Color Me Evolved!

Have you even wondered how and why there are so many variations of skin color? I mean even people within the same family are of different color. Well if you want to know how the initial variation came to be, keep reading! If you want to know why family members have different skin colors do some research, it is very interesting! 


Is this post about convergent evolution or human skin pigmentation? Well, let me clear that up, it’s both! 


The differences in human skin pigmentation result from a combination of supporting the beneficial aspect of UV light while also preventing the detrimental aspect. Places with high UV light concentration such as central Africa have enough UV light to provide a sufficient amount of Vitamin D despite the high amount of eumelanin in the inhabitants' skin--this is why the indigenous people could have dark skin. However, when the human population started to migrate north there was not enough UV light to penetrate the eumelanin and provide vitamin D. To get the necessary amount of Vitamin D there would need to be less melanin in the skin cells of individuals living in these regions, causing gradually lighter skin. Having lighter skin in these regions became an adaptation and resulted in the change in phenotype of the population.

Now how does convergent evolution factor into this? Well, if you look at the lovely skin pigmentation map above, you will notice that some areas have similar colors despite being thousands of miles apart. The people in these indigenous populations did not interact, so how is there skin color so similar? Because of convergent evolution! Skin pigment is an “evolutionary balancing act” because it is the human population’s way of responding to new environments. This balancing act accounts for the protection of the B vitamin folate, which allow for normal embryonic development and healthy sperm production, but also the absorption of Vitamin D. Interesting, right? The differing populations skin adapted to the amount of UV light available in their own areas.

Rock Pocket Mice

Convergent evolution of skin color can also be seen in other species such as mice, specifically in two independent populations of rock pocket mice, Chaetodipus intermedius. These mice usually have light fur color that allows them to live on light-color rocks. Populations of rock pocket mice have been found on dark lava, and interestingly enough they have primarily dark fur coats. Now how did this change occur? Well in the populations of mice who lived in the lighter environment, having a light fur coat was advantageous because it allowed them to blend in with environment and better hide from predators. However, when the population was introduced to an environment containing dark lava, the light fur color stood out to predators and having a dark fur coat became advantageous because it provided camouflage. This change did not occur in just one population of mice but several, which supports the convergent evolution theory. Now since the change in fur color was similar between the populations, one would think that it was the same mutation that caused this change to occur. This is not the case. Two different mutations occurred in these populations, supporting convergent evolution and natural selection. When the initial mutation occurred in the populations randomly it became advantageous so more genes from that mouse were passed on.

Brightly-Colored Frog 

Convergent evolution of skin color is even more interesting in different species of frogs because both bright colors and muddled colors can increase frog's fitness. Frog’s skin color provides camouflage and protection and can also serve as a warning to predators. Frogs that are dark green, brown, or black use camouflage as their main source of protection from predators, and interestingly enough, melanin is the dark skin pigment that attributes to these colors. Some frogs take the bright-color route for protection, because bright colors and toxicity are correlated. Predators who have experienced the toxicity of bright prey will be less likely to try to eat other bright prey, so bright colors can be advantageous within certain frog populations even if the frogs themselves are not toxic. Wow, who knew frogs were so tricky? Also, the fact that the melanin protein is prevalent in both human and frog population shows how it is a vital protein and highly conserved, since it has remained intact despite a great deal of speciation and adaptive radiation. I wonder what the most recent ancestors of frogs and humans looked like!

And Another Bright Frog! (Because why not!)

Dull, Green Frog