Mutation and the Tree of Life

 Mutations and the Tree of Life

    Have you ever wondered why you might have one hair color, and your friend has a different one? Or why your friend who is the basketball all star is so tall and why you might not be? We all have something called a genome, which like a code for your favorite video games, tells your body how to grow and function. In this genome, there are billions of letters that repeat over and over within your DNA that determine what color your hair is, how tall you are, and every feature that makes you, YOU! No genome is perfect however, this is where mutations come in. Mutated things are not always like what we see in TV where a regular turtle undergoes a random change and becomes a ninja. Instead, a mutation, can be just a small change to a single one of those repeating letters in your DNA. A small change to your DNA could make a major change on your body, causing cancer or an autoimmune disease, it could have zero effect whatsoever, or it could be somewhere in between, maybe changing your hair color, or height. 

    For simplicity's sake, we will invent a new organism., the rainbow fish (Imagine the fish from the children's picture book we used to read). The rainbow fish had many colorful scales, but due to a toxic waste spill in the ocean, nearby his reef, his genome was exposed to the harmful waste. Just as the sun can damage our skin and cause cancerous tumors, external factors can play a big role in mutating our genome. Instead of causing a tumor, like we may experience in the sun, it caused this fish's red scales to fall out, leaving behind every other color that it had before. The letters on the rainbow fish's DNA were coded for differently, and the toxic waste only affected the letters that coded for the red scales. This gene was located on a sex chromosome and had a high likelihood of being passed on to offspring. As this first mutated rainbow fish reproduced, its offspring also showed the new mutation of having no red scales. Due to genetic probability, there is now a population of rainbow fish that do not have red scales, as shown in the images. 

    Mutations can be neutral, beneficial, or harmful. In this example, since the fish had so many colored scales left, the fish was still able to easily blend into the surrounding reef environment to camoflauge while hiding from predators. Because this did not have a detrimental effect on the fish, but also did not have a life-enhancing effect on the fish, this is considered a neutral mutation. If the lack of the red scales made them appear less venomous to predators and mow became easier to kill, then this would be a detrimental mutation. If the lack of red scales allowed them to blend into their environment more to hide from predators better than before, then this would have been considered a beneficial mutation as it made their lives better. 

    In this image the square represents the environment, and the blue dots represent a species. The original is a light blue dot. The gene coding for color could mutate to express a red color that is beneficial because it scares off predators, or green which would be harmful because predators are attracted to that color. For the neutral mutations, there are two examples: One in which the color did not change. Just because the color didn't change, does not mean that the genome wasnt mutated. Sometimes, we can have silent mutations that change the base pairs, but not the final product. We also have another neutral mutation in which the physical appearance did change, but it is still a shade of blue and blends in to its environment like the original dot, therefore there was no major change, positive or negative.

    Here you can see that the fish would blend into its colorful environment with or without its red scales, showing that the loss of the scales would be a neutral mutation.

    Each of these mutation types (Beneficial, neutral, and harmful) can affect the trajectory of the organism's population moving forward. A neutral mutation would pose no major changes to the survival or development of the rainbow fish population. Since a positive mutation helps the population and in this case, increases their chances of survival, they will be more likely to reproduce and their population will flourish/ become more successful. The opposite logic applies to harmful mutations. If the mutation decreases the rainbow fish's chance at survival, then there is a good chance the population will decrease and the mutated rainbowfish might go extinct.