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Question
Which of the following best describes Allen’s rule?
Which of the following best describes Allen’s rule?
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Solution
The correct option is A Mammals adapted to colder climates have shorter limbs and ears
Adaptation is a mechanism (morphological, physiological or behavioural) that allows organisms to adjust to new environment or changes in the environment in which they are living.
Allen’s rule describes a morphological adaptation in animals, stating that mammals living in colder climates adapt to their surroundings by having shorter extremities (limbs and ears). This helps them to reduce heat loss from the body. Hence option a is correct.
Mammals are able to maintain homeostasis (a constant state of the internal environment). They have several mechanisms to restrict the lose of body heat in cold conditions and to lose body heat in hot conditions.
Mammals such as seals, which live in colder climates, have a thick layer of fat beneath the skin that can lock the heat inside the body. But the organs present at the body’s extremities, such as the limbs and ears usually do not have thick insulation and can be potential sites of heat loss.
Heat loss or gain is a function of surface area and smaller animals have larger surface area compared to their volume so the heat loss is more from the body. Heat production in the body depends on its volume but loss or gain of heat in an organism depends on the surface area.
Jackrabbits have longer ears and Arctic hares have short ears. So mammals of the same species living in different climates have difference in the size of extremities.
In colder climates, like the polar regions, mammals need to conserve as much as body heat possible, to maintain a constant body temperature (homeostasis). Thus their limbs and ears are shorter to reduce the heat loss from the body.
Adaptation is a mechanism (morphological, physiological or behavioural) that allows organisms to adjust to new environment or changes in the environment in which they are living.
Allen’s rule describes a morphological adaptation in animals, stating that mammals living in colder climates adapt to their surroundings by having shorter extremities (limbs and ears). This helps them to reduce heat loss from the body. Hence option a is correct.
Mammals are able to maintain homeostasis (a constant state of the internal environment). They have several mechanisms to restrict the lose of body heat in cold conditions and to lose body heat in hot conditions.
Mammals such as seals, which live in colder climates, have a thick layer of fat beneath the skin that can lock the heat inside the body. But the organs present at the body’s extremities, such as the limbs and ears usually do not have thick insulation and can be potential sites of heat loss.
Heat loss or gain is a function of surface area and smaller animals have larger surface area compared to their volume so the heat loss is more from the body. Heat production in the body depends on its volume but loss or gain of heat in an organism depends on the surface area.
Jackrabbits have longer ears and Arctic hares have short ears. So mammals of the same species living in different climates have difference in the size of extremities.
In colder climates, like the polar regions, mammals need to conserve as much as body heat possible, to maintain a constant body temperature (homeostasis). Thus their limbs and ears are shorter to reduce the heat loss from the body.
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