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1. Old divergence and restricted gene flow between torrent duck ( Merganetta armata ) subspecies in the Central and Southern Andes

   https://doi.org/10.1002/ece3.5538  

   Alza, Luis ; Lavretsky, Philip ; Peters, Jeffrey L. ; Cerón, Gerardo ; Smith, Matthew ; Kopuchian, Cecilia ; Astie, Andrea ; McCracken, Kevin G. ( August 2019 , Ecology and Evolution)

   To investigate the structure and rate of gene flow among populations of habitat‐specialized species to understand the ecological and evolutionary processes underpinning their population dynamics and historical demography, including speciation and extinction.

   Peruvian and Argentine Andes.

   Two subspecies of torrent duck (Merganetta armata).

   We sampled 156 individuals in Peru (M. a. leucogenis;Chillón River,n = 57 and Pachachaca River,n = 49) and Argentina (M. a. armata;Arroyo Grande River,n = 33 and Malargüe River,n = 17), and sequenced the mitochondrial DNA (mtDNA) control region to conduct coarse and fine‐scale demographic analyses of population structure. Additionally, to test for differences between subspecies, and across genetic markers with distinct inheritance patterns, a subset of individuals (Peru,n = 10 and Argentina,n = 9) was subjected to partial genome resequencing, obtaining 4,027 autosomal and 189 Z‐linked double‐digest restriction‐associated DNA sequences.

   Haplotype and nucleotide diversities were higher in Peru than Argentina across all markers. Peruvian and Argentine subspecies showed concordant species‐level differences (Φ_STmtDNA = 0.82; Φ_STautosomal = 0.30; Φ_STZ chromosome = 0.45), including no shared mtDNA haplotypes. Demographic parameters estimated for mtDNA using IM and IMa2 analyses, and for autosomal markers using∂a∂i(isolation‐with‐migration model), supported an old divergence (mtDNA = 600,000 years before present (ybp), 95% HPD range = 1.2 Mya to 200,000 ybp; and autosomal∂a∂i = 782,490 ybp), between the two subspecies, characteristic of deeply diverged lineages. The populations were well‐differentiated in Argentina but moderately differentiated in Peru, with low unidirectional gene flow in each country.

   We suggest that the South American Arid Diagonal was preexisting and remains a current phylogeographic barrier between the ranges of the two torrent duck subspecies, and the adult territoriality and breeding site fidelity to the rivers define their population structure.

    

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2. Efficient summary statistics for detecting lineage fusion from phylogeographic datasets

   https://doi.org/10.1111/jbi.13932  

   Garrick, Ryan C. ; Hyseni, Chaz ; Arantes, Ísis C. ( July 2020 , Journal of Biogeography)

   Lineage fusion (merging of two or more populations of a species resulting in a single panmictic group) is a special case of secondary contact. It has the potential to counteract diversification and speciation, or to facilitate it through creation of novel genotypes. Understanding the prevalence of lineage fusion in nature requires reliable detection of it, such that efficient summary statistics are needed. Here, we report on simulations that characterized the initial intensity and subsequent decay of signatures of past fusion for 17 summary statistics applicable to DNA sequence haplotype data.

   Global.

   Diploid out‐crossing species.

   We considered a range of scenarios that could reveal the impacts of different combinations of read length versus number of loci (arrangement of DNA sequence data), and whether or not pre‐fusion populations experienced bottlenecks coinciding with their divergence (historical context of fusion). Post‐fusion gene pools were sampled along 10 successive time points representing increasing lag times following merging of sister populations, and summary statistic values were recalculated at each.

   Many summary statistics were able to detect signatures of complete merging of populations after a sampling lag time of 1.5N_egenerations, but the most informative ones included two neutrality tests and four diversity metrics, withZ_nS(a linkage disequilibrium‐based neutrality test) being particularly powerful. Correlation was relatively low among the two neutrality tests and two of the diversity metrics. There were clear benefits of many short (200‐bp × 200) loci over a handful of long (4‐kb × 10) loci. Also, only the latter genetic dataset type showed impacts of bottlenecks during divergence upon the number of informative summary statistics.

   This work contributes to identifying cases of lineage fusion, and advances phylogeography by enabling more nuanced reconstructions of how individual species, or multiple members of an ecological community, responded to past environmental change.

    

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3. Thickness dependence of structural relaxation in spin‐cast polynorbornene films with high glass transition temperatures (>613 K)

   https://doi.org/10.1002/polb.24434  

   Lewis, Elizabeth A. ; Vogt, Bryan D. ( September 2017 , Journal of Polymer Science Part B: Polymer Physics)

   The isothermal structural relaxation (densification) of a family of glassy polynorbornene films with high glass transition temperatures (T_g > 613 K) is assessed via spectroscopic ellipsometry. Three polymers were examined: poly(butylnorbornene) (BuNB), poly(hydroxyhexafluoroisopropyl norbornene) (HFANB), and their random copolymer, BuNB‐r‐HFANB. The effective aging rate,β(T), of thick (∼1.2 μm) spun cast films of BuNB‐r‐HFANB is approximately 10⁻³over a wide temperature window (0.49 < T/T_g < 0.68). At higher temperatures, these polymers undergo reactions that more dramatically decrease the film thickness, which prohibits erasing the process history by annealing aboveT_g. The aging rate for thick BuNB‐r‐HFANB films is independent of the casting solvent, which infers that rapid aging is not associated with residual solvent.β(at 373 K) decreases for films thinner than ∼500 nm. However, the isothermal structural relaxation of thin films of BuNB‐r‐HFANB exhibits nonmonotonic temporal evolution in thickness for films thinner than 115 nm film. The thickness after 18 h of aging at 373 K can be greater than the initial thickness. The rapid aging of these polynorbornene films is attributed to the unusual rapid local dynamics of this class of polymers and demonstrates the potential for unexpected structural relaxations in membranes and thin films of high‐T_gpolymers that could impact their performance. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2018,56, 53–61

    

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4. Secret lifestyles of pyrophilous fungi in the genus Sphaerosporella

   https://doi.org/10.1002/ajb2.1482  

   Hughes, Karen W. ; Case, Alexis ; Matheny, P. Brandon ; Kivlin, Stephanie ; Petersen, Ronald H. ; Miller, Andrew N. ; Iturriaga, Teresa ( June 2020 , American Journal of Botany)

   Pyrophilous fungi form aboveground fruiting structures (ascocarps) following wildfires, but their ecology, natural history, and life cycles in the absence of wildfires are largely unknown.Sphaerosporellais considered to be pyrophilous. This study exploresSphaerosporellaascocarp appearance following a rare 2016 wildfire in the Great Smoky Mountains National Park (GSMNP), compares the timing of ascocarp formation with recovery ofSphaerosporellaDNA sequences in soils, and explores the association ofSphaerosporellawith post‐fire Table Mountain pine (Pinus pungens) seedlings.

   Burned sites in the GSMNP were surveyed for pyrophilous fungal ascocarps over 2 years. Ascocarps, mycorrhizae, and endophyte cultures were evaluated morphologically and by Sanger sequencing of the nuclear ribosomal ITS gene region (fungal barcode; Schoch et al., 2012). DNA from soil cores was subjected to Illumina sequencing.

   The timing and location of post‐fireSphaerosporellaascocarp formation was correlated with recovery ofSphaerosporellaDNA sequences in soils. Genetic markers (fungal barcode) ofSphaerosporellawere also recovered from mycorrhizal root tips and endophyte cultures from seedlings ofPinus pungens.

   This study demonstrates thatSphaerosporellaspecies,in the absence of fire,are biotrophic, forming both mycorrhizal and endophytic associations with developingPinus pungensseedlings and may persist in nature in the absence of wildfire as a conifer symbiont. We speculate thatSphaerosporellamay fruit only after the host plant is damaged or destroyed and that after wildfires, deep roots, needle endophytes, or heat‐resistant spores could serve as a source of soil mycelium.

    

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5. Antifeedant, contact toxicity and oviposition deterrent effects of phyllostine acetate and phyllostine isolated from the endophytic fungus Diaporthe miriciae against Plutella xylostella larvae

   https://doi.org/10.1002/ps.5673  

   Ratnaweera, Pamoda B. ; M Jayasundara, J. M. Nisansala ; Herath, H. H. M. Suseema D. ; Williams, David E. ; Rajapaksha, Sasini U. ; Nishantha, K. M. D. W. Prabath ; de Silva, E. Dilip ; Andersen, Raymond J. ( December 2019 , Pest Management Science)

   Larvae of the diamond back moth (DBM),Plutella xylostella, are destructive cabbage pests causing economic losses worldwide. Continuous application of synthetic pesticides to control this pest has resulted in environmental pollution and resistant pest strains. Thus, there is a crucial need to seek natural alternatives with minimal detrimental effects. This study was designed to investigate the antifeedant activities of endophytic fungi ofCyperus iriaand to determine the antifeedant, contact toxicity and oviposition deterrent activities of phyllostine acetate and phyllostine of the endophyticDiaporthe miriciaefungus.

   Two cyclohexeneoxidediones, phyllostine acetate (1) and phyllostine (2), isolated from an ethyl acetate extract ofD. miriciaeexhibited strong antifeedant, contact toxicity, and oviposition deterrent activities againstP. xylostella. Phyllostine acetate (1) and phyllostine (2) showed feeding deterrent indexes of 100% at 50 μg cm⁻²in the no‐choice leaf disc assay and 50% feeding deterrence (DC₅₀) values of 9 and 4.7 μg cm⁻²respectively. The median lethal concentration (LC₅₀) values of phyllostine acetate (1) and phyllostine (2) were 4.38 and 6.54 μg/larva in the contact toxicity assay. The oviposition deterrent indexes of the two compounds were 100% for phyllostine acetate (1) and 28.6% for phyllostine (2) at 50 μg cm⁻².

   Phyllostine acetate and phyllostine show promise as compounds for the control ofP. xylostella. This study encourages further investigation of endophytic fungi of the family Cyperacea, for the development of natural pest control agents in agriculture. © 2019 Society of Chemical Industry

    

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