Wild Animals/polar bear

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Question
why the polar bears are white?

Answer
Dear Jessica,

Polar bears evolved from grizzly bears, meaning that they were originally brownish but evolved white fur over a long period of time. Evolution is a process driven by random mutations and selection pressure. Some mutations may be deleterious to an organism's fitness, while other mutations can be neither harmful nor beneficial to an organism. Harmful mutations are blotted out of the population gene pool because they're negatively selected for, while neutral mutations may later go on to be beneficial and increase in frequency throughout the population gene pool. Such would be the case for the transition from brownish fur to whitish fur among polar bears.

Sincerely,

Fady

Wild Animals

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Fady D. Isho

Expertise

I can answer general questions about any and all of the phyla within the kingdom Animalia. I am most knowledgeable on the predatory, reproductive, and intraspecific and interspecific behavior of megafauna, including but not limited to the big cats, ursines, hyenas, canids, and the like. I can also answer some questions about animal conservation, but please do not ask me how to rehabilitate feral animals. Virtually every state in America has a local animal shelter or rehabilitation center that serves that purpose. I would also prefer not to answer questions about hypothetical animal fights.

Experience

I've read about animals for the majority of my life, and have researched and studied them independently and academically.

Education/Credentials
I am a few semesters away from obtaining a B.S. in biology.

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