Perspectives on Evolution, Speciation, and Adaptations

Today’s 101 lecture began coverage of the study of evolution.  Monday’s myth lecture set the stage of talking about science as a process and how scholars frequently revise their storytelling in light of new data and interpretation.  Early scholars like Linnaeus, Charles Lyell, Cuvier, and Lamarck all made significant contributions in their fields and in the study of taxonomy, geology, and evolution, but had significantly flawed theoretical understandings of genetic variation and species diversity. Cuvier believed catastrophes guided by a divine hand led to extinctions and new species, yet he made real contributions in the study of fossils. Lyell’s work made important gains in the field of geologic processes despite his continued belief in a divine force driving the transmutation of species. I compared these early perspectives on evolution and species development to antiquated, geocentric views of the universe. Much like Galileo, Darwin had to convince existing scholars (and the church) that all of the world’s diversity wasn’t created, but rather, evolved from common ancestors.

From theories of evolution I switched gears to Darwin’s study of Galapagos finches to demonstrate how one species of finch is transformed into multiple species, depending upon selective pressures – for finches, this was typically measured through changes in beak morphology. I showed them some data from the Grants’ book, Beak of the Finch, and demonstrated to them how quickly different species of finch develop.  Finally, I ended with a question about adaptation – traits are shaped by selective pressure and those traits are adaptations.  There are many kinds of adaptation, and my question to them was about bipedalism – why did hominids evolve bipedalism so early?  What were the forces driving selection? Was it freeing up our hands to carry things, or to chase down prey, or to view threats over grasses, or to reduce sun exposure (which very few students picked….). This is where we’ll pick up Friday, but I think the lecture went well and helped the students to think through, 1) science as a process, 2) how sometimes you can be right for the wrong reasons, and 3) how natural selection creates species.

 

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