Crayfish Species Proves to Be the Ultimate Survivor

ScienceDaily (Aug. 3, 2012) — One of the most invasive species on the planet is able to source food from the land as well as its usual food sources in the water, research from Queen Mary, University of London has found.

Researchers studied red swamp crayfish in Kenya’s Lake Naivasha. They found that when the water level of the lake was low, the crayfish found additional food sources on land. (Credit: © chungking / Fotolia)


Scientists analyzed the  of red swamp crayfish in Kenya’s Lake Naivasha and found that when the water level of the lake was low, the crayfish found additional food sources on land. The study was published in the journal PLoS ONE  August 3, 2012.

Lead author Dr Jonathan Grey from Queen Mary, University of London explained: “These crayfish are incredible survivors; our research shows they are able to feed off terrestrial plants directly, as well as aquatic plants — the first study to demonstrate this.

“It has significant implications for anyone looking to introduce these species in other areas.”

The research team looked at the diet of the crayfish through a technique called stable isotope analysis, where they used a natural chemical signal of diet in the species’ tissues to determine what they were eating.

They found a proportion of the crayfish population had left the main lake and were surviving by burrowing in hippopotamus footprints which left small pools of water. After dark the crayfish clambered out from the footprints and grazed on the surrounding terrestrial plants.

“This study demonstrates how the red swamp crayfish is such an extraordinarily successful invader,” Dr Grey said.

The red swamp crayfish has been introduced to multiple locations throughout East Africa from the 1960s to enhance fisheries and to attempt to control populations of snails which carry a parasite causing river blindness in humans.

“While they are useful to counteract other harmful species in ecosystems, they are also extremely damaging to fish populations and the balance of the food web. They eat plants, fish eggs, fly larvae, snails and leeches and since we have now shown that they are able to tap into extra resources from the land, they can sustain higher populations under adverse conditions such as low water and could cause more of a problem in a variety of environments than we initially thought.”

 

Link:

http://www.eurekalert.org/pub_releases/2012-08/qmuo-csp080112.php

Journal Reference:

  1. Jonathan Grey, Michelle C. Jackson. ‘Leaves and Eats Shoots’: Direct Terrestrial Feeding Can Supplement Invasive Red Swamp Crayfish in Times of Need. PLoS ONE, 2012; 7 (8): e42575 DOI: 10.1371/journal.pone.0042575

Citation:

Queen Mary, University of London (2012, August 3). Crayfish species proves to be the ultimate survivor. ScienceDaily. Retrieved August 5, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120803193804.htm

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Birds That Live With Varying Weather Sing More Versatile Songs

ScienceDaily (Aug. 3, 2012) — A new study of North American songbirds reveals that birds that live with fluctuating weather are more flexible singers.

Northern oriole. Researchers analyzed song recordings from more than 400 male birds spanning 44 species of North American songbirds — a data set that included orioles, blackbirds, warblers, sparrows, cardinals, finches, chickadees and thrushes. (Credit: © Richard L. Carlson / Fotolia)


Mixing it up helps birds ensure that their songs are heard no matter what the habitat, say researchers at Australian National University and the National Evolutionary Synthesis Center.

To test the idea, the researchers analyzed song recordings from more than 400 male birds spanning 44 species of North American songbirds — a data set that included orioles, blackbirds, warblers, sparrows, cardinals, finches, chickadees and thrushes.

They used computer software to convert each sound recording — a medley of whistles, warbles, cheeps, chirps, trills and twitters — into a spectrogram, or sound graph. Like a musical score, the complex pattern of lines and streaks in a spectrogram enable scientists to see and visually analyze each snippet of sound.

For each bird in their data set, they measured song characteristics such as length, highest and lowest notes, number of notes, and the spacing between them.

When they combined this data with temperature and precipitation records and other information such as habitat and latitude, they found a surprising pattern — males that experience more dramatic seasonal swings between wet and dry sing more variable songs.

“They may sing certain notes really low, or really high, or they may adjust the loudness or tempo,” said co-author Clinton Francis of the National Evolutionary Synthesis Center.

The Pyrrhuloxia or desert cardinal from the American southwest and northern Mexico and Lawrence’s goldfinch from California are two examples.

In addition to variation in weather across the seasons, the researchers also looked at geographic variation and found a similar pattern. Namely, species that experience more extreme differences in precipitation from one location to the next across their range sing more complex tunes. House finches and plumbeous vireos are two examples, Francis said.

Why might this be?

“Precipitation is closely related to how densely vegetated the habitat is,” said co-author Iliana Medina of Australian National University. Changing vegetation means changing acoustic conditions.

“Sound transmits differently through different vegetation types,” Francis explained. “Often when birds arrive at their breeding grounds in the spring, for example, there are hardly any leaves on the trees. Over the course of just a couple of weeks, the sound transmission changes drastically as the leaves come in.”

“Birds that have more flexibility in their songs may be better able to cope with the different acoustic environments they experience throughout the year,” Medina added.

A separate team reported similar links between environment and birdsong in mockingbirds in 2009, but this is the first study to show that the pattern holds up across dozens of species.

Interestingly, Francis and Medina found that species with striking color differences between males and females also sing more variable songs, which means that environmental variation isn’t the only factor, the researchers say.

 

Link:

http://www.eurekalert.org/pub_releases/2012-08/nesc-btl080312.php

Journal Reference:

  1. I. Medina, C. D. Francis. Environmental variability and acoustic signals: a multi-level approach in songbirds. Biology Letters, 2012; DOI: 10.1098/rsbl.2012.0522

Citation:

National Evolutionary Synthesis Center (NESCent) (2012, August 3). Birds that live with varying weather sing more versatile songs. ScienceDaily. Retrieved August 5, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120803131930.htm

Irony Seen Through the Eye of MRI

ScienceDaily (Aug. 3, 2012) — In the cognitive sciences, the capacity to interpret the intentions of others is called “Theory of Mind” (ToM). This faculty is involved in the understanding of language, in particular by bridging the gap between the meaning of the words that make up a statement and the meaning of the statement as a whole.

(Credits: Charly Franklin/Getty Images)


In recent years, researchers have identified the neural network dedicated to ToM, but no one had yet demonstrated that this set of neurons is specifically activated by the process of understanding of an utterance. This has now been accomplished: a team from L2C2 (Laboratoire sur le Langage, le Cerveau et la Cognition, Laboratory on Language, the Brain and Cognition, CNRS / Université Claude Bernard-Lyon 1) has shown that the activation of the ToM neural network increases when an individual is reacting to ironic statements.

Published in Neuroimage, these findings represent an important breakthrough in the study of Theory of Mind and linguistics, shedding light on the mechanisms involved in interpersonal communication.

In our communications with others, we are constantly thinking beyond the basic meaning of words. For example, if asked, “Do you have the time?” one would not simply reply, “Yes.” The gap between what is said and what it means is the focus of a branch of linguistics called pragmatics. In this science, “Theory of Mind” (ToM) gives listeners the capacity to fill this gap. In order to decipher the meaning and intentions hidden behind what is said, even in the most casual conversation, ToM relies on a variety of verbal and non-verbal elements: the words used, their context, intonation, “body language,” etc.

Within the past 10 years, researchers in cognitive neuroscience have identified a neural network dedicated to ToM that includes specific areas of the brain: the right and left temporal parietal junctions, the medial prefrontal cortex and the precuneus. To identify this network, the researchers relied primarily on non-verbal tasks based on the observation of others’ behavior[1]. Today, researchers at L2C2 (Laboratoire sur le Langage, le Cerveau et la Cognition, Laboratory on Language, the Brain and Cognition, CNRS / Université Claude Bernard-Lyon 1) have established, for the first time, the link between this neural network and the processing of implicit meanings.

To identify this link, the team focused their attention on irony. An ironic statement usually means the opposite of what is said. In order to detect irony in a statement, the mechanisms of ToM must be brought into play. In their experiment, the researchers prepared 20 short narratives in two versions, one literal and one ironic. Each story contained a key sentence that, depending on the version, yielded an ironic or literal meaning. For example, in one of the stories an opera singer exclaims after a premiere, “Tonight we gave a superb performance.” Depending on whether the performance was in fact very bad or very good, the statement is or is not ironic.

The team then carried out functional magnetic resonance imaging (fMRI) analyses on 20 participants who were asked to read 18 of the stories, chosen at random, in either their ironic or literal version. The participants were not aware that the test concerned the perception of irony. The researchers had predicted that the participants’ ToM neural networks would show increased activity in reaction to the ironic sentences, and that was precisely what they observed: as each key sentence was read, the network activity was greater when the statement was ironic. This shows that this network is directly involved in the processes of understanding irony, and, more generally, in the comprehension of language.

Next, the L2C2 researchers hope to expand their research on the ToM network in order to determine, for example, whether test participants would be able to perceive irony if this network were artificially inactivated.

Note:

[1] For example, Grèzes, Frith & Passingham (J. Neuroscience, 2004) showed a series of short (3.5 second) films in which actors came into a room and lifted boxes. Some of the actors were instructed to act as though the boxes were heavier (or lighter) than they actually were. Having thus set up deceptive situations, the experimenters asked the participants to determine if they had or had not been deceived by the actors in the films. The films containing feigned actions elicited increased activity in the rTPJ (right temporal parietal junction) compared with those containing unfeigned actions.

 

Link:

http://www.alphagalileo.org/ViewItem.aspx?ItemId=122977&CultureCode=en

Journal Reference:

  1. Nicola Spotorno, Eric Koun, Jérôme Prado, Jean-Baptiste Van Der Henst, Ira A. Noveck. Neural evidence that utterance-processing entails mentalizing: The case of irony. NeuroImage, 2012; 63 (1): 25 DOI: 10.1016/j.neuroimage.2012.06.046

Citation:

CNRS (Délégation Paris Michel-Ange) (2012, August 3). Irony seen through the eye of MRI. ScienceDaily. Retrieved August 5, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120803103048.htm

Students With Strong Hearts and Lungs May Make Better Grades

ScienceDaily (Aug. 3, 2012) — Having a healthy heart and lungs may be one of the most important factors for middle school students to make good grades in math and reading, according to findings presented at the American Psychological Association’s 120th Annual Convention.

(Credits: Wesley College)


“Cardiorespiratory fitness was the only factor that we consistently found to have an impact on both boys’ and girls’ grades on reading and math tests,” said study co-author Trent A. Petrie, PhD, professor of psychology and director of the Center for Sport Psychology at the University of North Texas. “This provides more evidence that schools need to re-examine any policies that have limited students’ involvement in physical education classes.”

The researchers gathered data at five Texas middle schools from 1,211 students, of whom 54 percent were female with an average age of about 12. Overall, the group was 57 percent white. Among the boys, the breakdown was 57.2 percent white, 24.2 percent Mexican-American, 9.1 percent African American, 1.1 percent Asian-American and 1.2 percent American Indian. For the girls, 58.6 percent were white, 23.4 percent were Mexican-American, 9.2 percent were African-American, 2.3 percent Asian-American and 0.6 percent were American Indian.

While previous studies have found links between being physically fit and improved academic performance, this study also examined several other potential influences, including self-esteem and social support. It also took into account the students’ socioeconomic status and their self-reported academic ability, Petrie said.

In addition to cardiorespiratory fitness, social support was related to better reading scores among boys, according to the study. It defined social support as reliable help from family and friends to solve problems or deal with emotions. For girls, having a larger body mass index was the only factor other than cardiorespiratory fitness that predicted better reading scores. For boys and girls, cardiorespiratory fitness was the only factor related to their performance on the math tests. “The finding that a larger body mass index for girls was related to better performance on the reading exam may seem counterintuitive, however past studies have found being overweight was not as important for understanding boys and girls performances on tests as was their level of physical fitness,” Petrie said.

From one to five months before the students were to take annual standardized reading and math tests, they answered questions about their level of physical activity, and how they viewed their academic ability, self-esteem and social support. The school district provided information on the students’ socioeconomic status and reading and math scores at the end of the year.

To determine students’ physical fitness, the researchers worked with physical education teachers to administer a fitness assessment program widely used in U.S. schools. The program includes a variety of tests to assess aerobic capacity, muscular strength, muscular endurance, flexibility and body composition. The assessment provides an objective measure of cardiorespiratory fitness through the Progressive Aerobic Cardiovascular Endurance Run, or PACER, and body composition through measuring BMI, the study said.

“Because this is a longitudinal study, these variables can now be considered risk factors in relation to middle school students’ performance on math and reading examinations,” Petrie said. “And that is essential to developing effective programs to support academic success.”

Presentation: “Physical Fitness and Academic Performance: A Longitudinal Investigation,” Sudhish Srikanth, lead author, Trent A. Petrie, PhD, Christy Greenleaf, PhD, and Scott Martin, PhD, University of North Texas; Session 2120, Friday, Aug. 3, 10 — 10:50 a.m. Convention Center, Room W310A, Level III.

 

Link:

http://www.apa.org/news/press/releases/2012/08/better-grades.aspx

Citation:

American Psychological Association (APA) (2012, August 3). Students with strong hearts and lungs may make better grades. ScienceDaily. Retrieved August 5, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120803102933.htm

Bilingualism ‘Can Increase Mental Agility’

ScienceDaily (Aug. 3, 2012) — Bilingual children outperform children who speak only one language in problem-solving skills and creative thinking, according to research led at the University of Strathclyde.

(Credits: Marzanna Syncerz from  Fotolia.com )


A study of primary school pupils who spoke English or Italian- half of whom also spoke Gaelic or Sardinian- found that the bilingual children were significantly more successful in the tasks set for them. The Gaelic-speaking children were, in turn, more successful than the Sardinian speakers.

The differences were linked to the mental alertness required to switch between languages, which could develop skills useful in other types of thinking. The further advantage for Gaelic-speaking children may have been due to the formal teaching of the language and its extensive literature.

In contrast, Sardinian is not widely taught in schools on the Italian island and has a largely oral tradition, which means there is currently no standardised form of the language.

Dr Fraser Lauchlan, an Honorary Lecturer at the University of Strathclyde’s School of Psychological Sciences & Health, led the research. It was conducted with colleagues at the University of Cagliari in Sardinia, where he is a Visiting Professor.

Dr Lauchlan said: “Bilingualism is now largely seen as being beneficial to children but there remains a view that it can be confusing, and so potentially detrimental to them.

“Our study has found that it can have demonstrable benefits, not only in language but in arithmetic, problem solving and enabling children to think creatively. We also assessed the children’s vocabulary, not so much for their knowledge of words as their understanding of them. Again, there was a marked difference in the level of detail and richness in description from the bilingual pupils.

“We also found they had an aptitude for selective attention- the ability to identify and focus on information which is important, while filtering out what is not- which could come from the ‘code-switching’ of thinking in two different languages.”

In the study, a total of 121 children in Scotland and Sardinia- 62 of them bilingual- were set tasks in which they were asked to reproduce patterns of coloured blocks, to repeat orally a series of numbers, to give clear definitions of words and to resolve mentally a set of arithmetic problems. The tasks were all set in English or Italian and the children taking part were aged around nine.

During the research, Dr Lauchlan’s post at the University of Cagliari was funded by the Sardinian Regional Government (Regione Autonoma della Sardegna).

 

Link:

http://www.alphagalileo.org/ViewItem.aspx?ItemId=122967&CultureCode=en

Journal Reference:

  1. F. Lauchlan, M. Parisi, R. Fadda. Bilingualism in Sardinia and Scotland: Exploring the cognitive benefits of speaking a ‘minority’ language. International Journal of Bilingualism, 2012; DOI: 10.1177/1367006911429622

Citation:

University of Strathclyde (2012, August 3). Bilingualism ‘can increase mental agility’. ScienceDaily. Retrieved August 5, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120803082915.htm

Speaking Multiple Languages Can Influence Children’s Emotional Development

ScienceDaily (Aug. 2, 2012) — On the classic TV show “I Love Lucy,” Ricky Ricardo was known for switching into rapid-fire Spanish whenever he was upset, despite the fact Lucy had no idea what her Cuban husband was saying. These scenes were comedy gold, but they also provided a relatable portrayal of the linguistic phenomenon of code-switching.

(Credits: PsychCentral)


This kind of code-switching, or switching back and forth between different languages, happens all the time in multilingual environments, and often in emotional situations. In a new article in the July issue of Perspectives on Psychological Science, a journal of the Association for Psychological Science, psychological scientists Stephen Chen and Qing Zhou of the University of California, Berkeley and Morgan Kennedy of Bard College delve deeper into this linguistic phenomenon.

Drawing on research from psychology and linguistics, the researchers seek to better understand how using different languages to discuss and express emotions in a multilingual family might play an important role in children’s emotional development. They propose that the particular language parents choose to use when discussing and expressing emotion can have significant impacts on children’s emotional understanding, experience, and regulation.

“Over the past few years, there’s been a steadily growing interest in the languages multilingual individuals use to express emotions,” says Chen. “We were interested in the potential clinical and developmental implications of emotion-related language shifts, particularly within the context of the family.”

Existing research from psychological science underscores the fact that language plays a key role in emotion because it allows the speakers to articulate, conceal, or discuss feelings. When parents verbally express their emotions, they contribute to their children’s emotional development by providing them a model of how emotions can be articulated and regulated.

When parents discuss emotion, they help their children to accurately label and consequently understand their own emotions. This explicit instruction can further help children to better regulate their emotions.

Additionally, research from linguistics suggests that when bilingual individuals switch languages, the way they experience emotions changes as well. Bilingual parents may use a specific language to express an emotional concept because they feel that language provides a better cultural context for expressing the emotion. For example, a native Finnish speaker may be more likely to use English to tell her children that she loves them because it is uncommon to explicitly express emotions in Finnish.

Thus, the language that a parent chooses to express a particular concept can help to provide cues that reveal his or her emotional state. Language choice may also influence how children experience emotion, such expressions can potentially elicit a greater emotional response when spoken in the child’s native language. Shifting from one language to another may help children to regulate their emotional response by using a less emotional, non-native language as a way to decrease negative arousal, or to help model culture specific emotional regulation.

Overall, the authors argue that research from psychological science and linguistics suggests that a child’s emotional competence is fundamentally shaped by a multilingual environment. These findings may be particularly useful in the development of intervention programs for immigrant families, helping intervention staff to be aware of how the use of different languages in various contexts can have an emotional impact.

“Our aim in writing this review was to highlight what we see as a rich new area of cross-disciplinary research,” says Chen. “We’re especially excited to see how the implications of emotion-related language switching can be explored beyond the parent-child dyad — for example, in marital interactions, or in the context of therapy and other interventions.”

Deep-Sea Squid Can ‘Jettison Arms’ as Defensive Tactic

ScienceDaily (Aug. 2, 2012) — A postdoctoral researcher at the University of Rhode Island has observed a never-before-seen defensive strategy used by a small species of deep-sea squid in which the animal counter-attacks a predator and then leaves the tips of its arms attached to the predator as a distraction.

Still image from video of the discovery. (Credit: Monterey Bay Aquarium Research Institute)


Stephanie Bush said that when the foot-long octopus squid (Octopoteuthis deletron) found deep in the northeast Pacific Ocean “jettisons its arms” in self-defense, the bioluminescent tips continue to twitch and glow, creating a diversion that enables the squid to escape from predators.

“If a predator is trying to attack them, they may dig the hooks on their arms into the predator’s skin. Then the squid jets away and leaves its arm tips stuck to the predator,” explained Bush. “The wriggling, bioluminescing arms might give the predator pause enough to allow the squid to get away.”

The discovery was published in the July issue of the journal Marine Ecology Progress Series.

While Bush was a graduate researcher working with the Midwater Ecology Lab at the Monterey Bay Aquarium Research Institute, she observed that many octopus squid had arms of different lengths. Scientists had speculated that they may release their arms, just as lizards can release their tails when attacked, but no one had seen it happen. Using a remotely operated vehicle in the Monterey Bay Submarine Canyon off the coast of California, Bush poked at a squid with a bottlebrush.

“The very first time we tried it, the squid spread its arms wide and it was lighting up like fireworks,” she said. “It then came forward and grabbed the bottlebrush and jetted backwards, leaving two arms on the bottlebrush. We think the hooks on its arms latched onto the bristles of the brush, and that was enough for the arms to just pop off.”

The squid are able to re-grow their missing arms.

“There is definitely an energy cost associated with this behavior, but the cost is less than being dead,” Bush said.

In further experiments, Bush found that some octopus squid appeared hesitant to sacrifice their limbs, but some did so after being prodded several times. When she provoked seven other squid species similarly, none dropped their arm tips.

Bush’s research on squid began in 2003 when she decided to investigate the assumptions that some scientists had made about deep-sea animals.

“Scientists had assumed that squid living in the deep-sea would not release ink as a defensive measure, but all the species I’ve observed did release ink,” she said. “They assumed that because they’re in the dark all day every day that they’re not doing the same things that shallow water squids are doing. They also assumed that deep-sea squid don’t change color because of the dark, but they do.”

The URI scientist’s current research focuses on a tiny squid that lives in the Gulf of California that migrates every day from the dark depths where there is little oxygen to the surface waters to feed. She is examining their oxygen consumption rates and how increasing water temperatures will affect their survival.

“They’re a really abundant species in the Gulf, so presumably if they are that abundant, they must be feeding on lots of different things and there must be lots of things feeding on them,” Bush said. “They could be very important to the health of the ecosystem.”

 

Link:

http://www.eurekalert.org/pub_releases/2012-08/uori-dsc080212.php

Journal Reference:

  1. SL Bush. Economy of arm autotomy in the mesopelagic squid Octopoteuthis deletron. Marine Ecology Progress Series, 2012; 458: 133 DOI: 10.3354/meps09714

Citation:

University of Rhode Island (2012, August 2). Deep-sea squid can ‘jettison arms’ as defensive tactic. ScienceDaily. Retrieved August 5, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120802150437.htm

 

How Elephants Produce Their Deep ‘Voices’: Same Physical Mechanism Produces Vocalizations in Elephants and Humans

ScienceDaily (Aug. 2, 2012) — African elephants are known to be great communicators that converse with extremely low-pitched vocalizations, known as infrasounds, over a distance of miles. These infrasounds occupy a very low frequency range — fewer than 20 Hertz, or cycles, per second — that is generally below the threshold of human hearing.

African elephants are known to be great communicators that converse with extremely low-pitched vocalizations, known as infrasounds, over a distance of miles. (Credit: © catfish07 / Fotolia)


Now, a new study shows that elephants rely on the same mechanism that produces speech in humans (and the vocalizations of many other mammals) to hit those extremely low notes. Christian Herbst from the University of Vienna, along with colleagues from Germany, Austria and the United States, used the larynx of a recently deceased elephant to recreate some elephant infrasounds in a laboratory.

Their findings are published in the 3 August issue of the journal Science, which is published by AAAS, the nonprofit science society.

“These vocalizations are called infrasounds because their fundamental frequency is below the range of human hearing,” explained Herbst during a phone interview. “We only hear the harmonics of such sounds, or multiples of that fundamental frequency. If an elephant’s vocal folds were to clap together at 10 Hertz, for example, we would perceive some energy in that sound at 20, 30, 40 Hertz and so on. But these higher overtones are usually weaker in amplitude.”

Until now, researchers have wondered whether these low, rumbling elephant infrasounds were created by intermittent muscle contractions, as a cat’s purr is, or by flow-induced vocal fold vibrations, fueled by air from the lungs, as is a human’s voice. But, the natural death of an elephant at a zoo in Berlin gave Herbst and his colleagues a somewhat serendipitous chance to study the mechanism firsthand.

The researchers removed the elephant’s larynx and froze it within a few hours of the animal’s death. They then took it over to the larynx laboratory in the Department of Cognitive Biology at the University of Vienna, where Tecumseh Fitch, a senior author of the Science paper, studied it in depth.

Herbst and the other researchers imitated the elephant’s lungs by blowing controlled streams of warm, humid air through the excised larynx while adjusting the elephant vocal folds into a phonatory, or vocal-ready, position. In this way, the scientists were able to coax the vocal folds into a periodic, low-frequency vibration that matched an elephant’s infrasound in every detail.

The fact that they were able to duplicate the elephant’s infrasounds in a laboratory demonstrates that the animals rely on a myoelastic-aerodynamic, or “flow-driven,” mode of speech to communicate in the wild. The elephant’s brain would have been required to recurrently tense and relax the vocal muscles if the other mechanism, which produces a cat’s purr, was involved, they say.

This flow-induced mechanism demonstrated by the researchers is likely to be employed by a wide range of mammals. From echolocating bats with their incredibly high vocalizations to African elephants and their extremely low-pitched infrasounds, this mode of voice production seems to span four to five orders of magnitude across a wide range of body sizes and sonic frequencies.

The researchers also saw some interesting “nonlinear phenomena” in the way the elephant vocal folds vibrated. These mostly irregular patterns of vibration occur when babies cry or heavy metal singers scream and the physical mechanism that elephants use is again identical to that seen in humans, they say.

“If I scream, it’s no longer a periodic vibration,” said Herbst. “It becomes chaotic and you can hear a certain degree of roughness. This can also be observed in young elephants, in situations of high excitement.”

Herbst says that the findings were only made possible by a collaborative effort between voice scientists and biologists, and that voice science is an essential aspect of our social and economic lives.

Link:

http://www.eurekalert.org/pub_releases/2012-08/aaft-ssh080212.php

Journal Reference:

  1. C. T. Herbst, A. S. Stoeger, R. Frey, J. Lohscheller, I. R. Titze, M. Gumpenberger, W. T. Fitch. How Low Can You Go? Physical Production Mechanism of Elephant Infrasonic Vocalizations. Science, 2012; 337 (6094): 595 DOI: 10.1126/science.1219712

Citation:

American Association for the Advancement of Science (2012, August 2). How elephants produce their deep ‘voices’: Same physical mechanism produces vocalizations in elephants and humans. ScienceDaily. Retrieved August 5, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120802141527.htm

Cuckoo Tricks to Beat the Neighborhood Watch

ScienceDaily (Aug. 2, 2012) — To minimise the chance of being recognised and thus attacked by the birds they are trying to parasitize, female cuckoos have evolved different guises. The new research, funded by the Natural Environment Research Council, was published August 3, in the journal Science.

Common Cuckoo in flight, Cuculus canorus. (Credit: © FLORIAN ANDRONACHE / Fotolia)


The common cuckoo (Cuculus canorus) lays its eggs in the nests of other birds. On hatching, the young cuckoo ejects the host’s eggs and chicks from the nest, so the hosts end up raising a cuckoo chick rather than a brood of their own. To fight back, reed warblers (a common host across Europe) have a first line of defence: they attack, or ‘mob’, the female cuckoo, which reduces the chance that their nest is parasitized.

Some female common cuckoos are grey and hawk-like, and previous research has shown that their resemblance to hawks reduces host bird attack. However, other females are bright rufous (brownish-red). The presence of alternate colour morphs in the same species is rare in birds, but frequent among the females of parasitic cuckoo species. The new research shows that this is another cuckoo trick: cuckoos combat reed warbler mobbing by coming in different guises.

Cuckoos are secretive. To widen their source of information about local cuckoo activity, reed warblers eavesdrop on the mobbing behaviour of their neighbours. In the study, the researchers manipulated local frequencies of the more common grey colour cuckoo and the less common (in the United Kingdom) rufous colour cuckoo by placing models of the birds at neighbouring nests. They then recorded how the experience of watching neighbours mob changed reed warbler responses back at their own nest.

They found that reed warblers increased their mobbing, but only to the cuckoo morph that their neighbours had mobbed. Therefore, as one cuckoo morph increases in frequency, local host populations will become alerted specifically to that morph. This means the alternate morph will be more likely to slip past host defences and lay undetected. This is the first time that ‘social learning’ has been documented in the evolution of mimicry as well as the evolution of different observable characteristics — such as colour — in the same species (called polymorphism).

Dr Rose Thorogood, of the University of Cambridge and co-author on the paper, said: “When mimetic disguises become less effective, evolving a polymorphism can be a successful trick. Our research shows that individuals assess disguises not only from personal experience, but also by observing others. However, because their learning is so specific, this social learning then selects for alternative cuckoo disguises and the arms race continues.”

Professor Nick Davies, of the University of Cambridge and co-author on the paper, added: “It’s well known that cuckoos have evolved various egg types which mimic those of their hosts in order to combat rejection. This research shows that cuckoos have also evolved alternate female morphs to sneak through the hosts’ defences. This explains why many species which use mimicry, such as the cuckoo, evolve different guises.”

 

Link:

http://www.eurekalert.org/pub_releases/2012-08/uoc-ctt080112.php

Journal Reference:

  1. Rose Thorogood and    Nicholas B. Davies. Cuckoos Combat Socially Transmitted Defenses of Reed Warbler Hosts with a Plumage Polymorphism. Science, 3 August 2012: 578-580 DOI: 10.1126/science.1220759

Citation:

University of Cambridge (2012, August 2). Cuckoo tricks to beat the neighborhood watch. ScienceDaily. Retrieved August 5, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120802141525.htm