| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1991: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1990: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Dormancy and dispersion are adaptation for spatially and temporally fluctuating environments, and are widely adopted in animals and plants. Many researchers have investigated theoretical models to find the optimal dormancy and dispersal rates under a certain condition. Dormancy and dispersion, however, have been treated separately in mathematical models. The previous models have also assumed that spatial structure consists of many equivalent patches. I treated dormancy and dispersion at the same time in my model, and introduced heterogeneous spatial structure, consisting of main and sub patches. I specially refereed to the life history of lady beetles, when I made the model.
I derived the following results, when temporal fluctuation does not occur ;
(1) Dormancy does not evolve if lady beetles are univoltine.
(2) There is a negative correlation between dormancy rate and dispersal rate if lady beetles are bivoltine.
(3) As the main patch becomes inferior, individuals should employ firstly the dispersal strategy and secondly the dormancy strategy.
The dormancy rate and the dispersal rate were assumed to be constant when environments do not fluctuate. I compared three strategies when environments fluctuate temporally : The dormancy and dispersal rates are (1) constant, (2) density- dependent, and (3) dependent on the profitability of the main patch. I made these three strategies compete under the same fluctuating environments in numerical experiments. There was a tendency that the sensitive strategy to the fluctuating environment is the strongest.
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