title: Transcriptional noise and the evolution of gene number.
abstract: Several proposals are made to explain the apparent increase in complexity of certain lineages during evolution. The proposals (not made in this order) are: (1) that gene number is a valid measure of biological complexity; (2) that gene number has not increased continuously during evolution, but has risen in discrete steps; (3) that two of the biggest steps occurred at the transition from prokaryotes to eukaryotes and the transition from invertebrates to vertebrates; (4) that these steps were made possible by 'systemic' changes in the way that genetic information is managed in the genome; (5) that the ability to silence inappropriate promoters is the primary limitation on gene number; (6) that the invention of nucleosomes (and perhaps the nuclear membrane) facilitated the evolution of eukaryotes from prokaryotic ancestors; (7) that the spread of low density methylation throughout the genome facilitated the evolution of vertebrates from invertebrate ancestors.
authors.affiliation: Institute of Cell and Molecular Biology, University of Edinburgh, U.K.
authors.forename: A
authors.initials: A
authors.lastname: Bird
authors.forename: S
authors.initials: S
authors.lastname: Tweedie
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004247:DNA / Q000378:metabolism; D005057:Eukaryotic Cells; D019143:Evolution, Molecular; D005796:Genes; D016678:Genome; D006801:Humans; D007448:Invertebrates / Q000235:genetics; D008745:Methylation; D008954:Models, Biological; D008957:Models, Genetic; D011387:Prokaryotic Cells; D014158:Transcription, Genetic; D014714:Vertebrates / Q000235:genetics
chemical_list: D004247:DNA