Wright’s Shifting Balance Process: Phase 3 part 2

Last week I tried to establish that group selection by differential migration can work.   On both experimental and theoretical grounds we find it does work, and in fact will frequently be stronger than individual selection. The question comes where does it fit into Wright’s shifting balance process. The first problem we need to confront is […]

Phase 3: Group selection by differential migration

Having taken a week off (blame it on Jason Wolf – he is the one who gave me a writing assignment!) it is time to get back to it. This week we turn to the final phase of Wright’s shifting balance process, phase three the phase of interdeme selection. In Wright’s view populations centered on […]

The Phase of Mass Selection and Long Term Selection Experiments

On to Phase 2 of Wright’s Shifting Balance Process. But before I do I should probably start with a shameless attempt to up my standings in the next Carnival of Evolution World Cup Competition by alerting the committee responsible to the following figure that I found: Obvious evidence of Pre-Cambrian Bunnies (unapologetically lifted from http://clubschadenfreude.com/2013/02/19/not-so-polite-dinner-conversation-part-9-the-second-half-of-19-limestone-coelacanths-and-circular-reasoning/) […]

Was Fisher (W)right?

Once again without internet, thundering my way north on the Silver Star. It is hard to keep focus on what I intended on the subject I am writing on. The Evolution meetings were inspiring to say the least. Lots of great talks, many of which I could easily write a blog about, but I must […]

The 1984 founder event debate: Its relation to Phase 1 of Wright’s Shifting Balance Process

Today I am speeding south on the Empire State in the morning and the Silver Star in the afternoon. I should be in Raleigh Durham for the Evolution meetings late this evening. For the uninitiated Amtrak trains have names that reflect where they are going. Thus, the famous Steve Goodman/Arlo Guthrie song, “City of New […]

Wright’s Shifting Balance Process

Now that I have talked about how Wright thought evolution didn’t occur on adaptive landscapes, now it is time to talk about how he thought it did occur. The 7 assumptions and the adaptive topography were all basically background for his “shifting balance” process of evolution (Wright 1977 Evolution and Genetics of Populations. Vol. III. […]

Of Population Structure and the Adapative Landscapes

Last week I talked about adaptive topographies, and while my discussion may have done little more than add to the confusion, at least it got across Wright’s view that there are multiple selective peaks, which in essence means that there are multiple solutions to the problem of achieving high fitness. Figure taken from http://locustofauthority.wordpress.com/ Wright […]

Some thoughts on adaptive topographies

Last week I discussed Wright’s “seven generalizations” about populations. His seventh generalization, that there were multiple selective peaks, led him to develop his famous “adaptive topography” metaphor. As Provine (2001) discussed, there is considerable controversy over exactly what Wright meant by an adaptive topography. My understanding is that Wright never meant his topography to be […]

Sewall Wright’s Seven Generalizations about Populations

Once again I seem to be reorganizing my plan of attack, and this will be a big one. I think it would be entertaining to move over to a discussion of Wright’s shifting balance theory. This is not a minor topic, and indeed, I am told that the two longest papers ever published in Evolution […]

Soft Selection: Why it is Multilevel Selection

It has come to my attention that it makes sense to spend a blog entry talking strictly about contextual analysis and soft selection. The problem which, as Okasha (2006 Evolution and the levels of selection) puts it, some “theorists find deeply counter-intuitive” is that in soft selection every group puts out exactly the same number […]