Tag Archives: #survival

Plants Set A “Bedtime” Alarm To Ensure Their Survival (Botany)

Plants have a metabolic signal that adjusts their circadian clock in the evening to ensure they store enough energy to survive the night, a new study reveals.

The research – involving scientists from the University of York – suggests this signal might provide important information to the plant about the amount of sugar available at dusk and therefore how to adjust metabolism to last the night.

Plants use sunlight to make their own sugars from photosynthesis during the day and store them to provide energy during the night.

The ability to predict sunrise and estimate the duration of the night, and fine-tune metabolism accordingly, is critical for plant survival and to maximise growth. This depends on a biological time-keeper called a circadian clock which is an oscillating gene network which drives rhythms of about 24 hours.

Dr Mike Haydon, formerly from the Department of Biology, University of York and now based at the University of Melbourne said: “We think this metabolic signal is acting rather like setting an alarm clock before bedtime to ensure the plant’s survival.

“Plants must coordinate photosynthetic metabolism with the daily environment and adapt rhythmic physiology and development to match carbon availability.”

To understand how sugars alter the circadian clock, the researchers measured gene expression in seedlings while modifying photosynthesis or sugar supply.

They discovered a set of genes known to be regulated by the chemical compound, superoxide, a molecule associated with metabolic activity. Most of these genes are active in the evening, including key genes that act in the circadian clock. They found by inhibiting the production of superoxide, they also inhibited the effect of sugar on these circadian clock genes in the evening.

Professor Ian Graham from the Department of Biology’s Centre for Novel Agricultural Products added: “Distinguishing the effects of light and sugars in photosynthetic cells is challenging. Our data suggest a new role for superoxide as a rhythmic sugar-related signal which acts in the evening and affects circadian gene expression and growth.”

The research was conducted on Arabidopsis (thale cress) which is a small flowering plant related to cabbage and mustard.

The research was funded by BBSRC (BB/L021188/1)

The paper, “Superoxide is promoted by sucrose and affects amplitude of circadian rhythms in the evening,” is published in the journal, PNAS.

Featured image: Watching the Arabidopsis clock: Seedlings expressing a light emitting firefly gene controlled by the plant’s circadian rhythm. © Mike Haydon


Provided by University of York

Friends Matter: Giraffes that Group with Others Live Longer (Biology)

Adult female giraffes who spend time in larger groups with other females live longer than less sociable individuals. The effects of sociability on survival outweigh other factors such as environment or human presence, a study of giraffes in Tanzania led by the University of Zurich has shown.

A research team led by Monica Bond, research associate at the Department of Evolutionary Biology and Environmental Studies of the University of Zurich (UZH), studied giraffes in Tanzania for five years. The biologists examined the relative effects of sociability, the natural environment, and human factors on survival of the mega-herbivore. They have now shown that adult female giraffes living in larger groups have higher survival chances than more socially isolated individuals.

Gregariousness leads to better survival

Giraffe group formations are dynamic and change throughout the day, but adult females maintain many specific friendships over the long term. “Grouping with more females, called gregariousness, is correlated with better survival of female giraffes, even as group membership is frequently changing,” says Bond. “This aspect of giraffe sociability is even more important than attributes of their non-social environment such as vegetation and nearness to human settlements.”

The benefits of many friends

Aside from poaching, the main causes of adult female giraffe mortality are likely to be disease, stress or malnutrition, all of which are interconnected stressors. “Social relationships can improve foraging efficiency, and help manage intraspecific competition, predation, disease risk and psychosocial stress,” says UZH professor Barbara König, senior author of the study. Female giraffes may seek out and join together with an optimal number of other females in order to share and obtain information about the highest-quality food sources. Other benefits to living in larger groups might be lowering stress levels by reducing harassment from males, cooperating in caring for young, or simply experiencing physiological benefits by being around familiar females. The study also finds that females living closer to towns had lower survival rates, possibly due to poaching.

Social habits similar to humans and primates

The team documented the social behaviors of the wild free-ranging giraffes using network analysis algorithms similar to those used by big-data social media platforms. According to the results, the giraffes are surprisingly similar in their social habits to humans and other primates, for whom greater social connectedness offers more opportunities. Chimpanzees and gorillas, for example, live in communities where ties between many individuals facilitate the flexibility of feeding strategies. “It seems to be beneficial for female giraffes to connect with a greater number of others and develop a sense of larger community, but without a strong sense of exclusive subgroup affiliation,” adds Monica Bond.

Featured image: Female giraffes benefit from living in groups with several other females. (Image: Sonja Metzger)


Literature:

M. L. Bond, D. E. Lee, D. R. Farine, A. Ozgul, and B. König. Sociability increases survival of adult female giraffes. 10 February 2021. Proceeding of the Royal Society B. DOI: 10.1098/rspb.2020.2770


Provided by University of Zurich

Natural Antibiotics Produced in Wounds Increase Sleep and Survival After Injury (Neuroscience)

Sleep is the best medicine, as the old saying goes. Indeed, studies showed that longer sleep leads to a better recovery. It is no surprise that our brains respond to an injury by extending our sleep. But how does that happen? How does the brain know about the injury? Is there some kind of long-range message sent to the brain from the wound?

C. elegans worm expressing a gene (in green) that promotes production of the antimicrobial molecules (AMP). Credit: Henrik Bringmann

A team of scientist focused on these questions by looking at injury and sleep in worms. “C. elegans worm is the simplest animal which we could look at to study sleep. It is a model that allows for a wide range of molecular biology techniques to explore fundamental biological processes in detail,” explains Prof. Bringmann, research group leader at the Biotechnology Center (BIOTEC) of the TU Dresden and guest group leader at Max Planck Institute for Biophysical Chemistry.

A team led by Prof. Bringmann started by looking for genes responsible for prolonging sleep in worms. They conducted a large-scale genetic screen and analyzed over 4,500 different genetic mutations. One of the genes they found caught their particular attention. Boosting activity of that gene led to an enormous increase in production of antimicrobial peptides (AMPs). The AMPs are natural antibiotics that the body produces inside the wound to fight off the pathogens locally.

To find out the connection between the antimicrobial peptides and sleep signaling, the scientists from Dresden worked with immunologists, Dr. Nathalie Pujol and Dr. Jonathan Ewbank from Centre d’Immunologie de Marseille-Luminy (CIML) in France. Together, the team has manipulated gene expression of worms. They switched off production of the natural antibiotics and looked at what happens to the injured worms. What sounds like flipping a switch was in reality not an easy task at all. It turned out that antimicrobial peptides are highly redundant. The scientists found that a total of 19 different genes responsible for producing AMPs had to be simultaneously switched off to observe a striking difference. “We have seen that the worms which did not produce antimicrobial peptides had much less sleep following an injury,” explains Prof. Bringmann. “Normally, worms survive injuries quite well. However, we observed that sleep loss increased the number of worms that did not survive a seemingly non-threatening injury,” adds Prof. Bringmann.

The researchers could show that once released from the skin wound, the AMPs act as a messenger and activate receptors in the brain. This activation works as a switch and further prompts sleep neurons to increase sleep. “AMPs have long been known to act locally, but our work suggested that they also act as long-range messenger molecules to signal need for sleep from wounds to the nervous system,” says Prof. Bringmann.

These results further strengthen the role of sleep in recovery from injuries. “Since sleep occurs in virtually all animals, our results hint at how sleep could be crucial to recover and survive an injury not only for C. elegans worms but also for other animals and possibly even humans” concludes Prof. Bringmann. His group is funded by the European Research Council (ERC) Starting Grant SLEEPCONTROL.

The results have been published in the journal Current Biology.

Reference: Marina P. Sinner et al, Innate Immunity Promotes Sleep through Epidermal Antimicrobial Peptides, Current Biology (2020). DOI: 10.1016/j.cub.2020.10.076

Provided by Dresden University of Technology

What Do Guys Think of Other Guys’ Beards? (Psychology)

A new study suggests men have stronger opinions about beards than women do.

Somewhere in our evolutionary past, hair provided humans with warmth and protection against the elements. Today, it has become more of a fashion statement than a survival feature.

As we have evolved, so too have our views on the attractiveness of body hair — especially male facial hair. For instance, psychologists have found: article continues after advertisementnull

  • Women associate men’s facial hair with aggressiveness and dominance.
  • Facial hair is related to men’s success on the marriage market.
  • Men with facial hair are judged by women to have higher social status and better parental skills.

A new study published in the journal Evolutionary Psychology takes this research one step further.

A team of scientists led by Lukasz Jach of the University of Silesia in Poland conducted two studies to better understand the preferences for male facial hair among men and women. They found that women’s preferences for male facial hair were ambiguous; in some cases they liked it, in other cases they didn’t. Men, on the other hand, preferred facial hair for themselves but not for other males.

The finding that men prefer facial hair for themselves but not for others has a clear Darwinian explanation.

“These results are in accordance with a signaling role of beardedness in intrasexual competition,” say the researchers. “Men may prefer having facial hair to deter their enemies and display greater masculinity or a higher social position.”

This is consistent with other research that has found angry faces to be recognized more quickly when they are accompanied by a beard.

Moreover, the lack of consistent results among women underscores just how context-dependent ratings of attractiveness can be. In Poland, for instance, researchers found women to prefer clean-shaven faces over faces with stubble or full beards. Research in the United Kingdom has found British women to prefer light stubble over full beards and clean-shaven faces.

In this study, the researchers recruited 287 men and 285 women to take part in a short survey. The researchers asked women to indicate whether, in general, they liked men to have clean-shaven faces or faces with facial hair. They asked male participants the same question in relation to their own faces.

They found that 57% of women indicated a preference for facial hair while 43% preferred clean-shaven male faces. Among men, 77% preferred facial hair for themselves while 23% preferred a clean-shaven look.

The scientists conducted a second study in which male and female participants were asked to view five visual examples of male facial hair (clean-shaven, light stubble, heavy stubble, light beard, and full beard) and were asked to indicate which look they preferred.

Preferences differed by gender. The authors write, “The majority of women preferred clean-shaven male faces (43.84%), followed by heavy stubble (26.03%) and light stubble (16.44%). Faces with light beard (10.96%) and full beard (2.74%) were the least preferred.”

For men, approximately 60% preferred some type of facial hair for themselves while 40% preferred a clean-shaven look. When judging other men, the results narrowed: approximately 50% of men preferred other males to have a clean-shaven look while 50% preferred some type of facial hair.

Perhaps the most convincing finding in this research is that women care a lot less about men’s facial hair than men might think they do. “The hypothesis that men’s preference to have facial hair is greater than the female preferences associated with male facial hair was supported,” write the authors.

References: Jach, Ł., & Moroń, M. (2020). I Can Wear a Beard, but you Should Shave… Preferences for Men’s Facial Hair From the Perspective of Both Sexes. Evolutionary Psychology, 18(4), 1474704920961728.

This article is originally written by Mark Travers, who is a psychologist and writes about human potential and the science of reaching it and is republished here from psychology today.

Geoscientists Discover Ancestral Puebloans Survived From Ice Melt In New Mexico Lava Tubes (Archeology)

A lava tube in the El Malpais National Monument yields centuries-old insights of survival in the face of harsh climate change.

For more than 10,000 years, the people who lived on the arid landscape of modern-day western New Mexico were renowned for their complex societies, unique architecture and early economic and political systems. But surviving in what Spanish explorers would later name El Malpais, or the “bad lands,” required ingenuity now being explained for the first time by an international geosciences team led by the University of South Florida.

USF geosciences professor Bogdan Onac is pictured with ice deposit in New Mexico. ©University of South Florida

Exploring an ice-laden lava tube of the El Malpais National Monument and using precisely radiocarbon- dated charcoal found preserved deep in an ice deposit in a lava tube, USF geosciences Professor Bogdan Onac and his team discovered that Ancestral Puebloans survived devastating droughts by traveling deep into the caves to melt ancient ice as a water resource.

Dating back as far as AD 150 to 950, the water gatherers left behind charred material in the cave indicating they started small fires to melt the ice to collect as drinking water or perhaps for religious rituals. Working in collaboration with colleagues from the National Park Service, the University of Minnesota and a research institute from Romania, the team published its discovery in “Scientific Reports.”

The droughts are believed to have influenced settlement and subsistence strategies, agricultural intensification, demographic trends and migration of the complex Ancestral Puebloan societies that once inhabited the American Southwest. Researchers claim the discovery from ice deposits presents “unambiguous evidence” of five drought events that impacted Ancestral Puebloan society during those centuries.

Archeological site next to the cave where it is believed that Ancestral Puebloans left circle-shaped stones while out hunting or used for ceremonial purposes. ©University of South Florida

“This discovery sheds light on one of the many human-environment interactions in the Southwest at a time when climate change forced people to find water resources in unexpected places,” Onac said, noting that the geological conditions that supported the discovery are now threatened by modern climate change.

“The melting cave ice under current climate conditions is both uncovering and threatening a fragile source of paleoenvironmental and archaeological evidence,” he added.

Onac specializes in exploring the depths of caves around the world where ice and other geological formations and features provide a window to past sea level and climate conditions and help add important context to today’s climate challenges.

Their study focused on a single lava tube amid a 40-mile swatch of treacherous ancient lava flows that host numerous lava tubes, many with significant ice deposits. While archaeologists have suspected that some of the surface trails crisscrossing the lava flows were left by ancient inhabitants searching for water, the research team said their work is the earliest, directly dated proof of water harvesting within the lava tubes of the Southwest.

Cibola Gray Ware discovered at El Malpais National Monument in New Mexico. ©University of South Florida

The study characterizes five drought periods over an 800-year period during which Ancestral Puebloans accessed the cave, whose entrance sits more than 2,200 meters above sea level and has been surveyed at a length of 171 meters long and about 14 meters in depth. The cave contains an ice block that appears to be a remnant of a much larger ice deposit that once filled most of the cave’s deepest section. For safety and conservation reasons, the National Park Service is identifying the site only as Cave 29.

In years with normal temperatures, the melting of seasonal ice near cave entrances would leave temporary shallow pools of water that would have been accessible to the Ancestral Puebloans. But when the ice was absent or retreated in warmer and dryer periods, the researchers documented evidence showing that the Ancestral Puebloans repeatedly worked their way to the back of the cave to light small fires to melt the ice block and capture the water.

They left behind charcoal and ash deposits, as well as a Cibola Gray Ware pottery shard that researchers found as they harvested a core of ancient ice from the block. The team believes the Ancestral Puebloans were able to manage smoke within the cave with its natural air circulation system by keeping the fires small.

The discovery was an unexpected one, Onac said. The team’s original goal in its journey into the lava tube was to gather samples to reconstruct the paleoclimate using ice deposits, which are slowly but steadily melting.

“I have entered many lava tubes, but this one was special because of the amount of charcoal present on the floor in the deeper part of the cave,” he said. “I thought it was an interesting topic, but only once we found charcoal and soot in the ice core that the idea to connect the use of ice as a water resource came to my mind.”

Unfortunately, researchers are now racing against the clock as modern climate conditions are causing the cave ice to melt, resulting in the loss of ancient climate data. Onac said he recently received support from the National Science Foundation to continue the research in the lava tubes before the geological evidence disappears.

Provided by University of South Florida

High Temperatures Threaten The Survival of Insects (Biology)

Insects have difficulties handling the higher temperatures brought on by climate change, and might risk overheating. The ability to reproduce is also strongly affected by rising temperatures, even in northern areas of the world, according to a new study from Lund University in Sweden.

Insects cannot regulate their own body temperature, which is instead strongly influenced by the temperature in their immediate environment. In the current study, the researchers studied two closely related species of damselflies in Sweden. The goal was to understand their robustness and ability to tolerate changes in temperature.

To study this, the researchers used a combination of field work in southern Sweden and infrared camera technology (thermography), a technology that makes it possible to measure body temperature in natural conditions. This information was then connected to the survival rates and reproductive success of the damselflies in their natural populations.

The results show that survivorship of these damselflies was high at relatively low temperatures, 15 – 20 C °. The reproductive capacity, on the other hand, was higher at temperatures between 20 and 30 C °, depending on the species.

“There is therefore a temperature-dependent conflict between survival on one hand and the ability to reproduce on the other”, says Erik Svensson, professor at the Department of Biology at Lund University, who led the study.

The study also shows that the damselflies ability to handle heat-related stress is limited. Insects are cold-blooded invertebrates, so they rely on external sources such as the sun or hot stones to raise their body temperature.

“Our results show that cold-blooded animals can suffer from overheating even if they live far up in the northern hemisphere, and that their ability to buffer their body temperature against rising external temperatures is limited. The results also challenge a popular theory that animals’ plasticity, i. e. their individual flexibility, can help them survive under harsher environmental conditions, such as during heat waves”, says Erik Svensson.

Provided by Lund University

Coral Larvae Movement Is Paused In Reaction To Darkness (Biology)

Coral larvae movement is paused in reaction to darkness. Researchers find a new light responding behavior that may affect where corals live.

Light is essential for the growth of reef-building corals. This is because corals grow by using the photosynthetic products of the algae living inside their cells as a source of nutrients. Therefore, the light environment of coral habitats are important for their survival.

A type of reef-building coral, Acropora tenuis. ©NIBB

A new study published in Scientific Reports shows that coral larvae swimming in seawater behave in such a manner so as to temporarily stop swimming due to reduced light, especially blue light. Researchers think that this behavior may play a role in determining where corals settle.

Corals can only move freely during the larval stage of their lives. Larvae that hatch from eggs are able to swim by moving the cilia on the surface of their bodies. After that, when the larva settles on the seabed and transforms into a sedentary form (called a “polyp”), it becomes immobile.

How the corals, whose growth requires light, select a suitable light environment for survival is a mystery. To solve it, a research team led by Dr. Yusuke Sakai, Professor Naoto Ueno of the National Institute for Basic Biology in Japan thoroughly observed the response of coral larvae to light. They found that coral larvae temporarily stop swimming in response to a decrease in light intensity and then subsequently resumed swimming at their initial speed.

Upon light attenuation (at the 0 sec mark in the movie), the larvae temporarily stopped swimming (from around 20 sec mark). After a certain period of time from the light attenuation, the larvae resume swimming (from around 120 sec mark).

Corals mostly lay eggs once a year. “In collaboration with Andrew Negri, principal investigator at the Australian Institute of Marine Science, and Professor Andrew Baird and his colleagues at James Cook University, we have not only tested corals in Japan, but also in Australia’s Great Barrier Reef, where coral spawning occurs at a different time than here. This was performed in order to repeat the experiment and thus validate our findings ” said Dr. Sakai.

A larvae of Acropora tenuis. ©NIBB

The research team then conducted a detailed analysis of the wavelengths of light that coral larvae react to. The Okazaki Large Spectrograph, the world’s largest spectroscopic irradiator at the National Institute for Basic Biology, was used for this experiment. Experiments with coral larvae exposed to various light wavelengths revealed that coral larvae respond strongly to purple to blue light.

How does pausing behavior in response to light decay affect the destination of coral larvae? To answer this question, researchers conducted mathematical simulations; the results of which show that the pause caused by the attenuation of light and the subsequent resumption of swimming have the effect of resetting the swimming direction of the larva once when it moves into a dark region and turning it in a random direction. As a result, it was suggested that it would lead to the gathering of larvae in a bright space.

Dr. Sakai said “In cnidarians, including corals, the mechanism of light reception is largely unknown. We would like to clarify the molecular mechanism of light reception in coral larvae, which do not have an eye structure”.

“In the future, it will be important to elucidate not only this phenomenon but also the mysterious ecology of coral at the molecular and cellular levels, such as the mechanism for controlling the spawning time” Professor Naoto Ueno commented.

References: “A step-down photophobic response in coral larvae: implications for the light-dependent distribution of the common reef coral, Acropora tenuis” by Yusuke Sakai, Kagayaki Kato, Hiroshi Koyama, Alyson Kuba, Hiroki Takahashi, Toshihiko Fujimori, Masayuki Hatta, Andrew Negri, Andrew Baird, Naoto Ueno, Science Reports, 2020. DOI: https://doi.org/10.1038/s41598-020-74649-x

Provided by National Institute Of Natural Sciences

Ahimsa: Kindness and Non-Violence Avoided a Planet of Apes (Psychology)

Did humans survive two million years ago because of kindness?

In the practice of Ashtanga Yoga, there are guidelines given for how to live a moral, ethical, meaningful life. As many of us sit, perched anxiously on the edge of our seats, waiting to see what apocalyptic, plague-like occurrence appears on our Bingo card today, the yogi practice of Ahimsa feels particularly important to explore.

Ahimsa instructs us to practice non-violence in action, in thoughts, and in words.

At face value, Ahimsa translates similar to our Western philosophy of “The Golden Rule”: Do unto others as you would have them do unto you. This sweet sentiment that we teach our children either through the kind and proper words of the modern-day mother, or the frightening fairy tales of yore, is a Jungian archetype of sorts: a pattern or belief system that repeats across time and culture.

If you study Ahimsa a bit more closely, you will note that included in the importance of being non-violent is being non-violent to yourself. This applies to self-inflicted injury to your physical self, punishing yourself through extremes such as gluttony, restrictive or extreme eating behavior, consuming harmful substances, etc.

But, Ahimsa also applies to being non-violent to your mental state, or as we are so fond of prescribing: the importance of practicing self-care.

This yogi mandate is not the succinct, biblical “Thou shalt not kill,” for Ahimsa takes the idea farther, and acknowledges that our thoughts about ourselves and others have the ability to cause harm, even if not instantly visible to the human eye. Ahimsa is about being kind to ourselves and to others, and it is acknowledged that this kindness could be to our benefit.

Guess what? Archeologists have proven that this is absolutely true.

Did our humanity save us from being casualties of the primates?Source: Joshua J. Cotten/Unsplash.

Two million years ago in Africa, early man lived as Hunter-Gatherer’s, which we often reference in terms of cavemen dividing tasks by gender: the big strong man would go kill some dinner, while the women remained home at the hearth, caring for the children, harvesting the crops, and having dinner on the table when the big, smelly man came home from a rough day of killing things.

(If you have seen the movie Croods, you have a general idea of the DreamWorks movie version of this era. And if you have not seen the movie Croods, you may want to seriously reconsider your life choices. It’s fantastic.)

The problem with our conception of this sexist-gender-biased-why-can’t-women-hunt-and-men-raise-kids and how-mad-would-RBG-have-been-if-she-had-been-alive-knitting-collars-out-of-palm-fronds-and-boar-tusks-outrage is that this assumption is false.

How do we know this?

Within the last twenty years, anthropologists began to take another look at the Hunter-Gatherer society, in large part to figure out why and how we humans, for whom the odds were so very much against, ended up not only surviving, but thriving to the point of becoming the current reigning species.

Our bodies are nearly hairless, making us an easy target for sun burn and sun poisoning for one half of the year, and an even easier target for freezing to death the other half of the year. Our canine teeth technically identify us as predators, rather than prey, but prey animals are more likely to have large eyes spaced out in a way that allows them to better scan their environment for dangers.

Nope! Not us!

Prey animals often have the ability to run very fast or fly in order to make a quick getaway, or the ability to camouflage themselves in order to blend into the environment or release a poison or venom should a predator attempt to make them a snack.

So, how is it possible that our current civilization is not (technically) run by a bunch of primates?

Ahimsa.

Hunter-Gatherers were nomads, constantly changing locations to take advantage of seasonal migration of animals and fluctuations in weather.

When was the last time you moved? Most of us try to lighten our load by getting rid of what we don’t need. Nomadic, primitive men (and women) acted similarly.

It has been a long-standing rule that money leads to power. But, two million years ago, man, as prey, focused on survival, and a more collectivist society increased their odds.

The truth is, no one wants to have to carry meat or onions or berries or anything on their own, while embarking on a really long hike without any semblance of a map.

And so, Ahimsa. Kindness. Non-violence in the absence of competition or jealousy or a hierarchy based on the Have’s and Have Not’s. The Hunter-Gatherers worked together for the safety of the herd.

And as for our primate predators? How did we manage to escape them, both in the moment all those years ago, and today, as we are not living in a Planet of The Apes-esque scenario?

(Yet)

Our animal ancestors were highly competitive within their own community, constantly trying to establish or overthrow the alpha male, a ruler who had all the control and power.

And so, while our numbers were growing because of our kindness and non-violence, theirs were dwindling.

Hence, the beauty of Ahimsa.

This article is republished here from psychology today under common creative licenses

Cheaters Don’t Always Win: Species That Work Together Do Better (Biology)

Extinction may be prevented by diverse communities of mutually beneficial species

The sign of a healthy personal relationship is one that is equally mutual – where you get out just as much as you put in. Nature has its own version of a healthy relationship. Known as mutualisms, they are interactions between species that are mutually beneficial for each species. One example is the interaction between plants and pollinators, where your apple trees are pollinated and the honeybee gets nectar as a food reward. But what makes these mutualisms persist in nature? If rewards like nectar are offered freely, does this make mutualisms more susceptible to other organisms that take those rewards without providing a service in return?

Wells of yeast in the top tray with only two mutualist species and a cheater showed higher extinction (indicated by the many dark wells). Yeast strains of complex communities and a cheater in the bottom tray showed better growth and less extinction. ©Syracuse University

A team of researchers from the College of Arts and Sciences at Syracuse University, including co-principal investigators Kari Segraves, professor of biology, and David Althoff, associate professor of biology, along with postdoctoral researcher Mayra Vidal, former research assistant professor David Rivers, and Sheng Wang ’20 Ph.D., recently researched that question and the results have been published in this month’s edition of the prestigious journal Science.

They investigated the abilities of simple versus diverse communities of mutualists, comparing how each deal with cheaters. Cheaters are species that steal the benefits of the mutualism without providing anything in return. An example of one of nature’s cheaters are nectar robbers. Nectar-robbing bees chew through the side of flowers to feed on nectar without coming into contact with the flower parts that would result in pollination.

The research team wanted to test if having multiple mutualists with similar roles allows the community as a whole to persist when cheaters take away the mutualists’ resources. The idea was to examine whether having more species involved in a mutualism, such as many pollinator species interacting with many different plant species, made the mutualism less susceptible to the negative effects of cheaters. They also wanted to analyze whether increasing the number of mutualist species allowed all the mutualists to persist or if competition would whittle down the number of mutualists species over time. In essence, the team wanted to understand the forces governing large networks of mutualists that occur in nature.

A&S researchers tested their ideas by producing mutualisms in the lab using yeast strains that function as mutualistic species. These strains were genetically engineered to trade essential food resources. Each strain produced a food resource to exchange with a mutualist partner. They engineered four species of each type of mutualist as well as two cheater strains that were unable to make food resources.

The researchers assembled communities of yeast that differed both in the number of species and the presence of cheaters. They found that communities with higher numbers of mutualist species were better able to withstand the negative effects of cheaters because there were multiple species of mutualists performing the same task. If one species was lost from the community due to competing with a cheater, there were other species around to perform the task, showing that the presence of more species in a community can lessen the negative effects of cheaters.

“It’s similar to thinking about a plant that has many pollinator species,” says Segraves. “If one pollinator species is lost, there are other pollinator species around to pollinate. If a plant only has one species of pollinator that goes extinct, the mutualism breaks down and might cause extinction of the plant.”

Their results highlight the importance of having multiple mutualist species that provide similar resources or services, essentially creating a backup in case one species goes extinct. Segraves compares this phenomenon to the relationship between retailers and consumers. Communities typically have multiple banks, grocery stores, restaurants and hospitals to ensure that there are always goods and services available should something happen to one company or facility, or, as with COVID today, grocery stores now have multiple suppliers to fend off shortages.

Segraves says future research will explore the possibility of a mutualist species becoming a cheater. The group is testing if mutualists that perform the same function might set up an environment that allows one of those mutualist species to become a cheater since there are other mutualists around that can fill that role. They predict that the mutualist species that is experiencing the most competition from the other mutualists will be the species that switches to cheating. They also hope to determine how the mutualists and cheaters evolved over time to provide a deeper understanding of the actual changes that led to differing outcomes in the communities.

References: Mayra C. Vidal, Sheng Pei Wang, David M. Rivers, David M. Althoff, Kari A. Segraves, “Species richness and redundancy promote persistence of exploited mutualisms in yeast”, Science 16 Oct 2020: Vol. 370, Issue 6514, pp. 346-350
DOI: 10.1126/science.abb6703 link: https://science.sciencemag.org/content/370/6514/346

Provided by Syracuse University