Question

Allen's rule applies to
(a) Tribes living in high altitudes
(b) Mammals from colder climates
(c) Fish living in Antarctic water
(d) Desert lizards
(e) Marine invertebrates

Answer 1

Hint: Allen's rule states that significant differences exist in the size of the external organs (the length of appendages) of animals, even within the same species, depending on the geographical region in which they are found.

Complete answer:
Allen's rule applies to mammals from colder climates. Animals living in colder regions of the world, for instance, have shorter limbs than those living in warmer regions. This is because in colder regions the animals are adapted in such a way to decrease the loss of body heat. So, they adapt according to the climate of the region. A smaller body surface area helps the animals in colder regions to stay warm.
So, the correct answer is, ‘Mammals from colder climates.’

Additional Information:
- Allen's rule was postulated by Joel Allen in 1877.
- Allen’s rule predicts that the body surface- area- to- volume ratio of endothermic animals (mammals and birds) tends to vary with the average temperature in which they are found (lower ratios in colder climates and higher ratios in hotter climates).
- Another example of Allen's rule is the correlation between ear length and air temperature for hares (genus Lepus) and foxes. It states that the hares and foxes in the colder climate tend to have furry faces and short ears to conserve body heat. No, such adaptation is found for a hotter climate.

- The idea of Allen’s rule is sometimes disputed. The critics point out that many other adaptations for heat conservation, notably fat layers, feathers, fur, and behavioral adaptations to avoid extreme temperatures are not shown by such mammals.

Note: Allen's rule applies to a wide range of homeotherms (warm- blooded) . Birds and mammals are homeothermic (warm-blooded) animals, hence Allen’s rule applies to them.