Recombination and the immortality of the germ line
Article first published online: 20 DEC 2002
Journal of Evolutionary Biology
Volume 1, Issue 1, pages 67–82, January 1988
How to Cite
Bell, G. (1988), Recombination and the immortality of the germ line. Journal of Evolutionary Biology, 1: 67–82. doi: 10.1046/j.1420-9101.1988.1010067.x
- Issue published online: 20 DEC 2002
- Article first published online: 20 DEC 2002
- Received 2 February, 1987; accepted 5 June 1987.
- Cited By
- Muller's Ratcher;
- DNA replication;
- DNA repair;
- evolution of sex;
Asexual populations irreversibly accumulate mildly deleterious mutations through the occasional stochastic loss of their least-loaded line, a process known as “Muller's Ratchet”. This paper explores the dynamics of this process, and the role of recombination in halting the Ratchet. Simulation studies show that an optimal class comprising no individuals is lost in about 10no generations, implying that adaptedness may deteriorate rather rapidly in geological time. Asexual organisms will persist only if they are very numerous, or if they have very small genomes, or if there is extensive negative interaction among nonallelic mutations. Otherwise, long-term persistence requires that unloaded genomes be continually generated by recombination. An approximate expression for the rate of recombination needed to halt the Ratchet is developed, and shows that substantial recombination is necessary in populations of fewer than about 1010 individuals. A further complication is introduced by mutations in sequences which specify proofreading enzymes. Since these will reduce the fidelity of their own replication, a process of positive feedback leading to an ever-accelerating loss of function is conceivable.