The Bergmann rule is a thermal rule, which explains that in cold climates the animals are larger to better conserve the temperature. Some examples are penguins, squid and human being. The environment modifies organisms. These have to respond with adaptations to perform in their environment, and above all to be able to fulfill their basic processes.
Biogeography is the branch of biology that studies how the surroundings affect the species, and within it are certain rules that can almost always be observed. Some of the most interesting are the thermal rules, which explain how certain organisms so closely related, can have such variable morphology. We invite you to read this ecology article where you will know What is the Bergmann rule and examplesIn addition, we will briefly explain two other thermal rules that are observed in zoology.
What is Bergmann’s rule
Bergmann’s rule is a thermal rule used in biology. This explains that latitudes where animal organisms are more cold are that where the temperature is higher. This applies to organizations of the same group and that are closely related, in which comparison can be made and where the difference is visible.
The larger body size there is a lower relationship with the volume, which derives in that there is a Better heat conservation. Thus, large animals can lose less heat in cold climates, and stay hot. Conversely, small animals radiate more heat, and can cool in hot places due to their small body size.
The larger an animal, The body surface is lower in relation to the volumealready less surface there is a lower loss of heat loss. This is why large animals have a lower heat loss, something beneficial for cold areas. Conversely, small animals have greater surface to radiate heat, and thus cool faster.
In general, this rule is applied to endoterms animals, but examples for exoterms animals have also been found. On the other hand, there are also some exceptions. Next, we present some examples where the Bergmann rule is applied.
Bergmann rule examples
Squid
The squid have variable sizes, but they are usually medium size with about 50 centimeters long. In this group of invertebrates we can corroborate the Bergmann rule. He Colossal squid (Mesonychoteuthis Hamiltoni) stands out because Measures 15 meters long. This huge size is because Inhabits marine depthswhere the sunlight does not arrive and the temperatures are around 0 ° C.
On the contrary, the Arrecife squid (SEPIOTHIS Lessoniana) is size 3 to 30 centimeters longwhich is considerably less to the size of the colossal squid. Now, the Arrecife squid lives in temperate and tropical areas of the Indian and Pacific Ocean, and this difference in size is relative to the latitude in which they live.
Pingüinos (Spheniscidae family)
The penguins living further towards the southern hemisphere are the largestas is the emperor penguin (Aptenodytes Forsterique) It measures 120 centimeters high. It is endemic to Antarctica and that is why they need a greater surface to better retain the temperature. Comparing it with the galapagos penguins (Spheniscus mendendulus)that measure 50 centimeters high.
Human being (Homo sapiens sapiens)
Man also meets this rule, as can be seen in the members of populations more towards the poles. Inuits are robust complexion and this helps them better keep heat. Height is also different according to temperature. For example, where there is More heat days individuals tend to be smallercompared to more north places. Of course, because of the great genetic exchange in modern times within the human population, these changes are no longer so visible.
Allen’s rule
Allen’s rule explains that endoterm animals develop larger body parts when there is a higher temperatureBecause they help them cool.
Some examples are:
- The ears: Rabbits in more equatorial areas have large ears to be able to cool in high temperatures, compared to rabbits from temperate areas that have smaller ears. You may interest this post about animals with large ears.
- Nose: This can be seen in humans. Native populations of warmer areas have larger nostrils and graves to cool, while temperate areas have smaller noses.
- Line: In mice it was experienced by raising the temperature in one group, and decreasing it in another. The result was that cold -raised mice had shorter queues than heat. This is because those of high temperature have to dissipate more heat through the extremities or appendages.
GLOGER RULE
This is the third thermal rule, and indicates that Pygmentation is also influenced by temperature. In warm and wet areas the coloration is brown. In drier and cold areas the coloration is of lighter tones.
The best example of this is the bears. He polar bear (Ursus matirimus) is white, while the grizzly bear (Ursus arctos) It is brown. In mammals, this rule serves to protect against UV rays thanks to melanin. This is also observed in birds, and it is suggested that they are due to the fact that dark feathers are less likely to grow bacteria and are more resistant.
Now that you know what the Bergmann rule is and you know other thermal rules, you may be interested in reading this article about which animals live in the North and South Pole.
If you want to read more articles similar to Bergmann rule: what is and exampleswe recommend that you enter our biology category.
- Scholastic León, C., Claramunt Vallespí, T. (2013). Ecology I: Introduction. Organisms and populations. Spain: UNED.
