Chapter 20 : Better than Sex

MyBook is a cheap paperback edition of the original book and will be sold at uniform, low price.

Preview this chapter:
Zoom in

Better than Sex, Page 1 of 2

| /docserver/preview/fulltext/10.1128/9781555818470/9781555815400_Chap20-1.gif /docserver/preview/fulltext/10.1128/9781555818470/9781555815400_Chap20-2.gif


A single picture in Darwin’s book displays a hypothetical tree of organisms. Microbiologists helped to put flesh on this skeleton by formulating the universal tree of life based on genome sequence information. From first principles, it is not clear why sexless bacteria should be so diverse. Sex is commonly interpreted as the motor for genetic diversity in a population. Sexless bacteria are in principle immortal-this link between sex and mortality was already intuitively felt in the book of Genesis. Phage provide a mobile source of new DNA, and bacteria can rapidly screen the viral DNA sequence space for useful genes. This process is much quicker than evolving new pathogenic traits de novo. Without exaggeration one might argue that phages-together with other mobile DNA like plasmids or transposons are the major motor for the generation of genetic diversity in bacteria. However, as infections are typically horizontal events occurring between unrelated individuals—in contrast to sex, which relies on vertical gene transmission, i.e., from parent to progeny—the problem with the complicated structure of the bacterial tree finds an easy explanation. Evolution depends on selection applied to genetically distinct organisms, but whether this diversity is created by sex or bacteriophage infection does not matter. Sex is a special case of a more generally defined driver of biological diversity. In fact, Darwinian evolution was operative long before sex evolved. The discussion about the tree of life is not only about its branching pattern, but also is now about the tree itself.

Citation: Brüssow H. 2012. Better than Sex, p 145-150. In Kolter R, Maloy S (ed), Microbes and Evolution. ASM Press, Washington, DC. doi: 10.1128/9781555818470.ch20
Highlighted Text: Show | Hide
Loading full text...

Full text loading...



This is a required field
Please enter a valid email address
Please check the format of the address you have entered.
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error