bluuebunny/crossref_metadata_2025 huggingface dataset:
Each Man's Father Served as his Teacher: Constructing Relatedness in Pliny'sLetters: In loving memory of Harry Bernstein (1913–2008)
Authors: Bernstein Neil W.
Published: November 2008

Recent scholarship has examined Pliny's efforts to embed his acts of patronage in the rhetorical context of paternity. This paper examines how Pliny employs the discourse of paternity in representing himself as a mentor and exemplary model for young men, with particular focus on Book 8 of the Letters. Though he lacks a child or adoptive heir himself, Pliny embeds his work in a tradition in which Roman writers from the Elder Cato onward presented literary authority as coextensive with paternal authority. In Ep. 8.14, Pliny presents an idealized image of education by fathers or paternal surrogates that legitimates both his receipt of benefits from his mentors and his own efforts to instruct young men in the manner of a father. Pliny presents his published work as a model for Genialis in Ep. 8.13 and his personal life as an example for Junius Avitus in Ep. 8.23. Ep. 8.10, 11 and 18 provide further contexts for Pliny's discourse of paternity. Two additional examples of the creation of relatedness in elite Roman culture (interactions with caregivers and the experience of contubernium) are briefly discussed. I consider in conclusion how study of Pliny's Letters may contribute to the larger cross-cultural project of understanding how otherwise unrelated persons, through informal activities such as mentorship, may construct relationships more salient to them than their biological or legal kinships.
Aristophanes'Adôniazousai
Authors: Reitzammer L.
Published: November 2008

A scholiast's note on Lysistrata mentions that there was an alternative title to the play: Adôniazousai. A close reading of the play with this title in mind reveals that Lysistrata and her allies metaphorically hold an Adonis festival atop the Acropolis. The Adonia, a festival that is typically regarded as “marginal” and “private” by modern scholars, thus becomes symbolically central and public as the sex-strike held by the women halts the Peloponnesian war. The public space of the Acropolis becomes, notionally, a private rooftop, and Adonia-like activity proliferates; boars, myrrh, Aphrodite, “gardens of Adonis,” and lamentation all play important roles. The notion that the women of Lysistrata hold an unexpected Adonis festival on the Acropolis, at the very heart of the Athenian polis, provides a more nuanced reading of the play and forces us to rethink the place of the Adonia at Athens as well as, more generally, the distinction between public and private festivals.
Giovanni Maria Bononcini and the Uses of the Modes
Authors: Barnett Gregory
Published: November 2008

The persistence of the modes in the seventeenth century, their significance in Baroque-era musical thought, and the impact of modal theory on composition are all exemplified in the work of Giovanni Maria Bononcini (1642–78), violinist, maestro di cappella, and energetic proponent of twelve-mode theory. He sought to incorporate modal technique in an unprecedented array of musical styles, and the realization of his modal principles in his duos, madrigals, and sonatas—motivated in part by professional circumstances and by the interests of his patrons—represents the most detailed demonstration of the modes in his time. As applied in his compositions, Bononcini's modal theory proves to be less a system of tonal organization than a musical symbol—of erudition, history, and Catholic tradition—whose meanings he could shape.
The Pacific Coast Maritime Strike of 1936: Another View
Authors: Safford Jeffrey J.
Published: November 2008

The Pacific Coast maritime strike of 1936 lasted ninety-nine days and cost the maritime and related industries almost $700 million. For seventy years scholars have placed primary blame on the shipowners and waterfront operators, who are seen as preferring to tie up their ships rather than grant union demands. The records of the U.S. Maritime Commission (1936–1950) reveal a different story about the conflict. From the Maritime Commission's perspective, the maritime and longshore unions were at fault for refusing to grasp opportunities offered them by management. The article also includes hitherto unrecorded involvement on the part of Frances Perkins and the Department of Labor, as well as key reminiscences and documents from the private papers of one of the commission's primary actors in government efforts to prevent the strike through mediation and arbitration.
Expression and localization of two-pore domain K+ channels in bovine germ cells
Authors: Hur Chang-Gi , Choe Changyong , Kim Gyu-Tae , Cho Seong-Keun , Park Jae-Yong , Hong Seong-Geun , Han Jaehee , Kang Dawon
Published: November 2008

Two-pore domain K+(K2P) channels that help set the resting membrane potential of excitable and nonexcitable cells are expressed in many kinds of cells and tissues. However, the expression of K2Pchannels has not yet been reported in bovine germ cells. In this study, we demonstrate for the first time that K2Pchannels are expressed in the reproductive organs and germ cells of Korean cattle. RT-PCR data showed that members of the K2Pchannel family, specifically KCNK3, KCNK9, KCNK2, KCNK10, and KCNK4, were expressed in the ovary, testis, oocytes, embryo, and sperm. Out of these channels,KCNK2andKCNK4mRNAs were abundantly expressed in the mature oocytes, eight-cell stage embryos, and blastocysts compared with immature oocytes. KCNK4 and KCNK3 were significantly increased in eight-cell stage embryos. Immunocytochemical data showed that KCNK2, KCNK10, KCNK4, KCNK3, and KCNK9 channel proteins were expressed at the membrane of oocytes and blastocysts. KCNK10 and KCNK4 were strongly expressed and distributed in oocyte membranes. These channel proteins were also localized to the acrosome sperm cap. In particular, KCNK3 and KCNK4 were strongly localized to the post-acrosomal region of the sperm head and the equatorial band within the sperm head respectively. These results suggest that K2Pchannels might contribute to the background K+conductance of germ cells and regulate various physiological processes, such as maturation, fertilization, and development.
Sporadic hypercalcitoninemia: clinical and therapeutic consequences
Authors: Scheuba C , Kaserer K , Moritz A , Drosten R , Vierhapper H , Bieglmayer C , Haas O A , Niederle B
Published: November 2008

‘Calcitonin screening’ is not accepted as the standard of care in daily practice. The clinical and surgical consequences of ‘calcitonin screening’ in a series of patients with mildly elevated basal calcitonin and pentagastrin stimulated calcitonin levels are presented. 260 patients with elevated basal (>10 pg/ml) and stimulated calcitonin levels (>100 pg/ml) were enrolled in this prospective study. None of the patients was member of a known medullary thyroid carcinoma family. Thyroidectomy and bilateral central and lateral neck dissections were performed. Testing for the presence of germ-line mutations was performed in all patients. Histological and immunohistochemical findings were compared with basal and stimulated calcitonin levels. All patients were subsequently followed biochemically. C-cell hyperplasia (CCH) was found in 126 (49%) and medullary thyroid cancer was found in 134 (51%) patients. RET proto-oncogen mutations were documented in 22 (8%) patients (medullary thyroid cancer:18, CCH:4). In 56 (46%) of 122 patients, sporadic CCH was classified neoplastic (‘carcinoma in situ’). Of 97 (72%; 10 with hereditary medullary thyroid cancer) had pT1 (International Union against Cancer recommendations 2002) and 33 (25%) had pT2 or pT3 and 4 (3%) pT4 tumors. Of 39 (29.1%) had lymph node metastases. 106 (79.1%; 15 (38.5%) with lymph node metastases) patients were cured. Evaluation of basal and stimulated calcitonin levels enables the prediction of medullary thyroid cancer. All patients with basal calcitonin >64 pg/ml and stimulated calcitonin >560 pg/ml have medullary thyroid cancer. Medullary thyroid cancer was documented in 20% of patients with basal calcitonin >10 pg/ml but <64 pg/ml and stimulated calcitonin >100 pg/ml but <560 pg/ml.
Anaplastic thyroid cancer: molecular pathogenesis and emerging therapies
Authors: Smallridge Robert C , Marlow Laura A , Copland John A
Published: November 2008

Anaplastic thyroid cancer (ATC) is a rare malignancy. While external beam radiation therapy has improved locoregional control, the median survival of ∼ 4 months has not changed in more than half a century due to uncontrolled systemic metastases. The objective of this study was to review the literature in order to identify potential new strategies for treating this highly lethal cancer. PubMed searches were the principal source of articles reviewed. The molecular pathogenesis of ATC includes mutations in BRAF, RAS, catenin (cadherin-associated protein), beta 1, PIK3CA, TP53, AXIN1, PTEN, and APC genes, and chromosomal abnormalities are common. Several microarray studies have identified genes and pathways preferentially affected, and dysregulated microRNA profiles differ from differentiated thyroid cancers. Numerous proteins involving transcription factors, signaling pathways, mitosis, proliferation, cell cycle, apoptosis, adhesion, migration, epigenetics, and protein degradation are affected. A variety of agents have been successful in controlling ATC cell growth both in vitro and in nude mice xenografts. While many of these new compounds are in cancer clinical trials, there are few studies being conducted in ATC. With the recent increased knowledge of the many critical genes and proteins affected in ATC, and the extensive array of targeted therapies being developed for cancer patients, there are new opportunities to design clinical trials based upon tumor molecular profiling and preclinical studies of potentially synergistic combinatorial novel therapies.
The nuclear receptors NUR77 and SF1 play additive roles with c-JUN through distinct elements on the mouse Star promoter
Authors: Martin Luc J , Tremblay Jacques J
Published: November 2008

The steroidogenic acute regulatory protein plays an essential role in steroid biosynthesis in steroidogenic cells. It is involved in the transport of cholesterol through the mitochondrial membrane where the first step of steroidogenesis occurs. Star gene expression in testicular Leydig cells is regulated by the pituitary LH through the cAMP signaling pathway. So far, several transcription factors have been implicated in the regulation of Star promoter activity in these cells. These include the nuclear receptors NUR77 and SF1, AP-1 family members (particularly c-JUN), GATA4, C/EBPβ, DLX5/6, and CREB. Some of these factors were also shown to act in a cooperative manner to further enhance Star promoter activity. Here, we report that NUR77 and c-JUN have additive effects on the Star promoter. These effects were abolished only when both elements, NUR77 at −95 bp and AP-1 at −78 bp, were mutated. Consistent with this, in vitro co-immunoprecipitation revealed that NUR77 and c-JUN interact and that this interaction is mediated through part of the ligand binding domain of NUR77. Furthermore, we found that SF1 could cooperate with c-JUN on the mouse Star promoter but this cooperation involved different regulatory elements. Collectively, our data not only provide new insights into the molecular mechanisms that control mouse Star transcription in Leydig cells but also reveal a novel mechanism for the regulation of NR4A1-dependent genes in tissues where NUR77 and c-JUN factors are co-expressed.
RISK‐SENSITIVE ANTIPREDATOR BEHAVIOR IN THE TRINIDADIAN GUPPY,POECILIA RETICULATA
Authors: Botham M. S. , Hayward R. K. , Morrell L. J. , Croft D. P. , Ward J. R. , Ramnarine I. , Krause J.
Published: November 2008

The comparative approach has become a powerful tool for understanding how predation has shaped prey behavior. In this study we recorded the occurrence of common aquatic predator species and their densities in seven natural populations of Trinidadian guppies,Poecilia reticulata. We then exposed shoals of guppies from each of these populations to a series of predator treatments. Predator treatments differed in the species of predator used (pike cichlids,Crenicichla frenata; rivulus,Rivulus hartii; and freshwater prawns,Macrobrachium carcinus) and thus in the level of risk posed. We recorded the antipredator responses of guppies in each of these predator treatments.

The strength of antipredator behavior shown by guppies was affected by both the type of predator they were exposed to and the level of predation risk they experienced naturally in the wild. Importantly, we found that guppies from high‐risk populations showed a heightened response, compared to those from lower risk populations, only when exposed to the predator species that posed the greatest risk. Our results show the importance of individual predator species in shaping the behavioral traits of prey species at the population level. This has implications for prey movement between habitats that are geographically close but differ greatly in predator fauna.
FORMATION AND PROPAGATION OF FEEDING FRONTS IN BENTHIC MARINE INVERTEBRATES: A MODELING APPROACH
Authors: Lauzon-Guay Jean-Sébastien , Scheibling Robert E , Barbeau Myriam A.
Published: November 2008

Feeding fronts are a striking pattern of spatial distribution observed in both marine and terrestrial ecological systems. These fronts not only determine the abundance and distribution of prey populations, but on a broader scale they may also affect the structure and dynamics of entire communities. Several mechanisms leading to the formation of feeding fronts have been proposed, and chemotaxis has been suggested as an important component. Here we develop two mathematical models that show front formation can occur with simple kinesis (and without chemotaxis) in two marine invertebrates with different feeding habits: a microphagous sea star (Oreaster reticulatus) that feeds on sediments and an herbivorous sea urchin (Strongylocentrotus droebachiensis) that grazes kelp beds. We utilize a large body of detailed empirical information on movement pattern, foraging behavior, and front dynamics for each species to develop, parameterize, and evaluate our models. We found that our model predictions for the rate of advance of a front and its relationship to the density of consumers at the front were in close agreement with independently collected, empirical observations in both systems. This work shows that simple local interactions between mobile consumers and a stationary resource can result in large‐scale heterogeneous patterns of abundance of both species.
CLIMATIC INFLUENCES ON DEEP‐SEA OSTRACODE (CRUSTACEA) DIVERSITY FOR THE LAST THREE MILLION YEARS
Authors: Yasuhara Moriaki , Cronin Thomas M.
Published: November 2008

Ostracodes are small, bivalved crustaceans with the finest‐scale fossil resolution of any metazoan, rivaled only by the fossil record of the protistan Foraminifera. This article presents a synthesis of the patterns and possible causes of alpha species diversity variation in benthic deep‐sea ostracodes at drilling sites in the North Atlantic and Arctic Oceans. Taken together, these sites represent a period of great climatic variability covering the past three million years. Sediment cores taken from the Mid‐Atlantic Ridge show a positive correlation between warm temperatures and high species diversity. These Mid‐Atlantic Ridge cores, at the same latitude as northern Spain, show the same positive correlation during the last two glacial–interglacial cycles (200–0 ka [thousands of years ago]) as they do during the pre‐glacial Pliocene 2.85–2.4 Ma (millions of years ago). This positive correlation is also found in Pliocene cores from the Rockall Plateau, at the same latitude as Ireland. During the last 200 thousand years, however, this correlation is reversed in cores taken from both the Rockall and Iceland Plateaus. The discovery of high diversity during colder periods in recent high‐latitude Rockall and Iceland cores seems to be explained by spikes in diversity caused by ice‐rafting events, which would not affect the lower‐latitude Mid‐Atlantic Ridge. The Heinrich ice‐rafting events reduce North Atlantic surface temperatures and salinity every ∼6–12 ka, dramatically decreasing surface productivity. This increase in diversity during Heinrich events may be explained either by a negative correlation between surface productivity and benthic diversity or by increase in diversity caused by moderate disturbance when ice rafted debris fall to the bottom of the ocean.
MODELING THE RESPONSE OF POPULATIONS OF COMPETING SPECIES TO CLIMATE CHANGE
Authors: Poloczanska Elvira S. , Hawkins Stephen J. , Southward Alan J. , Burrows Michael T.
Published: November 2008

Biotic interactions will modulate species' responses to climate change. Many approaches to predicting the impacts of climate change on biodiversity so far have been based purely on a climate envelope approach and have not considered direct and indirect species interactions. Using a long‐term observational data set (>30 years) of competing intertidal barnacle species, we built a hierarchy of age‐structured two‐taxa population models (Semibalanus balanoides vs. Chthamalus montagui and C. stellatus combined as one taxon) to test if the presence of a dominant competitor can mediate climatic influence on the subordinate species. Models were parameterized using data from populations on the south coast of southwest England and verified by hindcasting using independent north coast population data. Recruitment of the dominant competitor, S. balanoides, is driven by temperature. The mechanisms of competition explored included simple space preemption and temperature‐driven interference competition. The results indicate that interspecific competition between juvenile barnacles is important in regulating chthamalid density but not that of the dominant competitor S. balanoides. Simulations were carried out using alternative future climate scenarios to predict barnacle population abundance over the next century. Under all emission scenarios, the cold‐water S. balanoides is predicted to virtually disappear from southwest England by the 2050s, leading to the competitive release of Chthamalus throughout the entire region and thereby substantially increasing its abundance and occupied habitat (by increasing vertical range on the shore). Our results demonstrate that climate change can profoundly affect the abundance and distribution of species through both the direct effects of temperature on survival, and also by altering important negative interactions through shifting competitive balances and essentially removing dominant competitors or predators. Climate change impacts on organisms are unlikely to lead only to straightforward, easily predictable changes in population size and distribution. The complex, indirect effects of climate change need to be taken into account if we are to accurately forecast the long‐term effects of global warming.
ALIEN BUMBLE BEE AFFECTS NATIVE PLANT REPRODUCTION THROUGH INTERACTIONS WITH NATIVE BUMBLE BEES
Authors: Dohzono Ikumi , Kunitake Yoko Kawate , Yokoyama Jun , Goka Koichi
Published: November 2008

The invasive alien bumble bee Bombus terrestris may hinder the reproduction of native plants that have established specialized pollination systems with native bumble bees. To test this hypothesis, we examined the visitation frequency and behavior of native and alien bumble bee species and resultant seed production in Corydalis ambigua, a native plant in Hokkaido, Japan. This species is self‐incompatible: the flower has a spur and requires visitation by bumble bees for effective seed production. We compared visitation frequency as well as fruit and seed set after cross‐ and open pollination at five sites of C. ambigua. Four of these sites occurred near a residential district and included naturalized populations of B. terrestris, and the fifth site was located in a forested habitat with no B. terrestris. The native species B. ardens and B. hypocrita and the alien B. terrestris frequently visited C. ambigua. Bombus ardens legitimately consumed nectar, whereas B. hypocrita and B. terrestris rob nectar by perforating spurs. The legitimate pollinator B. ardens produced fruits and seeds more efficiently than the nectar robbers. At three sites, the proportion of robbed flowers per inflorescence gradually increased through the flowering period, which may be caused by the intrusion of alien B. terrestris into the native plant–pollinator interactions. At these sites, C. ambigua suffered from pollen limitation, as seed production from open pollination was lower than from cross‐pollination, despite the fact that the total abundance of three bumble bees was higher than in the other two sites. Legitimate B. ardens visited fewer flowers within inflorescences with more robbed flowers, suggesting that nectar robbing may reduce the frequency of visitations by B. ardens within inflorescences, and resulting in decreased fruit set. Furthermore, reduced seed set implies a reduction in the pollination quality by B. ardens, probably due to decreases in visiting time per flower. Thus, introduction of alien B. terrestris may alter the native plant–pollinator mutualism: C. ambigua could establish a novel pollination relationship with B. terrestris because of its nonzero pollination efficiency, similar to the native robber B. hypocrita.
COMPARATIVE TRANSMISSION DYNAMICS OF COMPETING PARASITE SPECIES
Authors: Harbison Christopher W. , Bush Sarah E. , Malenke Jael R. , Clayton Dale H.
Published: November 2008

Competition–colonization trade‐off models explain the coexistence of competing species in terms of a trade‐off between competitive ability and the ability to colonize competitor‐free patches of habitat. A simple prediction of these models is that inferior competitors will be superior dispersers. This prediction has seldom been tested in natural populations because measuring dispersal is difficult. Host–parasite systems are promising in this regard, especially those involving “permanent” parasites that complete their entire life cycle on the body of the host. Because of this close association with the host, the dispersal, i.e., transmission, of these parasites can be monitored very accurately. We tested the dispersal prediction of the competition–colonization model by documenting the transmission dynamics of feather‐feeding lice, which are permanent, relatively host‐specific parasites of birds. We compared two groups known as “wing” lice and “body” lice that are common parasites of Rock Pigeons (Columba livia Gmelin). The two groups are ecologically similar, and they compete for resources on the host. Previous work shows that body lice are competitively superior to wing lice, leading us to predict that wing lice should be better than body lice at dispersing to new host individuals. We tested this prediction by comparing the ability of wing and body lice to disperse between hosts using vertical‐ and horizontal‐transmission mechanisms, including phoretic hitchhiking on parasitic flies (Diptera: Hippoboscidae). A series of experiments with both captive and wild birds confirmed that wing lice are much better than body lice at colonizing new hosts. Wing lice showed significantly greater vertical transmission to nestlings, and they were quite capable of phoretic transmission to new hosts on flies. In contrast, body lice were not phoretic. These results provide the first rigorous demonstration of phoretic transmission in lice, and they underscore the importance of a community‐level approach to understanding the ecology of parasite transmission dynamics.
SKEWED SEX RATIOS, POLLEN LIMITATION, AND REPRODUCTIVE FAILURE IN THE DIOECIOUS SEAGRASS PHYLLOSPADIX
Authors: Shelton Andrew Olaf
Published: November 2008

Dioecious mating systems in angiosperms, in which individuals are unisexual, require that pollen disperses between male and female individuals and may cause dioecious species to be vulnerable to reduced reproductive success via pollen limitation. This potential cost has rarely been documented, in part because of a dearth of studies investigating abiotic pollen dispersal, which tends to be associated with dioecy. I document widespread variation in reproductive success in an ecologically important, habitat‐forming group, the seagrasses (marine angiosperms), using two species of the dioecious genus Phyllospadix. At multiple sites in the state of Washington, USA, I demonstrate pervasive male rarity (all sites <24% male by area). Male abundance is shown to predict female reproductive success at two scales. Within sites, the ratio of maturing seeds to total ovules declines rapidly with increasing distance to the nearest male, while among sites, mean seed : ovule ratios scale positively with male abundance. At some sites, less than 1 in 100 ovules mature into seeds. A field experiment conducted at a high pollen availability site shows that manipulating pollen availability could produce the range of seed sets observed across sites, but pollen limitation was not definitively demonstrated. Overall my results are consistent with pollen limitation in Phyllospadix and comprise the first strong evidence of this phenomenon in seagrass populations. In addition, seed production rates predicted local seedling recruitment, demonstrating a measurable demographic consequence of low pollen availability.
DIVERSITY ENHANCES COVER AND STABILITY OF SEAWEED ASSEMBLAGES: THE ROLE OF HETEROGENEITY AND TIME
Authors: Stachowicz John J. , Graham Michael , Bracken Matthew E. S. , Szoboszlai Amber I.
Published: November 2008

Generalizations regarding the mechanisms underlying the effects of plant diversity on ecosystem processes, and whether the patterns transcend study systems remain elusive. Many terrestrial plant diversity manipulations have found that plant biomass increases with diversity, but most marine studies find little or no effect of seaweed diversity on producer biomass or production. However, differences in experimental approach (field vs. mesocosm) and duration (years vs. weeks) between published terrestrial and marine experiments confound the interpretation of these differences in response to changing diversity. We conducted a three‐year field manipulation of seaweed diversity on intertidal rocky reefs in central California, USA, to examine the effect of diversity on seaweed cover. We found that diversity increased standing algal cover and decreased the availability of free space relative to monocultures, but this effect took nine months to materialize. Furthermore, diverse assemblages did not consistently exceed the best performing monocultures until 18 months after the experiment was initiated, suggesting that the effect of diversity strengthens over time. Overall, diversity's effect was consistently stronger than that of individual species and not attributable to the influence of any particular species (sampling effect) because (1) polycultures eventually achieved higher cover than even the best performing monoculture and (2) monocultures rarely differed much, precluding a strong sampling effect. Instead, mechanisms such as facilitation and differential use of microhabitats in a heterogeneous environment likely caused the higher cover in polycultures. Our findings contrast with short‐term experiments with other seaweeds but are similar to longer‐term experiments with terrestrial plants, suggesting that experimental design and approach, rather than inherent differences between marine and terrestrial ecosystems, underlie contrasting responses among systems. We argue that experiments conducted in the field, and for a greater length of time, allow for the manifestation of a greater number of potential mechanisms of overyielding in diverse communities, increasing the likelihood of observing a strong diversity effect.
ECOSYSTEM SIZE, BUT NOT DISTURBANCE, DETERMINES FOOD‐CHAIN LENGTH ON ISLANDS OF THE BAHAMAS
Authors: Takimoto Gaku , Spiller David A. , Post David M.
Published: November 2008

Ecologists have long struggled to explain variation in food‐chain length among natural ecosystems. Food‐chain length is predicted to be shorter in ecosystems subjected to greater disturbance because longer chains are theoretically less resilient to perturbation. Moreover, food‐chain length is expected to be longer in larger ecosystems because increasing ecosystem size increases species richness and stabilizes predator–prey interactions, or increases total resource availability. Here we test the roles of disturbance and ecosystem size in determining the food‐chain length of terrestrial food webs on Bahamian islands. We found that disturbance affected the identity of top predators, but did not change food‐chain length because alternative top predators occupied similar trophic positions. On the other hand, a 106‐fold increase in ecosystem size elevated food‐chain length by one trophic level. We suggest that the effect of disturbance on food‐chain length is weak when alternate top predators are trophic omnivores and have similar trophic positions. This and previous work in lakes suggest that ecosystem size may be a strong determinant of food‐chain length in both aquatic and terrestrial ecosystems.
PERSISTENCE OF SPATIAL VARIANCE AND SPATIAL PATTERN IN THE ABUNDANCE OF A SUBMERGED PLANT
Authors: Klaassen Raymond H. G. , Nolet Bart A.
Published: November 2008

Organisms usually benefit from heterogeneous conditions, but, by doing so, may reduce the degree of heterogeneity. The question therefore arises how heterogeneity is maintained. We investigated within‐year spatiotemporal patterns in a monospecific stand of a submerged plant (fennel pondweed, Potamogeton pectinatus), with the novelty that we distinguished between different forms of heterogeneity: spatial variance (the frequency distribution of densities) and spatial pattern (the spatial distribution of densities). We repeatedly measured plant biomass that was affected by swan predation, winter mortality, and summer regrowth. Spatial variance was enhanced mostly by swan foraging, despite the fact that swans appear to exploit patches to the same threshold level. Spatial pattern, which had vanished after swan foraging, reestablished due to spatial pattern in winter mortality and was further enhanced by plant regrowth. We found that variance and pattern each have their own temporal dynamics and are maintained by different biological processes. We therefore advocate that it is pivotal to distinguish between variance and pattern in the study of spatial heterogeneity.
PHOTOSYNTHETIC SYMBIONTS AND ENERGY SUPPLY DETERMINE OCTOCORAL BIODIVERSITY IN CORAL REEFS
Authors: Fabricius K. E. , De'ath G.
Published: November 2008

Many coral reef organisms live in symbiotic relationships with photosynthetic microalgae. This symbiosis extends the energy resources available to reef organisms, thereby potentially influencing biodiversity. In octocorals, about one‐half of the taxa contain photosynthetic symbionts while the rest do not, and thus octocorals are an ideal model to assess the relationships between biodiversity, spatial and environmental factors, and photosynthetic symbionts. Data collected from 1106 sites on the Great Barrier Reef, Australia, between 12° and 24° S showed that taxa with photosynthetic symbionts (phototrophs) had higher abundances, wider ranges, and a wider spread of locations than taxa without symbionts (heterotrophs). In phototrophic assemblages, spatial turnover comprised both exchange and loss of taxa, and their richness was high across a broad range of environmental conditions. In contrast, heterotrophs were uncommon, had short ranges, and were located where energy supply was highest and disturbance lowest. Turnover between heterotrophic assemblages comprised taxonomic loss rather than exchange of taxa. The biodiversity patterns and differences between phototrophic and heterotrophic octocorals are similar to those recorded in more spatially limited studies of phototrophic sponges and hard corals, and heterotrophic sponges. This study therefore suggests that the association, or not, with photosynthetic symbionts, and spatial and environmental factors related to energy supply and disturbance are principal drivers of biodiversity, community composition, and ranges of coral reef benthos.
MECHANISMS OF TOLERANCE TO FLORAL LARCENY IN TWO WILDFLOWER SPECIES
Authors: Irwin Rebecca E. , Galen Candace , Rabenold Jessica J. , Kaczorowski Rainee , McCutcheon Meghan L.
Published: November 2008

Tolerance of foliar damage is widely recognized as an effective defense against herbivores and pathogens. However, tolerance of the impacts of antagonists on pollination success is less well understood. Here, we extend the framework of tolerance to foliar damage to understand how plants mitigate the pollination and fitness costs of floral larceny (i.e., the consumption of floral nectar often without pollination). We focused on two mechanisms: high nectar rewards per flower to feed all floral visitors and high flower production to compensate for reproductive losses under reduced pollination and seed set. We compared the efficacy of these mechanisms in two plant species:Polemonium viscosumandIpomopsis aggregata. InPolemonium, ants acting as larcenists reduce nectar accumulation but do not completely empty flowers. When nectar reserves were augmented, ant consumption increased, negating the efficacy of this putative tolerance mechanism. Similarly, inIpomopsis, nectar addition had little effect on tolerance to larceny by bumble bees, perhaps because residual intact flowers do not have enough nectar to compensate for lost rewards. Flower production in both species mitigated some of the negative impacts of larceny on seed set. InPolemonium, flower number was not plastic in response to larceny, but large inflorescences enhanced female fitness only when larcenists were present, suggesting that “surplus” flowers in large inflorescences can function to replace reproductive losses due to larceny. InIpomopsis, high rates of larceny induced flower production, but the fecundity benefits of making more flowers declined inversely to larcenist intensity. Overall, our results suggest (1) that tolerance to floral larceny involves “banking” extra flowers to replace lost reproduction rather than maintaining pollination of ones with larceny, and (2) that the efficacy of flower production as a tolerance mechanism varies inversely to larceny rate.
RAPID CARBON RESPONSE OF PEATLANDS TO CLIMATE CHANGE
Authors: Bridgham Scott D. , Pastor John , Dewey Bradley , Weltzin Jake F. , Updegraff Karen
Published: November 2008

Peatlands comprise a globally important carbon pool whose input–output budgets may be significantly altered by climate change. To experimentally determine the sensitivity of the carbon stored in peatlands to climate change, we constructed a mesocosm facility with 54 peat monoliths from a bog and fen in northern Minnesota, USA. These mesocosms were subjected to nine combinations of heat and water‐table levels over eight years. Bog mesocosms initially accumulated soil carbon, with greater gains in wetter mesocosms, but after three years no further water‐table effects occurred. In contrast, fen mesocosms lost or had no change in soil carbon, with the greatest losses in drier and warmer mesocosms. Changes in soil‐carbon storage resulted in concomitant changes in water‐table depth, so that water‐table depths were similar to those in the natural source sites by the end of the experiment regardless of the initial treatment. These results were primarily due to water‐table effects onSphagnummoss production in the bog mesocosms and to a more complicated suite of warming and water‐table effects on production and decomposition in the fen mesocosms. We show that different kinds of peatlands will rapidly gain or lose carbon following hydrological disturbance until they return to their characteristic (“equilibrium”) water‐table levels. Our results illustrate the potential for a rapid homeostatic response of these ecosystems to future climate change at small spatial scales. Climate change will likely also interact with other carbon cycle–hydrological feedbacks at the scale of the entire peatland over longer time frames and larger spatial scales.
DENSITY‐DEPENDENT EFFECTS OF PREDATOR SPECIES‐RICHNESS IN DIVERSITY–FUNCTION STUDIES
Authors: Griffiths Georgianne J. K. , Wilby Andrew , Crawley Michael J. , Thomas Matthew B.
Published: November 2008

Ecological systems often exhibit a positive but saturating diversity–function curve. Variation in the mechanisms generating this relationship can alter the slope and variance of the curve, with implications for the optimal management of biodiversity for ecosystem services. In biological control, prevalence of selection effects supports augmentation of the most effective natural enemy, but complementarity effects support augmentation of natural enemy diversity. Optimization of biological control strategies from the results of diversity–function studies is limited because few consider changes in function with relative or absolute changes in abundance, and many confound the relative importance of richness and density through experimental designs (additive and substitutive). By manipulating species richness across an abundance gradient we show that effects of species richness are density dependent and indicate how this may be incorporated into experimental designs or models predicting resource consumption in diverse communities. Furthermore, the underlying mechanisms causing an observed diversity–function response, and its associated variation, changed across the richness–abundance gradient. Finally, species‐rich assemblages provided higher levels of minimum function than species‐poor assemblages, without any compromise on the maximum function possible.
High-Resolution 3D VSP Processing - An Example from the Middle East
Authors: Chavarria J. Andres , Paulsson Bjorn , Goertz Alexander , Karrenbach Martin , Mueller Klaus , Marmash Samer , Al-Baloushi Mariam , Soroka William
Published: November 2008

The 3D VSP method is being increasingly employed as a tool to produce high-resolution images for detailed reservoir characterization and to address reservoir challenges. These challenges include thin layer reservoirs, thief zones and stratigraphic features that affect recovery. The main challenges in processing VSP datasets are twofold: First to ensure that the high frequency and better vector fidelity is being used and carried through to the final image. This requires special care and appropriately adapted processing techniques to the smaller scale and high frequency contained in the VSP data. Second, is dealing with the unique geometry of a 3D VSP, which has laterally varying fold coverage and aperture that has to be accounted for in order to minimize any footprint on the final image.

In this project VSP processing advances have been made using data from the largest 3D VSP recorded to date, which was acquired in an Abu Dhabi oil field. Different types of static corrections were tested and optimized to recover the high frequencies required for optimum event delineation. A combination of static corrections that takes full advantage of the 3D VSP geometry and includes surface seismic data results that helped achieve optimal coherency of events. A careful analysis of the irregular fold geometry resulted in good target imaging using a detailed illumination analysis. Such an analysis aids in the correct treatment of the high resolution events and helps to interpret their character along the area illuminated. This analysis provides critical information about the velocity model and the corresponding kinematics. The ability of VSP's to recover high frequencies is demonstrated in this processing flow, by showing the difference in resolution between new high resolution surface seismic and the final 3D VSP image.
Estimating Available Soil Phosphorus Increases after Phosphorus Additions in Mollisols
Authors: Rubio Gerardo , Cabello María J. , Gutiérrez Boem Flavio H. , Munaro Eugenia
Published: November 2008

Accurate critical levels must be accompanied by predictive models on the amount of P required to increase P availability to a target value to obtain reliable P recommendations. We estimated, based on information on soil properties, the increase in soil available P after the addition of a unit of P (b coefficient) in an area of homogeneous although geographically distant soils. All 71 selected soils were noncalcareous, belonging to the Mollisol order and located in the Pampean Region (Argentina). Samples (0–20 cm) were incubated for 45 d after the addition of five doses of P. Soils were characterized for parameters related to soil P availability: pH, particle size distribution, organic C, total P, initial soil available P, and two P retention indices differing in the interaction period between the added P and the soil matrix (1 or 18 h). Obtained b values ranged from 0.27 to 0.74. Soils located at the northern area of the study region had higher b values (mean = 0.58) than southern ones (mean = 0.42). The best multiple regression model for estimating the b coefficient (R2 = 0.70) included initial soil P, a binary variable that accounts for the location of the soil, and the P retention index with the shorter interaction period. The strong effect of the geographic position of the soil on the estimation of the b coefficient led us to hypothesize about a possible role of the mineralogic characteristics of the parent material on P dynamics. Our results indicate that single independent variable models may not be enough to predict the b coefficient in homogeneous soils.
Soluble Element Distributions in a Mojave Desert Soil
Authors: Marion G. M. , Verburg P. S. J. , Stevenson B. , Arnone J. A.
Published: November 2008

The distribution of chemical species in desert soils is a complex function of atmospheric inputs, rock weathering, chemical equilibria, soil leaching, and plant cycling. In this study of the surface 1 m of desert soils at the Nevada Test Site, we examined the distribution of soluble soil elements beneath plant canopies and in intershrub zones. We extracted water‐soluble chemical species using saturation extracts that were equilibrated overnight and more dilute extracts that were incubated for 1 mo. All soil horizons were supersaturated with calcite and undersaturated with gypsum. Calcite supersaturation was a function of soil organic C (inhibitor) and water content (inhibitor diluent). It is critical that the latter two properties be explicitly recognized in modeling CaCO3mobility through soils. Plant‐essential cations (K, Ca, and Mg) were highest in concentration in surface soils beneath plant canopies. Sodium, Cl, NO3, and SO4were generally highest in concentration around 1‐m depth. The dissimilar patterns of essential nutrient accumulations between the cations (Ca, K, and Mg) and the anions (NO3and SO4) were probably due to the greater mobility of anions than cations. Also, these surface soils were “N saturated” due to their low N retention capacity, which accounts, at least in part, for the anomalous NO3accumulations at depths >1 m in Mojave Desert soils. Furthermore, once NO3or SO4have leached to deeper soil depths, they may be relatively unavailable for plant uptake. The soil elemental patterns are consistent with elemental plant requirements and elemental mobility.
Improved Estimation of Soil Organic Carbon Storage Uncertainty Using First‐Order Taylor Series Approximation
Authors: Panda Dileep K. , Singh R. , Kundu D. K. , Chakraborty H. , Kumar A.
Published: November 2008

Assessment of soil organic C (SOC) stocks is important for monitoring the effect of land use change in the C cycle and for formulation of C sequestration strategies in the context of global climate change. Discrepancies among the recent global SOC estimates by different researchers underscore the importance of precise estimation of the uncertainty associated with the SOC stocks. A method was recently proposed to estimate the SOC storage uncertainty using the Taylor series of approximations. Here we show that the accuracy of SOC storage uncertainty can be improved by incorporating the covariance among the input variables. Measurement of input variables from independent samples or use of an incomplete model leads to either over‐ or underestimation of the SOC storage uncertainty. The application of the method to an experimental data set indicated that ignoring covariance would lead to a substantial overestimate of the uncertainty.
Mineral Sources of Calcium and Phosphorus in Soils of the Northeastern United States
Authors: Nezat Carmen A. , Blum Joel D. , Yanai Ruth D. , Park Byung Bae
Published: November 2008

Apatite is ubiquitous in igneous, metamorphic, and sedimentary rocks, although usually in trace amounts. Apatite is the primary source of P and, due to its relatively rapid dissolution rate, can be an important Ca source in noncarbonate soils. We investigated the distribution of apatite using a 1 mol L−1HNO3extraction of glacial till soils at 31 sites across the northeastern United States. Parent materials formed from crystalline silicate and clastic sedimentary rocks contained 0.2 to 41 mmol Ca kg−1soil and 1 to 27 mmol P kg−1soil; at most of these sites, the P/Ca ratio was approximately 3:5, indicating the dominance of apatite. Parent materials underlain by carbonate rocks had 3 to 16 mmol P kg−1soil, similar to the noncarbonate groups, but had large concentrations of easily weathered Ca (56–1890 mmol kg−1soil) due to the extraction of carbonates. The same extraction procedure applied to samples from the upper 30 cm of mineral soil at the same sites showed lower concentrations of both Ca and P than in the C horizon, except for a few sites where the upper soil layers probably developed in different parent materials than the current C horizon. We also measured neutral‐salt‐exchangeable Ca concentrations in the 10‐ to 20‐cm depth increment. Exchangeable Ca concentrations in soils underlain by carbonate bedrock were an order of magnitude higher than in soils underlain by crystalline silicate and clastic sedimentary rocks. For this reason, the exchangeable Ca concentration in the upper soil was correlated to the concentration of 1 mol L−1HNO3extractable Ca in the underlying soil parent material. To predict concentrations of apatite in parent materials and the concentrations of exchangeable Ca in overlying horizons in greater detail would require more specific characterization of bedrock sources.
Charcoal Distribution Affects Carbon and Nitrogen Contents in Forest Soils of California
Authors: MacKenzie M. Derek , McIntire E. J. B. , Quideau S. A. , Graham R. C.
Published: November 2008

Fire is the dominant natural disturbance regime in most ecosystems of California. The long‐term relict of fire is charcoal, which has been shown to increase N mineralization and also represents a pool of chemically stabilized C whose quantity and spatial distribution have not been well characterized in forest soils. We examined the charcoal content in three different ecosystems of the Sierra Nevada, including oak woodland (low elevation), mixed conifer (middle elevation), and red fir (high elevation). Using a fine‐scale (2.5‐m minimum resolution) spatially explicit sampling protocol applied to plots ranging between 0.25 to 0.5 ha, we examined the autocorrelation of forest floor and mineral soil properties including charcoal C. Charcoal C content ranged from 1000 to 5000 kg ha−1in the surface 6 cm of soil and increased with increasing elevation and latitude. Spatial patterns of forest floor and mineral soil properties were generally patchy at a scale of 5 to 20 m, except in the mixed conifer ecosystem (no pattern). The patchiness that existed at the other sites was largely a result of the distribution of total C and total N in the mineral soil. A spatial mixed‐effect ANOVA indicated that charcoal had a 10 to 20% effect on C and N contents in both forest floor and mineral soil surface horizons, independent of other parameters including ecosystem type and total C or N. These results provide evidence that charcoal has a relationship with soil C and N content, which may influence soil biogeochemistry.