antibiotic resistance = microbial evolution

Well, now we are working our way to the halfway point of Intro to Evolution. And here is where it really gets interesting, because at this point frankly we have discussed all the nuts and bolts, the mechanisms, of evolution. It is mostly detail, mathematical and conceptual, that adds to the topic for the rest of the semester. However, the reality of the evolutionary process is understanding that it is happening right now. It isn't a topic about dinosaurs, or melanic moths, or how giraffes got their necks. What we are really getting into now is understanding why we may be moving into a "post-antibiotic" era, understanding which species will most likely survive ocean acidification and climate change, and exploring how to keep sustaining an agricultural system that so far has avoided Malthus' predictions that the human population could not keep growing as rapidly as it has.

Our class has been exploring these topics on the pages of this site, and yet the learning objectives for this class are very simple: understand the most basic mechanisms, and we will see how they apply to all of these complicated scenarios. By focusing on the most basic elements, we can see that there is essentially zero controversy about whether drift, selection, mutation, non-random mating, or migration cause a population to evolve. We can also see that humans are playing a huge role in causing these very evolutionary mechanisms to occur by limiting the population size of some species, by haphazardly applying selective agents like antibiotics, by moving species around the globe. In a way, it is a great time to be an evolutionary biologist, because there are so many experiments going on as we speak. We just didn't plan for most of them to happen!

Antibiotic resistance is a global problem! This article from the WHO explains what causes this resistance and how it affects our world.


Natural Selection by De Novo mutations in men

We have been talking in lecture for sometime over how mutations are a vital part of natural selection. De novo (Latin for "anew") mutations are small mutations that neither parent originally possessed. They are usually harmless but may be the reason for humans having blue eyes or blonde hair. However, these mutations, in men, are being studied to see if they are a possible reason for autism in children. Over time the frequency of these mutations increase as men age and more and more of these mutations are potentially passed on. This paper (see link below) talks about how male-driven de novo mutations in gametes are a driving force for natural selection. It is about four pages so not a long read, enjoy!

NOTE: You will need a Galileo password to read the paper but not for the abstract.




Evolution on NPR & BBC

Listen to the story from NPR about how some rattlesnakes are losing their warning rattle in parts of South Dakota. We have covered enough material in the classroom to think about whether this is a heritable trait, and that the distribution of this trait may be associated with particular populations of rattlesnakes. One intriguing hypothesis - that rattling is bad for their fitness since humans will often kill them - implicates US as a mechanism of selection.

As it turns out, too, the goal of this class website is to dip into how overuse of antibiotics can lead to evolution in microbes; they are becoming resistant to the drugs humans have developed. Again, we are an agent of selection! Today NPR had another story about the use of antibiotics on farms and the development of drug-resistant bacteria. Now you know why, if you go to the University Health Center, the best doctors will be very hesitant to prescribe antibiotics, especially when they have a strong hunch that you have a virus instead.

This hour long documentary analyzes the future of humans as predicted by scientists. Where will we be in thousands of year?

Here is a nice article on NPR about Dr. Lenski's E. coli experiment, and it talks about how evolution is an on-going process that never stops.



The semester has started, and we currently have 187 students, 3 graduate teaching assistants, and 1 professor who gather a few times a week to discuss evolutionary biology. We are going to spend a lot of time on nuts and bolts - the very basics, the assumptions, the algebra that helps explain observations about the natural world - but we are all here for more than just curiosity. The goal of science is to be able to make predictions about how things work, and this website is a place where our community is putting our heads together to think about how resistance to change in the environment evolves. More specifically, we are dealing with how microbes become antibiotic resistant, how plants and fungi tolerate herbicide and fungicide, how have rats become tolerant to rat poison. These are topics that are of vital interest to public health, agriculture, and understanding how humans are shaping the world.

I'm happy to see that at the beginning of week #2, we are already starting to contribute to this webpage. Sure - there are grade incentives involved. But if we really want to understand how this material can help, we have to each take ownership of the ideas involved.

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