How Environment Dictates Size In Evolution

How Environment Dictates Size 

As time progresses animals evolve to suit their environments, features such as color or size are subject to change due to evolution. In this blog we will examine how certain subspecies of animals evolve to fit their environments.

Evolution In Penguins

                                                  
                                                  

A question you may have is why does one of these penguins look like he is tall enough to ride the rollercoasters at Dollywood while the others could be thrown like a football? The answer is that these penguins have evolved in two very different ways.

The Emperor penguin on the top lives in a cold environment and needed to evolve to live in extreme cold. A common evolutionary trend seen in cold weather animals is a bigger body, this is called Bergmann's Rule, basically as the temperature drops animals evolve to have larger frames to combat the cold.

Bergmann's Rule also applies in the inverse, as temperatures increase body sizes decrease, thus the African penguin on the bottom evolves to have a smaller frame because freezing temperatures are not a problem they have to face.

Evolution In Bears

Another good example of Bergmann's Rule can be seen in bears.
The Polar bear on the top is the height of an adult man while the Sun bear on the bottom is dwarfed by some types of dogs. Again this is an example of how members of the same species have evolved to survive in their environments, the Polar bear has evolved to be the apex predator of its environment while the Sun bear has evolved to look like a chunky dog.

The Ice Age

The astute reader will have begun to draw some connections between this rule and the Ice Age and they would be absolutely right. Animals from the Ice Age are giants compared to the size of their modern day descendants. 
The Wooly mammoth stands head and shoulders over the modern day elephant, and this trend is seen in other Ice Age animals such as the Sabretooth tiger. As the world warmed back up these animals either had to evolve back to a smaller frame or as was the case for many die out.

References

Britannica, T. Editors of Encyclopedia (2011, October 11). Bergmann’s Rule. Encyclopedia Britannica. https://www.britannica.com/science/Bergmanns-Rule

Rafferty, J. P. (2024, August 22). African penguin. Encyclopedia Britannica. https://www.britannica.com/animal/African-penguin

Rafferty, J. P. (2024, August 23). emperor penguin. Encyclopedia Britannica. https://www.britannica.com/animal/emperor-penguin









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