skip to main content


Search for: All records

Award ID contains: 1928514

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract

    Peatlands are crucial sinks for atmospheric carbon but are critically threatened due to warming climates.Sphagnum(peat moss) species are keystone members of peatland communities where they actively engineer hyperacidic conditions, which improves their competitive advantage and accelerates ecosystem-level carbon sequestration. To dissect the molecular and physiological sources of this unique biology, we generated chromosome-scale genomes of twoSphagnumspecies:S. divinumandS. angustifolium.Sphagnumgenomes show no gene colinearity with any other reference genome to date, demonstrating thatSphagnumrepresents an unsampled lineage of land plant evolution. The genomes also revealed an average recombination rate an order of magnitude higher than vascular land plants and short putative U/V sex chromosomes. These newly described sex chromosomes interact with autosomal loci that significantly impact growth across diverse pH conditions. This discovery demonstrates that the ability ofSphagnumto sequester carbon in acidic peat bogs is mediated by interactions between sex, autosomes and environment.

     
    more » « less
  2. Premise

    TheSphagnum recurvumcomplex comprises a group of closely related peat mosses that are dominant components of many northern wetland ecosystems. Taxonomic hypotheses for the group range from interpreting the whole complex as one polymorphic species to distinguishing 6–10 species. The complex occurs throughout the Northern Hemisphere, and some of the putative species have intercontinental ranges. Our goals were to delimit the complex and assess its phylogenetic structure in relation to morphologically defined species and intercontinental geography.

    Methods

    RADseq analyses were applied to a sample of 384 collections from Europe, North America, and Asia. The data were subjected to maximum likelihood phylogenetic analyses and analyses of genetic structure using the software STRUCTURE and multivariate ordination approaches.

    Results

    TheS. recurvumcomplex includesS. angustifolium,S. fallax,S. flexuosum,S. pacificum, andS. recurvumas clades with little evidence of admixture. We also resolved an unnamed clade that is referred to here asS. “pseudopacificum.” We confirm thatS. balticumandS. obtusumare nested within the complex. Species with bluntly acute to obtuse stem leaf apices are sister to those with acute to apiculate leaves. Most of the species exhibit some differentiation between intraspecific population systems disjunct on different continents.

    Conclusions

    We recognize seven species in the amendedS. recurvumcomplex, includingS. balticumandS. obtusum, in addition to the informal cladeS. “pseudopacificum.” Although we detected some geographically correlated phylogenetic structure within widespread morphospecies, our RADseq data support the interpretation that these species have intercontinental geographic ranges.

     
    more » « less
  3. Species delimitation is problematic in many plant groups and among the mosses, Sphagnum is one of the more contentious genera because of high levels of morphological variation. The allopolyploid species, Sphagnum majus, comprises one such problematic complex. Two morphologically differentiated but overlapping subspecies have been described. We conducted morphometric and molecular analyses with samples from around the Northern Hemisphere to test for phenotypic and phylogenetic differentiation between the subspecies. Although field collections of the two species can be statistically differentiated morphologically, there is substantial overlap. Genome-scale molecular data do not suggest any differentiation between S. majus ssp. majus and ssp. norvegicum, including samples assigned to the two taxa from sympatric sites. Sequence data from the plastid genome were employed to infer parentage of allopolyploid S. majus. Our results support the hypothesis that S. annulatum is the paternal parent and S. cuspidatum is the maternal parent. We conclude that the morphological differences between them are either plastic responses to habitat heterogeneity or segregating genetic variation within a single taxon. Formal taxonomic recognition of two taxa is not supported by our molecular data. 
    more » « less