Chapter

Prometheus Unbound: releasing the constraints on natural selection

Graham Bell

in Selection

Second edition

Published in print December 2007 | ISBN: 9780198569725
Published online May 2008 | e-ISBN: 9780191717741 | DOI: https://dx.doi.org/10.1093/acprof:oso/9780198569725.003.0004
 Prometheus Unbound: releasing the constraints on natural selection

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The evolution of asexual organisms in laboratory microcosms is constrained by the lack of genetic exchange and by isolation from the rest of the world. When these constraints are relaxed, the rate of adaptation and how it is acquired may change. The first section in this chapter is called Horizontal transmission and details gene transfer agents; gene cassettes; and conjugative plasmids. The second section is entitled Sex and it explains all about dominance; sorting in asexual diploid populations; sorting in sexual diplonts; heterozygotes; recombination; the limits to adaptation; purifying selection in sexual populations: mutation clearance; synthetic lethal mutations; mean fitness under purifying selection; directional selection in sexual populations: mutation assembly; directional selection in sexual populations: mutation liberation; the effect of recombination in phage; the effect of sex in microbes; the effect of recombination in Drosophila; and finally sex and the response to selection. The third section is about dispersal and informs on population structure; subdivided asexual populations; subdivided sexual diploid populations; the shifting balance.

Keywords: horizontal transfer; gene cassettes; conjugative plasmids; heterozygosity; recombination; mutation clearance; synthetic lethal; mutation assembly; mutation liberation; population structure

Chapter.  20621 words.  Illustrated.

Subjects: Evolutionary Biology

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