Complex Transient
Dynamics of Stage-Structured Populations in Response to Environmental
Changes
Thomas M. Massie, Alexei Ryabov,
Bernd Blasius, Guntram Weithoff, and Ursula
Gaedke
The American Naturalist, Vol. 182, No. 1 (July 2013), pp. 103-119
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Summury:
Stage structures of populations has a profound influence on the
dynamics. Here we combine model results the reply is shown both
experimentally and modeling and However, not much is known about the
transient dynamics that follow a disturbance in such systems. Here we
combined chemostat experiments with dynamical modeling to study the
response of the phytoplankton species Chlorella vulgaris to press
perturbations. From an initially stable steady state, we altered either
the concentration or dilution rate of a growth-limiting resource. This
disturbance induced a complex transient response—characterized by the
possible onset of oscillations—before population numbers relaxed to a
new steady state. Thus, cell numbers could initially change in the
opposite direction of the long-term change. We present quantitative
indexes to characterize the transients and to show that the dynamic
response is dependent on the degree of synchronization among life
stages, which itself depends on the state of the population before
perturbation. That is, we show how identical future steady states can
be approached via different transients depending on the initial
population structure. Our experimental results are supported by a
size-structured model that accounts for interplay between cell-cycle
and population-level processes and that includes resource-dependent
variability in cell size. Our results should be relevant to other
populations with a stage structure including organisms of higher
order.
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