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Edgewater, MD, United States

The Smithsonian Environmental Research Center is a United States 2,800-acre environmental research and educational facility operated by the Smithsonian Institution. It is located on the Rhode and West Rivers near Edgewater in Anne Arundel County, Maryland, near the western shore of Chesapeake Bay. The center's focus of study is the ecosystems of coastal zones, particularly in the Chesapeake Bay estuary and nearby wetlands. Wikipedia.

Mccormick M.K.,Smithsonian Environmental Research Center | Jacquemyn H.,Catholic University of Leuven
New Phytologist | Year: 2014

Summary: The distribution and abundance of orchid populations depend on a suite of biological and ecological factors, including seed production and dispersal, availability of mycorrhizal fungi and appropriate environmental conditions, with the weighting of these factors depending on the spatial scale considered. Disentangling the factors determining successful orchid establishment represents a major challenge, involving seed germination experiments, molecular techniques and assessment of environmental conditions. Identification of fungi from large-scale surveys of mycorrhizal associations in a range of orchid species has shown that mycorrhizal fungi may be widespread and occur in varied habitats. Further, a meta-analysis of seed introduction experiments revealed similar seed germination in occupied and unoccupied habitat patches. Orchid rarity was also unrelated to mycorrhizal specificity. Nonetheless, seed germination within sites appears to depend on both biotic and abiotic conditions. In the few cases that have been examined, coexisting orchids have distinct mycorrhizal communities and show strong spatial segregation, suggesting that mycorrhizal fungi are important drivers of niche partitioning and contribute to orchid coexistence. A broader investigation of orchid mycorrhizal fungus distribution in the soil, coupled with fungus and recruitment mapping, is needed to translate fungal abundance to orchid population dynamics and may lead to better orchid conservation. © 2013 New Phytologist Trust. Source

Oftedal O.T.,Smithsonian Environmental Research Center
Animal | Year: 2012

Lactation represents an important element of the life history strategies of all mammals, whether monotreme, marsupial, or eutherian. Milk originated as a glandular skin secretion in synapsids (the lineage ancestral to mammals), perhaps as early as the Pennsylvanian period, that is, approximately 310 million years ago (mya). Early synapsids laid eggs with parchment-like shells intolerant of desiccation and apparently dependent on glandular skin secretions for moisture. Mammary glands probably evolved from apocrine-like glands that combined multiple modes of secretion and developed in association with hair follicles. Comparative analyses of the evolutionary origin of milk constituents support a scenario in which these secretions evolved into a nutrient-rich milk long before mammals arose. A variety of antimicrobial and secretory constituents were co-opted into novel roles related to nutrition of the young. Secretory calcium-binding phosphoproteins may originally have had a role in calcium delivery to eggs; however, by evolving into large, complex casein micelles, they took on an important role in transport of amino acids, calcium and phosphorus. Several proteins involved in immunity, including an ancestral butyrophilin and xanthine oxidoreductase, were incorporated into a novel membrane-bound lipid droplet (the milk fat globule) that became a primary mode of energy transfer. An ancestral c-lysozyme lost its lytic functions in favor of a role as α-lactalbumin, which modifies a galactosyltransferase to recognize glucose as an acceptor, leading to the synthesis of novel milk sugars, of which free oligosaccharides may have predated free lactose. An ancestral lipocalin and an ancestral whey acidic protein four-disulphide core protein apparently lost their original transport and antimicrobial functions when they became the whey proteins β-lactoglobulin and whey acidic protein, which with α-lactalbumin provide limiting sulfur amino acids to the young. By the late Triassic period (ca 210 mya), mammaliaforms (mammalian ancestors) were endothermic (requiring fluid to replace incubatory water losses of eggs), very small in size (making large eggs impossible), and had rapid growth and limited tooth replacement (indicating delayed onset of feeding and reliance on milk). Thus, milk had already supplanted egg yolk as the primary nutrient source, and by the Jurassic period (ca 170 mya) vitellogenin genes were being lost. All primary milk constituents evolved before the appearance of mammals, and some constituents may have origins that predate the split of the synapsids from sauropsids (the lineage leading to 'reptiles' and birds). Thus, the modern dairy industry is built upon a very old foundation, the cornerstones of which were laid even before dinosaurs ruled the earth in the Jurassic and Cretaceous periods. © Copyright The Animal Consortium 2011. Source

Oftedal O.T.,Smithsonian Environmental Research Center | Dhouailly D.,Joseph Fourier University
Journal of Mammary Gland Biology and Neoplasia | Year: 2013

We propose a new scenario for mammary evolution based on comparative review of early mammary development among mammals. Mammary development proceeds through homologous phases across taxa, but evolutionary modifications in early development produce different final morphologies. In monotremes, the mammary placode spreads out to form a plate-like mammary bulb from which more than 100 primary sprouts descend into mesenchyme. At their distal ends, secondary sprouts develop, including pilosebaceous anlagen, resulting in a mature structure in which mammary lobules and sebaceous glands empty into the infundibula of hair follicles; these structural triads (mammolobular-pilo-sebaceous units or MPSUs) represent an ancestral condition. In marsupials a flask-like mammary bulb elongates as a sprout, but then hollows out; its secondary sprouts include hair and sebaceous anlagen (MPSUs), but the hairs are shed during nipple formation. In some eutherians (cat, horse, human) MPSUs form at the distal ends of primary sprouts; pilosebaceous components either regress or develop into mature structures. We propose that a preexisting structural triad (the apocrine-pilo-sebaceous unit) was incorporated into the evolving mammary structure, and coupled to additional developmental processes that form the mammary line, placode, bulb and primary sprout. In this scenario only mammary ductal trees and secretory tissue derive from ancestral apocrine-like glands. The mammary gland appears to have coopted signaling pathways and genes for secretory products from even earlier integumentary structures, such as odontode (tooth-like) or odontode-derived structures. We speculate that modifications in signal use (such as PTHrP and BMP4) may contribute to taxonomic differences in MPSU development. © 2013 Springer Science+Business Media New York. Source

An ongoing field study of the effects of elevated atmospheric CO2 on a brackish wetland on Chesapeake Bay, started in 1987, is unique as the longest continually running investigation of the effects of elevated CO2 on an ecosystem. Since the beginning of the study, atmospheric CO2 increased 18%, sea level rose 20 cm, and growing season temperature varied with approximately the same range as predicted for global warming in the 21st century. This review looks back at this study for clues about how the effects of rising sea level, temperature, and precipitation interact with high atmospheric CO2 to alter the physiology of C3 and C4 photosynthetic species, carbon assimilation, evapotranspiration, plant and ecosystem nitrogen, and distribution of plant communities in this brackish wetland. Rising sea level caused a shift to higher elevations in the Scirpus olneyi C3 populations on the wetland, displacing the Spartina patens C4 populations. Elevated CO2 stimulated carbon assimilation in the Scirpus C3 species measured by increased shoot and root density and biomass, net ecosystem production, dissolved organic and inorganic carbon, and methane production. But elevated CO2 also decreased biomass of the grass, S. patens C4. The elevated CO2 treatment reduced tissue nitrogen concentration in shoots, roots, and total canopy nitrogen, which was associated with reduced ecosystem respiration. Net ecosystem production was mediated by precipitation through soil salinity: high salinity reduced the CO2 effect on net ecosystem production, which was zero in years of severe drought. The elevated CO2 stimulation of shoot density in the Scirpus C3 species was sustained throughout the 28 years of the study. Results from this study suggest that rising CO2 can add substantial amounts of carbon to ecosystems through stimulation of carbon assimilation, increased root exudates to supply nitrogen fixation, reduced dark respiration, and improved water and nitrogen use efficiency. © 2014 John Wiley & Sons Ltd. Source

Maloney K.O.,Smithsonian Environmental Research Center | Munguia P.,University of Texas at Austin
Ecography | Year: 2011

The decay of community similarity with distance (distance decay) is reported for many taxa in a variety of geographic settings. However, the importance of scale, distance measure, ecoregions, and ecological transition zones to distance decay has not been thoroughly examined. The goal of our study was to test the effects of these factors on distance decay in two freshwater assemblages (benthic macroinvertebrates and fish) with differing dispersal abilities in small streams within the Patuxent River basin, Maryland, USA. The Patuxent basin contains a geologic Fall Line, an ecological transition zone separating the two main regions of the basin. For both assemblages, we examined distance decay in similarity at several extents: entire Patuxent, Piedmont sub-region, and Plains sub-region using both linear geographic and stream network distances. Decay patterns were observed across all extents and distances. At the Patuxent extent decay rates differed between linear and stream distance only for macroinvertebrates (linear>stream); with both distance measures, similarity in fish decayed faster than similarity in macroinvertebrates. Within the Plains, decay rates for macroinvertebrates were lower than at the Patuxent for both distance measures; no difference in decay rates for this assemblage were detected in the Piedmont. Decay rates of similarity for fish only differed (lower) from rates at the Patuxent when examined at the Piedmont extent with stream distance. Similarity for the subset of sites that were located in separate ecoregions decayed at a slower rate than similarity for the entire data set only for macroinvertebrates with linear distance, suggesting a weak effect of the transition zone on distance decay. Together, these results suggest multiple factors contribute to the distance decay pattern and therefore regional diversity patterns, suggesting conjoint examination of these factors will further our understanding of the mechanisms governing regional diversity patterns. © 2011 The Authors. Ecography © 2011 Ecography. Source

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