AP BIOLOGY

EVOLUTION

PATTERNS OF EVOLUTION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What type of structure shows evolution when arctic animals have white fur, short ears and limbs, and extra fat even though they don’t share a common ancestor?
A
Analogous structures
B
Homologous structures
C
Identical structures
D
Vestigial structures
Explanation: 

Detailed explanation-1: -Polar bears have white fur so that they can camouflage into their environment. Their coat is so well camouflaged in Arctic environments that it can sometimes pass as a snow drift. Interestingly, the polar bear’s coat has no white pigment; in fact, a polar bear’s skin is black and its hairs are hollow.

Detailed explanation-2: -Examples of convergent evolution include the relationship between bat and insect wings, shark and dolphin bodies, and vertebrate and cephalopod eyes. Analogous structures arise from convergent evolution, but homologous structures do not.

Detailed explanation-3: -Arctic foxes have many physical adaptations that allow them to survive in the Arctic. For instance, the characteristically white fur of the arctic fox is not only beautiful but also acts as a super effective camouflage, helping them blend in with the snow and ice.

Detailed explanation-4: -Convergent evolution occurs when species occupy similar ecological niches and adapt in similar ways in response to similar selective pressures. Traits that arise through convergent evolution are referred to as ‘analogous structures’. They are contrasted with ‘homologous structures’, which have a common origin.

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