The difference between evolution and development in biology* is that evolution is change between organisms as they descend from each other, one giving birth to another, thereby passing genetic information along to it. Development is the process by which a single individual changes, and this difference can in some instances make it rather arbitrary whether we call it one or the other. For example, is a multicullular organisms like a human evolving in its lifetime? No, we say that is develops. However, the cells that make of the body is most certainly undergoing evolution, as individual cells give rise to new cells ad infinitum (until the human organism dies), which mutates and therefore results in evolution of the cell lineages (cancer comes to mind as well).
So, it is a question of preference, really, whether we'd call the changes that's happening to Carnival of Evolution for evolution or development. Is each edition a new organism? I like to think of them that way, in which case we can say that CoE (the lineage) is evolving. That there is not a population of CoE individuals, but only one linear progression of parent to offspring, to me only highlights the fact that evolution in theory need neither populations nor selection (no populations => no selection), though I am not arguing that this is how biological evolution happens on Earth (because it is not). Then all that is needed is for CoE to have traits that are partly inherited from edition to edition. The way that is done is by individual hosts taking cues from past hosts (which might not be solely from the previous edition), and copying the way that it is done. This, in addition to submissions being inspired by what was submitted to previous editions.
So, having established that CoE evolves, how does it? Well, for one thing submissions probably change in quality and content. I have not looked at this (hey, I'm a theorist), but I suspect that the posts in the early editions differ in consistent ways compared to those of later editions. This is probably primarily because of changes in what people submit, and I trust this is in part affected by recent previous editions. That is, submitters look to (recent) previous carnivals and inspired, which affects what they write about, and how they write it. And I would argue that this is tantamount to saying that there is heritability between the "generations".
On top of that, there is the form that each edition take. There has definitely been a change in that (which ought to be quantified), as when later editions markedly more thematic in nature than the early editions. I suppose this may have to do with a desire to stand out - something that I as administrator urge hosts to do.
Also, more and more people submit to CoE, which means that it is growing in size. And while I can speculate not only about causes, but also expertly about what the data should look like, I admit that I do sometimes on rare occasions go look, and that is exactly what I have just done in this case.
Figure 1: Number of posts included in CoE by month from its conception in August 2008 through May 2012. Not all months are included, because not all past editions are accessible. Numbers are approximate (counted one time by one person).
Notice that very consistent increase in body size of CoE over through time. A one-tailed t-test with unequal variance on the first half of editions vs. the second half gives p= 4.7072e-5, which is highly significant. That is, the average change in size from the first half (18.81) to the second (33.95) is not due to random fluctuations in number of posts included in the editions. CoE is definitely evolving. Creationists, go redacted!
Another intriguing question is what the role of Carnival of Evolution is going to be in the future. Here is the goal as stated on Facebook (btw, you can now follow/like CoE on Facebook):
Plans for Carnival of Evolution:What do you think post like this will look like in another four years? will the number of posts have stagnated, or even declined? Will a larger community of people have started to pay attention? Is blogging about evolution (and other sciences) ever going to be an integral part of science education in schools? Will it start to really matter in reaching out to laymen? Only time will tell.
1) Within ten years there will be a session dedicated to CoE at all major evolution conferences.
2) Within fifteen years it will be common for educators in college to utilize CoE in teaching evolution.
3) Within twenty years high school teachers commonly refer to CoE as a resource when discussing evolution.
* The original meaning of 'evolution' was actually that of 'development'. It originally meant "folding according to a pre-destined plan", which is more or less what biological development is. The meaning probably changed around the time of Darwin, when it was discovered that biological evolution is as pre-determined as that. This older meaning is retained in the literature of astronomy and astrophysics; 'galaxy evolution' refers to the development of a single galaxy.