X-Message-Number: 27668 From: "Basie" <> Subject: Our master Date: Sat, 4 Mar 2006 21:27:02 -0500 For example, if a single harmful mutation lowers fitness by 5 percent on average, then successive mutations are expected to lead to a progressive decline in 5 percent steps if the mutations don't interact with each other. Negative epistasis, however, comes into play, for example, if the second mutation decreased fitness by 10 percent, the third by 15 percent and so forth. While biologists have been trying to figure out just how prevalent negative epistasis is in nature to test MDH, relatively little attention has been paid to the question of what conditions could lead to the existence of negative epistasis in the first place. If those conditions were known, it would help scientists decide whether it's even worth looking for it or not. Azevedo's study suggests that it is. In many of their simulated worlds, sexual reproduction generated negative epistasis, thus creating the conditions required for its own maintenance. If this is true about the real world, this would constitute a spectacular example of evolution forging its own path. Thus we are merely the extension of our sexual organs. Not vice versa. Sad. Basie Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=27668