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Abstract Plants produce an astonishingly diverse array of specialized metabolites. A crucial step in understanding the origin of such chemodiversity is describing how chemodiversity manifests across the spatial and ontogenetic scales relevant to plant–biotic interactions.Focusing on 21 sympatric species ofPsychotriaandPalicourea sensu lato(Rubiaceae), we describe patterns of specialized metabolite diversity across spatial and ontogenetic scales using a combination of field collections, untargeted metabolomics, and ecoinformatics. We compare α, β, and γ diversity of specialized metabolites in expanding leaves, unripe pulp, immature seed, ripe pulp, mature seed, and fine roots.Within species, fruit tissues from across ontogenetic stages had ≥α diversity than leaves, and ≤β diversity than leaves. Pooled across species, fruit tissues and ontogenetic stages had the highest γ diversity of all organs, and fruit tissues and ontogenetic stages combined had a higher incidence of organ‐specific mass spectral features than leaves. Roots had ≤α diversity than leaves and the lowest β and γ diversity of all organs. Phylogenetic correlations of chemical distance varied by plant organ and chemical class.Our results describe patterns of specialized metabolite diversity across organs and species and provide support for organ‐specific contributions to plant chemodiversity. This study contributes to the growing understanding within plant evolutionary ecology of the biological scales of specialized metabolite diversification. Future studies combining our data on specialized metabolite diversity with biotic interaction data and experiments can test existing hypotheses on the roles of ecological interactions in the evolution of chemodiversity. 

ABSTRACT Spatially resolved images of debris discs are necessary to determine disc morphological properties and the scattering phase function (SPF) thatantifies the brightness of scattered light as a function of phase angle. Current high-contrast imaging instruments have successfully resolved several dozens of debris discs around other stars, but few studies have investigated trends in the scattered-light, resolved population of debris discs in a uniform and consistent manner. We have combined Karhunen-Loeve Image Projection (KLIP) with radiative-transfer disc forward modelling in order to obtain the highest-quality image reductions and constrain disc morphological properties of eight debris discs imaged by the Gemini Planet Imager at H-band with a consistent and uniformly applied approach. In describing the scattering properties of our models, we assume a common SPF informed from solar system dust scattering measurements and apply it to all systems. We identify a diverse range of dust density properties among the sample, including critical radius, radial width, and vertical width. We also identify radially narrow and vertically extended discs that may have resulted from substellar companion perturbations, along with a tentative positive trend in disc eccentricity with relative disc width. We also find that using a common SPF can achieve reasonable model fits for discs that are axisymmetric and asymmetric when fitting models to each side of the disc independently, suggesting that scattering behaviour from debris discs may be similar to Solar system dust. 

Abstract We present near-infrared Large Binocular Telescope LMIRCam imagery of the disk around the Herbig Ae/Be star AB Aurigae. A comparison of the surface brightness at K s (2.16 μ m), H 2 O narrowband (3.08 μ m), and L ′ (3.7 μ m) allows us to probe the presence of icy grains in this (pre)transitional disk environment. By applying reference differential imaging point-spread function subtraction, we detect the disk at high signal-to-noise ratios in all three bands. We find strong morphological differences between the bands, including asymmetries consistent with the observed spiral arms within 100 au in L ′ . An apparent deficit of scattered light at 3.08 μ m relative to the bracketing wavelengths ( K s and L ′ ) is evocative of ice absorption at the disk surface layer. However, the Δ( K s − H 2 O) color is consistent with grains with little to no ice (0%–5% by mass). The Δ ( H 2 O − L ′ ) color, conversely, suggests grains with a much higher ice mass fraction (∼0.68), and the two colors cannot be reconciled under a single grain population model. Additionally, we find that the extremely red Δ ( K s − L ′ ) disk color cannot be reproduced under conventional scattered light modeling with any combination of grain parameters or reasonable local extinction values. We hypothesize that the scattering surfaces at the three wavelengths are not colocated, and that the optical depth effects in each wavelength result from probing the grain population at different disk surface depths. The morphological similarity between K s and H 2 O suggests that their scattering surfaces are near one another, lending credence to the Δ( K s − H 2 O) disk color constraint of <5% ice mass fraction for the outermost scattering disk layer.