The Evolutionary Origin of Complex Features

Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, USA.
Nature (Impact Factor: 41.46). 06/2003; 423(6936):139-44. DOI: 10.1038/nature01568
Source: PubMed


A long-standing challenge to evolutionary theory has been whether it can explain the origin of complex organismal features. We examined this issue using digital organisms--computer programs that self-replicate, mutate, compete and evolve. Populations of digital organisms often evolved the ability to perform complex logic functions requiring the coordinated execution of many genomic instructions. Complex functions evolved by building on simpler functions that had evolved earlier, provided that these were also selectively favoured. However, no particular intermediate stage was essential for evolving complex functions. The first genotypes able to perform complex functions differed from their non-performing parents by only one or two mutations, but differed from the ancestor by many mutations that were also crucial to the new functions. In some cases, mutations that were deleterious when they appeared served as stepping-stones in the evolution of complex features. These findings show how complex functions can originate by random mutation and natural selection.

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    • "We evolved the self-replicators of length 15 in an environment where nine Boolean logic operations, and hence nine phenotypic traits, are under positive selection; this is often referred to as the logic-9 environment (Lenski et al., 2003). For this experiment, we evolved these replicators for 10 4 generations at a population size of 10 4 individual (ten replicates). "
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    • "The medium in which the evolutionary process is unfolding must allow the possibility of a practically unlimited diversity of organism organisations, processes and interactions. Much previous work within artificial life has concentrated on the ability of organisms to evolve complex computational and information processing capabilities , such as the ability of digital organisms in Avida to solve logic functions (Lenski et al., 2003 "
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    Presented at the EvoEvo Workshop at the European Conference on Artificial Life 2015 (ECAL 2015), University of York, UK; 07/2015
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