nils-herrmann/clean_scirepeval huggingface dataset:
Integumental water movement and rate of water ingestion during rain harvesting in the Texas horned lizard, Phrynosoma cornutum
Venue: Amphibia-reptilia

Capture of rainfall on skin surfaces and its transport via capillary channels between scales to the mouth for drinking has been documented in a few agamid ( Moloch and Phrynocephalus ) and iguanid ( Phrynosoma spp.) lizards. Associated behaviors include a postural stance and jaw motions. This experimental study documents that rate of jaw opening and closing cycles is positively correlated with rate of water delivery to lizards' backs and to gain in mass of lizards attributable to drinking. The mean mass of water that can be held by the interscalar, capillary-flow system is correlated with body size, smaller lizards holding a larger percentage of their body mass in the rain-harvesting system. Ingestion mechanisms for water flow from the integumental channels to the mouth surfaces for drinking are discussed, with note being made of the possible roles of a fold of skin at the jaw angle (at the postlabial scales) and tongue actions. Recent hatchlings exhibit rain-harvesting behavior, suggesting its innate nature.
Behavioral and morphological adaptations of a tropical plant to high rainfall
Venue: Biotropica

Machaerium arboireum (Leguminosae), a liana of Panamanian lowland forests, sheds water from upper leaflet surfaces through thigmonastic and nyctinastic leaf movements. Experiments show that leaflets with acuminate tips have an improved water-shedding ability. A STUDY WAS CONDUCTED to test the effects of leaf shape and leaf movement on shedding of rain water by juvenile plants of Machaerium aorboreum (Jacq.) Vogel (Leguminosae), a liana of Panamanian lowland forests. The leaflets have acuminate tips ("driptips"), and exhibit both thigmonasty (movement in response to tacile stimuli) and nyctinasty (diurnal movement patterns). Thigmonasty also occurs in Mimosa pudica L. (Leguminosae), the "sensitive plant" (Roblin 1976), and many other tropical legumes The leaflets of Mimosa fold within a few seconds following gentle stimuli. Raindrops initiate thigmonastic responses in other tropical plants (von Denffer et al. 1976). The functional significance of this response has not been determined. Nyctinastic leaves may protect meristematic tissue from frost damage in some high-elevation plants (Smith 1974), but their adaptive significance in low-elevation tropical plants is undear (Darwin 1881, Satter and Galston 1971, Schwintzer 1971). Jungner (1891) was one of the first to regard drip-tips as an adaptation for rapid draining of the leaf surface. He observed that leaves with drip-tips dried more quickly, and were less overgrown with epiphyllae, than leaves without drip-tips. He believed that by facilitating water runoff, drip-tips kept the leaf surface relatively clear of spores of epiphyllae, and soluble substances which might encourage epiphyllae growth. Stahl (1898) showed that by removing the drip-tips he could increase the time required for a leaf to dry, but he doubted there was any correlation between drip-tips and the presence or absence of epiphyllae. He instead proposed that driptips functioned to prevent a lingering surface film of water, which would lower the surface temperature of the leaf, which in turn would slow the rate of transpiration by the plant. A low rate of transpiralPresent address: Department of Zoology, University of Iowa, Iowa City, Iowa 52242, U.S.A. tion, he reasoned, would slow the uptake of mineral salts by the roots, which would be disadvantageous to the plant. Shreve (1914), working in the understory in the montane forest of Jamaica, was unable to detect any difference in the rate of drying in leaves with driptips removed versus those with drip-tips intact. Richards (1966) maintains that Shreve worked with plants with atypical, abbreviated drip-tips, and that his results do not therefore disprove the hypothesis that drip-tips have a drying function. According to Richards and to Edmisten (1970), the controversy about the ecological significance of drip-tips remains unsolved.
Water homeostasis in bees, with the emphasis on sociality
Venue: The Journal of Experimental Biology

Avenues of water gain and loss in bees are examined here at two levels of organisation: the individual and the colony. Compared with the majority of terrestrial insects, bees have a high water turnover. This is due to their nectar diet and, in larger species, substantial metabolic water production during flight, counteracted by high evaporative and excretory losses. Water fluxes at the colony level can also be very high. When incoming nectar is dilute, honeybees need to remove large volumes of water by evaporation. On the other hand, water is not stored in the nest and must be collected for evaporative cooling and for feeding the brood. Water regulation has many similarities at individual and colony levels. In particular, manipulation of nectar or water on the tongue is extensively used by bees to increase evaporation for either food-concentrating or cooling purposes.
Optical properties of the iridescent organ of the comb-jellyfish Beroë cucumis (Ctenophora).
Venue: Physical Review E

Using transmission electron microscopy, analytical modeling, and detailed numerical simulations, the iridescence observed from the comb rows of the ctenophore Beroë cucumis was investigated. It is shown that the changing coloration which accompanies the beating of comb rows as the animal swims can be explained by the weakly-contrasted structure of the refractive index induced by the very coherent packing of locomotory cilia. The colors arising from the narrow band-gap reflection are shown to be highly saturated and, as a function of the incidence angle, cover a wide range of the visible and ultraviolet spectrum. The high transparency of the structure at the maximal bioluminescence wavelength is also explained.
Bioprospecting Finds the Toughest Biological Material: Extraordinary Silk from a Giant Riverine Orb Spider
Venue: PLOS ONE

Combining high strength and elasticity, spider silks are exceptionally tough, i.e., able to absorb massive kinetic energy before breaking. Spider silk is therefore a model polymer for development of high performance biomimetic fibers. There are over 41.000 described species of spiders, most spinning multiple types of silk. Thus we have available some 200.000+ unique silks that may cover an amazing breadth of material properties. To date, however, silks from only a few tens of species have been characterized, most chosen haphazardly as model organisms (Nephila) or simply from researchers' backyards. Are we limited to ‘blindly fishing’ in efforts to discover extraordinary silks? Or, could scientists use ecology to predict which species are likely to spin silks exhibiting exceptional performance properties?  We examined the biomechanical properties of silk produced by the remarkable Malagasy ‘Darwin's bark spider’ (Caerostris darwini), which we predicted would produce exceptional silk based upon its amazing web. The spider constructs its giant orb web (up to 2.8 m2) suspended above streams, rivers, and lakes. It attaches the web to substrates on each riverbank by anchor threads as long as 25 meters. Dragline silk from both Caerostris webs and forcibly pulled silk, exhibits an extraordinary combination of high tensile strength and elasticity previously unknown for spider silk. The toughness of forcibly silked fibers averages 350 MJ/m3, with some samples reaching 520 MJ/m3. Thus, C. darwini silk is more than twice tougher than any previously described silk, and over 10 times better than Kevlar®. Caerostris capture spiral silk is similarly exceptionally tough.  Caerostris darwini produces the toughest known biomaterial. We hypothesize that this extraordinary toughness coevolved with the unusual ecology and web architecture of these spiders, decreasing the likelihood of bridgelines breaking and collapsing the web into the river. This hypothesis predicts that rapid change in material properties of silk co-occurred with ecological shifts within the genus, and can thus be tested by combining material science, behavioral observations, and phylogenetics. Our findings highlight the potential benefits of natural history–informed bioprospecting to discover silks, as well as other materials, with novel and exceptional properties to serve as models in biomimicry.
Iridescence: a functional perspective
Venue: Journal of the Royal Society Interface

In animals, iridescence is generated by the interaction of light with biological tissues that are nanostructured to produce thin films or diffraction gratings. Uniquely among animal visual signals, the study of iridescent coloration contributes to biological and physical sciences by enhancing our understanding of the evolution of communication strategies, and by providing insights into physical optics and inspiring biomimetic technologies useful to humans. Iridescent colours are found in a broad diversity of animal taxa ranging from diminutive marine copepods to terrestrial insects and birds. Iridescent coloration has received a surge of research interest of late, and studies have focused on both characterizing the nanostructures responsible for producing iridescence and identifying the behavioural functions of iridescent colours. In this paper, we begin with a brief description of colour production mechanisms in animals and provide a general overview of the taxonomic distribution of iridescent colours. We then highlight unique properties of iridescent signals and review the proposed functions of iridescent coloration, focusing, in particular, on the ways in which iridescent colours allow animals to communicate with conspecifics and avoid predators. We conclude with a brief overview of non-communicative functions of iridescence in animals. Despite the vast amount of recent work on animal iridescence, our review reveals that many proposed functions of iridescent coloration remain virtually unexplored, and this area is clearly ripe for future research.
The Fastest Flights in Nature: High-Speed Spore Discharge Mechanisms among Fungi
Venue: PLOS ONE

A variety of spore discharge processes have evolved among the fungi. Those with the longest ranges are powered by hydrostatic pressure and include “squirt guns” that are most common in the Ascomycota and Zygomycota. In these fungi, fluid-filled stalks that support single spores or spore-filled sporangia, or cells called asci that contain multiple spores, are pressurized by osmosis. Because spores are discharged at such high speeds, most of the information on launch processes from previous studies has been inferred from mathematical models and is subject to a number of errors.  In this study, we have used ultra-high-speed video cameras running at maximum frame rates of 250,000 fps to analyze the entire launch process in four species of fungi that grow on the dung of herbivores. For the first time we have direct measurements of launch speeds and empirical estimates of acceleration in these fungi. Launch speeds ranged from 2 to 25 m s−1 and corresponding accelerations of 20,000 to 180,000 g propelled spores over distances of up to 2.5 meters. In addition, quantitative spectroscopic methods were used to identify the organic and inorganic osmolytes responsible for generating the turgor pressures that drive spore discharge.  The new video data allowed us to test different models for the effect of viscous drag and identify errors in the previous approaches to modeling spore motion. The spectroscopic data show that high speed spore discharge mechanisms in fungi are powered by the same levels of turgor pressure that are characteristic of fungal hyphae and do not require any special mechanisms of osmolyte accumulation.
Protein Phylogenetic Analysis of Ca2+/cation Antiporters and Insights into their Evolution in Plants
Venue: Frontiers in Plant Science

Cation transport is a critical process in all organisms and is essential for mineral nutrition, ion stress tolerance, and signal transduction. Transporters that are members of the Ca2+/cation antiporter (CaCA) superfamily are involved in the transport of Ca2+ and/or other cations using the counter exchange of another ion such as H+ or Na+. The CaCA superfamily has been previously divided into five transporter families: the YRBG, Na+/Ca2+ exchanger (NCX), Na+/Ca2+, K+ exchanger (NCKX), H+/cation exchanger (CAX), and cation/Ca2+ exchanger (CCX) families, which include the well-characterized NCX and CAX transporters. To examine the evolution of CaCA transporters within higher plants and the green plant lineage, CaCA genes were identified from the genomes of sequenced flowering plants, a bryophyte, lycophyte, and freshwater and marine algae, and compared with those from non-plant species. We found evidence of the expansion and increased diversity of flowering plant genes within the CAX and CCX families. Genes related to the NCX family are present in land plant though they encode distinct MHX homologs which probably have an altered transport function. In contrast, the NCX and NCKX genes which are absent in land plants have been retained in many species of algae, especially the marine algae, indicating that these organisms may share “animal-like” characteristics of Ca2+ homeostasis and signaling. A group of genes encoding novel CAX-like proteins containing an EF-hand domain were identified from plants and selected algae but appeared to be lacking in any other species. Lack of functional data for most of the CaCA proteins make it impossible to reliably predict substrate specificity and function for many of the groups or individual proteins. The abundance and diversity of CaCA genes throughout all branches of life indicates the importance of this class of cation transporter, and that many transporters with novel functions are waiting to be discovered.
Squalamine as a broad-spectrum systemic antiviral agent with therapeutic potential
Venue: Proceedings of the National Academy of Sciences of the United States of America

Antiviral compounds that increase the resistance of host tissues represent an attractive class of therapeutic. Here, we show that squalamine, a compound previously isolated from the tissues of the dogfish shark (Squalus acanthias) and the sea lamprey (Petromyzon marinus), exhibits broad-spectrum antiviral activity against human pathogens, which were studied in vitro as well as in vivo. Both RNA- and DNA-enveloped viruses are shown to be susceptible. The proposed mechanism involves the capacity of squalamine, a cationic amphipathic sterol, to neutralize the negative electrostatic surface charge of intracellular membranes in a way that renders the cell less effective in supporting viral replication. Because squalamine can be readily synthesized and has a known safety profile in man, we believe its potential as a broad-spectrum human antiviral agent should be explored.
The diving bell and the spider: the physical gill of Argyroneta aquatica
Venue: The Journal of Experimental Biology

Argyroneta aquatica is a unique air-breathing spider that lives virtually its entire life under freshwater. It creates a dome-shaped web between aquatic plants and fills the diving bell with air carried from the surface. The bell can take up dissolved O2 from the water, acting as a ‘physical gill’. By measuring bell volume and O2 partial pressure (PO2) with tiny O2-sensitive optodes, this study showed that the spiders produce physical gills capable of satisfying at least their resting requirements for O2 under the most extreme conditions of warm stagnant water. Larger spiders produced larger bells of higher O2 conductance (GO2). GO2 depended on surface area only; effective boundary layer thickness was constant. Bells, with and without spiders, were used as respirometers by measuring GO2 and the rate of change in PO2. Metabolic rates were also measured with flow-through respirometry. The water–air PO2 difference was generally less than 10 kPa, and spiders voluntarily tolerated low internal PO2 approximately 1–4 kPa before renewal with air from the surface. The low PO2 in the bell enhanced N2 loss from the bell, but spiders could remain inside for more than a day without renewal. Spiders appeared to enlarge the bells in response to higher O2 demands and lower aquatic PO2.
Survival of the cheapest
Venue: Materials Today

Most of our resources, especially materials, are treated by economics as if the supply were infinite, when demonstrably it is not for those that are non-renewable. In his engineering, use of materials and energy, man lets design takes second place, whereas nature treats materials as expensive and designs with apparent care and attention to detail. This results in durable materials and cheap structures that are easy to recycle under ambient conditions. Examples illustrating this principle, which are given here, are drawn from both animals and plants with comments on the underlying mechanisms such as self-assembly of liquid crystal systems, use of composite structures, and control of fracture properties. The natural world, of which we are a significant part, has many examples of survival with minimum use of energy. These examples range from the production and use of materials to the organization of entire populations. But not all organisms exist in a half-lit, miserly half-life. Their (that is to say, our) driving purpose in life is to reproduce, and no organism (that is, me or you) would be here unless our parents had a strong urge to reproduce, something which we, mostly, inherit. So any way that we can have the largest number of surviving offspring will be favored. In doing this we are in competition with nearly all the other organisms in the vicinity. The ones with which we are overtly friendly are our immediate genetic (or to a lesser extent, social) relatives, and much has been made of the concept that it is our genes, rather than ourselves, that crave dominance.
Light inside sponges
Venue: Journal of Experimental Marine Biology and Ecology

Sponges are the most basal metazoan organisms. As sessile filter feeders in marine or freshwater habitats, they often live in close association with phototrophic microorganisms. Active photosynthesis by the associated microorganisms has been believed to be restricted to the outer tissue portion of the sponge hosts. However, phototrophic microorganisms have also been detected in deeper tissue regions. In many cases they are found around spicules, siliceous skelettal elements of demosponges and hexactinellids. The finding of phototrophic organisms seemingly assembled around spicules led to the hypothesis of a siliceous light transmission system in sponges. The principle ability to conduct light was already shown for sponge derived, explanted spicules. However it was not shown until now, that in deed sponges have a light transmission system, and can harbour photosynthetically active microorganisms in deeper tissue regions. 
 
Here we show for the first time, that, as hypothesized 13 year ago, sponge spicules in living specimens transmit light into deeper tissue regions. Our results demonstrate that in opposite to the actual opinion, photosynthetically active microorganisms can also live in deeper tissue regions, and not only directly beneath the surface, when a light transmission system (spicules) is present. 
 
Our results show the possibility of massive or globular sponges being supplied with photosynthetic products or pathways throughout their whole body, implying not only a more important role of these endobioses. Our findings also elucidate the in-situ function of a recently more and more interesting biomaterial, which is unique not only for its mechanical, electrical and optical properties. Biosilica is of special interest for the possibility to produce it enzymatically under environmental conditions.
Shared decision-making drives collective movement in wild baboons
Venue: Science

Baboons follow the pack, not the leader How do groups of animals, including humans, make decisions that affect the entire group? Evidence collected from schooling animals suggests that the process is somewhat democratic, with nearest neighbors and the majority shaping overall collective behavior. In animals with hierarchical social structures such as primates or wolves, however, such democracy may be complicated by dominance. Strandburg-Peshkin et al. monitored all the individuals within a baboon troop continuously over the course of their daily activities. Even within this highly socially structured species, movement decisions emerged via a shared process. Thus, democracy may be an inherent trait of collective behavior. Science, this issue p. 1358 Democracy guides group decisions in baboons, even in the presence of strong social hierarchies. Conflicts of interest about where to go and what to do are a primary challenge of group living. However, it remains unclear how consensus is achieved in stable groups with stratified social relationships. Tracking wild baboons with a high-resolution global positioning system and analyzing their movements relative to one another reveals that a process of shared decision-making governs baboon movement. Rather than preferentially following dominant individuals, baboons are more likely to follow when multiple initiators agree. When conflicts arise over the direction of movement, baboons choose one direction over the other when the angle between them is large, but they compromise if it is not. These results are consistent with models of collective motion, suggesting that democratic collective action emerging from simple rules is widespread, even in complex, socially stratified societies.
Architecture of the wood-wide web: Rhizopogon spp. genets link multiple Douglas-fir cohorts.
Venue: New Phytologist

*The role of mycorrhizal networks in forest dynamics is poorly understood because of the elusiveness of their spatial structure. We mapped the belowground distribution of the fungi Rhizopogon vesiculosus and Rhizopogon vinicolor and interior Douglas-fir trees (Pseudotsuga menziesii var. glauca) to determine the architecture of a mycorrhizal network in a multi-aged old-growth forest. Rhizopogon spp. mycorrhizas were collected within a 30 x 30 m plot. Trees and fungal genets were identified using multi-locus microsatellite DNA analysis. Tree genotypes from mycorrhizas were matched to reference trees aboveground. Two trees were considered linked if they shared the same fungal genet(s). The two Rhizopogon species each formed 13-14 genets, each colonizing up to 19 trees in the plot. Rhizopogon vesiculosus genets were larger, occurred at greater depths, and linked more trees than genets of R. vinicolor. Multiple tree cohorts were linked, with young saplings established within the mycorrhizal network of Douglas-fir veterans. A strong positive relationship was found between tree size and connectivity, resulting in a scale-free network architecture with small-world properties. This mycorrhizal network architecture suggests an efficient and robust network, where large trees play a foundational role in facilitating conspecific regeneration and stabilizing the ecosystem.