Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

A semi-competent IRC

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

This is a collection of models which illustrate the idea of feedback loops, which form the basis of all living systems.

1. The first is an open-loop model - that is, it contains no feedback. The process of gravitational acceleration g changes the speed of a falling ball, but this speed has no feedback effect on gravity.

2. The second model contains a positive feedback loop. A greater number of Bacteria causes the number of cell divisions to increase, and the process of cell division itself also increases the number of Bacteria. The process 'division' and the state variable 'Bacteria' both have a positive effect on each other, generating unconstrained growth.

3. The third model contains a negative feedback loop. A greater number of TumourCells causes the number of cell deaths to increase, but the process of cell death itself decreases the number of TumourCells. The process 'death' negatively influences the state variable 'TumourCells', while 'TumourCells' positively influences 'death', causing the TumourCells to decay to zero.

This is a very general model of two interacting species which describes a wide variety of different kinds of interaction, for example: cooperation, symbiosis, competition or predation.

Note that in systems biology the word 'species' can mean species of organism, species of chemical or species of cell. Similarly, 'interaction' can mean chemical interaction, genetic interaction or phenotypic interaction. We are talking here about very general kinds of system.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Una pequeña modificación al modelo del mundo de las margaritas, se incluyo una nueva especie de margarita con posibilidad de mutar según vayan cambiando las condiciones de temperatura.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Simulation of a chemostat bioreactor.

X = microbiological mass
S = substrate concentration
D = dilution rate
Y = yield of microbiological massfrom a unit of substrate
mu = maximum growth rate
Ks = Michaelis-Menten-constant

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

Darwinian Daisyworld model from and Watson & Lovelock (1983), Robertson & Robinson (1998) and Lenton & Lovelock (2001).

Units of time are 40 Myr, giving R&R's span of 10 Gyr.

This model offers many opportunities for modification. Maybe the Black and White populations can mutate into each other? The role of q as a measure of segregation of the B and W populations is interesting, and while this model uses purely stigmergic communication between species, direct interaction would also be possible.

A damped, driven pendulum. The combination of damping and driving provokes a minimal case of chaos. The system is not in itself biological, however its chaotic behaviour arises from competing oscillatory influences - a situation which plays a role in many biological systems.