Comments on: Across the gap

By: Fly

Fly — Tue, 26 Jul 2005 11:47:57 +0000

?Is there any mathematical difference between the fitness of a gene being a function of other genes (its genetic environment) and its fitness being determined by external factors??

My guess is that the environment is unusually unaffected by a gene. Thus the environment?s dependence on that gene can be safely ignored. (Clearly humans do affect the environment so there is some dependence of the environment on the gene.) So a system of linear differential equations can model the gene/environment interaction.

I suspect genes are strongly affected by other genes. So the dependence of one gene on a different gene cannot be ignored. So the gene/gene interactions require a system of non-linear differential equations for modeling.

Non-linear differential equations are much harder to handle mathematically. (Linear differential equations are a subset of non-linear differential equations. Non-linear equations are usually solved by local approximation with linear solutions.)

?One reason for not writing in English is to dress up trivial results... like the 'sign epistasis' stuff posted not long ago.?

(I agree that jargon is used to dress up papers. I disagree that the result was trivial.)

The result that a gene?s fitness depends on other genes and can change signs was obvious. Successfully building a mathematical model that captures that genetic interaction isn?t trivial. In this case the meat is in the details, not the abstract. (I haven?t read the paper so I?m just guessing.)

By: bbartlog

bbartlog — Tue, 26 Jul 2005 09:04:31 +0000

Sounds interesting, but since I don’t know precisely what they mean by ‘map distance’ nor ‘mass selection’ I guess I’m still in the dark.

One reason for not writing in English is to dress up trivial results… like the ‘sign epistasis’ stuff posted not long ago.

By: David B

David B — Tue, 26 Jul 2005 04:24:53 +0000

I’m sure this is very important and interesting, but why the f**k can’t biologists write in English any more? Reading this stuff make my brain hurt.

By: David Boxenhorn

David Boxenhorn — Tue, 26 Jul 2005 00:51:16 +0000

Is there any mathematical difference between the fitness of a gene being a function of other genes (its genetic environment) and its fitness being determined by external factors? I'm thinking, for example of Darwin's finches (if I remember correctly): big bill + dry weather = fit, small bill + wet weather = fit, but not the other way around.

Of course, with genetic environment, you can turn the telescope around and look from the other end, but from the point of view of a single gene, it's always the case that its fitness depends on its environment.

Also, the genetic environment is itself subject to evolution, but so is the external environment as far as it's determined by other life forms. Maybe we should think of epistasis like Red Queen/Co-evolution?