Mechanisms of Evolution – Philipp Dettmer (2013)

Understanding how evolution works is fundamental for understanding nature. Mechanisms of Evolution is an infographic attempt to explain this very important concept. Philipp Dettmer is the person behind the concept, design and storyboarding of this production. Well crafted it is, the video is quite informative to reveal some of the misconceptions about Theory of Evolution. It is also missing one major mechanism called Genetic Drift whose theoretical foundations were laid in 1930s during the Modern Synthesis by influential geneticist Sewall Wright.

There are quite a few online sources to explain and teach evolution. Khan Academy has a curriculum based on natural selection. American Museum of Natural History also has an online course for educators and this narrated animation is a useful addition.

Animation begins with an explanation of the species concept. This is not a trivial job. As the questions get more detailed, biologists are finding more accurate and elaborate ways to define species. Evolution leads to formation of new species and this diversification process is called speciation. Later on in the video, a real life example is given involving Galapagos island finches. However, as the video says they didn’t speciate in just a few hundred years (!) but took much longer. We can also observe how new species form as it happens now through projects such as the Junco Project or the Long-Term Evolution Experiment by Richard Lenski of Michigan State University.

Evolution works on Variation and Uniqueness. How nature generates variation among individuals requires a brief introduction to genetics. How do children look like (but not exactly like) their parents yet different from each other? Major forces of nature (Mutation, Recombination and Selection) use genetic differences in shaping new species. Dettmer does a brilliant job of keeping it simple. Rules of heredity were discovered by Gregor Mendel long before DNA was discovered and the Central Dogma was resolved.

Dettmer’s animation also emphasizes a widespread observation that more organisms are born each generation than can possibly survive and reproduce. Darwin was very influenced by a book titled “An Essay on the Principle of Population” written by a young priest, reverend Thomas Malthus, published in 1798. Malthus argued that the population was increasing exponentially, and that food production could not keep pace; eventually a crisis would follow.

The video continues to explain esoteric sounding concepts like recombination and mutation that generate varitation. As populations grow effects of recombination and mutation also increase. Selection on the other hand acts to reduce this diversity. Evolution is a tug of war among these forces.

One important concept that the video never mentions (which is a huge chunk of evolutionary mechanism) is another random evolutionary force called Genetic Drift. This concept is omitted in almost every attempt to explain biological evolution because it requires a clear understanding of basic probability. Genetic drift operates in small populations (in large populations it’s effects are almost negligible). Our world consists of many fragmented small populations. Most of this fragmentation is mainly due to destructive human activities. Therefore genetic drift is increasingly becoming an influential evolutionary force.

The introductory writings in the following short video explaining Drift goes too quickly. So here they are in static form: “Our story begins with a population of Mr Potato Heads with a variety of different shoe colors. When the population suffers a catastrophic event the range of individuals with different shoe colors is randomly reduced. This is known as the Founder Effect. Eventually, through successive random (birth and death) events, we end up with a population of Mr Potato Heads with only one color of shoes. The other shoe colors are irrevocably lost from the population“.

This article is a part of the Evolution series aiming to categorize posts related to this central biological concept in Nature Documentaries.

 

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