共查询到20条相似文献,搜索用时 31 毫秒
1.
We develop a simple model for insect locomotion in the horizontal (ground) plane. As in earlier work by Seipel et al. (Biol
Cybern 91(0):76–90, 2004) we employ six actuated legs that also contain passive springs, but the legs, with “hip” and ‘knee’
joints, better represent insect morphology. Actuation is provided via preferred angle inputs at each joint, corresponding
to zero torques in the hip and knee springs. The inputs are determined from estimates of foot forces in the cockroach Blaberus discoidalis via an inverse problem. The head–thorax–body is modeled as a single rigid body, and leg masses, inertia and joint dissipation
are ignored. The resulting three degree-of-freedom dynamical system, subject to feedforward joint inputs, exhibits stable
periodic gaits that compare well with observations over the insect’s typical speed range. The model’s response to impulsive
perturbations also matches that of freely-running cockroaches (Jindrich and Full, J Exp Biol 205:2803–2823, 2002), and stability
is maintained in the face of random foot touchdowns representative of real insects. We believe that this model will allow
incorporation of realistic muscle models driven by a central pattern generator in place of the joint actuators, and that it
will ultimately permit the study of proprioceptive feedback pathways involving leg force and joint angle sensing. 相似文献
2.
Rolando Brawer Facundo D. Batista Oscar R. Burrone Daniel O. Sordelli M. C. Cerquetti 《Archives of microbiology》1998,169(6):530-533
A temperature-sensitive mutant of Salmonella typhimurium was isolated earlier after transposon mutagenesis with Tn10d Tet. The mutant D220 grows well at 28 °C but has a lower growth rate and forms filaments at 37 °C. Transposon-flanking fragments
of mutant D220 DNA were cloned and sequenced. The transposon was inserted in the dam gene between positions 803 and 804 (assigned allele number: dam-231 : : Tn10d Tet) and resulted in a predicted ten-amino-acid-shorter Dam protein. The insertion created a stop codon that led to a truncated
Dam protein with a temperature-sensitive phenotype. The insertion dam-231 : : Tn10d Tet resulted in a dam“leaky” phenotype since methylated and unmethylated adenines in GATC sequences were present. In addition, the dam-231 : : Tn10d Tet insertion rendered dam mutants temperature-sensitive for growth depending upon the genetic background of the S. typhimurium strain. The wild-type dam gene of S. typhimurium exhibited 82% identity with the Escherichia coli dam gene. 相似文献
3.
Temporal correlation of neuronal activity has been suggested as a criterion for multiple object recognition. In this work,
a two-dimensional network of simplified Wilson-Cowan oscillators is used to manage the binding and segmentation problem of
a visual scene according to the connectedness Gestalt criterion. Binding is achieved via original coupling terms that link
excitatory units to both excitatory and inhibitory units of adjacent neurons. These local coupling terms are time independent,
i.e., they do not require Hebbian learning during the simulations. Segmentation is realized by a two-layer processing of the
visual image. The first layer extracts all object contours from the image by means of “retinal cells” with an “on-center”
receptive field. Information on contour is used to selectively inhibit Wilson-Cowan oscillators in the second layer, thus
realizing a strong separation among neurons in different objects. Accidental synchronism between oscillations in different
objects is prevented with the use of a global inhibitor, i.e., a global neuron that computes the overall activity in the Wilson-Cowan
network and sends back an inhibitory signal.
Simulations performed in a 50×50 neural grid with 21 different visual scenes (containing up to eight objects + background)
with random initial conditions demonstrate that the network can correctly segment objects in almost 100% of cases using a
single set of parameters, i.e., without the need to adjust parameters from one visual scene to the next. The network is robust
with reference to dynamical noise superimposed on oscillatory neurons. Moreover, the network can segment both black objects
on white background and vice versa and is able to deal with the problem of “fragmentation.”
The main limitation of the network is its sensitivity to static noise superimposed on the objects. Overcoming this problem
requires implementation of more robust mechanisms for contour enhancement in the first layer in agreement with mechanisms
actually realized in the visual cortex.
Received: 25 October 2001 / Accepted: 26 February 2003 /
Published online: 20 May 2003
Correspondence to: Mauro Ursino (e-mail: mursino@deis.unibo.it, Tel.: +39-051-2093008, Fax: +39-051-2093073) 相似文献
4.
M. H. Tixier P. Sourdille G. Charmet G. Gay C. Jaby T. Cadalen S. Bernard P. Nicolas M. Bernard 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(7):1076-1082
An intervarietal molecular-marker map was used for the detection of genomic regions influencing crossability between wheat
(Triticum aestivum L. em Thell) and rye (Secale cereale L.). Analysis of deviance and logistic marker-regression methods were conducted on data from doubled haploid lines from a
cross between “Courtot” and “Chinese Spring”. A major quantitative trait locus (QTL) involved in crossability, associated
with the marker Xfba367-5B, was detected on the short arm of chromosome 5B. An additional locus, Xwg583-5B, was indicated on the long arm of chromosome 5B. This minor QTL might correspond to Kr1 which was presumed to be the major gene controlling crossability. Another locus of the genome, Xtam51-7A on chromosome 7A, was significantly associated with this trait. Alleles of “non-crossability” were contributed by the non-crossable
cultivar “Courtot”. The three-marker model explains 65% of the difference in crossability between the two parents. The present
results are discussed in relation to those previously carried out to locate the Kr genes by using the telocentric mapping technique.
Received: 27 February 1998 / Accepted: 15 May 1998 相似文献
5.
Ezrachi EA 《Biological cybernetics》2003,88(1):33-45
I present a comprehensive biologically oriented computational model to account for the escape response of the cockroach on
the ground. This model is an expansion of previous work that accounted only for discriminating left from right wind directions
[Ezrachi et al. (1999) Biol Cybern 81: 89–99]. The model is composed of computational elements describing the biological processes
taking place in the various neurons and includes input which emulates empirical data. With this model it is possible to obtain
escape behavior that resembles natural behavior. The model is used to address an ongoing debate as to whether the cockroach's
turn direction is determined by computations carried out by the entire neuronal population (PC) or rather by a “winner-take-all”
(WTA) mechanism. I suggest that the computation mechanism that underlies the cockroach escape response is composed of both
PC and WTA principles. Based on the properties of the suggested new mechanism I denote it a “Darwinian population code.”
Received: 26 March 2002 / Accepted in revised form: 24 June 2002
Acknowledgements. I thank H. Parnas for her advice and assistance, J. M. Camhi for helpful comments, and D. Lipson for developing the simulation
tools.
Correspondence to: E. A. Ezrachi (e-mail: erez@piano.ls.huji.ac.il, Tel.: +972-2-6585818, Fax: +972-2-6585569) 相似文献
6.
“Bacillus thermoantarcticus” sp. nov., from Mount Melbourne,Antarctica: a novel thermophilic species
B. Nicolaus Licia Lama Enrico Esposito Maria Cristina Manca Guido di Prisco Agata Gambacorta 《Polar Biology》1996,16(2):101-104
A novel thermophilic Gram-positive bacillus, “Bacillus thermoantarcticus”, isolated from geothermal soil near the crater of Mount Melbourne, is described. The organism grows at an optimal temperature
of 63°C at pH 6.0, is oxidase-positive, catalase-negative and produces an exopolysaccharide, an exocellular xylanase, an intracellular
alcohol dehydrogenase and exo- and endocellular α-glucosidase(s). The sequence of 16S rDNA is very similar to that of “Bacillus thermoglucosidasius”; however, the guanine-plus-cytosine (G+C) content is 8 mol% higher. The type strain is “Bacillus thermoantarcticus” (DSM 9572).
Received : 3 February 1995/Accepted : 12 May 1995 相似文献
7.
A. J. Monforte M. J. Asíns E. A. Carbonell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(4):706-713
A study of genotype-by-salinity interaction was carried out to compare the behavior of quantitative trait loci (QTLs) in
two F2 populations derived from crosses between the cherry tomato, Lycopersicon esculentum Mill. var. cerasiforme, and two wild relatives Lycopersicon pimpinellifolium (Jusl.) Mill. and Lycopersicon chesmannii f. minor (Hook. f.) Mull., grown at two environmental conditions (optimum and high salinity). QTLs for earliness and fruit yield could
be classified into four groups: “response-sensitive”, those detected only under control conditions or whose contribution significantly
decreased in salinity; “response-tolerant”, detected only in salinity or in which the direction of their additive effects
changed; “constitutive”, detected in both growing conditions; and “altered” QTLs, those where the degree of dominance changed
according to the presence or absence of salt. Epistatic interactions were also influenced by the salt treatment. This differential
allele effect at some (non-constitutive) QTLs induced by salt stress will make selection under an “optimum environment” unfruitful
for the “response-tolerant” QTLs. Similarly, selection under salinity will ignore “response-sensitive” QTLs. Given that salinity
is highly variable in the field, marker-assisted selection should take into account not only the “response-tolerant” but also
the “response-sensitive” QTLs although there might be cases where selection in some QTLs for both conditions is not feasible.
Comparing both populations, very few QTLs showed the same behavior.
Received: 5 August 1996 / Accepted: 25 October 1996 相似文献
8.
Abdel Gaffar Elhag Said Toshio Murashige 《In vitro cellular & developmental biology. Plant》1979,15(8):593-602
Summary Initial trials with tomato-root cultures disclosed the desirability of employing a gently agitated liquid medium containing
iron in the chelated form. For the normal cultivars “Ace” and “Tropic”, subcultures were best achieved by utilizing sectors
that possessed one or more newly emerged laterals. Continuous cultures of a nonlateral-forming tomato mutant, “Diageotropica”,
and of citron were accomplished by subculturing tips of the elongating primary roots. The tomato roots were cultured in White's
medium with the Fe2(SO4)3 replaced by 0.03 mM NaFeEDTA. Sustained growth of citron-root tips necessitated the use of a medium containing Murashige
and Skoog salts, 7.5% sucrose, 100 mg per I each of citric acid and thiamine HCl, and 5000 mg per li-inositol. The success with citron-root cultures was extendable to all cultivars ofC. medica L., but not to otherCitrus species relatives. Both citron and “Diageotropica” root cultures manifested undiminished elongation through repeated subcultures;
but neither produced laterals in response to any cultural treatments.
Research was supported in part by National Science Foundation Grant OIP75-10390 and Elvenia J. Slosson Fellowship in Ornamental
Horticulture. 相似文献
9.
Summary. Eight analogs 4a-7a and 4b-7b of philanthotoxin (PhTX) from wasp venom and nephilatoxin-8 (NPTX-8) from spider venom whose tyrosine or asparagine linker
is replaced by squaryl (sq) amino acid or 4-amino squaryl (4-asq) amino acid have been synthesized in an efficient manner
via coupling of N-acyl squaryl amino acid intermediate 19 or 26 with the corresponding polyamine part. Preliminary bioassay using crickets revealed that the analogs substituted by glutamate-type
squaryl amino acid-containing NPTX 7a and 7b showed more potent paralytic activities than that of NPTX-8.
Received April 25, 2002 Accepted June 21, 2002 Published online December 18, 2002
Acknowledgement This work was supported by a grant from Research for the Future Program from the Japan Society for the Promotion of Science
(JSPS).
Authors' address: Yasufumi Ohfune, Graduate School of Science, Osaka City University, Sugimoto, Osaka 558-8585, Japan, Fax: +81-6-6605-3153,
E-mail: ohfune@sci.osaka-cu.ac.jp 相似文献
10.
Tock Y Ljubisavljevic M Thunberg J Windhorst U Inbar GF Johansson H 《Biological cybernetics》2002,87(4):241-248
The information transmission properties of single, de-efferented primary muscle-spindle afferents from the hind limb of the
cat were investigated. The gastrocnemius medialis muscle was stretched randomly while recording spike trains from several
muscle-spindle afferents in the dorsal root. Two classes of input stimuli were used: (i) Gaussian noise with band-limited
flat spectrum, and (ii) Gaussian noise with a more “naturalistic” 1/f
n
spectrum. The “reconstruction” method was used to calculate a lower bound to the information rate (in bits per second) between
the muscle spindles and the spinal cord. Results show that in response to the flat-spectrum input, primary muscle-spindle
afferents transfer information mainly about high frequencies, carrying 2.12 bits/spike. In response to naturalistic-spectrum
inputs, primary muscle-spindle afferents transfer information about both low and high frequencies, with “spiking efficiency”
increasing to 2.67 bits/spike. A simple muscle-spindle simulation model was analyzed with the same method, emphasizing the
important part played by the intrafusal fiber mechanical properties in information transmission.
Received: 22 January 2002 / Accepted in revised form: 17 June 2002
Correspondence to: Y. Tock (e-mail: ytock@tx.technion.ac.il, Fax: +972-4-8323041) 相似文献
11.
V. B. Meyer-Rochow W. A. Reid 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,166(5):319-324
Fifty randomly selected publications dealing with aspects of crustacean vision had their Materials and methods sections examined. In half of the articles gleaned, only the name of the animal under study was given; the other half mentioned
“adult” or “mature” animals; twelve papers provided information on size or age of the experimental animal and six gave the
sex. In Petrolisthes elongatus, rhabdom microvilli not only become more regular in outline as the animal grows, but also decrease in diameter from 90.4±21.2 nm
in crabs of 5.0–8.9 mm carapace length via 86.6±13 nm in crabs of 9.0–12.9 mm carapace length to 79.7±7 nm in crabs of 13.0–16.9 mm
carapace length. Approximately 400 cross sectional diameters of microvilli from identical regions in four eyes of each size
class were measured and provided the basis for Anova-, Levene-, and t-tests. The three size classes possess microvilli of significantly different diameters and standard deviations. Our observations
show that investigators of the crustacean photoreceptor have frequently neglected to consider the size of their experimental
animals, but that this practice should not be continued as the now documented changes in microvillus diameters may influence
the amount of visual pigment present and, thus, the photoreceptor’s sensitivity to light.
Accepted: 7 May 1996 相似文献
12.
F. J. Gallego C. Benito 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(3):393-399
Aluminium (Al) tolerance in roots of two cultivars (“Ailés” and “JNK”) and two inbred lines (“Riodeva” and “Pool”) of rye
was studied using intact roots immersed in a nutrient solution at a controlled pH and temperature. Both the cultivars and
the inbred lines analysed showed high Al tolerance, this character being under multigenic control. The inbred line “Riodeva”
was sensitive (non-telerant) at a concentration of 150 μM, whereas the “Ailes” cultivar showed the highest level of Al tolerance
at this concentration. The segregation of aluminium-tolerance genes and several isozyme loci in different F1s, F2s and backcrosses between plants of “Ailés” and “Riodeva” were also studied. The segregation ratios obtained for aluminium
tolerance in the F2s analysed were 3 : 1 and 15 : 1 (tolerant : non-tolerant) while in backcrosses they were 1 : 1 and 3 : 1. These results indicated
that Al tolerance is controlled by, at least, two major dominant and independent loci in rye (Alt1 and Alt3). Linkage analyses carried out between Al-tolerance genes and several isozyme loci revealed that the Alt1 locus was linked to the aconitase-1 (Aco1), nicotinamide adenine dinucleotide dehydrogenase-2 (Ndh2), esterase-6 (Est6) and esterase-8 (Est8) loci, located on chromosome arm 6RL. The order obtained was Alt1-Aco1-Ndh2-Est6-Est8. The Alt3 locus was not linked to the Lap1, Aco1 and Ndh2 loci, located on chromosome arms, 6RS, 6RL and 6RL respectively. Therefore, the Alt3 locus is probably on a different chromosome.
Received: 18 March 1997 / Accepted: 21 March 1997 相似文献
13.
A small-scale, “no-use zone policy” has been implemented since 1992 at Eilat’s Coral Nature Reserve (Northern Red Sea). Six
years later, the status of this closed-to-the-public reef area was compared to two nearby open-to-the-public sites, by evaluating
populations of the scleractinian coral Stylophora pistillata in the strolling zone (0.5–1.5 m depth). Results from the open sites show that: (1) Live coral cover was three times lower
than at the closed site; (2) numbers of small colonies (recruits) were significantly higher than in the closed site, while
numbers of medium and large size colonies (geometric mean radius, rˉ>4.1 cm) per m2 were significantly lower; (3) maximum rˉ was almost half than that in the closed site (9.6 cm versus 16.7 cm); (4) average number of broken colonies was three times
higher than in the closed site; (5) significantly fewer colonies were partially dead. The latter result may reflect senescence
processes in the large colonies of the closed site. Although colony breakage is reduced, it appears that the “no-use zone”
policy is not sufficient for protecting small reef areas. The intense exploitation of Eilat’s coral reef by the tourist industry
requires’ in addition to the conventional protective measures, the initiation of novel management solutions such as reef restoration
by sexual and asexual recruits.
Accepted: 11 August 1999 相似文献
14.
Summary. Two glutamic acid analogs (1SR,3RS,4RS)- and (1SR,3SR,4SR)-1-amino-4-phosphono cyclopentane-1,3-dicarboxylic acids (APCPD) have been synthesized. Pure E-(diethoxy-phosphoryl)-acrylic
acid ethyl ester was obtained from ethyl propiolate, phenol and triethylphosphite. It was used as dienophile in a Diels-Alder
reaction. Oxidation and cyclization afforded 3-(ethoxy-carbonyl)-4-(diethoxy-phosphoryl)-cyclopentanone. Bucherer-Bergs reaction
and hydrolysis yielded APCPD-III and -IV which are inactive on mGlu1a receptor and antagonists on mGlu2 and mGlu8a receptors.
Received April 2, 2002 Accepted July 11, 2002 Published online December 18, 2002
Acknowledgments This work was supported by grants from the CNRS, the programs “Physique et Chimie du Vivant” (PCV00–134, CNRS) and “Molécules
et Cibles Thérapeutiques” (CNRS/INSERM), RETINA France and the Fondation de France (Comité Parkinson). A.-S. B. was supported
by fundings from Parke-Davis Pharmaceutical Research (Ann Arbor, MI) and the Fondation de la Recherche Médicale.
Authors' address: Dr Francine C. Acher, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601-CNRS, Université René
Descartes-Paris V, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France, Fax: (33) 1 42 86 83 87, E-mail: acher@biomedicale.univ-paris5.fr 相似文献
15.
This article presents a space-variant version of a standard spatial filter model of texture segregation of the “back-pocket”
type (i.e., two filter layers with an intermediate pointwise nonlinearity). The model was tested with psychophysical data
from experiments with line textures in which target lines differed in orientation from background lines. The textures were
presented briefly and then masked. Segregation performance was evaluated along the horizontal meridian up to retinal eccentricities
of about 10 deg. Data are reported from two experiments with different line densities (Kehrer 1989) and two experiments with
different orientation contrasts between target lines and background lines (Kehrer 1990). Segregation performance proved to
depend strongly on these texture variations, and it peaked several degrees from fixation in all cases. The filter model provided
satisfactory predictions of experimental data when model parameters were adjusted appropriately. It is concluded (1) that
filter models defined in strictly spatial terms (i.e., without temporal properties) offer a sufficient framework to account
for the psychophysical data and (2) that the particular course of the performance curve (i.e., the performance peak outside
the central region) must be attributed to the characteristics of second-layer filters.
Received: 28 June 2001 / Accepted in revised form: 10 October 2002 / Published online: 13 February 2003
Correspondence to: L. Kehrer (e-mail: lothar.kehrer@uni-bielefeld.de)
Acknowledgements. This work was supported by Grant Ke 388/3-2 from the Deutsche Forschungsgemeinschaft (DFG). We wish to thank Jonathan Harrow
for improving the English text and an anonymous reviewer for many constructive comments. 相似文献
16.
Cheryl J. Briggs Roger M. Nisbet William W. Murdoch 《Journal of mathematical biology》1999,38(4):317-345
Continuous-time, age structured, host–parasitoid models exhibit three types of cyclic dynamics: Lotka–Volterra-like consumer-resource
cycles, discrete generation cycles, and “delayed feedback cycles” that occur if the gain to the parasitoid population (defined
by the number of new female parasitoid offspring produced per host attacked) increases with the age of the host attacked.
The delayed feedback comes about in the following way: an increase in the instantaneous density of searching female parasitoids
increases the mortality rate on younger hosts, which reduces the density of future older and more productive hosts, and hence
reduces the future per head recruitment rate of searching female parasitoids. Delayed feedback cycles have previously been
found in studies that assume a step-function for the gain function. Here, we formulate a general host–parasitoid model with
an arbitrary gain function, and show that stable, delayed feedback cycles are a general phenomenon, occurring with a wide
range of gain functions, and strongest when the gain is an accelerating function of host age. We show by examples that locally
stable, delayed feedback cycles commonly occur with parameter values that also yield a single, locally stable equilibrium,
and hence their occurrence depends on initial conditions. A simplified model reveals that the mechanism responsible for the
delayed feedback cycles in our host–parasitoid models is similar to that producing cycles and initial-condition-dependent
dynamics in a single species model with age-dependent cannibalism.
Received: 24 October 1997 / Revised version: 13 June 1998 相似文献
17.
M. R. Duvall 《Plant Systematics and Evolution》2001,228(3-4):143-152
Critical morphological synapomorphies have not been found in support of the Acoranan hypothesis, the molecular phylogenetic
discovery that Acoranae are the basal monocots. The previously undetermined pattern of anther wall development in Acorus has been suggested to be one such character. Two main types of anther wall development have been recognized: 1) the “monocotyledonous”
type, which characterizes both monocots and dicots, and 2) the “dicotyledonous” type, which is almost exclusively found among
dicots. An anatomical study of anther wall development in Acorus was here undertaken using the electron microscope. Development of the anther wall in Acorus was found to be somewhat irregular or perhaps even intermediate between the two types although largely consistent with the
“monocotyledonous” type. The presumed significance of anther wall development and other critical morphological characters
to the Acoranan hypothesis in the absence of knowledge about the sister group to the monocots is evaluated.
Received August 28, 2000 Accepted February 19, 2001 相似文献
18.
Salt tolerance in Lycopersicon spp. VII. Pleiotropic action of genes controlling earliness on fruit yield 总被引:1,自引:0,他引:1
A. J. Monforte M. J. Asíns E. A. Carbonell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(3-4):593-601
The change from vegetative to reproductive development (earliness) in Lycopersicon chesmannii line L2 was delayed for 20 weeks when compared to other Lycopersicon species under greenhouse conditions. The interspecific hybrid of L. chesmannii L2 and L. esculentum E9, a cherry tomato cultivar, also showed this delay in reproductive development. The distribution of this character in the
F2-derived population showed a bimodal shape, plants could be scored easily as “early” or “late” in two nutrient conditions
(optimum and high salinity). A QTL with major effects on earliness was detected in salinity, which explained 35.6% of the
phenotypic variation. The effect of this QTL greatly diminished under control conditions, indicating differences in the genetic
control of earliness between treatments. ACC synthase or phytochrome B2 are the products of candidate genes for such a major
QTL. Other QTLs with minor effects, and epistatic interactions, are also involved in earliness under both conditions. A “late”
F2 subpopulation yielded twice as much as an “early” F2; conversely, “early” plants were taller than “late” plants, regardless of the treatment. QTL analysis, carried out in both
subpopulations, showed that yield differences may be explained by chesmannii alleles showing negative additive effects at some QTLs only in the “early” subpopulation. The effect of population subdivision
on QTL analysis was investigated by computer simulations to show sample-size or random effects; thus, important pleiotropic
or regulatory effects of genes controlling earliness on yield that affect QTL analysis, have been reveiled. Therefore alleles
controlling earliness in L. chesmannii have to be taken into account for a more efficient utilization of the genetic resources of this species.
Received: 30 June 1998 / Accepted: 31 August 1998 相似文献
19.
Albert Eschenmoser 《Origins of life and evolution of the biosphere》2007,37(4-5):309-314
The paper summarizes thoughts induced by some of the programmatic questions Pier Luigi Luisi posed for discussion at the Erice
workshop.
Presented at: International School of Complexity – 4th Course: Basic Questions on the Origins of Life; “Ettore Majorana” Foundation and Centre for Scientific Culture, Erice, Italy, 1–6 October 2006. 相似文献
20.
This article focuses on the analysis of coastal fish communities along the Norwegian Skagerrak coast. Species numbers are
estimated based on annual samples of the fish communities within 12 fjords from 1953 to 1994. On this basis, a community dynamics
model (incorporating both community-intrinsic and community-extrinsic processes) was developed and analyzed. This model is
then discussed on the basis of other community models available through the literature, both phenomenologically oriented and
process-oriented models.
Received: January 17, 2002 / Accepted: May 13, 2002
Acknowledgments We thank Dr. Masakado Kawata for the invi-tation to present this paper at the 19th Symposium of the Society of Population
Ecology held in Yamagata, Japan, October 26–28, 2001: “Evolution of Biodiversity: Theories and Facts.” Valuable input was
provided after the presentation at this meeting, which we greatly appreciated. The reformulation of the model in terms of
ΔS was kindly suggested to us by Prof. Joan Roughgarden. Thanks to Dr. Hildegunn Viljugrein for advice on the BUGS analyses
and to two anonymous reviewers for constructive comments. This work has been supported by grants from the Norwegian Science
Council (NFR).
Correspondence to:N.C. Stenseth 相似文献