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Fighting Australian Crayfish Do Not Forget The Face Of Foes:

The fighting Australian yabby, a type of crayfish, smaller than a lobster but similar in appearance, does not forget the face of its foes says new research from University of Melbourne zoologists. The two year study involving over 100 pairs of yabbies revealed that the species Cherax destructor is capable of facial recognition of individuals, particularly its opponents.

Why Juniper Trees Can Live On Less Water:

An ability to avoid the plant equivalent of vapor lock and a favorable evolutionary history may explain the unusual drought resistance of junipers, some varieties of which are now spreading rapidly in water-starved regions of the western United States, a Duke University study has found.

New Theory For Dogfish And Skate Population Outburst, Off New England Shore, US:

New research by scientists at the University of Maryland Center for Environmental Science Chesapeake Biological Laboratory questions the long-held belief that a lack of predators and competitors was the primary cause for the increase of skates and dogfish observed in Southern New England’s George’s Bank following overfishing of commercially important species in the 1980’s.

Evidence Of ‘Rain-making’ Bacteria Discovered In Atmosphere And Snow:

Brent Christner, LSU professor of biological sciences, in partnership with colleagues in Montana and France, recently found evidence that rain-making bacteria are widely distributed in the atmosphere. These biological particles could factor heavily into the precipitation cycle, affecting climate, agricultural productivity and even global warming. Christner and his colleagues published their results on Feb 29 in the journal Science.

Building Brains: Mammalian-like Neurogenesis In Fruit Flies:

The nerve cells in the brain of Drosophila are generated by neural stem cell-like progenitor cells called neuroblasts. In the currently accepted model of neurogenesis, these neuroblast divide asymmetrically both to self renew and to produce a smaller progenitor cell. This smaller cell then divides only once into two daughter cells, which receive cell fate determinants, causing them to exit the cell cycle and differentiate into postmitotic neural cells.

Enormous Jurassic Sea Predator, Pliosaur, Discovered In Norway:

Natural History Museum in Oslo, Norway has announced the discovery of one of the largest dinosaur-era marine reptiles ever found – an enormous sea predator known as a pliosaur estimated to be almost 15 meters (50 feet) feet long.

Chimps May Have A ‘Language-ready’ Brain:

An area of the brain involved in the planning and production of spoken and signed language in humans plays a similar role in chimpanzee communication, researchers report.

What Caused Westward Expansion In The United States?:

Western Expansion during the nineteenth century was an important determinant of geographic distribution and economic activity in the United States today. However, while explanations abound for why the migration occurred– from the low price of land to a pioneering spirit — little empirical work has been done to determine which specific market forces were the most important drivers.

Two of the papers published today in PLoS Genetics (now on the TOPAZ platform) got my attention:
Redundant Function of REV-ERBα and β and Non-Essential Role for Bmal1 Cycling in Transcriptional Regulation of Intracellular Circadian Rhythms:

Circadian clocks in plants, fungi, insects, and mammals all share a common transcriptional network architecture. At the cellular level, the mammalian clockwork consists of a core Per/Cry negative feedback loop and additional interlocking loops. We wished to address experimentally the contribution of the interlocking Bmal1 loop to clock function in mammals. Because behavioral rhythms do not always reflect cell-autonomous phenotypes and are subject to pleiotropic effects, we employed cell-based genetic approaches and monitored rhythms longitudinally using bioluminescent reporters of clock gene expression. We showed that REV-ERB repressors play a more prominent role than ROR activators in regulating the Bmal1 rhythm. However, significant rhythmicity remains even with constitutive expression of Bmal1, pointing to the resilience of the core loop to perturbations of the Bmal1 loop. We conclude that while the interlocking loop contributes to fine-tuning of the core loop, its primary function is to provide discrete waveforms of clock gene expression for control of local physiology. This study has important general implications not only for circadian biology across species, but also for the emerging field of systems biology that seeks to understand complex interactions in genetic networks.

Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken:

Many bird species possess yellow skin and legs whereas other species have white or black skin color. Yellow or white skin is due to the presence or absence of carotenoids. The genetic basis underlying this diversity is unknown. Domestic chickens with yellow skin are homozygous for a recessive allele, and white skinned chickens carry the dominant allele. As a result, chickens represent an ideal model for analyzing genetic mechanism responsible for skin color variation. In this study we demonstrate that yellow skin is caused by regulatory mutation(s) that inhibit expression of the beta-carotene dioxygenase 2 (BCDO2) enzyme in skin, but not in other tissues. Because BCDO2 cleaves colorful carotenoids into colorless apocarotenoids, a reduction in expression of this gene produces yellow skin. This study also provides the first conclusive evidence of a hybrid origin of the domestic chicken. It has been generally assumed that the red junglefowl is the sole ancestor of the domestic chicken. A phylogenetic analysis, however, demonstrates that though the white skin allele originates from the red junglefowl, the yellow skin allele originates from a different species, most likely the grey junglefowl. This result significantly advances our understanding of chicken domestication.

Greg Laden explains.

This Is Your Brain On Jazz: Researchers Use MRI To Study Spontaneity, Creativity:

A pair of Johns Hopkins and government scientists have discovered that when jazz musicians improvise, their brains turn off areas linked to self-censoring and inhibition, and turn on those that let self-expression flow.

More coverage from Smooth Pebbles, Mind Hacks, Wired Science, Neurophilosophy, Science A Go Go, PsychCentral and The Rehearsal Studio
Evolution Of Aversion: Why Even Children Are Fearful Of Snakes:

Some of the oldest tales and wisest mythology allude to the snake as a mischievous seducer, dangerous foe or powerful iconoclast; however, the legend surrounding this proverbial predator may not be based solely on fantasy. As scientists from the University of Virginia recently discovered, the common fear of snakes is most likely intrinsic.

By Sixth Grade Nearly One In Six Children Are Alcohol Users, Study Shows:

A study by the University of Minnesota School of Public Health and the University of Florida suggests that ‘tweens’ should receive alcohol prevention programs prior to sixth grade, when nearly one in six children are already alcohol users.

Chad Orzel comments.
Polluted Prey Causes Wild Birds To Change Their Tune:

Considerable attention has been paid to the effects of endocrine disrupting chemicals in aquatic environments, but rather less attention has been given to routes of contamination on land. A new study by researchers at Cardiff University, reveals that wild birds foraging on invertebrates contaminated with environmental pollutants, show marked changes in both brain and behaviour: male birds exposed to this pollution develop more complex songs, which are actually preferred by the females, even though these same males usually show reduced immune function compared to controls.

Catching Rats’ Twitchy Whiskers In Action:

Rats use their whiskers in a way that is closely related to the human sense of touch: Just as humans move their fingertips across a surface to perceive shapes and textures, rats twitch their whiskers to achieve the same goal. Now, in a finding that could help further understanding of perception across species, MIT neuroscientists have used high-speed video to reveal rat whiskers in action and show the tiny movements that underlie the rat’s perception of its tactile environment.

Spread Of Bird Flu Strains Slowed At Some Borders:

Several strains of the bird flu virus that raged across southern China were blocked from entering Thailand and Vietnam, UC Irvine researchers have discovered. This first-ever statistical analysis of influenza A H5N1’s genetic diversity helps scientists better understand how the virus migrates and could, in the future, help health officials determine whether efforts to thwart its spread were successful.

From Sharks To Microbes, Key Data At Central Pacific’s Line Islands Archipelago Captured:

An ambitious expedition led by scientists at Scripps Institution of Oceanography at UC San Diego to a chain of little-known islands in the central Pacific Ocean has yielded an unprecedented wealth of information about coral reefs and threats from human activities. The exploration of four atolls in the Line Islands, part of a chain approximately a thousand miles south of Hawaii, has produced the first study of coral reefs comprehensively spanning organisms from microbes to sharks. This in-depth description was replicated across a gradient of human impacts, from uninhabited Kingman Reef to Kiritimati, also called Christmas Island, with a population of 5,000 people.

More from Resilience Science

Bats Use Magnetic Substance As Internal Compass To Help Them Navigate:

They may not be on most people’s list of most attractive species, but bats definitely have animal magnetism. Researchers from the Universities of Leeds and Princeton have discovered that bats use a magnetic substance in their body called magnetite as an ‘internal compass’ to help them navigate.

Or, if you prefer a much livelier take, with context, check out Pondering Pikaia
Why Do We Love Babies? Parental Instinct Region Found In The Brain:

Why do we almost instinctively treat babies as special, protecting them and enabling them to survive? Darwin originally pointed out that there is something about infants which prompts adults to respond to and care for them which allows our species to survive. Nobel-Prize-winning zoologist Konrad Lorenz proposed that it is the specific structure of the infant face, including a relatively large head and forehead, large and low lying eyes and bulging cheek region, that serves to elicit these parental responses. But the biological basis for this has remained elusive.

Dave Munger explains.
Antidepressants Only Benefit Certain Depressed Patients, Study Suggests:

A new study suggests that antidepressants only benefit some, very severely depressed patients. “New generation” antidepressants, such as fluoxetine (Prozac) are widely prescribed for the treatment of clinical depression. However some studies have suggested that these drugs do not help the majority of depressed people get better by very much. Irving Kirsch, from the University of Hull, and his colleagues, studied this question in closer detail, looking at whether a patient’s response to antidepressant therapy depends on how badly depressed they are to start out with.

More coverage by Ben Goldacre, David Dobbs, Kevin Drum, James Hrynyshyn, Henry Gee, Greg Laden, Jonah Lehrer and Socratic Gadfly.
How Skin Color Is Determined:

Skin color is one of the most visible indicators that helps distinguish human appearance, and a new study provides more detail as to how one protein helps produce this wide palette.

Children Who Do Not Get Enough Sleep Sustain More Injuries:

Lack of adequate sleep can lead to increased injuries among preschool children, new research shows. This study shows that the average number of injuries during the preschool years is two times higher for children who don’t get enough sleep each day as described by their mothers.

Lemurs’ Evolutionary History May Shed Light On Our Own:

After swabbing the cheeks of more than 200 lemurs and related primates to collect their DNA, researchers at the Duke Institute for Genome Sciences & Policy (IGSP) and Duke Lemur Center now have a much clearer picture of their evolutionary family tree.

There are 48 new articles published this week in PLoS ONE. It’s hard to choose just a couple to highlight, so look around for what interests you (avian flu, the Plague?). How about these titles that piqued my interest:
Neural Substrates of Spontaneous Musical Performance: An fMRI Study of Jazz Improvisation:

To investigate the neural substrates that underlie spontaneous musical performance, we examined improvisation in professional jazz pianists using functional MRI. By employing two paradigms that differed widely in musical complexity, we found that improvisation (compared to production of over-learned musical sequences) was consistently characterized by a dissociated pattern of activity in the prefrontal cortex: extensive deactivation of dorsolateral prefrontal and lateral orbital regions with focal activation of the medial prefrontal (frontal polar) cortex. Such a pattern may reflect a combination of psychological processes required for spontaneous improvisation, in which internally motivated, stimulus-independent behaviors unfold in the absence of central processes that typically mediate self-monitoring and conscious volitional control of ongoing performance. Changes in prefrontal activity during improvisation were accompanied by widespread activation of neocortical sensorimotor areas (that mediate the organization and execution of musical performance) as well as deactivation of limbic structures (that regulate motivation and emotional tone). This distributed neural pattern may provide a cognitive context that enables the emergence of spontaneous creative activity.

A Specific and Rapid Neural Signature for Parental Instinct:

Darwin originally pointed out that there is something about infants which prompts adults to respond to and care for them, in order to increase individual fitness, i.e. reproductive success, via increased survivorship of one’s own offspring. Lorenz proposed that it is the specific structure of the infant face that serves to elicit these parental responses, but the biological basis for this remains elusive. Here, we investigated whether adults show specific brain responses to unfamiliar infant faces compared to adult faces, where the infant and adult faces had been carefully matched across the two groups for emotional valence and arousal, as well as size and luminosity. The faces also matched closely in terms of attractiveness. Using magnetoencephalography (MEG) in adults, we found that highly specific brain activity occurred within a seventh of a second in response to unfamiliar infant faces but not to adult faces. This activity occurred in the medial orbitofrontal cortex (mOFC), an area implicated in reward behaviour, suggesting for the first time a neural basis for this vital evolutionary process. We found a peak in activity first in mOFC and then in the right fusiform face area (FFA). In mOFC the first significant peak (p<0.001) in differences in power between infant and adult faces was found at around 130 ms in the 10-15 Hz band. These early differences were not found in the FFA. In contrast, differences in power were found later, at around 165 ms, in a different band (20-25 Hz) in the right FFA, suggesting a feedback effect from mOFC. These findings provide evidence in humans of a potential brain basis for the "innate releasing mechanisms" described by Lorenz for affection and nurturing of young infants. This has potentially important clinical applications in relation to postnatal depression, and could provide opportunities for early identification of families at risk.

Time Pressure Modulates Electrophysiological Correlates of Early Visual Processing:

Reactions to sensory events sometimes require quick responses whereas at other times they require a high degree of accuracy-usually resulting in slower responses. It is important to understand whether visual processing under different response speed requirements employs different neural mechanisms. We asked participants to classify visual patterns with different levels of detail as real-world or non-sense objects. In one condition, participants were to respond immediately, whereas in the other they responded after a delay of 1 second. As expected, participants performed more accurately in delayed response trials. This effect was pronounced for stimuli with a high level of detail. These behavioral effects were accompanied by modulations of stimulus related EEG gamma oscillations which are an electrophysiological correlate of early visual processing. In trials requiring speeded responses, early stimulus-locked oscillations discriminated real-world and non-sense objects irrespective of the level of detail. For stimuli with a higher level of detail, oscillatory power in a later time window discriminated real-world and non-sense objects irrespective of response speed requirements. Thus, it seems plausible to assume that different response speed requirements trigger different dynamics of processing.

Generalization Mediates Sensitivity to Complex Odor Features in the Honeybee:

Animals use odors as signals for mate, kin, and food recognition, a strategy which appears ubiquitous and successful despite the high intrinsic variability of naturally-occurring odor quantities. Stimulus generalization, or the ability to decide that two objects, though readily distinguishable, are similar enough to afford the same consequence [1], could help animals adjust to variation in odor signals without losing sensitivity to key inter-stimulus differences. The present study was designed to investigate whether an animal’s ability to generalize learned associations to novel odors can be influenced by the nature of the associated outcome. We use a classical conditioning paradigm for studying olfactory learning in honeybees [2] to show that honeybees conditioned on either a fixed- or variable-proportion binary odor mixture generalize learned responses to novel proportions of the same mixture even when inter-odor differences are substantial. We also show that the resulting olfactory generalization gradients depend critically on both the nature of the stimulus-reward paradigm and the intrinsic variability of the conditioned stimulus. The reward dependency we observe must be cognitive rather than perceptual in nature, and we argue that outcome-dependent generalization is necessary for maintaining sensitivity to inter-odor differences in complex olfactory scenes.

Memory in Microbes: Quantifying History-Dependent Behavior in a Bacterium:

Memory is usually associated with higher organisms rather than bacteria. However, evidence is mounting that many regulatory networks within bacteria are capable of complex dynamics and multi-stable behaviors that have been linked to memory in other systems. Moreover, it is recognized that bacteria that have experienced different environmental histories may respond differently to current conditions. These “memory” effects may be more than incidental to the regulatory mechanisms controlling acclimation or to the status of the metabolic stores. Rather, they may be regulated by the cell and confer fitness to the organism in the evolutionary game it participates in. Here, we propose that history-dependent behavior is a potentially important manifestation of memory, worth classifying and quantifying. To this end, we develop an information-theory based conceptual framework for measuring both the persistence of memory in microbes and the amount of information about the past encoded in history-dependent dynamics. This method produces a phenomenological measure of cellular memory without regard to the specific cellular mechanisms encoding it. We then apply this framework to a strain of Bacillus subtilis engineered to report on commitment to sporulation and degradative enzyme (AprE) synthesis and estimate the capacity of these systems and growth dynamics to ‘remember’ 10 distinct cell histories prior to application of a common stressor. The analysis suggests that B. subtilis remembers, both in short and long term, aspects of its cell history, and that this memory is distributed differently among the observables. While this study does not examine the mechanistic bases for memory, it presents a framework for quantifying memory in cellular behaviors and is thus a starting point for studying new questions about cellular regulation and evolutionary strategy.

Crayfish Recognize the Faces of Fight Opponents:

The capacity to associate stimuli underlies many cognitive abilities, including recognition, in humans and other animals. Vertebrates process different categories of information separately and then reassemble the distilled information for unique identification, storage and recall. Invertebrates have fewer neural networks and fewer neural processing options so study of their behavior may reveal underlying mechanisms still not fully understood for any animal. Some invertebrates form complex social colonies and are capable of visual memory-bees and wasps, for example. This ability would not be predicted in species that interact in random pairs without strong social cohesion; for example, crayfish. They have chemical memory but the extent to which they remember visual features is unknown. Here we demonstrate that the crayfish Cherax destructor is capable of visual recognition of individuals. The simplicity of their interactions allowed us to examine the behavior and some characteristics of the visual features involved. We showed that facial features are learned during face-to-face fights, that highly variable cues are used, that the type of variability is important, and that the learning is context-dependent. We also tested whether it is possible to engineer false identifications and for animals to distinguish between twin opponents.

The Blind Watchmaker Network: Scale-Freeness and Evolution:

It is suggested that the degree distribution for networks of the cell-metabolism for simple organisms reflects a ubiquitous randomness. This implies that natural selection has exerted no or very little pressure on the network degree distribution during evolution. The corresponding random network, here termed the blind watchmaker network has a power-law degree distribution with an exponent γ≥2. It is random with respect to a complete set of network states characterized by a description of which links are attached to a node as well as a time-ordering of these links. No a priory assumption of any growth mechanism or evolution process is made. It is found that the degree distribution of the blind watchmaker network agrees very precisely with that of the metabolic networks. This implies that the evolutionary pathway of the cell-metabolism, when projected onto a metabolic network representation, has remained statistically random with respect to a complete set of network states. This suggests that even a biological system, which due to natural selection has developed an enormous specificity like the cellular metabolism, nevertheless can, at the same time, display well defined characteristics emanating from the ubiquitous inherent random element of Darwinian evolution. The fact that also completely random networks may have scale-free node distributions gives a new perspective on the origin of scale-free networks in general.

Quantifying Variability of Avian Colours: Are Signalling Traits More Variable?:

Increased variability in sexually selected ornaments, a key assumption of evolutionary theory, is thought to be maintained through condition-dependence. Condition-dependent handicap models of sexual selection predict that (a) sexually selected traits show amplified variability compared to equivalent non-sexually selected traits, and since males are usually the sexually selected sex, that (b) males are more variable than females, and (c) sexually dimorphic traits more variable than monomorphic ones. So far these predictions have only been tested for metric traits. Surprisingly, they have not been examined for bright coloration, one of the most prominent sexual traits. This omission stems from computational difficulties: different types of colours are quantified on different scales precluding the use of coefficients of variation. Based on physiological models of avian colour vision we develop an index to quantify the degree of discriminable colour variation as it can be perceived by conspecifics. A comparison of variability in ornamental and non-ornamental colours in six bird species confirmed (a) that those coloured patches that are sexually selected or act as indicators of quality show increased chromatic variability. However, we found no support for (b) that males generally show higher levels of variability than females, or (c) that sexual dichromatism per se is associated with increased variability. We show that it is currently possible to realistically estimate variability of animal colours as perceived by them, something difficult to achieve with other traits. Increased variability of known sexually-selected/quality-indicating colours in the studied species, provides support to the predictions borne from sexual selection theory but the lack of increased overall variability in males or dimorphic colours in general indicates that sexual differences might not always be shaped by similar selective forces.

Frequency and Density-Dependent Selection on Life-History Strategies – A Field Experiment:

Negative frequency-dependence, which favors rare genotypes, promotes the maintenance of genetic variability and is of interest as a potential explanation for genetic differentiation. Density-dependent selection may also promote cyclic changes in frequencies of genotypes. Here we show evidence for both density-dependent and negative frequency-dependent selection on opposite life-history tactics (low or high reproductive effort, RE) in the bank vole (Myodes glareolus). Density-dependent selection was evident among the females with low RE, which were especially favored in low densities. Instead, both negative frequency-dependent and density-dependent selection were shown in females with high RE, which were most successful when they were rare in high densities. Furthermore, selection at the individual level affected the frequencies of tactics at the population level, so that the frequency of the rare high RE tactic increased significantly at high densities. We hypothesize that these two selection mechanisms (density- and negative frequency-dependent selection) may promote genetic variability in cyclic mammal populations. Nevertheless, it remains to be determined whether the origin of genetic variance in life-history traits is causally related to density variation (e.g. population cycles).

Effectiveness of Journal Ranking Schemes as a Tool for Locating Information:

The rise of electronic publishing [1], preprint archives, blogs, and wikis is raising concerns among publishers, editors, and scientists about the present day relevance of academic journals and traditional peer review [2]. These concerns are especially fuelled by the ability of search engines to automatically identify and sort information [1]. It appears that academic journals can only remain relevant if acceptance of research for publication within a journal allows readers to infer immediate, reliable information on the value of that research. Here, we systematically evaluate the effectiveness of journals, through the work of editors and reviewers, at evaluating unpublished research. We find that the distribution of the number of citations to a paper published in a given journal in a specific year converges to a steady state after a journal-specific transient time, and demonstrate that in the steady state the logarithm of the number of citations has a journal-specific typical value. We then develop a model for the asymptotic number of citations accrued by papers published in a journal that closely matches the data. Our model enables us to quantify both the typical impact and the range of impacts of papers published in a journal. Finally, we propose a journal-ranking scheme that maximizes the efficiency of locating high impact research.

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Religion Colors Americans’ Views Of Nanotechnology:

Is nanotechnology morally acceptable? For a significant percentage of Americans, the answer is no, according to a recent survey of Americans’ attitudes about the science of the very small.

Male Fertility May Be Harmed By Mix Of Endocrine Disrupters:

Endocrine-disrupting chemicals, which are harmless individually in small doses, can together be a dangerous cocktail. Concurrent exposure to several endocrine-disrupting substances may, among other things, result in malformed sexual organs. Risk assessments of chemical substances should therefore take potential cocktail effects into account.

Two Oxygenation Events In Ancient Oceans Sparked Spread Of Complex Life:

The rise of oxygen and the oxidation of deep oceans between 635 and 551 million years ago may have had an impact on the increase and spread of the earliest complex life, including animals, according to a new study.

Krill Discovered Living In The Antarctic Abyss:

Scientists have discovered Antarctic krill (Euphausia superba) living and feeding down to depths of 3000 metres in the waters around the Antarctic Peninsula. Until now this shrimp-like crustacean was thought to live only in the upper ocean. The discovery completely changes scientists’ understanding of the major food source for fish, squid, penguins, seals and whales.

Empty Nest Syndrome May Not Be Bad After All, Study Finds:

One day they are crawling, the next day they are driving and then suddenly they aren’t kids anymore. As children reach adulthood, the parent-child relationship changes as parents learn to adapt to newly independent children. A new study by a University of Missouri professor explored the differences in how mothers and fathers interacted with their young adult children. She found there were few differences in the way mothers and fathers felt and that many of the changes were positive, despite the perception that mothers in particular fall apart and experience the so-called empty nest syndrome.

Zoologists Challenge Longstanding Theory That ‘Eyespots’ Mimic The Eyes Of Predators’ Enemies:

Circular markings on creatures such as butterflies are effective against predators because they are conspicuous features, not because they mimic the eyes of the predators’ own enemies, according to research in the journal, Behavioral Ecology*. Zoologists based at the University of Cambridge challenge the 150-year-old theory about why these markings are effective against predators.

Busy Beavers Can Help Ease Drought:

They may be considered pests, but beaver can help mitigate the effects of drought, and because of that, their removal from wetlands to accommodate industrial, urban and agricultural demands should be avoided, according to a new University of Alberta study.

Snakes Locate Prey Through Vibration Waves:

It is often believed that snakes cannot hear. This presumption is fed by the fact that snakes lack an outer ear and that scientific evidence of snakes responding to sound is scarce. Snakes do, however, possess an inner ear with a functional cochlea.

Masters Of Disguise: Secrets Of Nature’s ‘Great Pretenders’ Revealed:

A gene which helps a harmless African butterfly ward off predators by giving it wing patterns like those of toxic species, has been identified. The mocker swallowtail butterfly, Papilio dardanus, is unusual because it emerges from its chrysalis with one of a large number of different possible wing patterns and colours. This is different from most butterfly species which are identified by a common wing pattern and colour. Furthermore, some of the different patterns that the mocker swallowtail exhibits mimic those of poisonous species, which affords this harmless insect a valuable disguise which scares off predators.

Salamanders Are ‘Keystone’ Species: Headwater Streams Critical In Food Chain:

University of Missouri scientist Ray Semlitsch studies creatures most people don’t ever see. These creatures are active only at night and thrive in the shallow, cool, wet surroundings of headwater streams, an oft-overlooked biological environment.

There are a bunch of new papers in PLoS Biology and PLoS Medicine and, somewhat out of usual schedule, in PLoS ONE. So, check out these and then look around for more:
Does Mutation Rate Depend on Itself:

Many a research paper, textbook chapter, and grant proposal has begun with the phrase “Mutation is the ultimate source of genetic variation.” Implicit in this phrase is the assumption that genetic variation is required for evolution. Without mutation, evolution would not be possible, and life itself could never have arisen in the first place. However, there is overwhelming evidence that the great majority of mutations with detectable effects are harmful [1-3]. Deleterious mutations are the price we living organisms pay for the ability to evolve.

Understanding the Web of Life: The Birds, the Bees, and Sex with Aliens:

When I was in school, I learned about a linear food chain in which, for example, flowers provide food for bees, which in turn are eaten by birds. The implications of this model are clear: if bees were to vanish, birds would starve and flowers would not be pollinated. Whether this concept was a hangover from the old idea of the great chain of being (scala naturæ) or a simplification deemed necessary for unsophisticated school children is unclear. Nevertheless, despite the appeal of this simple caricature, it couldn’t be further from the truth in most of the world’s ecosystems. Birds feed on a variety of plants and animals, and are themselves fed upon by mammals, other birds, a diverse array of parasites, and eventually carrion feeders. It takes little more than a passing glance at the natural world to notice that complexity is the rule, rather than the exception. Describing this complexity and understanding its importance, however, is anything but simple. Ecologists have for a long time struggled to find consistent patterns in the structure of complex webs of interacting species from disparate ecosystems. However, recent empirical and theoretical breakthroughs have begun to shed light on the structure of the web of life that connects living things, and the vulnerability of this web to perturbations such as the introduction of invasive alien species.

The Fall and Rise of US Inequities in Premature Mortality: 1960-2002:

Debates exist as to whether, as overall population health improves, the absolute and relative magnitude of income- and race/ethnicity-related health disparities necessarily increase–or derease. We accordingly decided to test the hypothesis that health inequities widen–or shrink–in a context of declining mortality rates, by examining annual US mortality data over a 42 year period. Using US county mortality data from 1960-2002 and county median family income data from the 1960-2000 decennial censuses, we analyzed the rates of premature mortality (deaths among persons under age 65) and infant death (deaths among persons under age 1) by quintiles of county median family income weighted by county population size. Between 1960 and 2002, as US premature mortality and infant death rates declined in all county income quintiles, socioeconomic and racial/ethnic inequities in premature mortality and infant death (both relative and absolute) shrank between 1966 and 1980, especially for US populations of color; thereafter, the relative health inequities widened and the absolute differences barely changed in magnitude. Had all persons experienced the same yearly age-specific premature mortality rates as the white population living in the highest income quintile, between 1960 and 2002, 14% of the white premature deaths and 30% of the premature deaths among populations of color would not have occurred. The observed trends refute arguments that health inequities inevitably widen–or shrink–as population health improves. Instead, the magnitude of health inequalities can fall or rise; it is our job to understand why.

The following three articles, two PLoS ONE research papers and a review in PLoS Biology are part of the same “package”, which, I hear, may be controversial in some circles (and I hope the expert bloggers will enlighten us all about it):
Shifting Baselines, Local Impacts, and Global Change on Coral Reefs:

Imagine trying to understand the ecology of tropical rainforests by studying environmental changes and interactions among the surviving plants and animals on a vast cattle ranch in the center of a deforested Amazon, without any basic data on how the forest worked before it was cleared and burned. The soil would be baked dry or eroded away and the amount of rainfall would be greatly decreased. Most of the fantastic biodiversity would be gone. The trees would be replaced by grasses or soybeans, the major grazers would be leaf-cutter ants and cattle, and the major predators would be insects, rodents, and hawks. Ecologists could do experiments on the importance of cattle for the maintenance of plant species diversity, but the results would be meaningless for understanding the rainforest that used to be or how to restore it in the future.
Fortunately, ecologists began to carefully describe tropical forests more than a century ago, and vast areas of largely intact forests have persisted until today, so there are meaningful baselines for comparison. Networks of 50-hectare plots are monitored around the world [1], and decades of experiments have helped to elucidate ecological mechanisms in these relatively pristine forests [2]. But the situation is very different for the oceans, because degradation of entire ecosystems has been more pervasive than on land [3] and underwater observations began much more recently. Monitoring of benthic ecosystems is commonly limited to small intertidal quadrats, and there is nothing like the high-resolution global monitoring network for tropical forests for any ocean ecosystem.
This lack of a baseline for pristine marine ecosystems is particularly acute for coral reefs, the so-called rainforests of the sea, which are the most diverse marine ecosystems and among the most threatened [4-8].

Baselines and Degradation of Coral Reefs in the Northern Line Islands:

Effective conservation requires rigorous baselines of pristine conditions to assess the impacts of human activities and to evaluate the efficacy of management. Most coral reefs are moderately to severely degraded by local human activities such as fishing and pollution as well as global change, hence it is difficult to separate local from global effects. To this end, we surveyed coral reefs on uninhabited atolls in the northern Line Islands to provide a baseline of reef community structure, and on increasingly populated atolls to document changes associated with human activities. We found that top predators and reef-building organisms dominated unpopulated Kingman and Palmyra, while small planktivorous fishes and fleshy algae dominated the populated atolls of Tabuaeran and Kiritimati. Sharks and other top predators overwhelmed the fish assemblages on Kingman and Palmyra so that the biomass pyramid was inverted (top-heavy). In contrast, the biomass pyramid at Tabuaeran and Kiritimati exhibited the typical bottom-heavy pattern. Reefs without people exhibited less coral disease and greater coral recruitment relative to more inhabited reefs. Thus, protection from overfishing and pollution appears to increase the resilience of reef ecosystems to the effects of global warming.

Microbial Ecology of Four Coral Atolls in the Northern Line Islands:

Microbes are key players in both healthy and degraded coral reefs. A combination of metagenomics, microscopy, culturing, and water chemistry were used to characterize microbial communities on four coral atolls in the Northern Line Islands, central Pacific. Kingman, a small uninhabited atoll which lies most northerly in the chain, had microbial and water chemistry characteristic of an open ocean ecosystem. On this atoll the microbial community was equally divided between autotrophs (mostly Prochlorococcus spp.) and heterotrophs. In contrast, Kiritimati, a large and populated (~5500 people) atoll, which is most southerly in the chain, had microbial and water chemistry characteristic of a near-shore environment. On Kiritimati, there were 10 times more microbial cells and virus-like particles in the water column and these microbes were dominated by heterotrophs, including a large percentage of potential pathogens. Culturable Vibrios were common only on Kiritimati. The benthic community on Kiritimati had the highest prevalence of coral disease and lowest coral cover. The middle atolls, Palmyra and Tabuaeran, had intermediate densities of microbes and viruses and higher percentages of autotrophic microbes than either Kingman or Kiritimati. The differences in microbial communities across atolls could reflect variation in 1) oceaonographic and/or hydrographic conditions or 2) human impacts associated with land-use and fishing. The fact that historically Kingman and Kiritimati did not differ strongly in their fish or benthic communities (both had large numbers of sharks and high coral cover) suggest an anthropogenic component in the differences in the microbial communities. Kingman is one of the world’s most pristine coral reefs, and this dataset should serve as a baseline for future studies of coral reef microbes. Obtaining the microbial data set, from atolls is particularly important given the association of microbes in the ongoing degradation of coral reef ecosystems worldwide.