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Evolution of host-parasitoid network through homeochaotic dynamics.
Takashi Ikegami1, Kunihiko Kaneko
1The Graduate School of Science and Technology, Kobe University, Rokkodai, Nada-ku, Kobe 657, JapanDepartment of Pure and Applied Sciences, College of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153, Japan.
Chaos (Woodbury, N.Y.)
|July 1, 1992
Summary
Evolving mutation rates in host-parasitoid systems dynamically maintain species diversity. A symbiotic state, driven by chaotic oscillations termed "homeochaos," is crucial for ecosystem stability.
Area of Science:
- Ecology
- Evolutionary Biology
- Theoretical Biology
Background:
- Host-parasitoid interactions are fundamental to ecosystem dynamics.
- The role of evolving mutation rates in maintaining biodiversity is not fully understood.
- Previous models often assume static mutation rates.
Purpose of the Study:
- To investigate the impact of evolving mutation rates on host-parasitoid systems.
- To explore how different host growth rates influence species diversity and stability.
- To identify the mechanisms underlying symbiotic states in these evolving systems.
Main Methods:
- Mathematical modeling of host-parasitoid dynamics.
- Analysis of species diversity under varying mutation rates and host growth rates.
- Characterization of system stability using Lyapunov spectra and chaos theory.
Main Results:
- Increased host growth rate dynamically maintains species diversity.
- Lower host growth rates lead to diversity through parasitism alone.
- Higher growth rates promote a symbiotic state characterized by chaotic oscillations ('homeochaos') and dynamic clustering.
- Homeochaos, a weak high-dimensional chaos, underpins symbiotic stability.
Conclusions:
- Evolving mutation rates are critical for maintaining biodiversity in host-parasitoid systems.
- Host growth rate is a key factor determining the nature of species interactions and diversity.
- The identified 'homeochaos' mechanism provides a novel explanation for symbiotic stability in complex ecosystems.
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