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Reading Okasha's "Evolution and the levels of selection" he talks about "the levels of selection problem." There is a bit of a problem with this opening chapter because, while he talks about why the levels of selection problem is a problem, he doesn't define what the levels of selection problem is.

The opening line from the book..

"The levels of selection problem is one of the most fundamental in evolutionary biology, for it arises directly from the underlying logic of Darwinism. The problem can be seen as the upshot of three factors..."

I think what he means by the "levels of selection problem" is that selection acts on many levels, and what is adaptive at one level may be maladaptive at another. Therefore we can not define selection as acting at one single level, and studying it as such is likely to lead to incorrect conclusions - studying selection is not a simple process. Can anyone provide a firm definition of what Okasha, and the general community on the matter, mean by the "levels of selection problem"?

(Note: The factors are the abstract nature of the principles of selection, the hierarchical nature of biological organisation, and the process of adaptation via natural selection).

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Reeve and Keller in the first chapter of Levels of Selection in Evolution (Princeton Univ. Press,1999) seem to address this question in the second item in the following paragraph.

The purpose of this volume is to sample current theoretical and empirical research on (1) how natural selection among lower-level biological units (e.g., organisms) creates higher-level units (e.g., societies), and (2) given that multiple levels exist, how natural selection at one biological level affects selection at lower or higher levels [boldface added]. These two problems together constitute what Leigh (chap. 2) calls the "fundamental problem of ethology." Indeed, as Leigh further suggests, they could be viewed jointly as the "fundamental problem of biology," when genes and organisms are also included as adjacent levels in the biological hierarchy. This generalization has the desirable property of immediately removing the long-standing conceptual chasm between organismal and molecular biologists.

The authors suggest definitions of fitness that account for hierarchical relationships (the level of selection problem) by considering the effect of a trait (nepotism among social insects) on "adjacent" biological levels, such as individual and colony.

By measuring what they call 'absolute fitness force' they propose to eclipse what they see as spurious debate over the fundamental level of selection (genes vs. individuals, say).

A somewhat surprising aspect of their discussion emerges here:

"It is still embarrassingly common to read inaccurate statements...that frogs have to produce many eggs to ensure the survival of the species because tadpoles suffer extremely high rates of predation, or that wolves have evolved ritualized displays to establish dominance hierarchies because physical combats would be too disadvantageous for the species. These naive statements betray a widespread and persistent misunderstanding of the level at which natural selection most commonly operates."

Their point is that such statements focus on the wrong level of selection (group), and that stronger selection may occur at the individual level; their overall argument being that both levels should be factored in.

I cannot present this as a 'community definition' but it may be a representative example.

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So I am pretty close with my understanding already then? Including selection at all levels is essential to understanding how traits and populations of the units of selection will evolve. –  GriffinEvo May 9 at 11:06
    
I think there is a debate with 'DNA fundamentalists' claiming that there really can only be one mediator of selection (there is no level of selection problem!) and the multilevel folks claiming that there are forces beyond kin selection that influence evolution. You might be just representing one pov here. The debate has been published in Science/Nature recently so I think its fair to say that it is not resolved. –  shigeta May 10 at 14:18
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@shigeta: Yes, the answer really only deals with the definition. Your comment is a good caveat or if you think it's preferable I can add a note to the answer. Thanks. –  daniel May 10 at 14:27

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