Avian visual ecologists should consider UV absorbance and all sensory modalities: A response to Wisenden et al. (2020)

In a recent publication, Wisenden et al. (2020) examined responses of territorial male Red-winged Blackbirds (Agelaius phoeniceus) to models constructed with ultraviolet (UV)-reflective red epaulets for the purpose of determining if the addition of UV reflectance to epaulets ( UV+ ) changed the effectiveness of signals to receivers relative to control epaulets under field conditions. The authors hypothesized that UV+epaulet coloration represents a visual signal with increased efficacy in territorial interactions. They presented behavioral data but no visual modeling data. Our aims in this commentary are to suggest alternative terms to those used by the authors, to express concern about the use of sunscreen to manipulate the UV condition of surfaces, and to make a plea for additional data collection in future studies of avian visual ecology. The terms UV+ and UV- should be reserved for studies that create environments free from UV radiation for comparison with environments that include UV radiation. We believe that commercial sunscreens are not an appropriate choice for altering the UV conditions of surfaces presented during behavioral trials because they potentially introduce confounding influences from other sensory inputs or irritation of peripheral nerves. Wisenden et al. altered the UV absorbance of their sunscreen-treated models but did not present absorbance spectra and may not have collected those data. We acknowledge that the lack of absorbance spectra is not unusual. We implore any such future studies to collect absorbance spectra of treated and control surfaces so that those data may be used to improve visual models for UV-sensitive animals. Los ec´ologos visuales de aves deben considerer la absorbencia UV y todas las modalidades sensoriales: respuesta a Wisenden et al. (2020) RESUMEN (Spanish)—En una publicaci´on reciente, Wisenden et al. (2020) examinaron las respuestas de machos territoriales del tordo Agelaius phoeniceus a modelos construidos con charreteras rojas reflejantes ultravioletas (UV) con el prop´osito de determinar si la adici´on de reflectancia a las charreteras (‘‘UVþ’’) cambiaba la efectividad de las se˜nales dirigidas a receptores en relaci´on con charreteras ‘‘control’’ bajo condiciones de campo. Los autores ten´ıan la hip´otesis de que ‘‘la coloraci´on UVþde las charreteras representa una se˜nal visual con eficacia aumentada en interacciones territoriales’’. Los autores presentaron datos conductuales pero no datos de modelado visual. Nuestra meta en este comentario es sugerir t´erminos alternativos a aquellos empleados por los autores, expresar preocupaci´on por el uso de bloqueador solar para manipular la condici´on UV de superficies y hacer un llamado para la colecta de datos adicionales en futuros estudios de ecolog´ıa visual aviar. Los t´erminos UVþy UV– deben estar reservados para comparaciones con ambientes que incluyan radiaci´on UV. Pensamos que el uso de bloqueadores solares comerciales no es una elecci´on adecuada para la alteraci´on de las condiciones UV de superficies durante pruebas de comportamiento porque podr´ıan introducir influencias confusas provenientes de otras se˜nales sensoriales o irritar nervios perif´ericos. Wisenden et al. alteraron la absorbencia UV de sus modelos tratados con bloqueador solar pero no presentaron espectros de absorbencia y podr´ıan no haber colectado esos datos. Reconocemos que la carencia de espectros de absorbencia no es inusual. Pedimos que cualquier estudio futuro colecte espectros de absorbencia en superficies tratadas y controles para que esos datos puedan ser usados para mejorar los modelos visuales de animales sensibles a UV

Functional visual sensitivity to ultraviolet wavelengths in the Pileated Woodpecker (\u3ci\u3eDryocopus pileatus\u3c/i\u3e), and its influence on foraging substrate selection

Most diurnal birds are presumed visually sensitive to near ultraviolet (UV)wavelengths, however, controlled behavioral studies investigating UV sensitivity remain few. Although woodpeckers are important as primary cavity excavators and nuisance animals, published work on their visual systems is limited. We developed a novel foraging-based behavioral assay designed to test UV sensitivity in the Pileated Woodpecker (Dryocopus pileatus). We acclimated 21 wild-caught woodpeckers to foraging for frozen mealworms within 1.2 m sections of peeled cedar (Thuja spp.) poles.We then tested the functional significance of UV cues by placing frozen mealworms behind UV-reflective covers, UV-absorptive covers, or decayed red pine substrates within the same 1.2 m poles in independent experiments. Behavioral responses were greater toward both UV-reflective and UV-absorptive substrates in three experiments. Study subjects therefore reliably differentiated and attended to two distinct UV conditions of a foraging substrate. Cue-naïve subjects showed a preference for UV-absorptive substrates, suggesting that woodpeckers may be pre-disposed to foraging from such substrates. Behavioral responses were greater toward decayed pine substrates (UV-reflective) than sound pine substrates suggesting that decayed pine can be a useful foraging cue. The finding that cue-naïve subjects selected UV-absorbing foraging substrates has implications for ecological interactions of woodpeckers with fungi.Woodpeckers transport fungal spores, and communication methods analogous to those of plant-pollinator mutualisms (i.e. UV-absorbing patterns) may have evolved to support woodpecker-fungus mutualisms

Visual cues for woodpeckers: light reflectance of decayed wood varies by decay fungus

The appearance of wood substrates is likely relevant to bird species with life histories that require regular interactions with wood for food and shelter. Woodpeckers detect decayed wood for cavity placement or foraging, and some species may be capable of detecting trees decayed by specific fungi; however, a mechanism allowing for such specificity remains unidentified.We hypothesized that decay fungi associated with woodpecker cavity sites alter the substrate reflectance in a species-specific manner that is visually discriminable by woodpeckers. We grew 10 species of wood decay fungi from pure cultures on sterile wood substrates of 3 tree species. We then measured the relative reflectance spectra of decayed and control wood wafers and compared them using the receptor noise-limited (RNL) color discrimination model. The RNL model has been used in studies of feather coloration, egg shells, flowers, and fruit to model how the colors of objects appear to birds. Our analyses indicated 6 of 10 decayed substrate/control comparisons were above the threshold of discrimination (i.e., indicating differences discriminable by avian viewers), and 12 of 13 decayed substrate comparisons were also above threshold for a hypothetical woodpecker. We conclude that woodpeckers should be capable of visually detecting decayed wood on trees where bark is absent, and they should also be able to detect visually species-specific differences in wood substrates decayed by fungi used in this study. Our results provide evidence for a visual mechanism by which woodpeckers could identify and select substrates decayed by specific fungi, which has implications for understanding ecologically important woodpecker–fungus interactions. El aspecto de los sustratos de madera posiblemente sea relevante para especies de aves que tienen historias de vida que dependen de interacciones regulares con la madera para alimentaci´on y resguardo. Los pa´jaros carpinteros detectan la madera degradada para establecer sus cavidades o para forrajear, y algunas especies podr´ıan ser capaces de detectar a´rboles que son degradadas por alg´un hongo en particular. Sin embargo, a´un no se identifica un mecanismo que permita identificar tal especificidad. Nuestra hip´otesis es que los hongos xil ´ofagos asociados a sitios con cavidades para carpinteros alteran la reflectancia del sustrato en una manera espec´ıfica a especie que es visualmente discernible para los carpinteros. Cultivamos 10 especies de hongos xil ´ofagos a partir de cultivos puros en sustratos est´eriles de madera de tres especies de a´rboles. A continuaci´on, medimos el espectro de reflectancia de la madera de la madera degradada y trozos de madera control, y las comparamos entre s´ı usando el modelo de discriminaci´on de color del receptor de ruido limitado (RNL, por sus siglas en ingl´es). El modelo RNL ha sido utilizado en estudios de coloraci´on de plumas, cascar´on de huevo, flores y frutos para modelar c´omo perciben las aves el color de los objetos. Nuestros ana´lisis indican que 6 de 10 comparaciones sustrato/control estuvieron por encima del umbral de discriminaci´on (e.g., indicando diferencias discernibles por observadores aviares) y que las comparaciones de 12 de los 13 sustratos degradados estuvieron por encima del umbral para un carpintero hipot´etico. Concluimos que los carpinteros deben ser capaces de detectar visualmente la madera degradada en a´rboles donde la corteza esta´ ausente y tambi´en deben detectar visualmente diferencias espec´ıficas a especie en los sustratos de madera degradada por los hongos utilizados en este estudio. Nuestros resultados proveen evidencia de un mecanismo visual por medio del cual los pa´jaros carpinteros pueden identificar y seleccionar los sustratos degradados por hongos espec´ıficos, lo cual tiene implicaciones en nuestro entendimiento de las importantes interacciones entre carpinteros y hongos

A prebiotic basis for ATP as the universal energy currency

ATP is universally conserved as the principal energy currency in cells, driving metabolism through phosphorylation and condensation reactions. Such deep conservation suggests that ATP arose at an early stage of biochemical evolution. Yet purine synthesis requires 6 phosphorylation steps linked to ATP hydrolysis. This autocatalytic requirement for ATP to synthesize ATP implies the need for an earlier prebiotic ATP equivalent, which could drive protometabolism before purine synthesis. Why this early phosphorylating agent was replaced, and specifically with ATP rather than other nucleoside triphosphates, remains a mystery. Here, we show that the deep conservation of ATP might reflect its prebiotic chemistry in relation to another universally conserved intermediate, acetyl phosphate (AcP), which bridges between thioester and phosphate metabolism by linking acetyl CoA to the substrate-level phosphorylation of ADP. We confirm earlier results showing that AcP can phosphorylate ADP to ATP at nearly 20% yield in water in the presence of Fe3+ ions. We then show that Fe3+ and AcP are surprisingly favoured. A wide range of prebiotically relevant ions and minerals failed to catalyse ADP phosphorylation. From a panel of prebiotic phosphorylating agents, only AcP, and to a lesser extent carbamoyl phosphate, showed any significant phosphorylating potential. Critically, AcP did not phosphorylate any other nucleoside diphosphate. We use these data, reaction kinetics, and molecular dynamic simulations to infer a possible mechanism. Our findings might suggest that the reason ATP is universally conserved across life is that its formation is chemically favoured in aqueous solution under mild prebiotic conditions

By the People: Hard Times, Hard Choices Michigan Residents Deliberate

Outlines the concept of deliberative polling and presents results from a face-to-face statewide deliberative poll on Michigan's economy and budget issues, including taxes, spending and benefits, the environment, and options for state assistance.For the first time, a scientific random sample of the people of Michigan gathered together to deliberate about the hard choices facing the state's economic future. Results of Michigan's first Deliberative Poll show what the people of the state would think if they could all become more informed and discuss the issues in depth. Highly representative in both attitudes and demographics, a sample of 314 participants deliberated for a long weekend in Lansing, with both small group discussions and questions answered by competing experts in plenary sessions. The resulting changes of opinion in the final survey offer some dramatic recommendations for both policymakers and the public

PG 2131+066: A Test of Pre-White Dwarf Asteroseismology

PG 2131+066 is a composite-spectrum binary with a hot pulsating PG 1159-type pre-white dwarf and an early M-type main sequence star. Analysis of Whole Earth Telescope observations of the pulsating pre-white dwarf component provided an asteroseismological determination of its mass, luminosity, and effective temperature. These determinations allowed Kawaler et al. (1995) to determine the distance to this star. In this paper, we refine the asteroseismological distance determination, and confirm the distance by an independent measurement to the system via the spectroscopic parallax of the M star. PG 2131+066 was observed by the HST using the original PC in September 1993. Exposures with filters F785LP and F555W both showed the companion at a distance of 0.3 arc seconds. Photometry of the images provides an apparent magnitude for the main sequence companion of v=18.97+/-0.15, from which we find a distance of 560 (+200 -134) pc. We also recalculated the asteroseismological distance to the pre-white dwarf using updated models and new spectroscopic constraints from UV spectra. The new seismological distance is 668 (+78 -83) pc, in satisfactory agreement with the distance of the secondary star. These results suggest that this is indeed a physical binary, and that seismological distance determination may be the best way to determine the distance to the pulsating hot pre-white dwarf stars.Comment: 13 pages, 4 figures, to appear in The Astrophysical Journal, Dec.10, 200

Monitoring and Modeling of Emissions from Concentrated Animal Feeding Operations: Overview of Methods

Accurate monitors are required to determine ambient concentration levels of contaminants emanating from concentrated animal feeding operations (CAFOs), and accurate models are required to indicate the spatial variability of concentrations over regions affected by CAFOs. A thorough understanding of the spatial and temporal variability of concentration levels could then be associated with locations of healthy individuals or subjects with respiratory ailments to statistically link the presence of CAFOs to the prevalence of ill health effects in local populations. This workgroup report, which was part of the Conference on Environmental Health Impacts of Concentrated Animal Feeding Operations: Anticipating Hazards—Searching for Solutions, describes instrumentation currently available for assessing contaminant concentration levels in the vicinity of CAFOs and reviews plume dispersion models that may be used to estimate concentration levels spatially. Recommendations for further research with respect to ambient air monitoring include accurately determining long-term average concentrations for a region under the influence of CAFO emissions using a combination of instruments based on accuracy, cost, and sampling duration. In addition, development of instruments capable of accurately quantifying adsorbed gases and volatile organic compounds is needed. Further research with respect to plume dispersion models includes identifying and validating the most applicable model for use in predicting downwind concentrations from CAFOs. Additional data are needed to obtain reliable emission rates from CAFOs

Fluctuation and flow probes of early-time correlations in relativistic heavy ion collisions

Fluctuation and correlation observables are often measured using multi-particle correlation methods and therefore mutually probe the origins of genuine correlations present in multi-particle distribution functions. We investigate the common influence of correlations arising from the spatially inhomogeneous initial state on multiplicity and momentum fluctuations as well as flow fluctuations. Although these observables reflect different aspects of the initial state, taken together, they can constrain a correlation scale set at the earliest moments of the collision. We calculate both the correlation scale in an initial stage Glasma flux tube picture and the modification to these correlations from later stage hydrodynamic flow and find quantitative agreement with experimental measurements over a range of collision systems and energies.Comment: Proceedings of the 28th Winter Workshop on Nuclear Dynamics, Dorado del Mar, Puerto Rico, April 7-14, 201