Bergmann's rule

Bergmann's rule is an ecogeographic principle that states that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, and species of smaller size are found in warmer regions. Although originally formulated in terms of species within a genus, it has often been recast in terms of populations within a species. It is also often cast in terms of latitude.

The rule is named after nineteenth century German biologist Carl Bergmann, who described the pattern in 1847, although he was not the first to notice it. Bergmann's rule is most often applied to mammals and birds which are endotherms, but some researchers have also found evidence for the rule in studies of ectothermic species such as the ant Leptothorax acervorum. While Bergmann's rule appears to hold true for many mammals and birds, there are exceptions.

There seems to be a tendency for larger-bodied animals to conform more closely than smaller-bodied animals, at least up to certain latitudes, perhaps reflecting a reduced ability to avoid stressful environments by burrowing or other means. In addition to being a general pattern across space, Bergmann’s rule has been reported in populations over historical and evolutionary time when exposed to varying thermal regimes. In particular, reversible dwarfing of mammals has been noted during two relatively brief upward excursions in temperature during the Paleogene: the Paleocene-Eocene thermal maximum and the Eocene Thermal Maximum 2.

Hesse

Hesse /ˈhɛs/ or Hessia (German: Hessen [ˈhɛsn̩], Hessian dialect: Hesse [ˈhɛzə]) is a federal state (Land) of the Federal Republic of Germany, with just over six million inhabitants. The state capital is Wiesbaden; the largest city is Frankfurt am Main. Until the formation of the German Reich in 1871, Hesse was an independent country ruled by a Grand Duke (Grand Duchy of Hesse). Due to divisions after World War II, the modern federal state does not cover the entire cultural region of Hesse which includes both the State of Hesse and the area known as Rhenish Hesse (Rheinhessen) in the neighbouring state of Rhineland-Palatinate.

The English name "Hesse" originates in the Hessian dialects. The variant "Hessia" comes from the medieval Latin Hassia. The German term Hessen is used by the European Commission because their policy is to leave regional names untranslated (paragraphs 1.31 & 1.35). The term "Hesse" ultimately derives from a Germanic tribe called the Chatti, who settled in the region in the first century B.C. An inhabitant of Hesse is called a Hessian (German: Hesse (masculine) or Hessin (feminine)). The synthetic element hassium, number 108 on the periodic table, is named after the state of Hesse.

Hesse (disambiguation)

Hesse is both a cultural region of Germany and the name of an individual German state.

Hesse may also refer to:

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Hesse (surname)

Hesse is a German surname. Notable people with the surname include:

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