Ecogeographical rule

The ecogeographical rules are a set of rules about animals and plants that grew out of the observation that closely related species differ in certain characteristics when they live in different geographic regions. The expression of these features depends in a characteristic way on the climatic conditions. These regular differences can also be observed within a species when comparing subspecies .

The rules thus reflect the range of variation within a family. At the same time, they describe convergent development because very different species in comparable regions also show similar characteristics.

Animal geographical rules

Bergmann's rule

The Bergmann's rule originally describes the observation that closely related species equally warm Animals (homoiothermer animals) the average height increases toward the poles. The Göttingen anatomist and physiologist Carl Bergmann described this relationship between average body size and climate in 1847, which is why it is known as Bergmann's rule. In the specialist literature, Bergmann's rule is now more broadly defined than originally. Today the rule is also used in various ways within a higher taxon such as B. of a genus or family , cold-blooded animals are also examined and, in addition to the temperature gradient of the geographical latitude , the temperature gradient of the height above sea level is also taken into account.

If the size of a body changes, the ratio between surface and volume also changes . When the body is enlarged, the surface grows more slowly than the volume, because the surface only grows squarely while the volume grows cubically . Since every body exchanges its heat via the surface with the environment , a large body has a lower heat exchange due to the lower surface-volume ratio , ie with increasing body size, the heat loss in a cold environment decreases. The larger the body of an animal at the same temperature, the better it can protect itself against heat loss in a cold environment because its skin surface becomes smaller in relation to its body volume.

Bergmann's rule is mainly observed in animals with a large geographical distribution such as brown bears , wild boars , foxes and penguins ; their body size increases with geographical latitude , ie the closer the habitat of such animals is to the polar regions , the larger they are. Although Bergmann's rule often applies, it by no means applies to all animal groups and temperature gradients examined.

Examples

Penguins : The Galápagos penguin is the smallest, the emperor penguin in Antarctica is the largest representative of the recent penguins. However, it must be taken into account that there are also a number of small penguin species in the Antarctic and on the sub-Antarctic islands.

Penguin art	Body length (in cm)	Body mass (in kg)	Spring length (in cm)	Occurrence (southern latitudes)
Galápagos penguin Spheniscus mendiculus	50	2.2	2.1	equator
Humboldt penguin S. humboldti	65	4.5	2.1	5 to 35
Magellanic penguin S. magellanicus	70	4.9	2.4	34 to 56
King penguin Aptenodytes patagonica	95	15th	2.9	50 to 60
Emperor penguin A. forsteri	120	40	4.2	65 to 77

Within the various subspecies of the brown bear ( Ursus arctos ), the Syrian brown bear ( U. a. Syriacus ) from the Middle East and Transcaucasia is smaller than the European brown bear ( U. a. Arctos ) and this is smaller than the Kodiak bear ( U. a . middendorfi ) on the island of Kodiak off Alaska . On average, the largest species among bears (Ursidae) is the polar bear ( Ursus maritimus ).

Allen's rule

The Allensche rule (by Joel Asaph Allen says from 1838 to 1921) that when close relatives homoiothermer (just warm) organisms , the relative length of the appendages ( limbs , tail , ears ) in cold climates is lower than in related species and subspecies in warmer areas.

The biological reason for this connection is that all extremities cause an increase in the body surface, and since homoiothermic animals keep their body temperature constant regardless of the ambient temperature, it is advantageous in colder areas to have the smallest possible body surface. Conversely, large body appendages can be observed in warmer areas, which improves the cooling of the body. Animals in hot areas, according to Allen's rule, also often have particularly long legs, possibly because the greater distance from the heat-radiating floor is a (selection) advantage.

Examples

The length of the ears take in the relationship series Fennec Vulpes (Fennecus) zerda ( desert ), red fox Vulpes (Vulpes) vulpes (temperate latitudes) Arctic fox Vulpes (Alopex) lagopes from (Tundra).

Fennec
Red fox
polar fox

The same applies to the desert lynx Caracal caracal and the lynx of the tundra Lynx lynx as well as the brown hare Lepus europaeus (capensis) and the mountain hare Lepus timidus .

Hessian rule or heart weight rule

According to Hesse's rule or heart weight rule , endothermic animals (birds, mammals) in colder climates ( higher geographical latitudes , mountains ) have a larger and heavier heart than conspecifics or closely related species in warmer regions. The reason for this is an increased metabolic performance to maintain the body temperature as an adaptation to a cold environment.

The rule established by Richard Hesse (1868–1944) is one of the ecogeographical rules of biogeography . Like Allen's rule , it is a supplement to Bergmann's more general rule . The ecogeographical rules relate the physiological adaptations of animals to their environment.

Example house sparrow Passer domesticus (data in grams of heart weight per kilogram of body weight): Saint Petersburg 15.7 - Hamburg 14.0 - Tübingen 13.1.

Gloger's rule or coloring rule

The Glogersche rule or rule of color was established by Constantin Wilhelm Lambert Gloger in his work The modification of birds by the influence of the climate (1833) . The rule was named after him.

The rule states that homoiothermic species that live in areas with higher humidity have a darker pigmentation . Conspecifics in drier climates are lighter in color.

One possible explanation for Gloger's observation would be that heavily pigmented hair and feathers are more resistant to corrosive bacteria. In humid areas, bacteria such as B. Bacillus licheniformis favors growth, but darker hair or feathers are less bacterially degradable. Therefore, dark brown-black eumelanins are more common in hot and humid areas , whereas reddish to sand-colored pheomelanins are more common in arid regions , possibly because of the better camouflage .

In mammals , there is a tendency to form a darker skin color in equatorial regions than north or south wild populations. Another explanation is the reduced intensity of UV radiation with increasing geographical latitude . With a lighter skin color, the UV light necessary for the production of vitamin D can be better used.

Rensch's rule

The Renschsche rule is a Allometric rule for gender-size ratio in animals, but without reference to geographical influences.

Plant geographical rules from Werner

Leaf size rule: In warm and humid regions ( tropical rainforest , laurel forest ) the plants develop larger leaves than in cold and dry regions ( mountain forest , polar regions). This can be explained by the fact that more water is evaporated from large leaves than from small ones.
Leaf shape rule: Plants of deciduous forests in the temperate latitudes show a greater variability than plants of tropical forests or the evergreen coniferous forests of northern latitudes.
Growth form rule : Woody plants develop dwarf forms in dry and cold areas with a short vegetation period .

literature

Carl Bergmann : About the relationship between the heat economy of animals and their size. In: Göttingen Studies. 1. Abt., 1847, ZDB -ID 514193-x , pp. 595-708.
Constantin Lambert Gloger : The changing of the birds by the influence of the climate. Schulz, Breslau 1833.
Eckhard Philipp (Ed.): Ecology (= Green Series, Materials SII: Biology ). Dr. A, 2. Schroedel, Braunschweig 2006, ISBN 3-507-10914-X .

Web links

Definition in the Glossary of Oceanography and the Related Geosciences
Carl Bergmann: About the relationship between the heat economy of animals and their size. In: Göttingen Studies. 1847.

Individual evidence

↑ Meiri, S. (2011). Bergmann's Rule - what's in a name? Global Ecology and Biogeography 20: 203-207, [1] .
↑ Meiri, S., Dayan, T. (2003). On the validity of Bergmann's rule. Global Ecology and Biogeography 30: 331-351, [2] .
^ Richard Hesse : Ecological animal geography. An authorized, rewritten edition based on animal geography on an ecological basis. Prepared by WC Allee and Karl P. Schmidt . J. Wiley & Sons, Inc., New York NY 1937, p. 392 .
^ ^A ^b Richard J. Huggett: Geoecology. An evolutionary approach. Routledge, London et al. 1995, ISBN 0-415-08689-2 , p. 95 .
↑ SM Tiquia, JM Ichida et al .: Bacterial community profiles on feathers during composting as determined by terminal restriction fragment length polymorphism analysis of 16S rDNA genes. In: Applied Microbiology and Biotechnology . Vol. 67, No. 3, May 2005, ISSN 0175-7598 , pp. 412-419, doi : 10.1007 / s00253-004-1788-y .
↑ Ehab Abouheif, Daphne J. Fairbairn: A comparative analysis of allometry for sexual size dimorphism: assessing Rensch's rule. In: American Naturalist 149, No. 3, March 1997, pp. 540-562.

[1] Meiri, S. (2011). Bergmann's Rule - what's in a name? Global Ecology and Biogeography 20: 203-207, [1] .

[2] Meiri, S., Dayan, T. (2003). On the validity of Bergmann's rule. Global Ecology and Biogeography 30: 331-351, [2] .

[3] Richard Hesse : Ecological animal geography. An authorized, rewritten edition based on animal geography on an ecological basis. Prepared by WC Allee and Karl P. Schmidt . J. Wiley & Sons, Inc., New York NY 1937, p. 392 .

[GEOECOLOGY-4] A ^b Richard J. Huggett: Geoecology. An evolutionary approach. Routledge, London et al. 1995, ISBN 0-415-08689-2 , p. 95 .

[Burtt_&_Ichida_(2004)-5] SM Tiquia, JM Ichida et al .: Bacterial community profiles on feathers during composting as determined by terminal restriction fragment length polymorphism analysis of 16S rDNA genes. In: Applied Microbiology and Biotechnology . Vol. 67, No. 3, May 2005, ISSN 0175-7598 , pp. 412-419, doi : 10.1007 / s00253-004-1788-y .

[6] Ehab Abouheif, Daphne J. Fairbairn: A comparative analysis of allometry for sexual size dimorphism: assessing Rensch's rule. In: American Naturalist 149, No. 3, March 1997, pp. 540-562.