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Actinocyclus diffusus Fleming

NMNH - Botany Dept.

Spatial gradients in dissolved carbon due to tidal marsh outwelling into a Chesapeake Bay estuary

Smithsonian Libraries
ABSTRACT: Tidal marshes have been previously shown to affect fluxes of carbon and nutrients in adjacent estuaries by acting as sources, sinks or transformers of compounds transported in water exchanged between the marsh and estuary. Relative to information on the amount and direction of these exchanges, much less is known about the distribution and fate of the distinctive dissolved organic compounds derived from marshes, and the spatial extent to which this 'marsh signature' affects optical and biogeochemical variability in the estuary. In the present study we address the spatial distribution of both dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC), as well as other biogeochemical components, in the Rhode River estuary-marsh complex of the Chesapeake Bay. High-spatial-resolution transects showed that the marshes are a major source of DOC, DIC and pCO2 to the adjacent estuary and atmosphere, and that they seem to trap algae and other suspended particulate matter while releasing high-molecular-weight, aromatic-rich, highly colored dissolved organic matter (CDOM) into the estuary through tidal flushing. These processes result in strong variability in water characteristics considerably beyond the marsh–estuary interface. Non-conservative mixing in CDOM with salinity was probably due to both intense processing of the more labile marsh-exported components, as well as to mixing with other terrestrial and wetland inputs into the estuary. Despite the possible role of the adjacent subtidal mudflat as a sink for some of the material released from the marshes, the marsh signature was distinguishable from the regional estuarine background over a distance of more than 1 km into the river.

Dielectric properties of lava flows west of Ascraeus Mons, Mars

Smithsonian Libraries
The SHARAD instrument on the Mars Reconnaissance Orbiter detects subsurface interfaces beneath lava flow fields northwest of Ascraeus Mons. The interfaces occur in two locations; a northern flow that originates south of Alba Patera, and a southern flow that originates at the rift zone between Ascraeus and Pavonis Montes. The northern flow has permittivity values, estimated from the time delay of echoes from the basal interface, between 6.2 and 17.3, with an average of 12.2. The southern flow has permittivity values of 7.0 to 14.0, with an average of 9.8. The average permittivity values for the northern and southern flows imply densities of 3.7 and 3.4 g cm(-3), respectively. Loss tangent values for both flows range from 0.01 to 0.03. The measured bulk permittivity and loss tangent values are consistent with those of terrestrial and lunar basalts, and represent the first measurement of these properties for dense rock on Mars. Citation: Carter, L. M., B. A. Campbell, J.W. Holt, R.J. Phillips, N.E. Putzig, S. Mattei, R. Seu, C. H. Okubo, and A. F. Egan (2009), Dielectric properties of lava flows west of Ascraeus Mons, Mars, Geophys. Res. Lett., 36, L23204, doi: 10.1029/2009GL041234.

Cumulative response of ecosystem carbon and nitrogen stocks to chronic CO2 exposure in a subtropical oak woodland

Smithsonian Libraries
* Rising atmospheric carbon dioxide (CO2) could alter the carbon (C) and nitrogen (N) content of ecosystems, yet the magnitude of these effects are not well known. We examined C and N budgets of a subtropical woodland after 11 yr of exposure to elevated CO2. * We used open-top chambers to manipulate CO2 during regrowth after fire, and measured C, N and tracer 15N in ecosystem components throughout the experiment. * Elevated CO2 increased plant C and tended to increase plant N but did not significantly increase whole-system C or N. Elevated CO2 increased soil microbial activity and labile soil C, but more slowly cycling soil C pools tended to decline. Recovery of a long-term 15N tracer indicated that CO2 exposure increased N losses and altered N distribution, with no effect on N inputs. * Increased plant C accrual was accompanied by higher soil microbial activity and increased C losses from soil, yielding no statistically detectable effect of elevated CO2 on net ecosystem C uptake. These findings challenge the treatment of terrestrial ecosystems responses to elevated CO2 in current biogeochemical models, where the effect of elevated CO2 on ecosystem C balance is described as enhanced photosynthesis and plant growth with decomposition as a first-order response.

Effects of stream map resolution on measures of riparian buffer distribution and nutrient retention potential

Smithsonian Libraries
Riparian ecosystems are interfaces between aquatic and terrestrial environments recognized for their nutrient interception potential in agricultural landscapes. Stream network maps from a broad range of map resolutions have been employed in watershed studies of riparian areas. However, map resolution may affect important attributes of riparian buffers, such as the connectivity between source lands and small stream channels missing in coarse resolution maps. We sought to understand the influence of changing stream map resolution on measures of the river network, near-stream land cover, and riparian metrics. Our objectives were: (1) to evaluate the influence of stream map resolution on measures of the stream network, the character and extent of near-stream zones, and riparian metrics; (2) to compare patterns of variation among different physiographic provinces; and (3) to explore how predictions of nutrient retention potential might be affected by the resolution of a stream map. We found that using fine resolution stream maps significantly increased our estimates of stream order, drainage density, and the proportion of watershed area occurring near a stream. Increasing stream map resolution reduced the mean distance to source areas as well as mean buffer width and increased the frequency of buffer gaps. Measures of percent land cover within 100 m of streams were less sensitive to stream map resolution. Overall, increasing stream map resolution led to reduced estimates of nutrient retention potential in riparian buffers. In some watersheds, switching from a coarse resolution to a fine resolution stream map completely changed our perception of a stream network from well buffered to largely unbuffered. Because previous, broad-scale analyses of riparian buffers used coarse-resolution stream maps, those studies may have overestimated landscape-level buffer prevalence and effectiveness. We present a case study of three watersheds to demonstrate that interactions among stream map resolution and land cover patterns make a dramatic difference in the perceived ability of riparian buffers to ameliorate effects of agricultural activities across whole watersheds. Moreover, stream map resolution affects inferences about whether retention occurs in streams or riparian zones.

Land use legacies and small streams: identifying relationships between historical land use and contemporary stream conditions

Smithsonian Libraries
The concept of landscape legacies has been examined extensively in terrestrial ecosystems and has led to a greater understanding of contemporary ecosystem processes. However, although stream ecosystems are tightly coupled with their catchments and, thus, probably are affected strongly by historical catchment conditions, few studies have directly examined the importance of landuse legacies on streams. We examined relationships between historical land use (1944) and contemporary (2000-2003) stream physical, chemical, and biological conditions after accounting for the influences of contemporary land use (1999) and natural landscape (catchment size) variation in 12 small streams at Fort Benning, Georgia, USA. Most stream variables showed strong relationships with contemporary land use and catchment size; however, after accounting for these factors, residual variation in many variables remained significantly related to historical land use. Residual variation in benthic particulate organic matter, diatom density, % of diatoms in Eunotia spp., fish density in runs, and whole-stream gross primary productivity correlated negatively, whereas streamwater pH correlated positively, with residual variation in fraction of disturbed land in catchments in 1944 (i.e., bare ground and unpaved road cover). Residual variation in % recovering land (i.e., early successional vegetation) in 1944 was correlated positively with residual variation in streambed instability, a macroinvertebrate biotic index, and fish richness, but correlated negatively with residual variation in most benthic macroinvertebrate metrics examined (e.g., Chironomidae and total richness, Shannon diversity). In contrast, residual variation in whole-stream respiration rates was not explained by historical land use. Our results suggest that historical land use continues to influence important physical and chemical variables in these streams, and in turn, probably influences associated biota. Beyond providing insight into biotic interactions and their associations with environmental conditions, identification of landuse legacies also will improve understanding of stream impairment in contemporary minimally disturbed catchments, enabling more accurate assessment of reference conditions in studies of biotic integrity and restoration.

Ocean Acidification and the Loss of Phenolic Substances in Marine Plants

Smithsonian Libraries
Rising atmospheric CO2 often triggers the production of plant phenolics, including many that serve as herbivore deterrents, digestion reducers, antimicrobials, or ultraviolet sunscreens. Such responses are predicted by popular models of plant defense, especially resource availability models which link carbon availability to phenolic biosynthesis. CO2 availability is also increasing in the oceans, where anthropogenic emissions cause ocean acidification, decreasing seawater pH and shifting the carbonate system towards further CO2 enrichment. Such conditions tend to increase seagrass productivity but may also increase rates of grazing on these marine plants. Here we show that high CO2 / low pH conditions of OA decrease, rather than increase, concentrations of phenolic protective substances in seagrasses and eurysaline marine plants. We observed a loss of simple and polymeric phenolics in the seagrass Cymodocea nodosa near a volcanic CO2 vent on the Island of Vulcano, Italy, where pH values decreased from 8.1 to 7.3 and pCO(2) concentrations increased ten-fold. We observed similar responses in two estuarine species, Ruppia maritima and Potamogeton perfoliatus, in in situ Free-Ocean-Carbon-Enrichment experiments conducted in tributaries of the Chesapeake Bay, USA. These responses are strikingly different than those exhibited by terrestrial plants. The loss of phenolic substances may explain the higher-than-usual rates of grazing observed near undersea CO2 vents and suggests that ocean acidification may alter coastal carbon fluxes by affecting rates of decomposition, grazing, and disease. Our observations temper recent predictions that seagrasses would necessarily be "winners" in a high CO2 world.

Fairbanks Recruiting Office Scale

National Museum of American History
In 1861, having recognized that there was “no portion of the care of an army more important than the furnishing of the supplies,” the Howe Scale Co. introduced an “exceedingly compact” Army Scale that could be closed up “to prevent injury in camp or in transporting.” The firm would later claim that its “Army or Commissary Scales” could “be closed in half a minute, so as to form a complete and that more than 4,000 of these scales “were used by the United States army during the late war.” The “Commissary Scale” for which Thaddeus Fairbanks obtained a U.S. patent in 1862 looked a lot like Howe’s Army Scale. It could be “reduced at will to a more compact form than that required when in use,” and locked for security. It could be used for “commissary and general army purposes,” and might “stand unwatched on wharves and other exposed places with little danger of the loss of any of its parts by theft.” E. and T. Fairbanks was soon manufacturing scales according to this design, and would continue doing so for many years. In 1897, the Fairbanks firm noted that their “Army and Navy Scales” had been found “very useful on board ship, where space is an object and compactness is desirable; also by contractors and army recruiting officers.” They also offered a similar “Recruiting Office Scale.” The inscriptions on this example read “FAIRBANKS” and “RECRUITING OFFICE SCALE.” The colored image of a terrestrial globe crossed with the words “FAIRBANKS SCALES” represents the trade mark for which E. and T. Fairbanks received a trade mark on September 5, 1893. Ref: “Howe’s Army Scale,” Scientific American (Oct. 12, 1861): 252. The Howe Scale Co., Illustrated Price List of the Improved Howe Scales (Rutland, Vt., 1880), p. 16. Thaddeus Fairbanks, “Improvement in Platform-Scales,” U.S. Patent 34,676 (March 18, 1862). Fairbanks & Co., Pricelist (July 1, 1897), p. 37.

Discriminatory power of different arthropod data sets for the biological monitoring of anthropogenic disturbance in tropical forests

Smithsonian Libraries
Arthropods were monitored by local parataxonomists at 12 sites of increasing anthropogenic disturbance (old and young secondary forests, savanna and cultivated gardens) at Gamba, Gabon. We report on the discriminatory power of different data sets with regard to the classification of sites along the disturbance gradient, using preliminary data accounting for 13 surveys and 142 425 arthropods collected by Malaise, pitfall and yellow-pan traps. We compared the performance of different data sets. These were based upon ordinal, familial and guild composition, or upon 22 target taxa sorted to morphospecies and either considered in toto or grouped within different functional guilds. Finally we evaluated `predictor sets' made up of a few families or other target taxa, selected on the basis of their indicator value index. Although the discriminatory power of data sets based on ordinal categories and guilds was low, that of target taxa belonging to chewers, parasitoids and predators was much higher. The data sets that best discriminated among sites of differing degrees of disturbance were the restricted sets of indicator families and target taxa. This validates the concept of predictor sets for species-rich tropical systems. Including or excluding rare taxa in the analyses did not alter these conclusions. We conclude that calibration studies similar to ours are needed elsewhere in the tropics and that this strategy will allow to devise a representative and efficient biotic index for the biological monitoring of terrestrial arthropod assemblages in the tropics.

Speciation Genes in Free-Spawning Marine Invertebrates

Smithsonian Libraries
Research on speciation of marine organisms has lagged behind that of terrestrial ones, but the study of the evolution of molecules involved in the adhesion of gametes in free-spawning invertebrates is an exception. Here I review the function, species-specificity, and molecular variation of loci coding for bindin in sea urchins, lysin in abalone and their egg receptors, in an effort to assess the degree to which they contribute to the emergence of reproductive isolation during the speciation process. Bindin is a protein that mediates binding of the sperm to the vitelline envelope (VE) of the egg and the fusion of the gametes' membranes, whereas lysin is a protein involved only in binding to the VE. Both of these molecules are important in species recognition by the gametes, but they rarely constitute absolute blocks to interspecific hybridization. Intraspecific polymorphism is high in bindin, but low in lysin. Polymorphism in bindin is maintained by frequency-dependent selection due to sexual conflict arising from the danger of polyspermy under high densities of sperm. Monomorphism in lysin is the result of purifying selection arising from the need for species recognition. Interspecific divergence in lysin is due to strong positive selection, and the same is true for bindin of four out of seven genera of sea urchins studied to date. The differences between the sea urchin genera in the strength of selection can only partially be explained by the hypothesis of reinforcement. The egg receptor for lysin (VERL) is a glycoprotein with 22 repeats, 20 of which have evolved neutrally and homogenized by concerted evolution, whereas the first two repeats are under positive selection. Selection on lysin has been generated by the need to track changes in VERL, permitted by the redundant structure of this molecule. Both lysin and bindin are important in reproductive isolation, probably had a role in speciation, but it is hard to determine whether they meet the strictest criteria of "speciation loci," defined as genes whose differentiation has caused speciation.

Spectrograph, DTM Image Tube

National Air and Space Museum
Original Image Tube Spectrograph built in the early 1960s by W. Kent Ford, Jr., which he then used in collaboration with Vera Rubin to explore an observational problem she had developed: to determine the detailed rotational properties of galaxies. The cascaded image tube developed by Ford at the Carnegie and then manufactered by RCA improved quantum efficiency of photographic detectors by over a factor of ten and made it feasible to perform difficult observational programs like this. Analysis of observational data from this instrument led Rubin to the conclusion that there was a huge amount of unseen mass distributed throughout the visible matter in galaxies causing them to rotate like rigid bodies. This observation yielded evidence for the existence of dark matter that stimulated general acknowledgement that it forms a majority of the mass in the Universe. For her revolutionary work, Vera Rubin was the second woman in history to be awarded the Gold Medal of England's Royal Astronomical Society. The spectrograph was originally on loan to NASM from the Carnegie Institution of Washington and has now been accessioned into the collection as it represents the successful application of electronic amplification technology that led to a profound change in our understanding of the nature of the Universe.

Effects of small-scale disturbance on invasion success in marine communities

Smithsonian Libraries
Introductions of non-indigenous species have resulted in many ecological problems including the reduction of biodiversity, decline of commercially important species and alteration of ecosystems. The link between disturbance and invasion potential has rarely been studied in the marine environment where dominance hierarchies, dynamics of larval supply, and resource acquisition may differ greatly from terrestrial systems. In this study, hard substrate marine communities in Long Island Sound, USA were used to assess the effect of disturbance on resident species and recent invaders, ascidian growth form (i.e. colonial and solitary growth form), and the dominant species-specific responses within the community. Community age was an additional factor considered through manipulation of 5-wk old assemblages and 1-yr old assemblages. Disturbance treatments, exposing primary substrate, were characterized by frequency (single, biweekly, monthly) and magnitude (20%, 48%, 80%) of disturbance. In communities of different ages, disturbance frequency had a significant positive effect on space occupation of recent invaders and a significant negative effect on resident species. In the 5-wk community, magnitude of disturbance also had a significant effect. Disturbance also had a significant effect on ascidian growth form; colonial species occupied more primary space than controls in response to increased disturbance frequency and magnitude. In contrast, solitary species occupied significantly less space than controls. Species-specific responses were similar regardless of community age. The non-native colonial ascidian Diplosoma listerianum responded positively to increased disturbance frequency and magnitude, and occupied more primary space in treatments than in controls. The resident solitary ascidian Molgula manhattensis responded negatively to increased disturbance frequency and magnitude, and occupied less primary space in treatments than in controls. Small-scale biological disturbances, by creating space, may facilitate the success of invasive species and colonial organisms in the development of subtidal hard substrate communities.

Numbers Don’t Lie: The CD Really Is Dead

Smithsonian Magazine

As streaming music gains popularity, record companies have insisted it’s not threatening their sales. But newly released statistics suggest that streaming music may be killing a format instead. For the first time ever, streaming revenues have surpassed those made by compact discs.

A new report from the Recording Industry Association of America shows that streaming outlets generated $1.87 billion in 2014—while CD sales fell to $1.85 billion. Streaming music’s edge is slight but significant: it now accounts for 27 percent of the industry’s total revenues. And while permanent downloads still dominate the digital music market (with $2.58 billion in revenues, they bring in about 38 percent more than streaming services), streaming is catching up quickly.

With digital music now capturing 65 percent of the market’s revenues, it’s easy to predict the demise of all physical formats. But there is one dark horse in the game. The RIAA’s report also showed that vinyl sales continue to rise (revenues are up 50 percent since 2013). LPs have staged what the Wall Street Journal calls “the biggest music comeback of 2014,” and the format is making gains with the same under-35 demographic that’s fueling streaming music. 

The humble CD isn’t the only format that’s being edged out by a changing music market, either. Streaming music is threatening another mainstay: the car radio. The New York Post reports that terrestrial radio is being edged out by streaming services like Sirius XM and Pandora—and by 2018, more than 60 percent of new vehicles in the United States will come equipped with the technology it takes to stream on the go.

Reading the Complex Skipper Butterfly Fauna of One Tropical Place

Smithsonian Libraries
Background: An intense, 30-year, ongoing biodiversity inventory of Lepidoptera, together with their food plants and parasitoids, is centered on the rearing of wild-caught caterpillars in the 120,000 terrestrial hectares of dry, rain, and cloud forest of Area de Conservacion Guanacaste (ACG) in northwestern Costa Rica. Since 2003, DNA barcoding of all species has aided their identification and discovery. We summarize the process and results for a large set of the species of two speciose subfamilies of ACG skipper butterflies (Hesperiidae) and emphasize the effectiveness of barcoding these species (which are often difficult and time-consuming to identify). Methodology/Principal Findings: Adults are DNA barcoded by the Biodiversity Institute of Ontario, Guelph, Canada; and they are identified by correlating the resulting COI barcode information with more traditional information such as food plant, facies, genitalia, microlocation within ACG, caterpillar traits, etc. This process has found about 303 morphologically defined species of eudamine and pyrgine Hesperiidae breeding in ACG (about 25% of the ACG butterfly fauna) and another 44 units indicated by distinct barcodes (n = 9,094), which may be additional species and therefore may represent as much as a 13% increase. All but the members of one complex can be identified by their DNA barcodes. Conclusions/Significance: Addition of DNA barcoding to the methodology greatly improved the inventory, both through faster (hence cheaper) accurate identification of the species that are distinguishable without barcoding, as well as those that require it, and through the revelation of species "hidden" within what have long been viewed as single species. Barcoding increased the recognition of species-level specialization. It would be no more appropriate to ignore barcode data in a species inventory than it would be to ignore adult genitalia variation or caterpillar ecology.

Conservatism of Late Pennsylvanian vegetational patterns during short-term cyclic and long-term directional environmental change, western equatorial Pangea

Smithsonian Libraries
Patterns of plant distribution by palaeoenvironment were examined across the Pennsylvanian–Permian transition in North–Central Texas. Stratigraphically recurrent packages of distinct lithofacies, representing different habitats, contain qualitatively and quantitatively different macrofloras and microfloras. The species pools demonstrate niche conservatism, remaining closely tied to specific habitats, during both short-term cyclic environmental change and a long-term trend of increasing aridity. The deposits examined principally comprise the terrestrial Markley and its approximate marine equivalent, the Harpersville Formation and parts of lower Archer City Formation. Fossiliferous deposits are lens-like, likely representing fill sequences of channels formed during abandonment phases. Palaeosols, represented by blocky mudstones, comprise a large fraction of the deposits. They suggest progressive climate change from minimally seasonal humid to seasonal subhumid to seasonal dry subhumid. Five lithofacies yielded plants: kaolinite-dominated siltstone, organic shale, mudstone beds within organic shale, coarsening upward mudstone–sandstone interbeds and channel sandstone. Both macro- and microflora were examined. Lithofacies proved compositionally distinct, with different patterns of dominance diversity. Organic shales (swamp deposits), mudstone partings (swamp drainages) and coarsening upward mudstone–sandstone interbeds (floodplains) typically contain Pennsylvanian wetland vegetation. Kaolinite-dominated siltstones and (to the extent known) sandstones contain taxa indicative of seasonally dry substrates. Some kaolinite-dominated siltstones and organic shales/coals yielded palynomorphs. Microfloras are more diverse, with greater wetland–dryland overlap than macrofloras. It appears that these two floras were coexistent at times on the regional landscape.

Lava flow surface roughness and depolarized radar scattering

Smithsonian Libraries
Surface roughness has a strong controlling influence on radar scattering and other types of remote sensing observations. We compare field measurements of surface topography and dielectric constant for a range of lava flow textures to aircraft multipolarization radar observations at 5.7, 24, and 68 cm (C, L, and P band) wavelengths. The roughness is found to vary with scale in a self-affine (fractal) manner for scale lengths between 25 cm (the smallest horizontal step size) and 3-5 m. This result is used to demonstrate that a two-component surface description, consisting of the fractal dimension and rms height or slope at some reference scale, can resolve some of the ambiguities in previous efforts to quantify roughness. At all three radar wavelengths, the HV backscatter cross section is found to vary in an approximately exponential fashion with the rms height or Allan deviation at some reference scale, up to a saturation point, where the surface appears entirely diffusely scattering to the radar. Based on these observations, we use a parameter, gamma, defined as the ratio of rms height to the particular scale of measurement. Backscatter values at 24-cm wavelength and the topographic profile data were used to derive expressions which link the HV radar cross section to gamma or to the analogous wavelength-scale rms slope. These equations provide a reasonable fit to 24- and 68-cm echoes and for rough surfaces at 5.7 cm, but yield poor results for 5.7-cm echoes on smooth terrain. We conclude that the roughness at the two larger scales is well described by a single fractal dimension and rms height, but that texture at very small scales is characterized by different statistics. This inference is supported by analysis of 5-cm horizontal spacing topographic profiles. The relationships defined here allow determination of the surface rms height or slope at the scale of the radar wavelength. Given radar data at additional wavelengths, a more complete view of the statistical properties of the surface can be developed. Such techniques may be useful in analyses of synthetic aperture radar images for terrestrial volcanic areas, Magellan data for Venus, and other planetary radar observations.

No post-Cretaceous ecosystem depression in European forests? Rich insect-feeding damage on diverse middle Palaeocene plants, Menat, France

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Insect herbivores are considered vulnerable to extinctions of their plant hosts. Previous studies of insect-damaged fossil leaves in the US Western Interior showed major plant and insect herbivore extinction at the Cretaceous–Palaeogene (K–T) boundary. Further, the regional plant–insect system remained depressed or ecologically unbalanced throughout the Palaeocene. Whereas Cretaceous floras had high plant and insect-feeding diversity, all Palaeocene assemblages to date had low richness of plants, insect feeding or both. Here, we use leaf fossils from the middle Palaeocene Menat site, France, which has the oldest well-preserved leaf assemblage from the Palaeocene of Europe, to test the generality of the observed Palaeocene US pattern. Surprisingly, Menat combines high floral diversity with high insect activity, making it the first observation of a ‘healthy’ Palaeocene plant–insect system. Furthermore, rich and abundant leaf mines across plant species indicate well-developed host specialization. The diversity and complexity of plant–insect interactions at Menat suggest that the net effects of the K–T extinction were less at this greater distance from the Chicxulub, Mexico, impact site. Along with the available data from other regions, our results show that the end-Cretaceous event did not cause a uniform, long-lasting depression of global terrestrial ecosystems. Rather, it gave rise to varying regional patterns of ecological collapse and recovery that appear to have been strongly influenced by distance from the Chicxulub structure.

Ecological divergence and medial cuneiform morphology in gorillas

Smithsonian Libraries
Gorillas are more closely related to each other than to any other extant primate and are all terrestrial knuckle-walkers, but taxa differ along a gradient of dietary strategies and the frequency of arboreality in their behavioral repertoire. In this study, we test the hypothesis that medial cuneiform morphology falls on a morphocline in gorillas that tracks function related to hallucial abduction ability and relative frequency of arboreality. This morphocline predicts that western gorillas, being the most arboreal, should display a medial cuneiform anatomy that reflects the greatest hallucial abduction ability, followed by grauer gorillas, and then by mountain gorillas. Using a three-dimensional methodology to measure angles between articular surfaces, relative articular and nonarticular areas, and the curvatures of the hallucial articular surface, the functional predictions are partially confirmed in separating western gorillas from both eastern gorillas. Western gorillas are characterized by a more medially oriented, proportionately larger, and more mediolaterally curved hallucial facet than are eastern gorillas. These characteristics follow the predictions for a more prehensile hallux in western gorillas relative to a more stable, plantigrade hallux in eastern gorillas. The characteristics that distinguish eastern gorilla taxa from one another appear unrelated to hallucial abduction ability or frequency of arboreality. In total, this reexamination of medial cuneiform morphology suggests differentiation between eastern and western gorillas due to a longstanding ecological divergence and more recent and possibly non-adaptive differences between eastern taxa. Published by Elsevier Ltd.

Exploring Tree-Habitat Associations in a Chinese Subtropical Forest Plot Using a Molecular Phylogeny Generated from DNA Barcode Loci

Smithsonian Libraries
Elucidating the ecological mechanisms underlying community assembly in subtropical forests remains a central challenge for ecologists. The assembly of species into communities can be due to interspecific differences in habitat associations, and there is increasing evidence that these associations may have an underlying phylogenetic structure in contemporary terrestrial communities. In other words, by examining the degree to which closely related species prefer similar habitats and the degree to which they co-occur, ecologists are able to infer the mechanisms underlying community assembly. Here we implement this approach in a diverse subtropical tree community in China using a long-term forest dynamics plot and a molecular phylogeny generated from three DNA barcode loci. We find that there is phylogenetic signal in plant-habitat associations (i.e. closely related species tend to prefer similar habitats) and that patterns of co-occurrence within habitats are typically non-random with respect to phylogeny. In particular, we found phylogenetic clustering in valley and low-slope habitats in this forest, indicating a filtering of lineages plays a dominant role in structuring communities in these habitats and we found evidence of phylogenetic overdispersion in high-slope, ridge-top and high-gully habitats, indicating that distantly related species tended to co-occur in these high elevation habitats and that lineage filtering is less important in structuring these communities. Thus we infer that non-neutral niche-based processes acting upon evolutionarily conserved habitat preferences explain the assembly of local scale communities in the forest studied.

Dip Circle

National Museum of American History
The Department of Terrestrial Magnetism of the Carnegie Institution of Washington bought this Kew pattern dip circle in 1919. The inscription reads "Dover, Charlton Kent, Circle 240." With four needles, tripod, case, Kew certificate of examination, and importation charges, it cost $184.70. The vertical circle is silvered, graduated to 30 minutes, and read by opposite verniers to single minutes. The horizontal circle is silvered, graduated to 30 minutes, and read by vernier to single minutes.

Juvet Time Globe

National Museum of American History
In 1880, Scientific American enthusiastically recommended Louis P. Juvet's time globe to its readers. It was, the magazine found, "a fit ornament for any library, a valuable adjunct in every business office, and a necessity in every institution of learning." The clockwork-driven globe was undeniably useful for studying geography, determining world time, and illustrating the rotation of the earth. The basis of its appeal, however, was even broader. Prominently displayed in the parlors and drawing rooms of Gilded Age America, the elegant time globe clearly demonstrated the wealth and culture of its owner. Available in a range of sizes and versions simple and ornate, the time globe consisted of three basic elements: a globe, a mechanism for rotating it, and a base. The globe most often featured a terrestrial map, but celestial globes were also offered. An equatorial ring indicated worldwide time and zones of daylight and darkness. A meridian ring supported a clock dial over the north pole. Concealed within the globe was a four-day, spring-driven brass movement that drove the clock dial and rotated the globe once every twenty-four hours. Manufactured for Juvet by Rood and Horton of Bristol, Connecticut, the movements featured a lever escapement and a balance wheel. Turning the feather end of the arrow-shaped axis wound the movement. Precisely when production of the globes began is uncertain. Juvet, a Swiss immigrant and a resident of Glens Falls, New York, first patented a mechanical globe in January 1867, and exhibited one at the Philadelphia Centennial Exposition of 1876. Probably sometime in 1879, Juvet formed a partnership with James Arkell. By the early 1880s, Juvet and Company of Canajoharie, New York, was making more than sixty varieties of globes. In October 1886, fire consumed the factory where the globes were assembled, ending their manufacture there forever. Pictured on the left. Overall measurements are 55 1/2 x 17 x 17 inches.

Differentiating successful and failed molluscan invaders in estuarine ecosystems

Smithsonian Libraries
Despite mounting evidence of invasive species' impacts on the environment and society, our ability to predict invasion establishment, spread, and impact are inadequate. Efforts to explain and predict invasion outcomes have been limited primarily to terrestrial and freshwater ecosystems. Invasions are also common in coastal marine ecosystems, yet to date predictive marine invasion models are absent. Here we present a model based on biological attributes associated with invasion success (establishment) of marine molluscs that compares successful and failed invasions from a group of 93 species introduced to San Francisco Bay (SFB) in association with commercial oyster transfers from eastern North America (ca. 1869 to 1940). A multiple logistic regression model correctly classified 83% of successful and 80% of failed invaders according to their source region abundance at the time of oyster transfers, tolerance of low salinity, and developmental mode. We tested the generality of the SFB invasion model by applying it to 3 coastal locations (2 in North America and 1 in Europe) that received oyster transfers from the same source and during the same time as SFB. The model correctly predicted 100, 75, and 86% of successful invaders in these locations, indicating that abundance, environmental tolerance (ability to withstand low salinity), and developmental mode not only explain patterns of invasion success in SFB, but more importantly, predict invasion success in geographically disparate marine ecosystems. Finally, we demonstrate that the proportion of marine molluscs that succeeded in the latter stages of invasion (i.e. that establish self-sustaining populations, spread and become pests) is much greater than has been previously predicted or shown for other animals and plants.

Climate and vegetational regime shifts in the late Paleozoic ice age earth

Smithsonian Libraries
The late Paleozoic earth experienced alternation between glacial and non-glacial climates at multiple temporal scales, accompanied by atmospheric CO2 fluctuations and global warming intervals, often attended by significant vegetational changes in equatorial latitudes of Pangaea. We assess the nature of climate2013vegetation interaction during two time intervals: middle2013late Pennsylvanian transition and Pennsylvanian2013Permian transition, each marked by tropical warming and drying. In case study 1, there is a catastrophic intra-biomic reorganization of dominance and diversity in wetland, evergreen vegetation growing under humid climates. This represents a threshold-type change, possibly a regime shift to an alternative stable state. Case study 2 is an inter-biome dominance change in western and central Pangaea from humid wetland and seasonally dry to semi-arid vegetation. Shifts between these vegetation types had been occurring in Euramerican portions of the equatorial region throughout the late middle and late Pennsylvanian, the drier vegetation reaching persistent dominance by Early Permian. The oscillatory transition between humid and seasonally dry vegetation appears to demonstrate a threshold-like behavior but probably not repeated transitions between alternative stable states. Rather, changes in dominance in lowland equatorial regions were driven by long-term, repetitive climatic oscillations, occurring with increasing intensity, within overall shift to seasonal dryness through time. In neither case study are there clear biotic or abiotic warning signs of looming changes in vegetational composition or geographic distribution, nor is it clear that there are specific, absolute values or rates of environmental change in temperature, rainfall distribution and amount, or atmospheric composition, approach to which might indicate proximity to a terrestrial biotic-change threshold.
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