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1.
Sub-Antarctic Marion Island has had a permanent research station for 50 years and the islands Wandering Albatrosses have been intensively studied for 20 years. The reactions of breeding birds to approaches by a human on foot were recorded. Three response variables were calculated: intensity of vocal reaction (IVR), intensity of non-vocal reaction (INR) and overall response index (ORI). At 5 m from the nest, twice as many birds stood and/or vocalised as at 15 m. Nearest neighbour distance, age and gender did not explain individual variability of responses. Study colony birds had higher IVR scores than non-study colony birds; birds at colonies closest to the station had the highest ORI scores. A better breeding record was associated with lower IVR and ORI scores, but a causative relationship remains to be demonstrated. A minimum viewing distance of 25 m is recommended for breeding Wandering Albatrosses.
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Marienne S. de VilliersEmail: Fax: +27-21-6503434 |
John CooperEmail: |
Peter G. RyanEmail: |
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The recent contribution by Jarmila Kukalová-Peck on Hennigian phylogenetics and hexapod limb evolution is critically evaluated.
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Michael S. Engel (Corresponding author)Email: |
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Anya Plutynski 《Biology & philosophy》2008,23(5):605-623
The discussion of the adaptive landscape in the philosophical literature appears to be divided along the following lines.
On the one hand, some claim that the adaptive landscape is either “uninterpretable” or incoherent. On the other hand, some
argue that the adaptive landscape has been an important heuristic, or tool in the service of explaining, as well as proposing
and testing hypotheses about evolutionary change. This paper attempts to reconcile these two views.
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Anya PlutynskiEmail: |
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Coral reef marine protected areas (MPA) are widely distributed around the globe for social and ecological reasons. Relatively
few of these MPAs are well managed. This review examines the governance of coral reef MPAs and the means to improve coral
reef MPA management. It highlights common governance challenges, such as confused goals, conflict, and unrealistic attempts
to scale up beyond institutional capacity. Recommendations, based on field experience and empirical evidence from around the
world, are made for best practices at various stages of MPA implementation.
相似文献
A. T. WhiteEmail: |
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Littorals in the in the Exuma Cays, Bahamas and the Bath Plantation, Barbados are comparative in many ways. These edges of
the sea have provided critical services to local people during the time of slavery and since. More than food and medicine,
the littoral is the nightly sea bath, where children are instructed, and the last ecosystem effectively used by the elderly.
Independence and self-respect derive from use and protection of these littoral by individuals and communities. Local patterns
of conservation and use are argued to be essential in the ecological structure and functions of the littoral. Development
projects and marine protected areas alike are seen as potentially breaking local ties with the littoral causing trophic skew
and damaging local society. If development occurs, mitigation solutions potentially derive from legally recognizing local
people as partners in the co-management of their traditional littoral.
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Richard W. Stoffle (Corresponding author)Email: |
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Mathematical neuronal models are normally expressed using differential equations. The Parker-Sochacki method is a new technique
for the numerical integration of differential equations applicable to many neuronal models. Using this method, the solution
order can be adapted according to the local conditions at each time step, enabling adaptive error control without changing
the integration timestep. The method has been limited to polynomial equations, but we present division and power operations
that expand its scope. We apply the Parker-Sochacki method to the Izhikevich ‘simple’ model and a Hodgkin-Huxley type neuron,
comparing the results with those obtained using the Runge-Kutta and Bulirsch-Stoer methods. Benchmark simulations demonstrate
an improved speed/accuracy trade-off for the method relative to these established techniques.
相似文献
Robert D. StewartEmail: |
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Peter Godfrey-Smith 《Biology & philosophy》2007,22(3):429-437
Jablonka and Lamb's claim that evolutionary biology is undergoing a ‘revolution’ is queried. But the very concept of revolutionary
change has uncertain application to a field organized in the manner of contemporary biology. The explanatory primacy of sequence
properties is also discussed.
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Peter Godfrey-SmithEmail: |
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A key point in the analysis of dynamical models of biological systems is to handle systems of relatively high dimensions.
In the present paper we propose a method to hierarchically organize a certain type of piecewise affine (PWA) differential
systems. This specific class of systems has been extensively studied for the past few years, as it provides a good framework
to model gene regulatory networks. The method, shown on several examples, allows a qualitative analysis of the asymptotic
behavior of a PWA system, decomposing it into several smaller subsystems. This technique, based on the well-known strongly
connected components decomposition, is not new. However, its adaptation to the non-smooth PWA differential equations turns
out to be quite relevant because of the strong discrete structure underlying these equations. Its biological relevance is
shown on a 7-dimensional PWA system modeling the gene network responsible for the carbon starvation response in Escherichia coli.
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Laurent Tournier (Corresponding author)Email: |
Jean-Luc GouzéEmail: |
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This paper examines change within farming systems in the Brong Ahafo Region in Ghana, and the impact of agricultural modernization
and mechanization on the regional economy and local farming systems. It combines anthropological, historical, and remote sensing
techniques to document changes in farming practice and land use and land cover. It argues that change is not the product of
simple evolutionary sequences of responses to population pressures or adoption of modern technologies, but arises out of a
complex set of factors interacting within wider regional economies, which are increasingly commodified and commercialized
and subject to global market pressures. These include technical, institutional, market, movements of labor, and transport
infrastructure development dimensions, which often create new opportunities for local farmers other than those envisaged in
agricultural development policies. Tracing the opening up of the transition zone over the last 40–50 years through the development
of state farms and mechanized synthetic agriculture, the paper examines the changing fortunes of farming systems within a
radius of 30–40 km from agricultural technology hubs and the implications for models of agricultural development.
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Opoku PabiEmail: |
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Methanogens growing on C-1 substrates synthesize 2-carbon acetyl groups in the form of acetyl-CoA for carbon assimilation
using the multienzyme complex acetyl-CoA decarbonylase/synthase (ACDS) which contains five different subunits encoded within
an operon. In species growing on acetate ACDS also functions to cleave the acetate C-C bond for energy production by methanogenesis.
A number of species of Methanosarcina that are capable of growth on either C-1 compounds or acetate contain two separate ACDS operons, and questions have been
raised about whether or not these operons play separate roles in acetate synthesis and cleavage. Methanosarcina thermophila genomic DNA was analyzed for the presence of two ACDS operons by PCR amplifications with different primer pairs, restriction
enzyme analyses, DNA sequencing and Southern blot analyses. A single ACDS operon was identified and characterized, with no
evidence for more than one. MALDI mass spectrometric analyses were carried out on ACDS preparations from methanol- and acetate-grown
cells. Peptide fragmentation patterns showed that the same ACDS subunits were present regardless of growth conditions. The
evidence indicates that a single form of ACDS is used both for acetate cleavage during growth on acetate and for acetate synthesis
during growth on C-1 substrates.
Electronic Supplementary Material Supplementary material is available for this article at
相似文献
David A. Grahame (Corresponding author)Email: |
Edward DeMoll (Corresponding author)Email: |
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Causal Explanation of Indonesian Forest Fires: Concepts, Applications, and Research Priorities 总被引:1,自引:0,他引:1
Andrew P. Vayda 《Human ecology: an interdisciplinary journal》2006,34(5):615-635
Problems with studies, claims, and assumptions that have been made about the causes of fires in Indonesia's tropical moist forests are identified, and the kinds of concepts, methods, prioritizing, and data needed to resolve the problems are discussed. Separate sections are devoted to studying ignitions, studying fire susceptibility and fire behavior, and using the goal of causal explanation to guide interdisciplinary research.
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Andrew P. VaydaEmail: |
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Robin E. Snyder 《Theoretical Ecology》2009,2(2):79-87
When a pattern of spatial or temporal environmental variation changes, it takes time for populations to reach their new stationary
distributions, and during this time, the competitive landscape is also in flux. As a first step toward understanding community
responses to altered variational regimes, I investigate the convergence of an annual–perennial plant system to its stationary
spatiotemporal distribution following a change in environmental variation. I find that, to good approximation, convergence
is the sum of two separate processes: global convergence, which governs changes in the total population, and local convergence,
which governs population redistribution. While the slower process (global or local) eventually governs convergence, the faster
process may initially dominate if it starts further from its stationary distribution, so that the populations converge quickly
at first, then slow down. That is, when disturbances are spatially heterogeneous, a system may be initially more resilient
under some initial conditions than others.
相似文献
Robin E. SnyderEmail: |
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Machado RR Lima Filho ES Jardim DF Ferreira MA de Faria CG Duarte RS Lesche B 《European biophysics journal : EBJ》2008,38(1):111-119
An interferometer that measures the refractive index changes due to bacterial metabolism is described. The apparatus permits
simultaneous and real time measurement of bacterial growth in several samples of slowly growing mycobacteria. The error sources
are discussed and the sensitivity of the apparatus is tested. For the species Mycobacterium bovis BCG and M. smegmatis, a relation between refractive index change and bacterial concentration is determined experimentally and the time constant
of bacterial growth is measured.
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B. LescheEmail: |