eyes in cave animals drifting away?

From: Scott Chase (ecphoric@hotmail.com)
Date: Thu 19 Feb 2004 - 06:21:11 GMT

  • Next message: Chris Taylor: "Re: memetics-digest V1 #1480"

    In a couple recent posts Keith has used the example of cave animals losing their eyes due to lack of light. In this post he tells the adaptionist tale of this loss being related to metabolic costs (ie- eyes too expensive to build so selected against):


    Has he ruled out the possibility of genetic drift? In an environment that lacks light, the major selective pressure for maintaining eyes has been negated, thus mutations of eye development related genes would be selectively neutral. Populations of cave dwelling animals might be quite small. Mutations of eye genes might accumulate, due to not being removed by selection. Eyes, as a structure, would deteriorate and the animals become blind, without metabolic cost being a significant factor in the process.

    Futuyma's text says one possibility is that (p. 423) : "mutations that cause degeneration of an unused character become fixed by genetic drift because variations in the character are selectively neutral". Selection is another and an hypothesis is explored which supports selection but it is noted that in some instances genetic drift may play a role.

    Futuyma DJ. 1997. Evolutionary Biology. Sinauer Associates, Inc. Sunderland, Massachusetts

    =============================================================== This was distributed via the memetics list associated with the Journal of Memetics - Evolutionary Models of Information Transmission For information about the journal and the list (e.g. unsubscribing) see: http://www.cpm.mmu.ac.uk/jom-emit

    This archive was generated by hypermail 2.1.5 : Thu 19 Feb 2004 - 06:32:27 GMT