White, Justin S. and Adami, Christoph (2004) Bifurcation into functional niches in adaptation. Artificial Life, 10 (2). pp. 135-144. ISSN 1064-5462 http://resolver.caltech.edu/CaltechAUTHORS:WHIal04
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One of the central questions in evolutionary biology concerns the dynamics of adaptation and diversification. This issue can be addressed experimentally if replicate populations adapting to identical environments Call be investigated in detail. We have studied 501 such replicas Using digital organisms adapting to at least two fundamentally different functional niches (survival strategies) present in the same environment: one in which fast replication is the way to live, and another where exploitation of the environment's complexity leads to complex organisms with longer life spans and smaller replication rates. While these two modes of survival are closely analogous to those expected to emerge in so-called r and K selection scenarios respectively, the bifurcation of evolutionary histories according to these functional niches occurs in identical environments, under identical selective pressures. We find that the branching occurs early, and leads to drastic phenotypic differences (in fitness, sequence length, and gestation time) that are permanent and irreversible. This study confirms an earlier experimental effort using microorganisms, in that diversification can be understood at least in part in terms of bifurcations on saddle points leading to peak shifts, as in the picture drawn by Sewall Wright.
|Additional Information:||© 2004 Massachusetts Institute of Technology. Posted Online March 11, 2006. We would like to thank D. Allan Drummond and Claus Wilke for helpful comments and suggestions. This work was supported in part by the National Science Foundation under Contract No. DEB-9981397. All data were obtained on a cluster of 160 processors at Michigan State University, supported by the NSF under the aforementioned contract.|
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|Deposited By:||Tony Diaz|
|Deposited On:||10 Jul 2009 17:18|
|Last Modified:||26 Dec 2012 10:51|
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