Thomas Kocher- East African Cichlids
On Wednesday, November 12, 2008, I went to the University of Maryland Bioscience day held at the Stamp Student Union. My lecture of chose that I attended was given by Thomas D. Kocher, a professor in the Department of Biology here at the University. Before actually speaking about his topic of choice, cichlid fish in East Africa, he gave “preamble” of specific scientists that led the way for evolutionary research. He spoke of scientific celebrities such as Charles Darwin, Gregor Mendel, and Ernst Mayr. One thing that I did learn before his actual lecture was that Mendel was heavily influenced by the thoughts of Darwin. I also learned that the Evolutionary Synthesis which was a set of ideas composed over a decade from 1936-1947, and it contained ideas of natural selection and Mendelian genetics. Kocher digressed that in the evolutionary synthesis, selection is the main mechanism of change. This is something that I had not really thought about. It makes sense; however, being substantially ignorant to the study of genetics, I had thought that there was some kind of random defect every so often that became a trend once it proved victorious for the species. That is natural selection, which is something that I came to realize as I sat in the audience of his lecture. His confirmation of my thoughts, though we have gone over it in colloquium, proved to finally engrain the idea in my head that favorable traits become common in certain species.
Once Kocher began his lecture, I found that what I had envisoned him talking about was much different than what he actually spoke about. Out of lectures that I have gone to at the University of Maryland, most lectures, aside from ELT professors, lack conviction about what they are lecturing about. On the contrary, Kocher spoke very enthusiastically about the cichlids, joking and laughing with the audience.
What did I take away from his lecture? Cichlids are a type of fish in East Africa. There are a huge number of different species. Tilapia, my mother’s fish favorite, is a type of cichlid, and I had no idea! In Lake Malawi, Mozambique, Kocher explained that this was a “textbook example of adaptive radiation.” Lake Malawi experienced the “most rapid rate of speciation in vertebrates.” I thought that this was impressive, considering the amount of vertebrates just on the continent of Africa, let alone the vertebrates world-wide. Towards the middle of the lecture, Kocher talked about the quantitive genetic analysis of morphology for cichlids. Using a two specific species of cichlids, Kocher went into extreme detail when describing difference of the fish’s beak and how it affected feeding. He explained that in cichlids with a wider lower ventral jaw meant that they were strong biters versus narrow jaw with a strong ligature jaw which made the cichlid have a fast shutter. In hearing this, I thought about an ELT trip to the Smithsonian and how certain dinosaurs must have had the same type of variation. I assumed that plant eaters would have a wider ventral jaw for strong biting, but yet meat eater must have had a combination of both, strong bite and fat shutter for the flinching prey.
Towards the end of the lecture, Kocher spoke about linkage maps, the role of sexual selection, and the diversity of color patterns for males and females. He explained that the male color pattern for some cichlids was a blue or yellow dorsal fin, but is a little different on every island around the lake. He also explained that males evolved with many bright colors while females were more drab and boring. When I got back to my dorm, I read an article on livesceince.com that confirmed what Dr. Kocher said. Female cichlids, boring and dull colored prefer the brighter most colorful males. In comparing this to college kids and humans alike, I found that the exact opposite holds true. The brightest most attractive gender seems to be female and they seem to be preferred by anyone!