Question

Animals of cold countries have shorter ears/extremities. This is
 A. Allen's law
 B. Cope's law
 C. Bergmann's law
 D. Dollo's law

Answer 1

Hint: Animals surviving in the cold regions have shorter ears and tails, also called extremities. It is because of the fact that more surface area will increase the heat loss. By reducing the size of limbs, ear and extremities, they decrease the surface area to volume ratio.

Complete answer: Allen’s law states that, in animals, a significant decrease in the size of the limb and other external organs depend on the geographical region in which they live. Animals living in a cold region should have a low surface area to volume ratio to survive, it is because they need to trap heat in all the possible manner. A factor that is associated with Allen’s law involves the growth of cartilage. Its growth may be dependent on the temperature. Temperature is a factor that could directly affect the growth of cartilage, providing the rule a proximate biological explanation.
a) Cope's law states that over the evolutionary period, the lineages tend to increase its body size.
b) Bergmann's law: It is an ecogeographical law which states that animals living in colder regions have a large body size, whereas animals living in warm regions have smaller body size.
c) Dollo's law: Dollo's law is the law of irreversibility. This law states that an evolved organism cannot return to its previous state even if it reaches similar environmental conditions or conditions of existence like the previous. The traces for intermediate stages of the organism are always present.
So, the correct answer is option A.

Note: Joel Allen was the American zoologist who proposed the law. Endothermic animals are animals that can maintain their body temperature according to the varying environment. They are also called warm blooded animals.