The best of last June
Note: Since writing this post a year ago, at the time of Scott’s talk, I learned something interesting that I think it is OK to share with you. Prior to the talk, Scott has received an injury, which was causing him considerable pain during the talk itself. He left from the podium directly to seek medical attention. In addition, his power point slides and notes were destroyed somehow, so he gave the talk cold. And you could not tell. It was an excellent talk.
The Evolution 2008 conference started out today with a special program for K-12 teachers (mainly life science teachers) organized by the Minnesota Citizens for Science Education (MNCSE). The opening speaker was Scott Lanyon, director of the Bell Museum of Natural History. (The Bell hosted this event.)
Scott’s objective was to outline several areas of evolutionary biology where fundamental changes had occurred over recent years. This was to provide perspective and food for thought for the Life Sciences teachers attending the event, and Scott was very successful in this effort.
In each case, Scott described a similar trope … “Not so many years ago, understanding [this or that thing] was thought nearly impossible…. but today, look what we have….”
Specifically, Scott, a bird phylogeny expert, outlined four areas of research corresponding to four major areas of evolutionary biology:
4) History (Phylogeny)
Comparing evolutionary thinking of a couple decades ago to the present, the genotype-phenotype one-to-one correspondence has weakened in its explanatory power and is being replaced by more complex yet more realistic models of developmental biology (“evodevo”). To me, this is very interesting because it is an example of science swimming upstream against parsimony … it turns out that the simplest explanation (a Cartesian gene-trait correspondence) is not correct, and a more subtle, nuanced, and complex set of relationships involving hierarchical effects and emergent properties is correct. As a firm disbeliever in the “Law of Parsimony” as it is usually applied, I like this.
Genomics replaces simple conceptions of the genotype. We have a more holistic understanding of the genome, we understand evolutionary scenarios involving whole genome duplication and other less drastic yet still genome-level evolutionary changes, and so on. Here I think we are conflating methods (genomics as a method) and evolutionary process (genome duplication) a bit, but Scott’s point is simple and well taken: Go back a couple of decades and try to imagine what we could be doing with genetics in 2008, and you couldn’t.
With respect to ‘speciation’ … the diversification of forms, the diversity of life, the disparity produced by evolutionary process … again, the same theme. Scott pointed out that we know of approximately 1.7 million species, but estimates suggest there may exist somewhere between 10 and 100 million species. Go back twenty years or so and you would have seen field biologists starting to confront this reality, especially in certain habitats, almost with a sense of disbelief. I remember hearing from a colleague just back from visiting an Amazonian research site … a fogging sample was taken from a large area of rainforest canopy in a previously uninvestigated area to see what percentage of the insect species (which would fall out of the canopy because of the “fog” ….) would be new species. Five or ten percent would be really cool.
So they fogged the canopy, about a thousand species were represented in what came out of the canopy, and the researchers did not recognize any of them. Probably a few had been described before, but if so, not many. Totally blew their minds. And I’m not exaggerating by more than one order of magnitude (hey, it was a long time ago).
Finally, Scott talked about his own field: He’s a bird phylogeny guy, and he noted, really, two different things. One is that now, compared to a couple/few decades ago, phylogenies are often seen in connection with evolutionary biology research projects … so much research is now couched in phylogenetic terms, and this is new.
This is incredibly important. Not only do we increasingly pay attention to phylogenetic context, but methods of study involving the phylogenetic structure of the data are now routinely applied.
Also, the scope of phylogenetic studies has changed dramatically. Scott published his first bird phylogeny a few years back (I don’t think he said exactly when) with something like 10 birds on one phylogenetic tree. That was actually pretty impressive at the time. Recently, he co-authored a paper with over 800 species on the tree. Effectively two orders of magnitude more, and that is not uncommon. If this trend continues, the birds may cause the trees to collapse!
I remember being at a AAAS meeting where Sibly and Alquist gave one of their papers on bird phylogeny. This was not when they first started out with this business of using DNA to assess relationships, but they had applied some new methodologies and had a “complete” tree for birds … complete in the sense that all major bird groups were represented. People were pretty excited, it was like a tipping point in the history of science because for the first time a whole symposium at a major meeting was all about phylogeny of birds. Another symposium at the same meeting addressed human evolution and DNA phylogeny. But it still was fewer than about 100 birds. Most of the arguing and fighting (and there was quite a bit) was about mutation rates.
Today, phylogenies are routinely used, massive phylogenetic analyses continue to reveal important features of evolutionary pattern and process, and our methods of analysis are very sophisticated.
We’re all still fightin’ about mutation rates, though.