Evolution before genes

Biology Direct

Vera Vasas²  Chrisantha Fernando¹  Mauro Santos⁴  Stuart Kauffman⁵  Eörs Szathmáry³ 

[1] Department of Informatics, University of Sussex, Falmer, Brighton, BN1 9RH, UK

[2] Institute of Biology, Eötvös University, 1/c Pázmány Péter sétány, H-1117 Budapest, Hungary

[3] Parmenides Foundation, Kirchplatz 1, D-82049 Munich/Pullach, Germany

[4] Departament de Genètica i de Microbiologia, Grup de Biologia Evolutiva (GBE), Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain

[5] Institute for Biocomplexity and Informatics, University of Calgary, Alta T2N, Canada

关键词: metabolism-first theory of origin of life;    protocells;    replicators;    autocatalytic sets;    catalytic reaction networks;    chemical evolution;    prebiotic evolution;    origin of life;   

Others  :  797027
DOI  :  10.1186/1745-6150-7-1

 received in 2011-09-25, accepted in 2012-01-05,  发布年份 2012

【 摘 要 】

Background

Our current understanding of evolution is so tightly linked to template-dependent replication of DNA and RNA molecules that the old idea from Oparin of a self-reproducing 'garbage bag' ('coacervate') of chemicals that predated fully-fledged cell-like entities seems to be farfetched to most scientists today. However, this is exactly the kind of scheme we propose for how Darwinian evolution could have occurred prior to template replication.

Results

We cannot confirm previous claims that autocatalytic sets of organic polymer molecules could undergo evolution in any interesting sense by themselves. While we and others have previously imagined inhibition would result in selectability, we found that it produced multiple attractors in an autocatalytic set that cannot be selected for. Instead, we discovered that if general conditions are satisfied, the accumulation of adaptations in chemical reaction networks can occur. These conditions are the existence of rare reactions producing viable cores (analogous to a genotype), that sustains a molecular periphery (analogous to a phenotype).

Conclusions

We conclude that only when a chemical reaction network consists of many such viable cores, can it be evolvable. When many cores are enclosed in a compartment there is competition between cores within the same compartment, and when there are many compartments, there is between-compartment competition due to the phenotypic effects of cores and their periphery at the compartment level. Acquisition of cores by rare chemical events, and loss of cores at division, allows macromutation, limited heredity and selectability, thus explaining how a poor man's natural selection could have operated prior to genetic templates. This is the only demonstration to date of a mechanism by which pre-template accumulation of adaptation could occur.

Reviewers

This article was reviewed by William Martin and Eugene Koonin.

【 授权许可】

   
2012 Vasas et al; licensee BioMed Central Ltd.

【 图 表 】

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