Question

Match the following.

(1) Bergmann’s rule	(i) Pigmentation of the skin
(2) Gloger’s rule	(ii) Metabolic rate
(3) Allen’s rule	(iii) Number of vertebrae of codfish
(4) Jordan’s rule	(iv) Body size(mammals)
(v) Size of extremities of body parts

The correct match is
(a) 1-iii, 2-v, 3-i, 4-iv
(b) 1-iv, 2-i, 3-iii, 4-v
(c) 1-iv, 2-i, 3-v, 4-ii
(d) 1-iv, 2-i, 3-v, 4-iii

Answer 1

These are some scientists who have given the rules or theories according to their observation over species of different geographical regions and how weather, climate, temperature effects in the changes of body parts, pigmentation, and vertebral column, etc.

Complete answer:
Bergmann’s Rule:
First of all this principle was proposed by Carl Bergmann, a 19th-century German biologist. He said that the principle interacts with external temperature and the ratio of body surface to weight in warm-blooded animals. He observed that the birds and mammals in cold regions to be bulkier than individuals of the same species in warm regions. He put forward this theory to account for an adaptive mechanism to conserve or to radiate body heat, depending on climate.
Gloger’s rule:
Gloger’s rule was named by Bernhard Rensch in 1929 to honor Constantin W.L. Gloger. He describes how variation in animal coloration relates to broad-scale climatic gradients. In 1833, he was one of the first to describe correlations between the pigmentation of animals and temperature.
Allen’s rule:
Allen's rule is named after an American zoologist Joel Allen (1838-1921) . The principle stated that in an animal species with hot-blood living in cold climates that have distinct geographic populations; their limbs, ears, and other appendages tend to be shorter than in animals of the same species that are living in warm climates. It is because elongated have more surface area than shorter and more compact body parts and thus radiates more body heat.
Jordan’s rule:
This rule is named against David Starr Jordan (1851–1931) . Jordan stated in his rule that the number of vertebrae in fishes increases with the latitude. This is also known as the Law of Vertebrae. According to this law, the fishes of certain groups that are found in the cold-water or regions have a larger number of vertebrae than those members which are found in tropical regions.

Additional Information:

1. The Bergmann's rule is widely accepted because modern humans conform to the rule, which holds that body size in endothermic species will increase as temperature decreases.
2. In the modern version of Gloger’s rule, it is stated that birds and mammals should be darker in humid and warm environments compared to colder and drier areas.
3. The Allen’s rule isn’t clear about what mechanisms that are underlying these differences and in what pattern they emerge since the morphology is traditionally thought to reflect naturally selected genomic adaptations for thermoregulation.
4. D. S. Jordan is known as the father of American ichthyology.
   So the correct answer is, ‘(d) 1-iv, 2-i, 3-v, 4-iii.’

Note: Both the Bergmann’s and Allen’s rules cause systematic changes in the surface area to volume ratios. In cold climates where a person needs to retain heat, so bodies are larger and more compact and in a warm climate, a person needs to expel heat, so bodies are smaller and more linear.