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Type of Document	Dissertation
Author	Chow, Stephanie S.
URN	etd-06062005-171257
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-06062005-171257
Title	Speciation in digital organisms
Degree	PhD
Option	Computation and Neural Systems
Advisory Committee	Advisor Name Title Barbara J. Wold Committee Chair Christoph Adami Committee Member Claus O. Wilke Committee Member Michael Clifford Cross Committee Member Steven Quartz Committee Member
Keywords	ecosystem stability diversity evolution resources speciation
Date of Defense	2005-05-18
Availability	unrestricted
Abstract Current estimates of the number of species on Earth range from four to forty million total species. Why are there so many species? The answer must include both ecology and evolution. Ecology looks at the interactions between coexisting species, while evolution tracks them through time. Both are required to understand aspects of environments which promote speciation, and which promote species persistence in time. The explanation for this biodiversity is still not well understood. I argue that resource limitations are a major factor in the evolutionary origin of complex ecosystems with interacting and persistent species. Through experiments with digital organisms in environment with multiple limited resources, I show that these conditions alone can be sufficient to induce differentiation in a population. Moreover, the observed pattern of species number distributions match patterns observed in nature. I develop a simple metric for phenotypic distance for digital organisms, which permits quantitative analysis of similarities within, and differences between species. This enables a clear species concept for digital organisms that may also be applied to biological organisms, thus helping to clarify the biological species concept. Finally, I will use this measurement methodology to predict species and ecosystem stability.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    thesis.pdf 1.41 Mb 00:06:30 00:03:20 00:02:55 00:01:27 00:00:07