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4 . SIMULATING GROWTH AND FORM
been developed only for single polyps and characterizes their behavior at
very high resolution. The output of this model is the time-varying behavior
of oscillations in polyp length or volume, not a morphogenetic pattern. In
contrast, conceptual models that associate gastrovascular transport or redox
chemistry with the regulation of form have emerged from lower resolution
studies of whole colonies that focus on only a portion of gastrovascular behavior hypothesized to be most important. Verification of each type of model
requires different experimental evidence.
The gastrovascular dynamics model needs to be tested for multi-polyp
cases arrayed in different geometries. The test of this model is a test of
whether, for a given geometry of colony architecture and input of food, the
collective oscillatory behavior of polyps generates predictable patterns of
vascular transport and redox variation within a colony. If so, then the second
critical test is whether specific patterns of flow and redox variation give rise
to specific and predictably spaced morphogenetic events.
There is considerable evidence demonstrating that patterns of vascular
transport and redox variation within a colony control morphological development, but the specificity of cause and effect is not yet resolved. In other
words, how much of a change is needed, and over what spatial scale, in the
characteristics of flow or redox potential to initiate a morphogenetic event
is unknown. Nevertheless, the link between gastrovascular physiology and
colony development is clear (Blackstone and Buss1992, Blackstone 1996, 1997,
1998, 1999, Dudgeon and Buss 1996).
This single polyp model can be scaled up to a multiple polyp colony,
ideally with polyp behaviors expressed in volume dynamics. Doing so would
necessitate equations to represent the behavior of each polyp in the colony
whose oscillations are triggered by a threshold concentration of nutrients
circulating in the gastrovascular system, and equations that represent volume
transport through the stolon, perhaps with parameters that represent the
length , diameter, and branching of the tube. Such a model would abstract the
gastrovascular system of a hydrozoan colony to a spatially distributed system
of coupled nonlinear oscillators.
4 . SIMULATING GROWTH AND FORM
been developed only for single polyps and characterizes their behavior at
very high resolution. The output of this model is the time-varying behavior
of oscillations in polyp length or volume, not a morphogenetic pattern. In
contrast, conceptual models that associate gastrovascular transport or redox
chemistry with the regulation of form have emerged from lower resolution
studies of whole colonies that focus on only a portion of gastrovascular behavior hypothesized to be most important. Verification of each type of model
requires different experimental evidence.
The gastrovascular dynamics model needs to be tested for multi-polyp
cases arrayed in different geometries. The test of this model is a test of
whether, for a given geometry of colony architecture and input of food, the
collective oscillatory behavior of polyps generates predictable patterns of
vascular transport and redox variation within a colony. If so, then the second
critical test is whether specific patterns of flow and redox variation give rise
to specific and predictably spaced morphogenetic events.
There is considerable evidence demonstrating that patterns of vascular
transport and redox variation within a colony control morphological development, but the specificity of cause and effect is not yet resolved. In other
words, how much of a change is needed, and over what spatial scale, in the
characteristics of flow or redox potential to initiate a morphogenetic event
is unknown. Nevertheless, the link between gastrovascular physiology and
colony development is clear (Blackstone and Buss1992, Blackstone 1996, 1997,
1998, 1999, Dudgeon and Buss 1996).
This single polyp model can be scaled up to a multiple polyp colony,
ideally with polyp behaviors expressed in volume dynamics. Doing so would
necessitate equations to represent the behavior of each polyp in the colony
whose oscillations are triggered by a threshold concentration of nutrients
circulating in the gastrovascular system, and equations that represent volume
transport through the stolon, perhaps with parameters that represent the
length , diameter, and branching of the tube. Such a model would abstract the
gastrovascular system of a hydrozoan colony to a spatially distributed system
of coupled nonlinear oscillators.