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1. Consequences of biodiversity shift across phylogenetic scales for aspen and willow growth, survival, and herbivory

   https://doi.org/10.1111/jvs.12716  

   Grossman, Jake J. ; Cavender‐Bares, Jeannine ; Bruun, ed., Hans Henrik ( March 2019 , Journal of Vegetation Science)

   It has been established that community biodiversity has consequences for ecosystem function. Yet research assessing these biodiversity–ecosystem function (BEF) relationships usually occurs at only one phylogenetic scale; as such, the dependence ofBEFrelationships on phylogenetic scale has not been characterized. We present a novel framework for considering the consequences of biodiversity across phylogenetic scales, allowing us to ask: Do the consequences of intraspecific and interspecific diversity affect the growth, survival, and leaf herbivory of three temperate tree species?

   Salicaceous tree plantation, Minnesota, northern USA.

   We established an experimental plantation consisting of trees of three species within the willow (Salicaceae) family. Two aspen (Populus tremuloides,P. alba) and one willow (Salix nigra) species were represented by three unique genotypes such that tree neighborhoods varied both in genotype richness (intraspecific diversity) and species richness (interspecific diversity). We assessed the consequences of tree identity and diversity across these two phylogenetic scales for all trees’ aboveground productivity and survival, and for herbivore damage (onP. tremuloides) at the end of the second full growing season of the experiment.

   Diversity at any phylogenetic scale had no effect on the growth and survival ofP. albaorS. nigra. However, intraspecific diversity increased the likelihood ofP. tremuloidessurvival while interspecific diversity reducedP. tremuloidessurvival. Intraspecific diversity also reduced leaf removal and galling herbivory onP. tremuloides, while interspecific diversity had no effect on leaf removal and increased galling herbivory. Neither scale of diversity affected leaf mining.

   Tree diversity within and among populations and species affected plant performance and ecosystem properties differentially, demonstrating thatBEFrelationships shift across phylogenetic scales in a taxon‐specific manner. We call for further experiments that explicitly span these scales by measuring ecosystem and physiological responses to the manipulation of diversity within and among species.

    

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2. Chemical defense over decadal scales: Ontogenetic allocation trajectories and consequences for fitness in a foundation tree species

   https://doi.org/10.1111/1365-2435.13425  

   Cope, Olivia L. ; Kruger, Eric L. ; Rubert‐Nason, Kennedy F. ; Lindroth, Richard L. ; Barton, ed., Kasey ( August 2019 , Functional Ecology)

   Expression of herbivore defense traits can change dramatically during the course of plant development. Little is known, however, about the degree of genetic or sexual variation in these ontogenetic defense trajectories or whether the trajectories themselves are adaptive, especially in long‐lived species.

   We used a 13‐year dataset of chemical defense traits, growth and survivorship from a common garden of trembling aspen (Populus tremuloides) genotypes to document long‐term defense trajectories and their relationship to tree fitness during juvenile and early mature stages.

   Overall, concentrations of the two principal classes of aspen defense compounds (salicinoid phenolic glycosides [SPGs] and condensed tannins [CTs]) decreased to differing degrees in foliage of juvenile trees and then remained relatively constant in maturity. Initial values, juvenile rates of change and average mature values all exhibited significant genetic variation for both SPGs and CTs.

   Relationships between defense trajectory parameters and metrics of tree fitness (growth and survivorship) depended on compound type and tree sex. Females with higher‐allocation SPG trajectories (high initial juvenile concentrations, slow juvenile declines, high mature concentrations) grew more slowly relative to females with lower‐allocation trajectories. In males, higher‐allocation SPG trajectories had a lesser effect on growth but were associated with reduced mortality. Juvenile CT trajectories were not correlated with tree fitness, but average CT concentration in maturity was positively related to growth in females.

   These results suggest that ontogenetic defense trajectories are adaptive and subject to natural selection. Genotypic variation and ontogeny shape tree defensive chemistry, both independently and interactively. These patterns of defense expression have the potential to structure trophic interactions and the genetic composition of forests in both space and time.

   A freePlain Language Summarycan be found within the Supporting Information of this article.

    

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3. Analysis of histidine‐tagged recombinant proteins from nickel and copper coated surfaces by direct electrospray ionization and desorption electrospray ionization mass spectrometry

   https://doi.org/10.1002/rcm.9516  

   Javanshad, Roshan ; Taylor, Christopher James ; Delavari, Niusha ; Barkman, Todd J. ; Stull, Frederick ; Venter, Andre R. ( April 2023 , Rapid Communications in Mass Spectrometry)

   Purification of recombinant proteins is a necessary step for functional or structural studies and other applications. Immobilized metal affinity chromatography is a common recombinant protein purification method. Mass spectrometry (MS) allows for confirmation of identity of expressed proteins and unambiguous detection of enzymatic substrates and reaction products. We demonstrate the detection of enzymes purified on immobilized metal affinity surfaces by direct or ambient ionization MS, and follow their enzymatic reactions by direct electrospray ionization (ESI) or desorption electrospray ionization (DESI).

   A protein standard, His‐Ubq, and two recombinant proteins, His‐SHAN and His‐CS, expressed inEscherichia coliwere immobilized on two immobilized metal affinity systems, Cu–nitriloacetic acid (Cu‐NTA) and Ni‐NTA. The proteins were purified on surface, and released in the ESI spray solvent for direct infusion, when using the 96‐well plate form factor, or analyzed directly from immobilized metal affinity‐coated microscope slides by DESI‐MS. Enzyme activity was followed by incubating the substrates in wells or by depositing substrate on immobilized protein on coated slides for analysis.

   Small proteins (His‐Ubq) and medium proteins (His‐SAHN) could readily be detected from 96‐well plates by direct infusion ESI, or from microscope slides by DESI‐MS after purification on surface from clarifiedE. colicell lysate. Protein oxidation was observed for immobilized proteins on both Cu‐NTA and Ni‐NTA; however, this did not hamper the enzymatic reactions of these proteins. Both the nucleosidase reaction products for His‐SAHN and the methylation product of His‐CS (theobromine to caffeine) were detected.

   The immobilization, purification, release and detection of His‐tagged recombinant proteins using immobilized metal affinity surfaces for direct infusion ESI‐MS or ambient DESI‐MS analyses were successfully demonstrated. Recombinant proteins were purified to allow identification directly out of clarified cell lysate. Biological activities of the recombinant proteins were preserved allowing the investigation of enzymatic activity via MS.

    

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4. Floral traits influence the opportunity for selection among male gametophytes: independent and combined effects of style length and petal area

   https://doi.org/10.1002/ajb2.1274  

   Mazer, Susan J. ; Chellew, Joseph P. ; Peach, Kristen ( April 2019 , American Journal of Botany)

   Strong correlations between traits can obscure their independent effects on components of reproduction. Style length (SL) and petal area (PA) vary within species, for example, but their independent effects on the opportunity for selection among pollen genotypes are poorly understood. Previous work inClarkiadetected a positive effect ofSLon pollen receipt, potentially intensifying selection. However, this apparent effect ofSLmay be influenced by a correlated trait, such asPA. Here, we examine the independent effects of these two traits on pollen receipt and performance.

   We collected petals and styles from wild populations of two insect‐pollinatedClarkiataxa and estimated the independent and combined effects ofSLandPAon pollen receipt and performance.

   In both taxa,SLandPAare positively correlated. InC. unguiculata, both traits positively and independently affect pollen receipt, but inC. xantianassp.xantiana, the two traits act only in combination to affect pollen receipt. In both taxa, pollen receipt positively affects the numbers of pollen tubes entering and penetrating the style, as well as pollen tube attrition.

   The effects ofSLandPAon pollen receipt and performance are taxon specific. InC. unguiculata, both traits may be independent targets of selection due to their effects on pollen receipt. InC. xantianassp.xantiana, by contrast, the combined (but not independent) effects ofSLandPAinfluence pollen receipt. Ecological differences between these taxa require exploration to understand the mechanisms by which these traits affect pollinator behavior.

    

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5. Effects of chemical preservation on bulk and amino acid isotope ratios of zooplankton, fish, and squid tissues

   https://doi.org/10.1002/rcm.8408  

   Hetherington, Elizabeth D. ; Kurle, Carolyn M. ; Ohman, Mark D. ; Popp, Brian N. ( April 2019 , Rapid Communications in Mass Spectrometry)

   It is imperative to understand how chemical preservation alters tissue isotopic compositions before using historical samples in ecological studies. Specifically, although compound‐specific isotope analysis of amino acids (CSIA‐AA) is becoming a widely used tool, there is little information on how preservation techniques affect amino acidδ¹⁵N values.

   We evaluated the effects of chemical preservatives on bulk tissueδ¹³C andδ¹⁵N and amino acidδ¹⁵N values, measured by gas chromatography/isotope ratio mass spectrometry (GC/IRMS), of (a) tuna (Thunnus albacares) and squid (Dosidicus gigas) muscle tissues that were fixed in formaldehyde and stored in ethanol for 2 years and (b) two copepod species,Calanus pacificusandEucalanus californicus, which were preserved in formaldehyde for 24–25 years.

   Tissues in formaldehyde‐ethanol had higher bulkδ¹⁵N values (+1.4,D. gigas; +1.6‰,T. albacares), higherδ¹³C values forD. gigas(+0.5‰), and lowerδ¹³C values forT. albacares(−0.8‰) than frozen samples. The bulkδ¹⁵N values from copepods were not different those from frozen samples, although theδ¹³C values from both species were lower (−1.0‰ forE. californicusand −2.2‰ forC. pacificus) than those from frozen samples. The mean amino acidδ¹⁵N values from chemically preserved tissues were largely within 1‰ of those of frozen tissues, but the phenylalanineδ¹⁵N values were altered to a larger extent (range: 0.5–4.5‰).

   The effects of preservation on bulkδ¹³C values were variable, where the direction and magnitude of change varied among taxa. The changes in bulkδ¹⁵N values associated with chemical preservation were mostly minimal, suggesting that storage in formaldehyde or ethanol will not affect the interpretation ofδ¹⁵N values used in ecological studies. The preservation effects on amino acidδ¹⁵N values were also mostly minimal, mirroring bulkδ¹⁵N trends, which is promising for future CSIA‐AA studies of archived specimens. However, there were substantial differences in phenylalanine and valineδ¹⁵N values, which we speculate resulted from interference in the chromatographic resolution of unknown compounds rather than alteration of tissue isotopic composition due to chemical preservation.

    

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