Module 2 Blog Post

I have chosen my favorite prediction Darwin's idea of descent with modification makes, and it is that species change through time (also known as microevolution). I chose this prediction because I know that there are many great examples of this, older and newer, so I feel that it gives very strong and compelling evidence supporting evolution. I found that a more current example of species changing through time is the prevalence of antibiotic resistance in bacteria! This is a huge, ongoing problem in the medical field so I felt that it would be good to discuss how evolution and antibiotic overuse is the reason for this happening. Before explaining antibiotic resistance, it would be beneficial to define antibiotics: "any class of organic molecule that inhibits or kills microbes by specific interactions with bacterial targets, without any consideration of the source of the particular compound or class" (Davies & Davies, 2010). Some strains of bacteria began to develop mutations over time that started to be selected for because it showed an advantage against antibiotics. As these mutations arise in bacteria, there are several reasons that bacteria have very quickly been able to develop antibiotic resistance. One of these reasons is that many of these bacteria contain plasmids (small, circular DNA outside of regular chromosomes) that are able to perform conjugative transfer of their DNA sequences--plasmids that are carrying these resistance mutations. Conjugative transfer is a form of horizontal gene transfer, which is a way of moving genetic information between two individuals non-sexually (Hawkey, 1998); in the simplest terms, one bacteria's plasmid is shooting its resistant DNA sequences into another bacteria's plasmid to give it the same advantages. This is not evidence for heritability as this is a non-sexual gene transfer, but it is still great evidence to support species changing through time and shows why bacteria were able to evolve this so quickly. Another, much simpler reason that bacteria have evolved this resistance so quickly is because most of them have extremely fast generation times--some of them as short as only a few minutes! Since these bacteria with resistance genes are being selected for by their environment, those bacteria are going to be much more capable of reproduction and will therefore produce more and more resistant bacteria. These fast generation times have allowed us to see natural selection in action, which is the mechanism by which evolution occurs. I think it is fascinating that small changes, and sometimes completely random mutations, can propel a species forward so much. Antibiotic resistance is becoming increasingly popular in many different strains of bacteria, and it's a course of evolution we have allowed to occur through misuse of antibiotics for problems they couldn't solve, or not using them to their completion of the course. Regardless, the mutation and selection for antibiotic resistance in bacteria is a great example of species changing through time, or microevolution.


References:

Davies, J., & Davies, D. (2010). Origins and evolution of antibiotic resistance. Microbiology and molecular biology reviews : MMBR, 74(3), 417–433. https://doi.org/10.1128/MMBR.00016-10

Hawkey P. M. (1998). The origins and molecular basis of antibiotic resistance. BMJ (Clinical research ed.), 317(7159), 657–660. https://doi.org/10.1136/bmj.317.7159.657

Comments

  1. Madison NSeptember 13, 2021 at 12:33 PM

    Ooo yeah, good example of microevolution! Real relevant, too. Where do you think we draw the line between micro- and macro-evolution? Where would that line be relative to the antibiotic resistance of bacteria, with confounding factors like horizontal gene transfer?

    ReplyDelete
  2. Emily DavorenSeptember 22, 2021 at 3:35 PM

    Hey Jenna! I really like your explanation of antibiotic resistance being an example of microevolution. It is really scary how it is becoming harder and harder to treat bacterial infections and sicknesses due to the rising prevalence of this issue. Good work.

    ReplyDelete

Post a Comment

Popular posts from this blog

Blog Post Module 7

     It has been so incredibly relieving to be able to sit through a lecture and really LISTEN to what is being said and participate while occasionally  writing down notes, compared to other classes where I am constantly scrambling to write things down so I hardly even hear what my professor says. I feel like I am much more involved in the lecture and I'm really learning from it because I'm not just trying to cram in information so I can do well on a test. ALSO: I consider myself to be quite computer-illiterate. I would never think I would be able to put together pieces of code to make graphs and do such cool functions--it makes me really happy and proud of myself because I'm doing something I probably never would have done if it weren't for taking this class.           I would say my first definition of evolution was pretty decent, just the basics of heritable traits changing over multiple generations in a population. However, something...
Read more

Blog Post Module 10

 I think when it comes to sexual dimorphism and who courts who, the most important thing to remember is that in reality--it's not about sex of the individuals involved at all. As we discussed in class, it's about who invests more into the offspring instead! In probably 99% of species on earth, it is the case that females of a population are the ones that "invest more" into the offspring because they are the ones who are pregnant, give birth, breastfeed, do more of the early life care, etc. In the case of pipefish, however, it is the males who carry the babies inside them into they are ready to make their grand entrance! It makes perfect sense when you think about it that this courting phenomenon takes place--since procreating is so much work for the sex carrying the babies, they want to be woo-ed into choosing the best possible mate. They aren't going to go through that for just anybody--they're going to need to see some showgirl-like fin action before they co...
Read more

Blog Post Module 9

Image
Blobfish: The Original "No Bones" Day Animal The Blobfish is an animal most of us may have seen in a meme or otherwise before because they are continuously regarded and one of the ugliest animals to ever exist. Photo evidence appears above. The reason Blobfish look like...that... is because they live extremely close to the ocean floor, between 2000 and 4000 feet below sea level depending on the area. This puts them living at a pressure between 60 and 120 times larger than sea level. To put this into perspective, here is this quote from an article on Australia's Science Channel: " There is so much pressure at that depth a human would feel as if a passenger aircraft was parked on top of them". Another fun fact: these fish don't look entirely this awful in their natural habitat--it's because the pressure on land is so much lower that they start to look like this pile of snot. It takes a lot of interesting adaptation to be able to live in these conditions ne...
Read more