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  • American Physical Society  (193,318)
  • University of Chicago Press
  • 2010-2014  (98,583)
  • 2005-2009  (93,159)
  • 1935-1939  (4,081)
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  • 1
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    University of Chicago Press
    Publication Date: 2022-05-25
    Description: Author Posting. © University of Chicago, 2010. This article is posted here by permission of University of Chicago for personal use, not for redistribution. The definitive version was published in American Naturalist 176 (2010): 96-98, doi:10.1086/653077.
    Description: There is growing interest in predicting the abundance of a species in a region from the occupancy of cells in a uniform grid overlaid on the region. When the number of individuals in each cell follows a negative binomial distribution, prediction is in general not possible from the number of unoccupied cells alone. A prediction method based on the number of unoccupied cells and the number containing a single individual is described and shown to work well on simulated and real data.
    Keywords: Negative binomial distribution ; Optimal prediction ; Species abundance ; Species occupancy
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
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    University of Chicago Press
    Publication Date: 2022-05-25
    Description: Author Posting. © University of Chicago Press, 2012. This article is posted here by permission of University of Chicago Press for personal use, not for redistribution. The definitive version was published in Quarterly Review of Biology 87 (2012): 315-324, doi:10.1086/668165.
    Description: The problem of eukaryogenesis—the evolutionary mechanism whereby eukaryotic cells evolved from prokaryotes—remains one of the great unsolved mysteries of cell biology, possibly due to the reductionist tendency of most scientists to work only within their subdisciplines. Communication between biologists who conduct research on the nucleus and those working on the cytoskeleton or endomembrane system are sometimes wanting, and yet, all of these quintessentially eukaryotic elements of the cell are interdependent, and are physically associated in many protists as the karyomastigont organellar system: nucleus, one or more basal bodies and flagella, nuclear connector, and Golgi apparatus. Here we suggest a more holistic view of the karyomastigont as not simply an organellar system, but an evolutionary seme, the archaic state of the eukaryotic cell. We also present a scheme whereby the karyomastigont may have dissociated, giving rise in more derived cells to one or more free nuclei and discrete flagellar apparati (akaryomastigonts).
    Description: Mark C. Alliegro is supported by grants from the National Institutes of Health (NIGMS) and National Science Foundation.
    Description: 2013-12-01
    Keywords: Karyomastigont ; Eukaryogenesis ; Flagellum ; Basal body ; Centrosome ; Nucleus
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2022-05-25
    Description: Author Posting. © University of Chicago Press, 2014. This article is posted here by permission of University of Chicago Press for personal use, not for redistribution. The definitive version was published in Physiological and Biochemical Zoology 87 (2014): 576-584, doi:10.1086/676309.
    Description: Cetaceans are obligate aquatic mammals derived from terrestrial artiodactyls. The defining characteristic of cetaceans is a thick and dense lip (pachyosteosclerotic involucrum) of an ear bone (the tympanic). This unique feature is absent in modern terrestrial artiodactyls and is suggested to be important in underwater hearing. Here, we investigate the mineralogical and biochemical properties of the involucrum, as these may hold clues to the aquatic adaptations of cetaceans. We compared bioapatites (enamel, dentine, cementum, and skeletal bone) of cetaceans with those of terrestrial artiodactyls and pachyosteosclerotic ribs of manatees (Sirenia). We investigated organic, carbonate, and mineral composition as well as crystal size and crystallinity index. In all studied variables, bioapatites of the cetacean involucrum were intermediate in composition and structure between those of tooth enamel on the one hand and those of dentine, cementum, and skeletal bone on the other. We also studied the amino acid composition of the cetacean involucrum relative to that of other skeletal bone. The central involucrum had low glycine and hydroxyproline concentrations but high concentrations of nonessential amino acids, unlike most bone samples but similar to the tympanic of hippos and the (pachyosteosclerotic) ribs of manatees. These amino acid results are evidence of rapid bone development. We hypothesize that the mineralogical and amino acid composition of cetacean bullae differs from that of other bone because of (1) functional modifications for underwater sound reception and (2) structural adaptations related to rapid ossification.
    Description: This research was conducted under NMFS permit 493-1848/MA130062 and funded by the National Science Foundation (EAR SGP 0847413 to M.T.C.).
    Description: 2015-06-03
    Repository Name: Woods Hole Open Access Server
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © University of Chicago Press, 2004. This article is posted here by permission of University of Chicago Press for personal use, not for redistribution. The definitive version was published in American Naturalist 164 (2004): E46-E61.
    Description: We present a Markov chain model of succession in a rocky subtidal community based on a long-term (1986–1994) study of subtidal invertebrates (14 species) at Ammen Rock Pinnacle in the Gulf of Maine. The model describes successional processes (disturbance, colonization, species persistence, and replacement), the equilibrium (stationary) community, and the rate of convergence. We described successional dynamics by species turnover rates, recurrence times, and the entropy of the transition matrix. We used perturbation analysis to quantify the response of diversity to successional rates and species removals. The equilibrium community was dominated by an encrusting sponge (Hymedesmia) and a bryozoan (Crisia eburnea). The equilibrium structure explained 98% of the variance in observed species frequencies. Dominant species have low probabilities of disturbance and high rates of colonization and persistence. On average, species turn over every 3.4 years. Recurrence times varied among species (7–268 years); rare species had the longest recurrence times. The community converged to equilibrium quickly (9.5 years), as measured by Dobrushin’s coefficient of ergodicity. The largest changes in evenness would result from removal of the dominant sponge Hymedesmia. Subdominant species appear to increase evenness by slowing the dominance of Hymedesmia. Comparison of the subtidal community with intertidal and coral reef communities revealed that disturbance rates are an order of magnitude higher in coral reef than in rocky intertidal and subtidal communities. Colonization rates and turnover times, however, are lowest and longest in coral reefs, highest and shortest in intertidal communities, and intermediate in subtidal communities.
    Description: This research was supported by National Science Foundation grants DEB-9527400, OCE-981267, OCE-9302238, and OCE-0083976 and by the National Oceanic and Atmospheric Administration’s National Undersea Research Program, University of Connecticut—Avery Point.
    Keywords: Markov chain ; Sensitivity analysis ; Transition matrix ; Species diversity ; Entropy ; Dobrushin’s coefficient
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
    Publication Date: 2022-05-25
    Description: Author Posting. © University of Chicago Press, 2007. This article is posted here by permission of University of Chicago Press for personal use, not for redistribution. The definitive version was published in American Naturalist 169 (2007): 543–551, doi:10.1086/512106.
    Description: Cephalopods are well known for their diverse, quick‐changing camouflage in a wide range of shallow habitats worldwide. However, there is no documentation that cephalopods use their diverse camouflage repertoire at night. We used a remotely operated vehicle equipped with a video camera and a red light to conduct 16 transects on the communal spawning grounds of the giant Australian cuttlefish Sepia apama situated on a temperate rock reef in southern Australia. Cuttlefish ceased sexual signaling and reproductive behavior at dusk and then settled to the bottom and quickly adapted their body patterns to produce camouflage that was tailored to different backgrounds. During the day, only 3% of cuttlefish were camouflaged on the spawning ground, but at night 86% (71 of 83 cuttlefish) were camouflaged in variations of three body pattern types: uniform (n=5), mottled (n=33), or disruptive (n=34) coloration. The implication is that nocturnal visual predators provide the selective pressure for rapid, changeable camouflage patterning tuned to different visual backgrounds at night.
    Description: This work was made possible by grant 7456-03 from the National Geographic Society Committee on Research and Exploration and support from the Sholley Foundation.
    Keywords: Crypsis ; Concealment ; Disruptive coloration ; Coincident disruptive coloration ; Cephalopod ; Sepia apama
    Repository Name: Woods Hole Open Access Server
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  • 6
    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors, 2006. This article is posted here by permission of American Physical Society for personal use, not for redistribution. The definitive version was published in Physical Review Letters 96 (2006): 018305, doi:10.1103/PhysRevLett.96.018305.
    Description: We study the liquid-crystalline phase behavior of a concentrated suspension of helical flagella isolated from Salmonella typhimurium. Flagella are prepared with different polymorphic states, some of which have a pronounced helical character while others assume a rodlike shape. We show that the static phase behavior and dynamics of chiral helices are very different when compared to simpler achiral hard rods. With increasing concentration, helical flagella undergo an entropy-driven first order phase transition to a liquid-crystalline state having a novel chiral symmetry.
    Description: M. S. and R. O. are supported by NIH Grant No. EB002583.
    Keywords: Entropy ; Molecular biophysics ; Liquid crystal phase transformations ; Symmetry ; Chirality
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 7
    Publication Date: 2022-05-25
    Description: This paper is not subject to U.S. copyright. The definitive version was published in Journal of Geology 118 (2010): 565-575, doi:10.1086/655114.
    Description: Increased study of submarine groundwater systems in recent years has provided a wealth of new data and techniques, but some ambiguity has been introduced by insufficient distinguishing of the relevant spatial scales of the phenomena studied. Submarine groundwater flow and discharge on passive continental margins can be most productively studied and discussed by distinct consideration of the following three spatial scales: (1) the nearshore scale, spanning approximately 0–10 m offshore and including the unconfined surficial aquifer; (2) the embayment scale, spanning approximately 10 m to as much as 10 km offshore and including the first confined submarine aquifer and its terminus; and (3) the shelf scale, spanning the width and thickness of the aquifers of the entire continental shelf, from the base of the first confined aquifer downward to the basement, and including influences of geothermal convection and glacio-eustatic change in sea level.
    Description: The U.S. Geological Survey’s Coastal and Marine Geology Program provided primary support for preparation of the manuscript and for participation in several field studies and scientific meetings that led to the recognition of the need for such a discussion.
    Repository Name: Woods Hole Open Access Server
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  • 8
    Publication Date: 2022-05-25
    Description: Author Posting. © University of Chicago, 2010. This article is posted here by permission of University of Chicago for personal use, not for redistribution. The definitive version was published in American Naturalist 175 (2010): 739-752, doi:10.1086/652436.
    Description: We present a new approach to modeling two‐sex populations, using periodic, nonlinear two‐sex matrix models. The models project the population growth rate, the population structure, and any ratio of interest (e.g., operational sex ratio). The periodic formulation permits inclusion of highly seasonal behavioral events. A periodic product of the seasonal matrices describes annual population dynamics. The model is nonlinear because mating probability depends on the structure of the population. To study how the vital rates influence population growth rate, population structure, and operational sex ratio, we used sensitivity analysis of frequency‐dependent nonlinear models. In nonlinear two‐sex models the vital rates affect growth rate directly and also indirectly through effects on the population structure. The indirect effects can sometimes overwhelm the direct effects and are revealed only by nonlinear analysis. We find that the sensitivity of the population growth rate to female survival is negative for the emperor penguin, a species with highly seasonal breeding behavior. This result could not occur in linear models because changes in population structure have no effect on per capita reproduction. Our approach is applicable to ecological and evolutionary studies of any species in which males and females interact in a seasonal environment.
    Description: H.C. acknowledges support from the National Science Foundation (DEB-0343820 and DEB-0816514) and the Ocean Life Institute and the hospitality of the Max Planck Institute for Demographic Research.
    Keywords: Two‐sex periodic matrix model ; Population structure ; Population growth rate ; Mating systems ; Sex ratio ; Emperor penguin
    Repository Name: Woods Hole Open Access Server
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  • 9
    Publication Date: 2020-12-15
    Description: A burning peat site in the Po Valley (Italy) has been investigated for the first time. Beyond the smoke from the smoldering combustion of peat, there are carbonatic concretions and huge amounts of methane in the soil (〉60% by vol.), leading to fluxes to the atmosphere of the order of 10 to the power of 2/10 to the power of 3 mg m to the power of -2 d to the power of -1. A wide range of analyses (gas composition, stable isotopes of CH4 and CaCO3, methane radiocarbon) were performed in order to understand whether methane is produced by peat layers or seeps from deeper natural gas reservoirs. The quasi-fossil character of CH4, methane-derived carbonates, methane-stable isotopic compositions related to marine carbonates reduction, the presence of helium, and a fault corresponding to the burning site all converge to indicate that the major part of the methane ascends from deep horizons. Such methane seepage is likely to feed the peat combustion, explaining the observed phenomena and the large outbursts of historical gas-emission events.
    Description: Published
    Description: 401-413
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Methane ; seep ; peat ; gas flux ; Po plain ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    University of Chicago Press
    In:  The American Naturalist, 180 (4). pp. 520-528.
    Publication Date: 2020-10-26
    Description: The evolution of reproductive isolation among populations is often the result of selective forces. Among those, parasites exert strong selection on host populations and can thus also potentially drive reproductive isolation. This hypothesis has yet to be explicitly tested, and here we set up a multigenerational coevolution experiment to explore this possibility. Five lines of Tribolium castaneum were allowed to coevolve with their natural parasite, Nosema whitei; five paired lines of identical origin were maintained in the absence of parasites. After 17 generations, we measured resistance within and reproductive isolation between all lines. Host lines from the coevolution treatment had considerably higher levels of resistance against N. whitei than their paired host lines, which were maintained in the absence of parasites. Reproductive isolation was greater in the coevolved selection regime and correlated with phenotypic differentiation in parasite resistance between coevolved host lines. This suggests the presence of a selection-driven genetic correlation between offspring number and resistance. Our results show that parasites can be a driving force in the evolution of reproductive isolation and thus potentially speciation.
    Type: Article , PeerReviewed
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