Universal scaling in the branching of the tree of life

Understanding the patterns and processes of diversification of life in the planet is a key challenge of science. The Tree of Life represents such diversification processes through the evolutionary relationships among the different taxa, and can be extended down to intra-specific relationships. Here we examine the topological properties of a large set of interspecific and intraspecific phylogenies and show that the branching patterns follow allometric rules conserved across the different levels in the Tree of Life, all significantly departing from those expected from the standard null models. The finding of non-random universal patterns of phylogenetic differentiation suggests that similar evolutionary forces drive diversification across the broad range of scales, from macro-evolutionary to micro-evolutionary processes, shaping the diversity of life on the planet.     

A Scientometric Prediction of the Discovery of the First Potentially Habitable Planet with a Mass Similar to Earth

Background

The search for a habitable extrasolar planet has long interested scientists, but only recently have the tools become available to search for such planets. In the past decades, the number of known extrasolar planets has ballooned into the hundreds, and with it, the expectation that the discovery of the first Earth-like extrasolar planet is not far off.

Methodology/Principal Findings

Here, we develop a novel metric of habitability for discovered planets and use this to arrive at a prediction for when the first habitable planet will be discovered. Using a bootstrap analysis of currently discovered exoplanets, we predict the discovery of the first Earth-like planet to be announced in the first half of 2011, with the likeliest date being early May 2011.

Conclusions/Significance

Our predictions, using only the properties of previously discovered exoplanets, accord well with external estimates for the discovery of the first potentially habitable extrasolar planet and highlight the the usefulness of predictive scientometric techniques to understand the pace of scientific discovery in many fields.     

The second warning to humanity—Why ethology matters?

In 2017, more than 15,000 scientists signed a second warning to humanity to halt human-made destruction of our planet. The authors of that study encouraged further contributions highlighting specific subjects. With this perspectives article, we follow their call and explore why and how behavioural studies can matter for a better stewardship of the planet. The second warning article suggested 13 effective steps humanity needs to take to transition to a sustainable life. Here, we first provide some examples of how concepts and tools of behavioural biology can aid understanding and solving real-world conservation problems relating to some of the effective sustainability steps suggested by Ripple et al., (Bioscience, 67, 2017, 1026). Then, we outline how ethological research can contribute to sustainability beyond its contributions to conserving species. Finally, we turn to the second warning and the behaviour of scientists themselves. Science has provided unequivocal evidence that we are destroying the very basis of the existence of millions of species including ourselves. To convince humanity about the urgent necessity to halt and change our behaviour, science organizations, funding bodies and scientists themselves need to become role models for sustainability.     

Characterizing habitable extrasolar planets using spectral fingerprints

The detection and characterization of an Earth-like planet is approaching rapidly thanks to radial velocity (RV) surveys (e.g. HARPS) and transit searches (Corot, Kepler). A rough characterization of these planets will be already achievable in 2014 with the James Webb Space Telescope, and more detailed spectral studies will be obtained by future large ground based telescopes (ELT, TNT, GMT), and dedicated space-based missions like Darwin, Terrestrial Planet Finder, New World Observer. In this article we discuss how we can read a planet's spectrum to assess its habitability and search for the signatures of a biosphere. Identifying signs of life implies understanding how the observed atmosphere physically and chemically works, and thus gathering information on the planet in addition to observing its spectral fingerprint.     

Putting Your Money Where Your Mouth Is: Why Sustainability Reporting Based on the Triple Bottom Line Can Be Misleading

In the packaged food industry, Corporate Social Responsibility (CSR) is an informal requirement for which firms account through sustainability reporting. CSR behaviors are often reported and analyzed using the Triple Bottom Line (3BL) framework, which categorizes them as affecting people, planet, or profit. 3BL is useful in determining which of these categories is most elaborated upon by the firm, but has a limited scope and many documented criticisms. This paper aims to address the aforementioned insufficiencies by augmenting the 3BL framework with two important attributes of CSR practices: (1) the presence of change in core firm behavior of the firm itself or of others in the supply chain, and (2) whether the behavior qualifies as being outside of the firm’s normal business practice or is something that they might have done anyway. We qualitatively analyze CSR behaviors described in sustainability reports and interviews from major players in the packaged food industry and categorize them using these attributes as a supplement to 3BL. This enables us to separate the behaviors from their framing and analyze them more critically. Our results demonstrate how the visible CSR efforts of a firm can be misleading at first glance. Using only 3BL, we find that the CSR focus of firms in this industry is people. We then discover that the codes focusing on people (as opposed to planet or profit) require the least amount of real structural change from a firm or its supply chain partners, and thus arguably, the least amount of effort. We also find that behaviors that focus on planet require the most effort within the firm itself, but for behaviors involving supply chain partners, effort is required for behaviors in all three categories. Finally, we find that CSR behavior that is related to planet tends to go beyond normal business practice.     

Life: past, present and future

Molecular methods of taxonomy and phylogeny have changed the way in which life on earth is viewed; they have allowed us to transition from a eukaryote-centric (five-kingdoms) view of the planet to one that is peculiarly prokarote-centric, containing three kingdoms, two of which are prokaryotic unicells. These prokaryotes are distinguished from their eukaryotic counterparts by their toughness, tenacity and metabolic diversity. Realization of these features has, in many ways, changed the way we feel about life on earth, about the nature of life past and about the possibility of finding life elsewhere. In essence, the limits of life on this planet have expanded to such a degree that our thoughts of both past and future life have been altered. The abilities of prokaryotes to withstand many extreme conditions has led to the term extremophiles, used to describe the organisms that thrive under conditions thought just a few years ago, to be inconsistent with life. Perhaps the most extensive adaptation to extreme conditions, however, is represented by the ability of many bacteria to survive nutrient conditions not compatible with eukaryotic life. Prokaryotes have evolved to use nearly every redox couple that is in abundance on earth, filling the metabolic niches left behind by the oxygen-using, carbon-eating eukaryotes. This metabolic plasticity leads to a common feature in physically stratified environments of layered microbial communities, chemical indicators of the metabolic diversity of the prokaryotes. Such 'metabolic extremophily' forms a backdrop by which we can view the energy flow of life on this planet, think about what the evolutionary past of the planet might have been, and plan ways to look for life elsewhere, using the knowledge of energy flow on earth.     

Viral information

Viruses are major drivers of global biogeochemistry and the etiological agents of many diseases. They are also the winners in the game of life: there are more viruses on the planet than cellular organisms and they encode most of the genetic diversity on the planet. In fact, it is reasonable to view life as a viral incubator. Nevertheless, most ecological and evolutionary theories were developed, and continue to be developed, without considering the virosphere. This means these theories need to be to reinterpreted in light of viral knowledge or we need to develop new theory from the viral point-of-view. Here we briefly introduce our viral planet and then address a major outstanding question in biology: why is most of life viral? A key insight is that during an infection cycle the original virus is completely broken down and only the associated information is passed on to the next generation. This is different for cellular organisms, which must pass on some physical part of themselves from generation to generation. Based on this premise, it is proposed that the thermodynamic consequences of physical information (e.g., Landauer’s principle) are observed in natural viral populations. This link between physical and genetic information is then used to develop the Viral Information Hypothesis, which states that genetic information replicates itself to the detriment of system energy efficiency (i.e., is viral in nature). Finally, we show how viral information can be tested, and illustrate how this novel view can explain existing ecological and evolutionary theories from more fundamental principles.     

We live in a changing world,but that shouldn’t mean we abandon the concept of equilibrium

Ecological systems are no longer at equilibrium, but over much of the history of the Earth, the natural world has been in stationary states, that are punctuated by periods of transience. Just because we have knocked our planet away from a stable state, doesn't mean we have to abandon the concept of equilibrium when we strive to understand the dynamics of the natural world.     

Born‐digital biodiversity data: Millions and billions

Given the dramatic pace of change of our planet, we need rapid collection of environmental data to document how species are coping and to evaluate the impact of our conservation interventions. To address this need, new classes of “born digital” biodiversity records are now being collected and curated many orders of magnitude faster than traditional data. In addition to the millions of citizen science observations of species that have been accumulating over the last decade, the last few years have seen a surge of sensor data, with eMammal's camera trap archive passing 1 million photo‐vouchered specimens and Movebank's animal tracking database recently passing 1.5 billion animal locations. Data from digital sensors have other advantages over visual citizen science observation in that the level of survey effort is intrinsically documented and they can preserve digital vouchers that can be used to verify species identity. These novel digital specimens are leading spatial ecology into the era of Big Data and will require a big tent of collaborating organizations to make these databases sustainable and durable. We urge institutions to recognize the future of born‐digital records and invest in proper curation and standards so we can make the most of these records to inform management, inspire conservation action and tell natural history stories about life on the planet.     

Pathways to Earth-Like Atmospheres

We discuss the evolution of the atmosphere of early Earth and of terrestrial exoplanets which may be capable of sustaining liquid water oceans and continents where life may originate. The formation age of a terrestrial planet, its mass and size, as well as the lifetime in the EUV-saturated early phase of its host star play a significant role in its atmosphere evolution. We show that planets even in orbits within the habitable zone of their host stars might not lose nebular- or catastrophically outgassed initial protoatmospheres completely and could end up as water worlds with CO₂ and hydrogen- or oxygen-rich upper atmospheres. If an atmosphere of a terrestrial planet evolves to an N₂-rich atmosphere too early in its lifetime, the atmosphere may be lost. We show that the initial conditions set up by the formation of a terrestrial planet and by the evolution of the host star’s EUV and plasma environment are very important factors owing to which a planet may evolve to a habitable world. Finally we present a method for studying the discussed atmosphere evolution hypotheses by future UV transit observations of terrestrial exoplanets.     

Genetic discrimination and the law.

The use of genetic tests can lead to genetic discrimination, discrimination based solely on the nature of an individual's genotype. Instances of the discriminatory uses of genetic tests by employers and insurance companies have already been reported. The recently enacted Americans with Disabilities Act of 1990 (ADA), together with other federal and state laws, can be used to combat some forms of this discrimination. In this article we define and characterize genetic discrimination, discuss the applicability of the various relevant federal and state laws, including the ADA, in the areas of employment and insurance discrimination, explore the limitations of these laws, and, finally, suggest some means of overcoming these limitations.     

When a virus is not a parasite: the beneficial effects of prophages on bacterial fitness

Most organisms on the planet have viruses that infect them. Viral infection may lead to cell death, or to a symbiotic relationship where the genomes of both virus and host replicate together. In the symbiotic state, both virus and cell potentially experience increased fitness as a result of the other. The viruses that infect bacteria, called bacteriophages (or phages), well exemplify the symbiotic relationships that can develop between viruses and their host. In this review, we will discuss the many ways that prophages, which are phage genomes integrated into the genomes of their hosts, influence bacterial behavior and virulence.     

Respect of law or respect through law?

What is the role of law and legality in social resilience? This review essay highlights how a sociology of law, culture, and institutions underwrites many of the findings of Getting Respect: Responding to Stigma and Discrimination in the United States, Brazil &; Israel. The book provides a trenchant analysis of group boundaries, stigma, and destigmatization across three cities worldwide. I suggest that in addition to the role of formal law and legal constraints that the book identifies, we can attend to how legality offers a repertoire for resilience on which people draw when faced with stigma, discrimination, or contentious situations, even when formal law falls short. In this way, combining a sociology of law with a sociology of culture can provide us with an understanding of how societies offer social resilience, and how this resource varies across social, national, and legal contexts.     

Accidental experiments: ecological and evolutionary insights and opportunities derived from global change

Humans are the dominant ecological and evolutionary force on the planet today, transforming habitats, polluting environments, changing climates, introducing new species, and causing other species to decline in number or go extinct. These worrying anthropogenic impacts, collectively termed global change, are often viewed as a confounding factor to minimize in basic studies and a problem to resolve or quantify in applied studies. However, these ‘accidental experiments’ also represent opportunities to gain fundamental insight into ecological and evolutionary processes, especially when they result in perturbations that are large or long in duration and difficult or unethical to impose experimentally. We demonstrate this by describing important fundamental insights already gained from studies which utilize global change factors as accidental experiments. In doing so, we highlight why accidental experiments are sometimes more likely to yield insights than traditional approaches. Next, we argue that emerging environmental problems can provide even more opportunities for scientific discovery in the future, and provide both examples and guidelines for moving forward. We recommend 1) a greater flow of information between basic and applied subfields of ecology and evolution to identify emerging opportunities; 2) considering the advantages of the ‘accidental experiment’ approach relative to more traditional approaches; and 3) planning for the challenges inherent to uncontrolled accidental experiments. We emphasize that we do not view the accidental experiments provided by global change as replacements for scientific studies quantifying the magnitude of anthropogenic impacts or outlining strategies for mitigating impacts. Instead, we believe that accidental experiments are uniquely situated to provide insights into evolutionary and ecological processes that ultimately allow us to better predict and manage change on our human‐dominated planet. Synthesis Humans have an increasingly large impact on the planet. In response, ecologists and evolutionary biologists are dedicating increasing scientific attention to global change, largely with studies documenting biological effects and testing strategies to avoid or reverse negative impacts. In this article, we analyze global change from a different perspective, and suggest that human impacts on the environment also serve as valuable ‘accidental experiments’ that can provide fundamental scientific insight. We highlight and synthesize examples of studies taking this approach, and give guidance for gaining future insights from these unfortunate ‘accidental experiments’.     

Non-light based ecosystems and bioastronomy.

The possibility of the existence of life beyond planet Earth has always fascinated humans. However, due to certain circumstances such as the failure of the Viking expeditions to detect any sign of biotic activity on Mars, and the understanding that the presence of life would lead to drastic alterations in the atmosphere of the host planet (alterations that have never been detected on other planets or planetoids of the solar system), the belief that our planet is the only planet to sustain life inside the solar system originated. During the last three decades a series of new complex biological communities have been discovered, in the deep sea, inside caves isolated from the external biosphere, and deep inside the crust of our planet, and found to depend on geothermal energy instead of solar energy for their survival. These discoveries give us new evidence and hope that life might exist not only on other planets, but perhaps even in other planetoids of our solar system. Life may exist in regions other than the surface of a planet, and these areas would be extremely difficult to identify.     

Resolving Conflicts between Agriculture and the Natural Environment

Agriculture dominates the planet. Yet it has many environmental costs that are unsustainable, especially as global food demand rises. Here, we evaluate ways in which different parts of the world are succeeding in their attempts to resolve conflict between agriculture and wild nature. We envision that coordinated global action in conserving land most sensitive to agricultural activities and policies that internalise the environmental costs of agriculture are needed to deliver a more sustainable future.     

Harvesting the fruit of the human mtDNA tree

Human mitochondrial DNA (mtDNA) studies have entered a new phase since the blossoming of complete genome analyses. Sequencing complete mtDNAs is more expensive and more labour intensive than restriction analysis or simply sequencing the control region of the molecule. But the efforts are paying off, as the phylogenetic resolution of the mtDNA tree has been greatly improved, and, in turn, phylogeographic interpretations can be given correspondingly greater precision in terms of the timing and direction of human dispersals. Therefore, despite mtDNA being only a fraction of our total genome, the deciphering of its evolution is profoundly changing our perception about how modern humans spread across our planet. Here we illustrate the phylogeographic approach with two case studies: the initial dispersal out of Africa, and the colonization of Europe.     

The early atmosphere: a new picture

Over the last several years, many of the fundamental ideas concerning the composition and chemical evolution of the Earth's early atmosphere have changed. While many aspects of this subject are clouded--either uncertain or unknown, a new picture is emerging. We are just beginning to understand how astronomical, geochemical, and atmospheric processes each contributed to the development of the gaseous envelope around the third planet from the sun some 4.6 billion years ago and how that envelope chemically evolved over the history of our planet. Simple compounds in that gaseous envelope, energized by atmospheric lightning and/or solar ultraviolet radiation, formed molecules of increasing complexity that eventually evolved into the first living systems on our planet. This process is called "chemical evolution" and immediately preceded biological evolution; once life developed and evolved, it began to alter the chemical composition of the atmosphere that provided the very essence of its creation. Photosynthetic organisms which have the ability to biochemically transform carbon dioxide and water to carbohydrates, which they use for food, produce large amounts of molecular oxygen (O2) as a by-product of the reaction. Atmospheric oxygen photochemically formed ozone, which absorbs ultraviolet radiation from the sun and shields the Earth's surface from this biologically lethal radiation. Once atmospheric ozone levels increased sufficiently, life could leave the safety of the oceans and go ashore for the first time. Throughout the history of our planet, there has been strong interaction between life and the atmosphere. Understanding our cosmic roots is particularly relevant as we embark on a search for life outside the Earth. At this very moment, several radio telescopes around the world are searching for extraterrestrial intelligence (SETI).     

What do tadpoles really eat? Assessing the trophic status of an understudied and imperiled group of consumers in freshwater habitats

1. Understanding the trophic status of consumers in freshwater habitats is central to understanding their ecological roles and significance. Tadpoles are a diverse and abundant component of many freshwater habitats, yet we know relatively little about their feeding ecology and true trophic status compared with many other consumer groups. While many tadpole species are labelled herbivores or detritivores, there is surprisingly little evidence to support these trophic assignments. 2. Here we discuss shortcomings in our knowledge of the feeding ecology and trophic status of tadpoles and provide suggestions and examples of how we can more accurately quantify their trophic status and ecological significance. 3. Given the catastrophic amphibian declines that are ongoing in many regions of the planet, there is a sense of urgency regarding this information. Understanding the varied ecological roles of tadpoles will allow for more effective conservation of remaining populations, benefit captive breeding programmes, and allow for more accurate predictions of the ecological consequences of their losses.     

Space Station Freedom: a unique laboratory for gravitational biology research

The advent of Space Station Freedom (SSF) will provide a permanent laboratory in space with unparalleled opportunities to perform biological research. As with any spacecraft there will also be limitations. It is our intent to describe this space laboratory and present a picture of how scientists will conduct research in this unique environment we call space. SSF is an international venture which will continue to serve as a model for other peaceful international efforts. It is hoped that as the human race moves out from this planet back to the moon and then on to Mars that SSF can serve as a successful example of how things can and should be done.