Saturday, February 6, 2010

Next lab meeting - wednesday 10 02 2010

For the next lab meeting, I thought that we could explore a bit a field that we are not all very familiar with: developmental evolution. The real reason is that I am planning a postdoc with Anna Qvarnström, from Uppsala University, which is gonna be about the role of ontogenetic trajectories on adaptive divergence and speciation, and I would be extremely grateful if I could get input on my VR-application from all of you who can come. The main idea is that heterochrony of for example secondary sexual characters may have an effect on assortative mating between populations and ultimately speciation. I will work on the flycacther hybrid zone and mainly using quantitative genetics techniques to answer this question among others. Thus, it would be really nice if you have the time to read my application and that we discuss what can be improved during the lab meeting. I will send you by email the application tomorrow. Erik and I thought that it would also be nice to read a short paper which discuss these kinds of questions, and I chose a paper by Sean Rice which is, I think, a nice introduction to the field: Proc. Natl. Acad. Sci. USA
Vol. 94, pp. 907–912, February 1997

Here is the abstract:

Heterochrony has become a central organizing concept relating development and evolution. Unfortunately, the standard definition of heterochrony—evolutionary change in the rate or timing of developmental processes—is so broad as to apply to any case of phenotypic evolution. Conversely, the standard classes of heterochrony only accurately describe a small subset of the possible ways that ontogeny can change. I demonstrate here that the nomenclature of heterochrony is meaningful only when there is a uniform change in the rate or timing of some ontogenetic process, with no change in the internal structure of that process. Given two ontogenetic trajectories, we can test for this restricted definition of heterochrony by asking if a uniform stretching or translation of one trajectory along the time axis superimposes it on the other trajectory. If so, then the trajectories are related by a uniform change in the rate or timing of development. If not, then there has been change within the ontogenetic process under study. I apply this technique to published data on fossil Echinoids and to the comparison of human and chimpanzee growth curves. For the Echinoids, some characters do show heterochrony (hypermorphosis), while others, which had previously been seen as examples of heterochrony, fail the test—implying that their evolution involved changes in the process of development, not just the rate at which it proceeded. Analysis of human and chimpanzee growth curves indicates a combination of neoteny and sequential hypermorphosis, two processes previously seen as alternate explanations for the differences between these species.

I hope you can all come. I will try to remember to bring fika.

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