Ackland. Maximization principlesand daisyworld. J. Theo. Biol. 227, 121-128.\n\n[[PDF|refs/dw/ackland_2004.pdf]]\n\nAbstract:\nWe investigate whether the equilibrium time-averaged state of a self-organizing system with many internal degrees of freedom, 2D-daisyworld, can be described by optimizing a single quantity. Unlike physical systems where a principle of maximum energy production has been observed, daisyworld follows evolutionary dynamics rather than Hamiltonian dynamics. We find that this is sufficient to invalidate the maximum entropy production principle, finding instead a different principle, that the system self organizes to a state which maximizesthe amount of life.
Ackland, Clark, Lenton. Catastrophic Desert Formation in Daisyworld. J. Theo. Biol 223, 39-44\n\n[[PDF|refs/dw/ackland_etal_2003.pdf]]
Adams, Carr, Lenton, White. One-dimmensional daisyworld: spatial interactions and pattern formation. J. Theo. Biol 223 505-513\n\n[[PDF|refs/dw/adams_etal_2003.pdf]]
\n[[PDF|refs/dw/akagi_2006.pdf]]
Andrew. The Challenge of Daisyworld. Kybernetes, Vol. 25 No. 7/8, 1996,pp. 94-99. © MCB University Press,\n0368-492X\n\n[[PDF|refs/dw/andrew_1996.pdf]]
Andrew. Daisyworld and Darwin. Kybernetes, Vol. 26 No. 8, 1997,pp. 939-942. © MCB University Press, 0368-492X\n\n[[PDF|refs/dw/1995-99/andrew_1997.pdf]]\n\nAn important paper emphasizing the significance of the Daisyworld idea is due\nto Saunders (1994). I am sorry to say that it had not come to my notice when I\nwrote my recent paper (Andrew, 1996) and I am grateful to Prof. James Lovelock\nfor remedying this. Saunders argues that evolution by natural selection may not\nhave been the crucial factor in establishing regulation in organisms, and that\nthe type of mechanism exemplified by Daisyworld has more relevance.
DENNIS D. BALDOCCHI, THERESA KREBS and MONIQUE Y. LECLERC. Tellus 57B, 175-188 Wet/dry Daisyworld”: a conceptual tool for quantifying the spatial scaling of heterogeneous landscapes and its impact on the subgrid variability of energy fluxes.\n\n[[PDF|refs/dw/baldocchi_etal_2005.pdf]]
Cohen & Rich. Interspecific competition affects temperature stability in Daisyworld. Tellus 52B, 980-984.\n\n[[PDF|refs/dw/cohen_rich_2000.pdf]]\n\nAbstract:\nThe model of Daisyworld showed that nonteleological mechanistic responses of life to the physical environment can stabilize an exogenously perturbed environment. In the model, 2 species of daisies, black and white, stabilize the global temperature of a planet exposed to different levels of insolation. In both species, the response of the growth rate to local temperature is identical, but differences in albedo between the 2 species generate differences in local temperatures. The shifting balance between the daisies keeps the global temperature in a range suitable for life. Watson and Lovelock made the stronger claim that ‘‘the model always shows greater stability with daisies than it does without them.’’ We examined this claim by introducing an extra source of competition into the equations that describe the interactions between the daisy species. Depending on the parameters of competition, temperatures can vary more widely with increasing insolation in the presence of daisies than without them. It now seems possible, timely\nand perhaps necessary, to include an accurate representation of interspecific competition when taking account of vegetational influences on climate.\n\n
\n[[PDF|refs/dw/dagg_2002.pdf]]
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[[Welcome]]
Dewar. STATISTICAL BASIS OF THE PRINCIPLE OF MAXIMUM ENTROPY PRODUCTION. Geophysical Research Abstracts, Vol 5, 01022.\n\n[[PDF|refs/mep/dewar_2003.pdf]]\n\nAbstract:\nThe principle of maximum entropy production (MEP) is explained from a statistical\nviewpoint. JaynesŠ information theory formalism of statistical mechanics - developed\nfrom the work of Boltzmann, Gibbs and Shannon - is applied to the stationary states of\nopen, non-equilibrium systems. In this formalism the path information entropy of the\nunderlying microscopic phase-space trajectories is maximised subject to the imposed\nconstraints. From the resulting microscopic path distribution three consequences may\nbe derived : (1) the MEP principle, (2) the fluctuation theorem describing the probability\nof deviations from the 2nd law of thermodynamics, and (3) the emergence of\nself-organized criticality for flux-driven systems in the slowly-driven limit. The implication\nis that the MEP state is selected because it is the most probable macroscopic\nstate, i.e. the one that is realised by the greatest number of microscopic paths compatible\nwith the imposed constraints.
\n[[PDF|refs/mep/dewar_2003b_abstract.pdf]]
Roderick Dewar. Maximum Entropy Production and Non-Equilibrium Statistical Mechanics. Chapter 4 NESM and Life.\n\n[[PDF|refs/mep/dewar_2005.pdf]]\n\nAbstract:\nOver the last 30 years empirical evidence in favour of the Maximum\nEntropy Production (MEP) principle for non-equilibrium systems has been accumulating\nfrom studies of phenomena as diverse as planetary climates, crystal growth\nmorphology, bacterial metabolism and photosynthesis. And yet MEP is still regarded\nby many as nothing other than a curiosity, largely because a theoretical justification\nfor it has been lacking. This chapter offers a non-mathematical overview\nof a recent statistical explanation of MEP stemming from the work of Boltzmann,\nGibbs, Shannon and Jaynes. The aim here is to highlight the key physical ideas\nunderlying MEP. For non-equilibrium systems that exchange energy and matter\nwith their surroundings and on which various constraints are imposed (e.g., external\nforcings, conservation laws), it is shown that, among all the possible steady\nstates compatible with the imposed constraints, Nature selects the MEP state because\nit is the most probable one, i.e., it is the macroscopic state that could be\nrealised by more microscopic pathways than any other. That entropy production\nis the extremal quantity emerges here from the universal constraints of local energy\nand mass balance that apply to all systems, which may explain the apparent\nprevalence of MEP throughout physics and biology. The same physical ideas also\nexplain self-organized criticality and a result concerning the probability of violations\nof the second law of thermodynamics (the Fluctuation Theorem), recently verified\nexperimentally. In the light of these results, dissipative structures of high entropy\nproduction, which include living systems, can be viewed as highly probable phenomena.\nThe prospects for applying these results to other types of non-equilibrium\nsystem, such as economies, are briefly outlined.\n
\n[[PDF|refs/mep/dewar_2005b.pdf]]
Downing & Zvirinsky. The Simulated Evolution of Biochemical Guilds: Reconciling Gaia Theory and Natural Selection. Articial Life 5: 291–318 (1999)\n\n[[PDF|refs/dw/downing_zvirinsky_1999.pdf]]\n\nAbstract:\nAbstract Gaia theory, which states that organisms both\naffect and regulate their environment, poses an interesting\nproblem to ~Neo-Darwinian evolutionary biologists and\nprovides an exciting set of phenomena for articial-life\ninvestigation. The key challenge is to explain the emergence\nof biotic communities that are capable, via their implicit\ncoordination, of regulating large-scale biogeochemical factors\nsuch as the temperature and chemical composition of the\nbiosphere, but to assume no evolutionary mechanisms\nbeyond contemporary natural selection. Along with\nproviding an introduction to Gaia theory, this article presents\nsimulations of Gaian emergence based on an articial-life\nmodel involving genetic algorithms and guilds of simple\nmetabolizing agents. In these simulations, resource\ncompetition leads to guild diversity; the ensemble of guilds\nthen manifests life-sustaining nutrient recycling and exerts\ndistributed control over environmental nutrient ratios. These\nresults illustrate that standard individual-based natural\nselection is sufcient to explain Gaian self-organization, and\nthey help clarify the relationships between two key metrics of\nGaian activity: recycling and regulation.
\n[[PDF|refs/dw/downing_2002.pdf]]
Dyke & Harvey. Hysteresis and the Limits of Homoestasis. From Daisyworld to Phototaxis. Proceedings of ECAL VIII\n\n[[PDF|refs/dyke_harvey_2005.pdf]]\n\nSynopsis:\nA simple agent that performs phototaxis is created based upon Harvey's simple two box model. When the essential range is increased, then the range of phototaxis actually decreases. Same idea as Alife X essentially.
Dyke & Harvey 2005. Pushing up the Daisies. Proceeding of Alife X.\n\n[[PDF|refs/dw/dyke_harvey_2005b.pdf]]\n\nSynopsis:\nFollowing on from [[Dyke & Harvey (2005)|refs/daisyworld/dyke_harvey_2005.pdf]] we further explore the effects of increasing the viability range of the daisies. It is shown that when heat conductance is within a certain range (we concentrate on when it is set to maximise the both daisy range) then increasing the viability range actually decreases viability of the entire system. Inman casts this in more dynamical systems language. I briefly discuss possible implications for evolution - in particular the potential of 'cheaters' to reduce the systems robustness to external perturbations.
\n[[PDF|refs/dw/franck_etal_2000.pdf]]
This site is an example of a ~TiddlyWiki site and so is easy and intuitive to use. Blue text is invariably a link of some sort, either to an entry (or 'tiddler') on this site, or a URL to an external resource. Moving your cursor over entry will display an options bar at the top of the entry. Whilst the 'edit' function may be displayed, and it may be possible to edit entries, it is not possible to save these entries.\n\nAll reference entries can be found listed on the.... yes 'References' entry which is permanently displayed on the left hand side along with 'Welcome', 'Getting Started' and 'Links'. On the opposite side is the 'close all' link, rather handy for tidying up the main window.\n\nThe blue '~InterfaceOptions' only apply to your browser, so feel free to experiment. Underneath, are a series of tabs that display all entries and tags.\n\nA ~TiddlyWiki tutorial can be found [[here|http://www.blogjones.com/TiddlyWikiTutorial.html]]. Have fun!
Harding & Lovelock. Exploiter mediated Coexistence and Frequency!Dependent Selection in a Numerical Model of Biodiversity. J. theor. Biol. 182, 109-116.\n\n[[PDF|refs/dw/harding_lovelock_1996.pdf]]\n\nAbstract:\nThe key feature of the Daisyworld approach is to explicitly model feedbacks between the competitive dynamics of a planetary biota "daisies with diferent albedos and the planets climate\snamely its surface temperature. Self regulation of surface temperature and stable population dynamics are striking emergent properties of this system despite increasing energy output from the models sun. In this paper we attempt to perturb Daisyworld by introducing herbivores endowed with one of four strategies for feeding on daisies in a system rich in daisy diversity and found that the herbivores only moderately diminish the temperature regulating abilities of the system. Furthermore we find that the precise trajectory of the systems temperature regulation depends critically on which daisy species the herbivore allows to co!exist thereby revealing that climate and patterns of biodiversity are highly interrelated in this model and possibly in the real world.
\n[[PDF|refs/dw/harvey_2004.pdf]]
Welcome to the Daisyworld Bibiliography. This site consists of a comprehensive collection of published papers refering to the daisyworld model. The majority of reference entries link to PDF version of the reference that can be downloaded from this site.\n\nThe site is based on TiddlyWiki, an excellent, open source online research journal that allows hassle free website construction. Unlike other Wikis, this site is primarily intended as a read only resource. It is currently not possible to edit and save changes online. Therefore, if you wish to notify the administrator of this site of any errors or omissions, please email James Dyke.\n\nTo navigate, simply single click blue text. This will open the relevent document (or 'tiddler' in TiddlyWiki speak. Passing your cusor over the document will bring up a number of options. Whilst it is possible to open documents for editing, you will not be allowed to save any changes. A TiddlyWiki tutorial can be found here. Have fun!
\n[[PDF|refs/dw/jascourt_raymond_1991.pdf]]
Jaynes. Macroscopic Prediction. Complex Systems - Operational Approaches in Neurobiology, Physics and Computers, H. Haken, Ed.; Spinger-Verlag, Berlin (1985), 254-269.\n\n[[PDF|refs/mep/jaynes_1985.pdf]]\n\nAbstract:\n\nSynopsis:\n
\n[[PDF|refs/dw/kleidon_2004.pdf]]
\n[[PDF|refs/dw/koelsag_etal_1999.pdf]]
Lansing et al. System!dependent Selection Ecological Feedback and the Emergence of Functional Structure in Ecosystems. J. Theo. Biol. 192, 377-391.\n\n[[PDF|refs/dw/lansing_etal_1998.pdf]]\n\nAbstract:\nMost models of natural selection assume either that the material environment remains constant or that it fluctuates in ways unrelated to changes in gene frequencies and therefore changes in the distribution of phenotypes of the organism undergoing selection. In this paper we consider what happens when this assumption does not hold, that is, when ecological feedback between organism and environment\nis included in the evolutionary process. Specically we examine the unusual volutionary dynamics that occur when changes in the distribution of phenotypes resulting from selection alter an environmental parameter in ways that in turn modify selection pressures. This process which we term "system-dependent selection" can produce stable phenotypic diversity which functions to regulate the relevant environmental parameter within a much narrower range than would occur in the absence of ecological feedback This environmental regulation raises the mean fitness of the population and reduces variance in fitness among diferent phenotypes. Thus system-dependent selection produces functional organization at the level of the system as a whole, rather than at the level of the individual organism. We use James Lovelock's model of the imaginary planet Daisyworld to describe the unusual dynamics of this selective process and then use a similar model to examine the structure of an ancient system of wet-rice farming on the Indonesian island of Bali. This model accurately predicts the actual structure of functional organization along two Balinese rivers. We investigate the stability of such systems by exploring the conditions under which mutant phenotypes can invade Daisyworld. The results suggest that the phenotypic diversity and functional organization produced by system-dependent selection may be maintained when there exists variation over evolutionary time in the environmental parameters underlying system-dependent dynamics.
\n[[PDF|refs/dw/lapenis_2002.pdf]]
Lenton & Lovelock (2000). Daisyworld is Darwinian. Constraints on Adapatation are Important for Planetary Self Regulation. J. Theo. Biol 2000 206 109-114\n\n[[PDF|refs/dw/lenton_lovelock_2000.pdf]]\n\nSynopsis:\nA reply to Robertson & Robinson (1998) in which they conclude that evolutionary competition will undermine global regulation. If indeed adapation was truly open ended, then there would be no need to regulate. If essential variables could get as wide as they like, then no need to regulate (first approach mentioned in Dyke & Harvey (2005b)). But there are chemical and thermodynamic limits to regulation. OK - so there are limits. Do those limits actually help global regulation?
Lenton & Lovelock. Daisyworld revisited: quantifying biological effects on planetary self-regulation. Tellus 53B, 288-305.\n\n[[PDF|refs/d/lenton_lovelock_2001.pdf]]\n\nSynopsis:\nRefers to [[Cohen & Rich (2000]] - competition undermines regulation and [[Stocker (1995)]].\n\nAbstract:\nDaisyworld demonstrates that self-regulation of the global environment can emerge from organisms altering their local environment in different ways. In Daisyworld, natural selection is directly linked to environmental effects such that what is selected for at the individual level is beneficial to the global environment. The model has been modified and extended in many studies that have highlighted the effect of biological processes on system self-regulation. Here we better quantify their effects and present new variants of the model in an attempt to resolve outstanding debates. The results confirm that Daisyworld is a remarkably robust self-regulating system and they offer some general lessons about systems where life has a strong effect on the environment, which we think are relevant to the Earth. As forcing becomes extreme, such systems can exhibit co-existing stable states with and without life (bi-stability), and rapid transitions from one to the other that are difficult to reverse. The growth response of organisms to the environment has a role in determining the range of forcing over which a system can regulate. Density-dependent ecological interactions improve Daisyworld’s regulatory properties, although increased inter-species competition destabilises the environment in one interval. Selfregulation\nis little affected by introducing organisms that ‘‘cheat’’ by not altering their local\nenvironment and in so doing gain a growth advantage. Increased variation in an environmentaltering trait (albedo) can weaken the negative feedback it provides on the environment. However, random mutation of this trait and subsequent natural selection can generate and extend the range of temperature regulation and improve the system’s response to perturbation with time. Internal adaptation of organisms toward prevailing environmental conditions, or to tolerate extremes, can also extend the range of forcing over which life persists.\n
\n[[PDF|refs/dw/lenton_wilkinson_2003.pdf]]
\n[[PDF|refs/dw/lenton_oijen_2002.pdf]]
Lenton. Gai and Natural Selection. Nature 394, 439-447\n\n[[PDF|refs/dw/lenton_1998.pdf]]\n\nAbstract:\nEvidence indicates that the Earth self-regulates at a state that is tolerated by life, but why should the organisms that\nleave the most descendants be the ones that contribute to regulating their planetary environment? The evolving Gaia\ntheory focuses on the feedback mechanisms, stemming from naturally selected traits of organisms, that could\ngenerate such self-regulation
\n[[PDF|refs/dw/lenton_2002.pdf]]
\n[[Daisyworld & Beyond Research Network|http://www.cogs.susx.ac.uk/daisyworld/index.html]]\n\n[[NANIA|http://www.ph.ed.ac.uk/nania/index.html]]\n\n[[Earth System Modelling Group at UEA|http://lgmacweb.env.uea.ac.uk/esmg]]\n
Lovelock. A Numerical Model for Biodiversity. Phil. Trans. Biol. Sci. 338, No. 1286, 383-391.\n\n[[PDF|refs/dw/lovelock_1992.pdf]]
Daisyworlds research Wiki.
[[Welcome]]\n[[Getting Started]]\n[[References]]\n[[Links]]\n\n[[James Dyke|http://www.sussex.ac.uk/Users/jgd20/index.html]] 2006
\n[[PDF|refs/dw/mccormack_2003.pdf]]
\n[[PDF|refs/dw/nature_2005.pdf]]
Nevinson, Gupta and Klinger. Self-sustained temperature oscillations on Daisyworld. Tellus 1999 51B 806-814\n\n[[PDF|refs/dw/nevinson_etal_1999.pdf]]\n\nAbstract:\nThe daisyworld model of Watson and Lovelock demonstrated that a simple biological feedback\nsystem involving coupling between black and white daisies and their physical environment can\nstabilize planetary temperature over a wide range of solar luminosity. Here, we show that the\naddition of a differential equation for temperature to the original daisyworld model leads to\nperiodic oscillations in temperature about a homeostatic mean. These oscillations, in which the\nmodel alternates between dominance by either black or white daisies, arise from the internal\ndynamics of the system rather than from external forcing. An important criterion for the oscillations\nto occur is that solar luminosity be within the range in which both daisy species are\nviable. A second important criterion is that the ratio of the timescales for daisy population\nturnover and climate system thermal response be bounded. While internally driven oscillations\nare well known in predator–prey biological models and in coupled ocean energy balance–\ncryosphere models, the present study shows that such oscillations also can arise in a model of\nthe biosphere coupled to its physical environment. The potential significance of this result to\nplanet Earth and the science of geophysiology is discussed.
\n[[PDF|refs/dw/pujol_2002.pdf]]
\n[[PDF|refs/dw/pujol_etal_2005.pdf]]
Currently under construction. If you have comments, suggestions, corrections etc, please contact [[James Dyke|mailto:j.g.dyke@sussex.ac.uk]].\n\n*[[Ackland (2004)]]\n*[[Ackland et al (2003)]]\n*[[Akagi 2006]]\n*[[Adams et al (2003)]]\n*[[Andrew (1996)]]\n*[[Andrew (1997)]]\n*[[Baldocchi et al (2005)]]\n*[[Cohen & Rich (2000)]]\n*[[Dagg (2002)]]\n*[[Dewar (2003)]]\n*[[Dewar (2005)]]\n*[[Downing (2002)]]\n*[[Downing & Zvirinsky (2000)]]\n*[[Dyke & Harvey (2005)]]\n*[[Dyke & Harvey (2005b)]]\n*[[Franck et al (2000)]]\n*[[Harding & Lovelock (1996)]]\n*[[Harvey (2004)]]\n*[[Jascourt & Raymond (1991)]]\n*[[Kleidon (2004)]]\n*[[Koelsag et al (1999)]]\n*[[Lansing et al (1998)]]\n*[[Lapenis (2002)]]\n*[[Lenton (1998)]]\n*[[Lenton (2002)]]\n*[[Lenton & Lovelock (2000)]]\n*[[Lenton & Lovelock (2001)]]\n*[[Lenton & van Oijen (2002)]]\n*[[Lenton & Wilkinson (2003)]]\n*[[Lovelock (1992)]]\n*[[McCormack(2003)]]\n*[[Nature (2005)]]\n*[[Nevinson et al (1999)]]\n*[[Pujol (2002)]]\n*[[Pujol et al (2005)]]\n*[[Robertson & Robinson (1998)]]\n*[[Saunders (1994)]]\n*[[Saunders (1998)]]\n*[[Saunders et al (2000)]]\n*[[Seto & Akagi (2005)]]\n*[[Staley (2002)]]\n*[[Stocker (1995)]]\n*[[Sugimoto (2002)]]\n*[[Von Bloh (1997)]]\n*[[Von Bloh (1999)]]\n*[[Weber (2001)]]\n*[[Wilkinson (2003)]]\n*[[Williams & Nobel (2005)]]\n*[[Zeng (1990)]]\n\n
Robertson & Robinson. Darwinian Daisyworld. J. Theo. Biol. 195 129-134.\n\n[[PDF|refs/dw/robertson_robinson_1998.pdf]]\n\nAbstract:\nThe Daisyworld model was developed to show that organisms can collectively regulate the\nglobal environment without assuming conscious or altruistic behaviour\s i[e[ that Gaia is\nfeasible[ We studied the e}ects of adaptive evolution on Daisyworld by allowing daisies to\nshift their optimal growth temperatures toward the prevailing temperature[ This eliminates\nDaisyworld|s homeostatic ability\s suggesting a trade!o} between the ability of organisms to\ncollectively regulate the environment and the abilities of evolving genotypes to adapt to it[
Saunders. Evolution without natural selection. J. Theo. Biol.\n\n[[PDF|refs/dw/saunders_1994.pdf]]
Saunders. Integral Rein Control in Physiology. J. T. Biol. 194, 163-173.\n\n[[PDF|refs/dw/saunders_1998.pdf]]\n\nAbstract:\nWe propose that blood glucose is regulated by a principle which we call integral rein control,\nin which under most conditions both glucagon and insulin are produced and control is\nachieved by altering the balance between the two. Like other integral control systems\s the\nmechanism achieves zero steady!state error\s which explains how the blood glucose level can\nremain very nearly constant over a wide range of input and demand[ In addition\s the use of\ntwo hormones makes the system stable against relatively large perturbations in either\ndirection\nAn important feature of the model is that the set point is not _xed by an external reference\nbut arises out of the dynamics, in particular out of the relation between the rates of\nproduction of the two hormones[ The model therefore predicts that the consequence of an\ninability to produce insulin will be not just that the control will be less e}ective but that the\nset point will be shifted[ This allows us to explain why patients with untreated Type I diabetes\nmellitus have high blood glucose levels even under conditions of low glucose input\s and why\nit is di.cult to maintain the normal level of 4 mmol:l in patients who are being treated with\ninsulin. It also explains why Type II diabetes is easier to treat
Saunders et al. Integral Rein Control in Physiology II: a General Model. J. Theo. Biol. 206, 211-220\n\n[[PDF|refs/dw/saunders_etal_2000.pdf]]\n\nAbstract:\nWe generalize the principle of integral rein control to include other systems which partition in such a way that the equilibrium values of some variables are not dependent on the equations governing those variables. Instead, they are determined by the dynamics of other variables. We improve our earlier model for the control of glucose by insulin and glucagon by relaxing the condition necessary for it to operate. The two hormones do not have to be inhibited in the same way; they need only respond to the same combination of their concentrations. We also present a model for the control of ionized calcium by PTH and calcitonin and suggest that the role of chromogranin A may be to stabilize an otherwise unstable system.
\n[[PDF|refs/dw/seto_akagi_2005.pdf]]
An online resource for Daisyworld references
Daisyworld Bibliography\n
http://www.sussex.ac.uk/Users/jgd20/daisywiki.html
\n[[PDF|refs/dw/staley_2002.pdf]]
Sabine Stocker. Regarding Mutations in Daisyworld. J. theo. Biol. 1995 175 495-501\n\n[[PDF|refs/dw/stocker_1995.pdf]]\n\n\n\n\n\n
Takeshi Sugimoto. Darwinian Evolution Does Not Rule Out the Gaia Hypothesis. J. Theo. Biol. 2002 218 447-455.\n[[PDF|refs/dw/sugimoto_2002.pdf]]\n\nSynopsis:\nAn analytical treatment of Robertson & Robinson (1998) and Lenton & Lovelock (2000). He concludes that Gaia and Darwinian evolution are not mutually exclusive - they can co-exist. He disagrees with R&R and actually asks if they obtianed the eq of pop dynamics at every forcing of the solar luminosity? i.e. was their spreadhseet wrong. I wonder if they replied? He also disagrees with L&L - adaptive daisies can actually regulate better, and putting a constraint on adaptation makes them less able to regulate.\n Interesting analysis of how both daisies co-exist from the start of simulations. He thinks L&L made the error of having black daisies establish themselves first, and simply adapting to local temperature. When the white daisies begin to grow, space competition results in them being unable to perform effective regulation.\n He gives a metric of adaptation 'a'. Low a can mean that white daisies are unable to evolve in response to increasing temperature - "weak adaptation leads white daiseis to a dead end of eveolution resulting in the early extincition; the strong adaptation make white daiseies survive longer than non-adaptive daisies." p455.
[[TiddlyWikki website|http://www.tiddlywiki.com/]]
\n[[PDF|refs/dw/toniazzo_etal_2004.pdf]]\n\nSummary. The Gaia hypothesis posits that the Earth’s climate is self-regulating,\nwhile the maximum entropy production (MEP) principle suggests that the climate\nsystem self-organizes in a state of maximum entropy production due to turbulent\ndissipative processes.We explore the relationship between the two by applying MEP\nto a toy model based on Daisyworld in which the temperature-albedo feedback is\ndependent on the heat transport rates within the system. We initially assume that\nthe dynamical response of the climate system to differential radiative heating is to\ncreate heat fluxes such that a steady state satisfying a maximum entropy-production\n(MEP) condition is obtained. The resulting system, which does not depend on free\nparameters, turns out to be thermostatic and to favour the existence of two, but\nnot several, daisy species simultaneously. Furthermore, it maximizes the range of\nluminosity over which daisies exist, that is, the lifespan of Daisyworld. However,\nif the daisy coverage is assumed to adjust more slowly than the heat fluxes, the\nrange of habitation is narrowed. Imposing a sinusoidal forcing allows more than\ntwo species to coexist, but only occasionally and not to a significant extent.\n
Von Bloh. Self-stabilization of the biosphere under global change: a tutorial geophysiological approach. Tellus 49B, 249-262.\n\n[[PDF|refs/dw/vonbloh_etal_1997.pdf]]\n\nSynopsis:\n2D daisyworld with bells & whistles. Intended as more realistic analgoue of earth system. Regulation evident until forcing fragments habitats and system can ultimately collapse.\n\nAbstract:
Von Bloh. Tutorial Modelling of geosphere{biosphere interactions: the e ect of percolation-type habitat fragmentation. Physica A 266, 186-196.\n\n[[PDF|refs/dw/vonbloh_etal_1999.pdf]]\n\nAbstract:\nA considerably extended two-dimensional version of the famous Lovelock{Watson model for\ngeosphere{biosphere interactions (\sDaisyworld") is employed to investigate the impact of habitat\nfragmentation. The latter is dynamically modelled through the standard percolation process rst\nintroduced by solid state theory. It is found that the connectivity of the space accessible for life\nis crucial for ecological performance. In particular, the self-stabilizing capacity of the biosphere\nstrongly depends on the fragmentation topology. An extremely rich and partially counter-intuitive\neco-dynamics is observed when a simple community structure, consisting of plants and herbivores,\nis introduced. Quite remarkably, high herbivore vitality destroys the stability of the entire\nbiosphere in a way reminiscent of desertification".
Weber. ON HOMEOSTASIS IN DAISYWORLD. Climate Change 48, 465-485.\n\n[[PDF|refs/dw/weber_2001.pdf]]\n\nAbstract:\nAbstract. The steady state solution of the Daisyworld model of Watson and Lovelock (1983) is\nexamined in detail. Focus is on the two-daisy state, which exhibits homeostasis over a large range\nof solar luminosities. The analytical approach used makes clear the dependence of the steady state\nand the size of the domain over which it exists on the various parameters of the system as well as the\nmechanism for its attractivity.\n It is shown that the self-regulatory effect of the biota is based on a priori specifying a relation\nbetween the equilibrium effective temperature T eq e and the equilibrium effective albedo A\neqe. This relation originates first, from the assumption that the local temperature contrast between the black\nand white daisies is given by the local albedo contrast, and second, from the requirement that the\nequilibrium expansion rates of the black and white daisies are equal. The regulation is found to work\nbest when the local albedo contrast is large and when the system is capable of redistributing heat\nin an efficient manner. It is shown that the attractivity of the steady state is due to the temperature dependence\nof the expansion rate of the daisies, i.e., the close-coupling between climate and the\nbiota.\n Some aspects of the Daisymodel seem fairly realistic, such as the conditions for optimal temperature\nregulation. On the other hand, the basic assumptions of the model give rise to local temperatures\n(of the regions of black daisies, white daisies and uncovered ground) which are independent of\nthe incoming radiation. This property of fixed local temperatures and the associated heat transport\nmechanism itself do not seem to have parallels in the real Earth system.
Welcome to the Daisyworld Bibiliography. This site consists of a collection of published papers refering to the daisyworld model. The majority of reference entries link to PDF version of the reference that can be downloaded from this site.\n\nThe site is based on [[TiddlyWiki|http://www.tiddlywiki.com/]], an excellent, open source online research journal that allows hassle free website construction. Unlike other Wikis, this site is primarily intended as a read only resource. It is currently not possible to save changes online. Therefore, if you wish to notify the administrator of this site of any errors or omissions, please contact [[James Dyke|http://www.sussex.ac.uk/Users/jgd20/index.html]] [[here|mailto:j.g.dyke@sussex.ac.uk]].\n\nFirst time visitors may wish to visit the [[Getting Started]] entry.\n\nThe site is currently under construction. If you have comments, suggestions, corrections etc, please contact James Dyke: j.g.dyke|at|sussex.ac.uk\n\n*[[Ackland (2004)]]\n*[[Ackland et al (2003)]]\n*[[Akagi 2006]]\n*[[Adams et al (2003)]]\n*[[Andrew (1996)]]\n*[[Andrew (1997)]]\n*[[Baldocchi et al (2005)]]\n*[[Cohen & Rich (2000)]]\n*[[Dagg (2002)]]\n*[[Dewar (2003)]]\n*[[Dewar (2003b)]]\n*[[Dewar (2005)]]\n*[[Dewar (2005b)]]\n*[[Downing (2002)]]\n*[[Downing & Zvirinsky (2000)]]\n*[[Dyke & Harvey (2005)]]\n*[[Dyke & Harvey (2005b)]]\n*[[Franck et al (2000)]]\n*[[Harding & Lovelock (1996)]]\n*[[Harvey (2004)]]\n*[[Jascourt & Raymond (1991)]]\n*[[Kleidon (2004)]]\n*[[Koelsag et al (1999)]]\n*[[Lansing et al (1998)]]\n*[[Lapenis (2002)]]\n*[[Lenton (1998)]]\n*[[Lenton (2002)]]\n*[[Lenton & Lovelock (2000)]]\n*[[Lenton & Lovelock (2001)]]\n*[[Lenton & van Oijen (2002)]]\n*[[Lenton & Wilkinson (2003)]]\n*[[Lovelock (1992)]]\n*[[McCormack(2003)]]\n*[[Nature (2005)]]\n*[[Nevinson et al (1999)]]\n*[[Pujol (2002)]]\n*[[Pujol et al (2005)]]\n*[[Robertson & Robinson (1998)]]\n*[[Saunders (1994)]]\n*[[Saunders (1998)]]\n*[[Saunders et al (2000)]]\n*[[Seto & Akagi (2005)]]\n*[[Staley (2002)]]\n*[[Stocker (1995)]]\n*[[Sugimoto (2002)]]\n*[[Toniazzo et al (2004)]]\n*[[Von Bloh (1997)]]\n*[[Von Bloh (1999)]]\n*[[Weber (2001)]]\n*[[Wilkinson (2003)]]\n*[[Williams & Nobel (2005)]]\n*[[Zeng (1990)]]\n\n
\n[[PDF|refs/dw/wilkinson_2003.pdf]]
\n[[PDF|refs/dw/williams_nobel_2005.pdf]]
\n[[PDF|refs/dw/zeng_1990.pdf]]