An interesting question and some complaints broke out in the comments last night: how can you have evolution without selection?

What's interesting about it is that this is coming from intelligent, informed supporters of good biology, and what it tells us is that our educational system is not doing its job. There are important concepts that should be taught in our public school system, and we're so caught up in this absolutely idiotic struggle with morons to keep stupid, disproven claims like "Evolution is false!" out of the curriculum that very few people are getting the fundamentals. Of course evolution proceeds in the absence of selection. There are even different kinds of selection.

All most people get in their education about evolution is the one, tiny idea of "survival of the fittest" and natural selection, and typically they only get a minute subset of that, the idea of directional selection. Populations interact with their environment and the weak are culled out, relentlessly driving the population towards some adaptive optimum. What's more, the most common mistake people with this idea make is to assume that removing the selective force means the population will stop evolving.

There is another form of selection, almost certainly more common than directional selection, called stabilizing selection. This process acts to eliminate forms that deviate from the norm, and tends to keep the properties of a population more constant. Remove this, by for instance putting the population under artificial conditions, like a lab, that allows or even encourages variants to flourish, and you get an increase in diversity.

And, of course, population genetics has all these fascinating mathematical formulas that reveal counterintuitive results, like that it is quite reasonable that even advantageous mutations to disappear from populations, or that deleterious alleles can become fixed. I could dig up some of this stuff for you, but I think pestering Reed Cartwright, who has done some nice work on his evomath series, could answer that even more effectively.

There are modes of change that are independent of selection. As a developmental biologist, I'm most interested in the intrinsic properties of developmental mechanisms that buffer organisms from change and also facilitate accommodation: variations in developmental genes don't necessarily mean the organism simply stops working or fails to develop, but instead, the flexibility of development means that either alternative processes stabilize the process, or more interestingly, the whole compensates to integrate the change in a continuous and non-disruptive manner. Brian Goodwin carries this idea to an extreme (to a point I find uncomfortable, actually, and I disagree with him on some things), but it's a similar idea that internal properties and physical factors dictate part of the features of an organism.

Stuart Kauffman is another source for the importance of physical and mathematical properties of the universe contributing to the parameters shaping life. Goodwin and Kauffman are out there on the bleeding edge, so I don't know that I'd necessarily endorse them as a place to start looking at the alternatives to selection…a better starting point would be SJ Gould. You don't have to read his monster Structure of Evolutionary Theory (although it would help: that book is all about the variety of modes of evolution), you can start small.

Try reading The Pleasures of Pluralism, an excellent critique of the excesses of the selectionists and in particular of evolutionary psychology, but also a paean to the other, too-often-neglected mechanisms of evolution.

In summary, Darwin cut to the heart of nature by insisting so forcefully that "natural selection has been the main, but not the exclusive means of modification"—and that hard-line adaptationism could only represent a simplistic caricature and distortion of his theory. We live in a world of enormous complexity in organic design and diversity—a world where some features of organisms evolved by an algorithmic form of natural selection, some by an equally algorithmic theory of unselected neutrality, some by the vagaries of history's contingency, and some as byproducts of other processes.

Another terrific and influential article by Gould and Lewontin is The Spandrels of San Marco. Again, they are deploring the narrow reductionism that blinkers much of molecular biology and evolutionary biology, but they are also promoting alternative ways of thinking.

An adaptationist programme has dominated evolutionary thought in England and the United States during the past 40 years. It is based on faith in the power of natural selection as an optimizing agent. It proceeds by breaking an organism into unitary 'traits' and proposing an adaptive story for each considered separately. Trade-offs among competing selective demands exert the only brake upon perfection; non-optimality is thereby rendered as a result of adaptation as well. We criticize this approach and attempt to reassert a competing notion (long popular in contental Europe) that organisms must be analyzed as integrated wholes, with Baupläne so constrained by phyletic heritage, pathways of development and general architecture that the constraints themselves become more interesting and more important in delimiting pathways of change than the selective force that may mediate change when it occurs. We fault the adaptationist programme for its failure to distinguish current utility from the reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plausibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of non-adaptive structures by developmental correlation with selected features (allometry, pleiotropy, material compensation, mechanically forced correlation), the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of non-adaptive structures. We support Darwin's own pluralistic approach to identifying the agents of evolutionary change.

(All emphases are mine)

Creationists lately have been babbling about "teaching the controversy". I'm all for that, but the controversy isn't what they think it is. None of these authors, not even the most radical, denies that evolution occurred. What they are arguing about is the relative importance of different modes of evolutionary change; and none of this discussion is filtering into our public schools, because a) teachers are intimidated from discussing evolution at all, and b) when they do, they have to address this ginned-up bogus bullshit promulgated by know-nothing creationists. If they were sincere about wanting to introduce controversial ideas into the classroom, they'd boot out everyone who even mentions that Intelligent Design creationism idiocy, and promote people who say they want to sink more hours into exploring the basic concepts of evolutionary biology more deeply. When do these bozos ever mention teaching about directional and stabilizing selection, or allometry, or pleiotropy, or developmental accommodation? Never. And that's the good stuff.

Gould SJ, Lewontin RC (1979) The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. Proc. R. Soc. Lond. B 205:581-598.