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Tal­mu­dic Ques­tion #80

 
Within the mi­cro­bial world, is the de­gree of pleiotropy dis­played by an or­gan­ism in­versely re­lated to its genome size?

 

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Ami Bachar
15 years ago

In­ter­est­ing ques­tion!
Let me see if I got it right: you mean to ask if for greater genome sizes, there is fewer pleiotropy go­ing on? Hmmm... some say that pleiotropy is in­versely re­lated to the evo­lu­tion­ary rate of genes — I won­der how true is that. On the con­di­tion that this is the case, AND if some mi­crobes ac­cu­mu­late some "junk" DNA (over time) that in­creases their genome di­men­sion, then I can see how the an­swer to your query is yes.
Higher level of pleiotropy -> lower gene evo­lu­tion­ary rate -> lower adap­ta­tion to new con­di­tions -> genome size may keep on grow­ing with un­nec­es­sary bits and pieces.
I spec­u­late that it is not that sim­ple though. If I had to gam­ble than I would bet on some kind of a bell curve for this pleiotropy — genome size re­la­tion. Af­ter a wile, you just can't do it no more and de­spite the higher pleiotropy de­gree of dis­play, you ei­ther push up the gene evo­lu­tion­ary rate or van­ish.
I would love to hear some other an­swers and your thoughts as well.

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