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Volume 6 Issue 7, July 2022

One-way flow

Polar bears diverged from brown bears roughly 500,000 years ago. However, analyses of a >100,000-year-old polar bear palaeogenome reveal that, as habitats shifted during the ice ages, the two species interbred. Today, although all brown bears exhibit ancestry from admixture with polar bears during the last interglacial period, polar bears do not retain brown bear ancestry.

See Wang, M.-S. et al

Image: Jenny E. Ross. Cover Design: Allen Beattie.


  • The bicentenary of the birth of Mendel is an opportunity to explore the origins of genetics and to confront some of its difficult subsequent history.




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Comment & Opinion

  • Life emerged from and amidst non-living phenomena that already possessed some of the hallmarks now used four billion years later to recognize fossil organisms. It may be next to impossible to distinguish the earliest signs of life against this background. What can we still learn from fossil-like materials on the early Earth and elsewhere?

    • Sean McMahon
    • Seán F. Jordan
  • Humans have influenced global fire activity for millennia and will continue to do so into the future. Given the long-term interaction between humans and fire, we propose a collaborative research agenda linking archaeology and fire science that emphasizes the socioecological histories and consequences of anthropogenic fire in the development of fire management strategies today.

    • Grant Snitker
    • Christopher I. Roos
    • Rachel A. Loehman
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Books & Arts

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Research Highlights

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News & Views

  • Analysis of sediment and pore water from three seagrass meadows around the world reveals an unexpected accumulation of labile carbon in the marine rhizosphere, explained by sediment chemistry.

    • Yuntao Hu
    • Trent R. Northen
    News & Views
  • Longitudinal data on gut microbiomes of wild baboons show that microbial communities are highly individualized, despite shared diet and environment within primate social groups.

    • Elin Videvall
    News & Views
  • Whole-genome sequencing and comparative omics analyses highlight recent and parallel paths to adaptive evolution involving expansions in zinc-binding proteins in the genomes of diverse cold-adapted algae.

    • Crysten E. Blaby-Haas
    News & Views
  • Examining the evolutionary history of ungulate migration shows that this behaviour has evolved multiple times in response to grassland expansion and increased seasonality of resources.

    • Marlee A. Tucker
    News & Views
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  • Seagrass meadows are important carbon sinks. Here, the authors show that organic carbon in the form of simple sugars can accumulate at high concentrations in seagrass rhizospheres because plant phenolic compounds inhibit their consumption by microorganisms.

    • E. Maggie Sogin
    • Dolma Michellod
    • Manuel Liebeke
    Article Open Access
  • A dataset of 16 plant traits sampled from 2,461 individual trees from 74 tropical forest sites around the world is used to show a strong link between climate and plant functional diversity and redundancy, with drier tropical forests likely being less able to respond to declines in water availability.

    • Jesús Aguirre‐Gutiérrez
    • Erika Berenguer
    • Yadvinder Malhi
  • The authors link fungal diversity to the stability of terrestrial ecosystem productivity across three global datasets, finding that richness of decomposers and mycorrhizae are positively associated with stability while the richness of plant pathogens is negatively related to stability.

    • Shengen Liu
    • Pablo García-Palacios
    • Manuel Delgado-Baquerizo
  • Genetic, ecological and simulation data demonstrate that the origin and coexistence of reproductively isolated sympatric groups in a fungus is driven by pleiotropic vegetative incompatibility genes under balancing selection.

    • S. Lorena Ament-Velásquez
    • Aaron A. Vogan
    • Hanna Johannesson
    Article Open Access
  • Introgression is an important source of genetic variation. Analysing genomes of two sympatric widespread Asian oak species, the authors find introgression across the genome and signatures of adaptive introgression in regions with suppressed recombination rate.

    • Ruirui Fu
    • Yuxiang Zhu
    • Jun Chen
  • A paleogenome from an approximately 100,000-year-old polar bear shows massive prehistoric, and largely unidirectional, gene flow from polar bears into brown bears at a time of climate change-induced overlap in the ranges of the two species. This admixture event cannot be detected using genomic data from living polar bears.

    • Ming-Shan Wang
    • Gemma G. R. Murray
    • Beth Shapiro
  • Social living has costs and benefits; here the authors use field studies, experiments and models to show that non-consumptive predation pressure in Trinidadian guppy shoals increases parasite transmission and selects for higher virulence.

    • Jason C. Walsman
    • Mary J. Janecka
    • Jessica F. Stephenson
  • Analysing gut microbial time series from wild baboons, the authors show that microbiome dynamics are rarely synchronized across hosts in shared environments but are highly individualized even within the same social groups.

    • Johannes R. Björk
    • Mauna R. Dasari
    • Elizabeth A. Archie
  • Polar microalgae have high zinc demand. Here, the authors use quantitative proteomics and transcriptomics of polar and non-polar model algae combined with cellular physiology to show that zinc plays an important role in supporting photosynthetic growth in eukaryotic polar phytoplankton.

    • Naihao Ye
    • Wentao Han
    • Thomas Mock
  • The authors examine present and past drivers of ungulate migratory behaviour, finding that current migratory ungulates are larger, more grass-dependent and live at higher latitudes on average than non-migrants, and that migration probably emerged after the rise of C4 grasslands and increased seasonality towards the poles.

    • Joel O. Abraham
    • Nathan S. Upham
    • Brett R. Jesmer
  • This paper examines the main approaches for studying gene expression evolution, tests their inherent biases and discusses open questions about the evolution of the transcriptome.

    • Peter D. Price
    • Daniela H. Palmer Droguett
    • Alison E. Wright
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Amendments & Corrections

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