Do Animals Match Their Environment?
The physical characteristics of plants and animals are related to their environment. There is nothing magical about this. If an organism cannot survive in an environment, then it won't be there! You won't find a whale in a forest.
There is more to it than that though. Suppose a species can survive in a cold climate. Any mutation in an individual’s genes – large or small – that gives that animal an edge in surviving in its habitat is more likely to be present in the next generation. Given enough generations, the organisms living in an environment will become more and more adapted to it.
Of course, the environment is constantly changing. Throughout the history of life on Earth, there has been (and is!) a dynamic interplay between changing genes and changing environments over time and space.
LET's explore the relationship between physical characteristics and environment with the Canadian Arctic and the polar bear.
The Arctic - Then and Now
An animal’s features are related to its environment. Changes in climate will influence where, and if, animals can survive.
Take a look at "Ecosystem", an artist rendition of Axel Heiberg Island 50 million years ago (mya).
Compare it to the photo of Axel Heiberg Island today. Using these photos, and your knowledge of the Canadian Arctic, make a chart or Venn diagram to compare the two.
This is an artist's interpretation of what the environment in this location looked like, based on the fossils found.
Arctic Adaptations - Then and Now
Now compare the physical characteristics of a few animals living in these two different habitats.
What features do you see in the animals depicted in the Axel Hieberg painting 50 mya that would prevent these creatures from living in the Arctic today? Conversely, what features do you see in these photos of the polar bear below that would have prevented it from surviving in the Arctic 50 mya?
View of a polar bear paw. See how big it appears. It can measure over 30 cm. Notice the big toes beneath the abundant fur, but no trace of claws. The grizzly bear and the polar bear have about the same size of paw. The difference lies in the amount of fur beneath the paw and the length of their claws.
Left profile of a polar bear skull. Notice the shape of the head, the pointy canines and the sharp premolars. The head is longer than the grizzly bear’s. This skull is 33 cm long. Imagine it covered with muscle and fur!
1. What do your comparisons tell you about how the environment and physical features are related?
2. How does the theory of natural selection explain your observations?
3. What do you think would happen to the polar bear if the Arctic warms up drastically again?
Grades 11,12 Evolution (ON, BC)
-describe the process of evolution
-relate evolutionary mechanisms to the products of evolution
-evaluate some scientific evidence that supports the theory of evolution
-practise critical thinking skills in comparing and contrasting two ecosystems
-interpret visual material and applying their knowledge of evolution to explain their observations