| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2004: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥2,100,000 (Direct Cost: ¥2,100,000)
|
|---|
| Research Abstract |
Factors governing the occurrence of unique territorial behavior termed barricade building by the brachyuran crab Ilyoplax pusilla (family Dotilllidae) living on tidal flat, have been explored for the following aspects.
1.Influence of external factors on frequency of barricade building
The frequency of barricade building increased in the breeding season, but was not correlated with the tidal regime. The frequency was also not related with the population density or with difference of the substratum condition.
2.Relationship of barricade building with mating success
Comparison of occurrence of barricade building between pairing males and non-pairing males revealed that the former made barricade building more frequently than the latter. This finding suggests that barricade functions advantageously for pair formation.
3.Interspecific comparison of earthen-structure avoiding tendency
Comparison of response to artificial earthen structure between Ilyoplax pusilla and other two dotillid species with
… More
out barricade building behavior, revealed that I.pusilla less frequently broke the structure or avoided it more frequently than the other two species.
4.Model construction
In one model, three strategies each for barricader (build, do not build, build to smaller) and barricadee (destroy, do not destroy, destroy to smaller) are assigned, and the evolutionary dynamics of their frequency has been investigated. The model shows that cost by barricade should be frequency dependent to explain why only part of population members build barricades. However, the equilibrium is only neutrally stable and random genetic drift should turn the system with no barricade. Introduction of frequency depended strategy, destroy barricade depending on their frequency, made the equilibrium with intermediate barricade frequency stable. In the other model, life history strategies have been investigated by dynamic programming method. In ESS, barricade is built only in the breeding season, which coincides with field data Less
|
