Editors' Choice

Science  13 Apr 2018:
Vol. 360, Issue 6385, pp. 167
  1. Social Signals

    Sexual signals not so strict

    1. Sacha Vignieri

    Bill color in waxbills changes with external temperature.

    PHOTO: MARTIN MECNAROWSKI/SHUTTERSTOCK

    Sexual signals in animals, such as bright plumage, are thought to be predetermined or to be badges of quality that can reflect an animal's current condition. Direct and immediate effects of the environment in which an animal lives are rarely considered to shape these phenotypes. Funghi et al., however, found that in waxbills, bill color—a trait that can change quickly—is not the result of predetermined sexual differences, aggression, or sexual selection, but rather appears to be influenced by changes in the abiotic environment. Bill brightness was reduced in females after a series of lower-temperature nights. The authors suggest that this indicates that environmental conditions place constraints on these types of traits, limiting the degree to which they can reflect quality or be used for social interaction.

    Behav. Ecol. Sociobiol. 10.1007/s00265-018-2486-6 (2018).

  2. Materials Science

    Silicon sheds its harmonicity

    1. Brent Grocholski

    The widespread technological uses for silicon make understanding this element's physical properties very important. Kim et al. performed inelastic neutron scattering experiments on single crystals of silicon to measure the vibrational properties up to 1500 K. Silicon has some odd thermal properties at certain temperatures, and these experiments show the need to account for a number of factors to explain the unusual thermal expansion behavior. This in-depth look at silicon helps refine theoretical models and provides a better understanding of this technologically important material.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1707745115 (2018).

  3. Environment

    Wildflower contamination with neonicotinoids

    1. Julia Fahrenkamp-Uppenbrink

    Exposure to pesticide-contaminated wildflowers harms common blue butterflies.

    PHOTO: LUSINE/SHUTTERSTOCK

    Neonicotinoid pesticides are the most widely used type of insecticides, but there are concerns that they are toxic to nontarget species such as bees and butterflies. Basley and Goulson report on a combined field and laboratory experiment aimed at assessing the impact of neonicotinoids on the common blue butterfly (Polyommatus icarus). Wildflowers planted along the margins of fields of neonicotinoid-treated wheat were contaminated with the pesticide at levels similar to those in the treated crops. Common blue butterfly larvae exposed to neonicotinoid-contaminated plants showed increased mortality and reduced growth in the early stages of development. Wildflower margins that specifically aim to boost pollinator populations may chronically expose these species to harmful levels of neonicotinoids.

    Environ. Sci. Technol. 52, 3990 (2018).

  4. Genomics

    Denisovans shaped our genomes, twice

    1. Steve Mao

    Studies of “molecular relics” from archaic humans in modern human genomes have shown that independent interbreeding events occurred between the ancestors of Eurasians and the Neandertals and Denisovans. Because these archaic admixtures happened after the out-of-Africa migration of the modern human ancestors, comparing present-day non-African and African genomes can reveal introgression events without the need for an archaic reference genome. Using this approach, Browning et al. found evidence for two pulses of gene flow from distinct Denisovan populations into modern humans in East Asian and Papuan genomes. These findings point to at least two populations of Denisovans that contributed genes to modern humans.

    Cell 173, 53(2018).

  5. Carbon Sequestration

    Reforestation to enhance the soil carbon sink

    1. Andrew M. Sugden

    Soil is a major pool of carbon and hence can play a key role as a carbon sink in strategies to mitigate climate change. For the United States, Nave et al. quantified the carbon stocks in forest topsoils, focusing on the potential of reforestation to enhance carbon sequestration. Their estimates indicate that managed reforestation of >500,000 km2 would increase the topsoil sink by 1.3 to 2.1 petagrams of carbon within a century, enhancing the forest carbon sink in the United States by 10% annually. Their results also indicate that this enhanced sink would persist for decades, contributing to the offsetting of greenhouse gas emissions and reversing a decline in the strength of the carbon sink in U.S. forests.

    Proc. Natl. Acad. Sci. U.S.A. 115, 2776 (2018).

  6. Structural Biology

    Seeing the clasps that stabilize prion fibrils

    1. Valda Vinson

    A cryo–electron microscopy method called MicroED (micro–electron diffraction) has been used to reveal the core structures of several amyloid fibrils. With this technique, Gallagher-Jones et al. determined a 0.72-Å-resolution structure of fibrils formed by a peptide at the core of the infectious scrapie form of mammalian prion protein (proto-PrPSc). Like the full PrPSc, the fibril is characterized by unusually high stability. The high-resolution structure shows β-strands that stack into β-sheets, with sheets pairing front-to-back to form fibrils. A network of hydrogen bonds within and between β-strands forms “polar clasps,” which are shielded by aromatic residues that stack in the fibrils.

    Nat. Struct. Mol. Biol. 25, 131 (2018).

  7. Technology Adoption

    Superstars drive regional drug use

    1. Brad Wible

    A recent study finds that early adoption of new cancer drugs was geographically influenced by high-profile investigators (“superstars”) on the key clinical trials supporting the drugs. Agha and Molitor combed treatment records and clinical trial publications for 21 newly approved drugs in the United States. Patients in the same region as the lead investigator on the key trial were 36% more likely to use the drug during the first 2 years after it was approved and showed better rates of survival. These findings suggest that policies to promote the adoption of technology may blunt the potential impact if they do not include improved local information.

    Rev. Econ. Stat. 100, 29 (2018).