who have been working on the problem for several years. The original observation of positron signatures — six years ago when Dr. Joseph Dwyer accidentally flew through several thunderclouds in a research plane – caused the scientists such skepticism that they refrained from publishing their findings.

“Thunderstorms are very strange places that we have only begun to explore,” lead researcher Dwyer, who is also a professor and head of the University of New Hampshire’s Physics and Space Sciences program, told The Speaker.

Antimatter created by thunderstorms -- NHU physicists -- mystery continues (1) — Dr. Joseph Dwyer

“The signatures of the positrons were very clear in the data. However, because the observations were so strange, we were hoping that further observations or modeling would give us some insight into what was going on. Eventually, we gave up and decided we needed to publish the observations, even though we couldn’t explain them.“

Familiar to most people, intense electric fields are created within thunder clouds, which producing lighting, but the clouds also create less well-known phenomena such as positrons, a form of antimatter.

Antimatter – composed of antiparticles – is a very rare material because it is annihilated as soon as it encounters the particles of matter.

“Of course thunderstorms are made up mostly of normal stuff, e.g. water and ice,” explained Dwyer. “Occasionally they can make more exotic particles such as positrons. We are not certain how they manage to do this.”

Dwyer’s data shows that thunderclouds produce antimatter, as well as the Y-rays — highly energetic photons — he was studying when he flew his Gulfstream V jet through a group of thunderstorms in 2009.

The pilots of the plane were aiming for what they mistakenly thought was the Georgia coast. When they entered what was actually a line of thunderstorms, the plane rolled back and plunged downwards.

“I was in the back with the instrument,” said Dwyer. “For most of it, I had my eyes closed. When I did look, it was cloud and I couldn’t see very far.”

During the ordeal, the particle detector fitted to the plane picked up Y-ray spikes at an energy of 511 kiloelectronvolts. The energy level is that of the annihilation of antimatter particles.

“These were large enhancements that appeared to happen without the things that we would normally expect to occur, such as gamma rays,” commented Dwyer. “This makes is very hard to explain where the positrons came from.

“The positrons and gamma rays that we recorded make up a very small part of the storm. There are some models, however, that suggest that they may sometimes get numerous enough to discharge the cloud like lightning.”

The team continues to search for answers in fresh data collection. Scientists are sending balloons into storms to collect data. Additionally, the US National Science Foundation is planning to send an anti-tank tough A-10 Warthog into such storms.

By Sid Douglas

Coastal dune life depends on restoration of disturbance — WU Research

January 26, 2021May 2, 2015 by The Speaker Editors

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Disturbance is a condition depended on by the species indigenous to coastal dunes, according to Washington University researchers who just completed a study putting numbers to claims that the restoration of such conditions is necessary for the variety and vibrancy of the West Coast’s dune life.

“Disturbance is actually a good thing in many ecosystems – in some places disturbance is supposed to be there and it’s actually required for the survival of important community members,” Dr. Eleanor Pardini, assistant director of environmental studies at St. Louis’s Washington University, told The Speaker.

“Some ecosystems are adapted to experience frequent disturbance, such as regular flooding along a river, or hurricanes and tidal changes in wetlands, or wind and wave action on dunes. These ecosystems can provide valuable ecosystem services, such as absorbing storm surge or absorbing storm water or high water during floods. If the early successional species actually need the disturbance to thrive, and if the communities need both early and late successional species to be diverse and intact, and we value these ecosystems for their function, then there is a compelling reason to restore historic disturbance regimes.”

Such a restoration of disturbance is what is necessary for the vitality of certain coastal dune species, according to recent research completed by Pardini and colleagues Kyle Vickstrom and Dr. Tiffany Knight. The research provides numbers that demonstrate the necessity of disturbance for germination of Tidestrom’s lupine and beach layia, which, Pardini noted, play a role in the ecosystem of the dunes.

“Coastal dunes are dynamic places,” explained Pardini. “They move in response to wind and wave action. The wind action creates undulating dune topography with ridges atop the dunes and low-lying areas between dunes. Some of these low-lying swales or slacks can collect water and host aquatic communities.”

The life that thrives in such areas thrives in a naturally disturbed environment, she continued.

“In ecological terms, a disturbance is a relatively discrete event that changes the physical environment and disrupts the community or ecosystem in some way,” stated Pardini. “Disturbances include things like hurricanes, floods, wind storms, fire, or grazing by elk, bison, or cattle, or in the case of dunes, frequent wind and wave action. Disturbance events often remove some vegetation, and open up space, light, or resources. This is what we call ‘early successional habitat’ Some species do particularly well in these environments – maybe they are good dispersers that can arrive to an area and utilize resources, or they germinate well in the low competition environment.”

The recent study measured plant germination on coastal areas at which European beachgrass had been introduced in the 1880s in order to hold the sand in place. The success of the project led to a beachfront that mounted higher and steeper, and which prevented sand from moving inland, but which aversely affected the species that had been habiting the dunes.

“In the case of the dunes at Point Reyes, federally endangered plant species like Tidestrom’s lupine and beach layia thrive in early successional habitat. Threatened western snowy plovers nests in open sandy areas at the front of the dunes near the beach. They can’t nest or forage in high foredunes where sand is locked into place by introduced grasses.

She directed us toward the National Park Service’s ongoing project to restore the original habitat of the dunes at Point Reyes.

“Restoration of the historic disturbance regime is accomplished by removing introduced grasses, which can be done with a combination of mechanical removal, herbicide, fire, and hand-pulling, depending on the location. Different methods are chosen for different areas based on the local and adjacent plant and animal communities, soil substrates, and community concerns.”

The report, “Early Successional Microhabitats Allow the Persistence of Endangered Plants in Coastal Sand Dunes,” was completed by Eleanor A. Pardini, Kyle E. Vickstrom, and Tiffany M. Knight, and was published online in PLOS One.

Offering too much weakens relationships in the microbe world

April 27, 2015April 27, 2015 by The Speaker Editors

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Some microbe species produce nutrients that are consumed by neighboring species, which in turn share nutrients that they produce, but a mystery of this relationship has puzzled scientists: Why do some of the shared molecules have chemical units that seemingly have the sole function of slowing the diffusion of nutrients to neighboring microbes? A team of researchers from Boston University thinks they may have found the answer in a consideration of cooperation in game theory.

“The diffusion of small molecules could have a profound effect on microbial population dynamics,” Boston University’s Rajita Menon told The Speaker. “The main effect of this diffusion is the reduction of the effective strength of natural selection, which can lead to the loss of mutualism.”

“We provide a theory for the phenomena observed in recent experiments that could potentially explain why cooperatively growing microbes modulate the diffusivities of secreted nutrients.”

When microbes produce shared nutrients at a small diffusion rate, they are brought close together to intermix, and this cooperation is stable over time. But, Menon and her adviser and follow researcher Dr. Kirill Korolev believe, as a species releases nutrients into its environment at a greater rate, mixing decreases.

This is because neighboring organisms can benefit from the diffusion even at significant distances from the producing organisms, and this means that the producing organisms lose their neighborhood benefits.

When two species share nutrients, the researchers found, the species that diffuses nutrients more slowly dominates the relationship. It can even force its neighbor towards extinction.

Biologists have used standard game theory to try to understand why some microbes produce biomolecules that have the sole purpose of slowing diffusion of nutrients to neighboring molecules, but until now the theory has not brought satisfactory answers. Menon and Korolev, however, state that the model can still be used if we consider that greater sharing of metabolites reduces cooperation strength, causing a nonequilibrium phase transition toward species extinction.

“Traditional game theory considers pair-wise microbe to microbe interactions under the assumption that microbes interact only with their closest neighbors,” Menon told us. “However, unlike human societies or bee colonies, microbial communities rarely rely on direct contact. Instead, microbes primarily communicate through a many to many exchange of diffusible molecules. Our theory describes how nutrient diffusion renormalizes the strength of selection and influences the spatial distribution of species. We are able to integrate the complex effects of nutrient diffusion in our model while retaining the essential simplicity and accessibility of game theory. “

“Simple models of cooperation in microbial ecosystems have not been able to take nutrient diffusion into account, while more complicated models that try to do so are difficult to analyze and test. Our work was motivated by this gap in understanding that could be potentially important to maintaining cooperation in microbial colonies. The results of our study indicate that fast-diffusing nutrients weaken mutualism.”

There is, the researchers conclude, a critical level of nutrient sharing the creates stable cooperation over time.

“It is… harder to establish mutualism than we would expect from models that neglect nutrient diffusion,” Menon stated. “Further, species can gain a fitness advantage by producing faster or slower diffusing nutrients in a natural environment. They have an incentive to actively control the diffusion constants of their nutrients.”

By Cheryl Bretton