36,219 research outputs found
Ant-Plant Relationships in a Re-Created Tallgrass Prairie
Relationships between the distributions of nesting ants and flora were investigated in a re-created tallgrass prairie located in northeastern Illinois. One-third of 167 randomly selected 1m2 quadrats in the prairie contained ant nests. Basal coverage of ground by tall grass shoots was greater in quadrats having ant nests than in those lacking ant nests. In addition, clumps of big bluestem (Andropogon gerardii) that were inhabited by the ant, Acanthomyops clavigera, had higher median rank densities than adjacent clumps lacking nests. The clumps also showed a negative correlation between big bluestem shoots/ cm2 and area occupied by the clump at ground level. These significant findings relating to the distribution of nesting ants and tall grasses indicate ants have ecologic importance in re-created prairie that warrants greater scrutiny among restoration scientists
Investigating the Ecology of the Mound-Building Ant, \u3ci\u3eAcanthomyops Claviger\u3c/i\u3e (Hymenoptera: Formicidae), in Re-Created Prairie
Acanthomyops claviger (Roger) (Hymenoptera: Formicidae) forms conspicuous mounds within clumps of big bluestem, Andropogon gerardii, and prairie dropseed, Sporobolus heterolepsis, within a re-created tallgrass prairie in northeastern Illinois. This study explored the ecology of the nesting ant in the recreated prairie regarding the persistence of colonies, soil characteristics, the growth of grass clumps, and the species richness of the surrounding flora. Persistence of nests over one year was positively correlated to the diameters of mounds created by the colonies. Differences in soil moisture at 10 cm depth were significant over a growing season between grass clumps having nests of A. claviger and those not. Soil temperature at 10 cm depth over a growing season, organic fraction of the soil, and above-ground oven-dried biomass of grasses did not significantly vary based on nest presence. Floral richness was significantly higher in the vicinity of A. claviger nests than where nests were absent. Benefits of the ant-grass relationship are unknown, although a commensalistic relationship is at least suggested by the location of nests in grass clumps. The presence of A. claviger nests appears to have a positive effect on the richness of the surrounding flora, possibly through soil tunneling and seed distribution
Airborne observations of the comet Ikeya- Seki /1965f/
Aerial photographs and observations of comet Ikeya-Sek
Congener Host Selection by the Pre-Dispersal Seed Predator, \u3ci\u3eApion Rostrum\u3c/i\u3e (Coleoptera: Apionidae)
Apion rostrum Say (Coleoptera: Apionidae) is the major seed predator of the wild indigo congeners, Baptisia alba and B. bracteata in the Russell Kirt Tallgrass Prairie, a reconstructed prairie located at College of DuPage, Illinois. This study, conducted during 2006, investigated factors attracting A. rostrum to each congener. The two Baptisia differ in developmental period, stature, and patterns of dispersion. B. bracteata flowers and initiates pods usually along a single raceme during late spring, and is a shorter plant that grows in clusters. In contrast, B. alba flowers and initiates pods beginning a month after B. bracteata, produces a tall central raceme with often several satellite racemes, and does not grow in dense clusters. Mating and ovipositing A. rostrum were observed on B. bracteata during the first half of June, and with greater abundance on B. alba from early June through mid July. Results of stepwise multiple regression showed a positive relationship of weevil counts per plant to raceme counts per cluster for B. bracteata and to inflated pod counts per plant for B. alba. The developmental synchrony between A. rostrum and pods of B. alba is evidence of a closer evolutionary relationship than the seed predator has with B. bracteata. This can explain the greater number of reproductive weevils seen on B. alba as well as the higher levels of pod infestations
Amphibians and Reptiles of United States Department of Defense Installations
The U.S. Department of Defense (DoD) occupies approximately 10.1 million ha of land within the U.S. spanning most ecosystems contained therein. To date, no comprehensive agency-wide inventory of amphibian and reptile species has been compiled. We developed an amphibian and reptile species inventory for 415 DoD installations/sites and evaluated species diversity. The amphibian and reptile species confirmed present on DoD sites represent 66% of the total native species documented in the continental U.S. Snakes are the most widespread group found on DoD lands. Of the military services, Army sites have the greatest number of confirmed species, federally listed, state-listed, and At-risk species. There are 24 federally listed (threatened or endangered), 55 state- listed, and 70 At-risk species confirmed present on DoD sites. Thirty non-native and native transplant amphibian and reptile species/subspecies are also confirmed present on DoD sites. Lastly, we verified that approximately half of the military sites evaluated in this study have at least one venomous snake species confirmed present. Our study results assist directly with ongoing management and conservation of amphibian and reptile species on DoD lands and confirm military lands comprise a significant contribution to biodiversity conservation
Selective Pod Abortion by \u3ci\u3eBaptista Leucantha\u3c/i\u3e (Fabaceae) as Affected by a Curculionid Seed Predator, \u3ci\u3eApion Rostrum\u3c/i\u3e (Coleoptera)
The effect of a seed predator, Apion rostrum (Coleoptera: Curculionidae), on selective pod abortion from Baptisia leucantha (Fabaceae) was investigated in a restored tallgrass prairie plot. Weevil densities in and undamaged seed contents of attached and detached pods were compared over four occasions during the summer of 1993. Detached pods had similar to lower counts of weevils/pod and fewer seeds/pod than attached pods. Weevil density in pods appears only important in promoting pod abortIon through affects on seed number/pod as pods having fewer seeds are selectively aborted
Binomial-coefficient multiples of irrationals
Denote by a random infinite path in the graph of Pascal's triangle (left
and right turns are selected independently with fixed probabilities) and by
the binomial coefficient at the 'th level along the path . Then
for a dense set of in the unit interval, is almost surely dense but not uniformly distributed modulo 1.Comment: 10 pages, to appear in Monatshefte f. Mat
Biosynthesis and expression of zona pellucida glycoproteins in mammals
The zona pellucida (ZP) is an extracellular matrix surrounding the oocyte and the early embryo that exerts several important functions during fertilization and early embryonic development. The ZP of most mammalian species is composed of three glycoproteins (ZPA, ZPB, ZPC), products of the gene families ZPA, ZPB and ZPC that have been found to be highly homologous within mammalian species. Most data on the structure and function of the ZP are obtained from studies in mouse. New data from pig and other domestic animals, however, indicate that the mouse model does not hold for all other species. Whereas in the mouse ZPB is the primary sperm receptor, in the pig ZPA has been shown to possess receptor activity. Contrary to the mouse, where the growing oocyte is the only source of zona glycoproteins, in domestic animals these proteins are expressed in both the oocyte and granulosa cells in a stage-specific pattern and may play also a role in granulosa cell differentiation. In several mammalian species, the epithelial secretory cells of the oviduct synthesize and secrete specific glycoproteins (oviductins) that become closely associated with the ZP of the ovulated oocyte. Once bound to the ZP, oviductin molecules could act as a protective layer around the oocyte and early embryo by virtue of their densely glycosylated mucin-type domains. Copyright (C) 2001 S. Karger AG, Basel
Utilization of nitrogen in legume-based mobile green manures stored as compost or silage
The utilization of nitrogen (N) in green manure leys can be improved by harvesting, storage and spreading of the plant material as manure in other crops. By green manure storage as silage, storage losses of N are lower than by composting. Also, a relatively high fertilizer value of silage N is achievable depending on the C/N ratio of the material. Nitrogen availability in green manure leys is higher after storage as silage compared to composting. Use of mobile green manures is mainly relevant in arable cropping systems without livestock where utilization of the roughage for animal feed or biogas production is impossible, as costs for ley/roughage harvest and transport can be relatively high. Our study showed that surface application of green manure silage to growing crops can damage plants and is therefore not recommended, whereas incorporation of silage before sowing has significant positive effects on crop yields
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