2002 Fiscal Year Final Research Report Summary
Structural Characteristics of evolutionally developed phase spaces of ecosystems and proteins
| Project/Area Number |
13831006
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Institution | Osaka University |
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Principal Investigator |
KIKUCHI Makoto Osaka University, Cybermedia Center, Professor, サイバーメディアセンター, 教授 (50195210)
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| Co-Investigator(Kenkyū-buntansha) |
TOKITA Kei Osaka University, Cybermedia Center, Associate Professor, サイバーメディアセンター, 助教授 (00263195)
CHAWANYA Tsuyoshi Osaka University, Graduate School of Information Science and Technology, Associate Professor, 大学院・情報科学研究科, 助教授 (80294148)
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| Project Period (FY) |
2001 – 2002
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| Keywords | ecosystem / protein / evolution / phase space / dynamical system / free-energy landscape / molecular motor |
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| Research Abstract |
In this project, we investigated structural characteristics of evolutionary developed phase spaces of ecosystems and proteins.
For large-scale ecosystems, the following properties were clarified: The replicator equation systems with random interactions can have a stable coexistent state of many species, when the interactions are "antisymmetric". This result serves as the first counterexample for so-called "May's paradox" which is famous in the field of mathematical ecology. In the resultant stable ecosystem, we observe a emergence of a hierarchical food web structure. We propose a new simple model based of the replicator equation systems for studying dynamics of the biodiversity by taking into account the effects of extinction, invasion and mutation.
As a basic research of dynamical systems which exhibit complex dynamics including ecosystems, we studied the intermittent transition behaviors between long-time persistent states. We found a new mechanism of emergence of chaotic metastability, and intermittent transition between these metastable states.
For proteins, we focused our attention to the free-energy landscape of Kinesine, which is one of the motor proteins. We successfully sampled the thermally equilibrium ensemble in case of a simplified interaction parameters and studied its free-energy landscape near the native state for the first time. We found that the largest fluctuating mode is localized at the switch region. In other word, large-fluctuation of the switch region is embedded in the evolutionary developed free-energy landscape of Kinesine.
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