Answer: wind, water, and gravity.
Explanation:
Hi
Before answering this question, we need to understand first that what a mutation is. <em>A mutation basically is a change in the DNA or genetic sequence of an organism that can significantly affect or not affect the function of a specific gene in organism. </em>
Now coming towards the question, yes ofcourse it is possible that a Norwar rats population carries a different genetic mutation than a population os same rats in Africa or any other region, Why? Because sometimes environmental factors of a certain area can cause the population of a region to undergo mutation (For example harsh UV rays) and the other population donot contains that mutation. This will cause a slight change in the genetic makeup of the population of rats of Norther America. However, if the changes in genetic makeup continues to happen in North American Norway rats, a time will come when they will be genetically very different from same rats in Africa and in this way they will become a separate or different specie, this phenomenon is called speciation.
Hope it helps!
The external ear structure is called the Pinna.
The Pinna helps to channel sound waves into the ear.
Many animals have the ability to move their pinna towards the direction of sound.
I have attached an image of a dog's ear to show you the external structure called the Pinna.
I hope this helps! I'm happy to answer any other questions you might have :)
[Image sourced from: https://www.msdvetmanual.com/dog-owners/ear-disorders-of-dogs/ear-structure-and-function-in-dogs]