Cline (biology)

Within a species, there are usually at each feature a range of variation. The feature continuously changed in parallel with a Ökogradienten, one calls this feature interactions as Kline (also Klin or Ökokline, English: cline or ecocline; Greek: κλίνω: lean, tend ).

Causes

The triggering factor need not be known in detail because frequently change several factors in difficult aufzulösender parallel manner, for example along the latitude or altitude of the mountain. The characteristic change can be a pure environment modification, but often has a genetic basis. To distinguish these cases usually breeds are carried out under controlled environmental conditions ( in the laboratory or greenhouse ). If the difference exist even under these conditions, it must be genetic. Even this gradual change in frequency of the trait -determining alleles is called Kline.

The explanation of genetic klinai is a problem in evolutionary biology, because of genetic exchange or gene flow between individuals and subpopulations such differences should actually homogenize. A Kline but can persist when either the gene flow is less than expected or the selection strong enough to sustain the difference despite the homogenizing effect of gene flow. The emergence of a genetic Kline might be an extremely rapid process that takes. When entrained to America the fruit fly Drosophila subobscura ranged 20 years to produce a hereditary Größengradienten in wing length between northern and southern populations.

Monoclinic often by the factor by which the observed variation in the population or species is correlated designated. So, for example, would a " thermocline " a feature change (or a Allelgradient ) along a temperature gradient. A characteristic change along an ecological environment factor, or more parallel is changing, ( Germanized rare: Ökokline ) commonly known as " ecocline " means. However, some scientists call it the causative Faktorengradienten itself (or the corresponding sequence of this habitats or sites ) that way. In this sense, the term can also be found on all of life Communities. Most scientists prefer in this case, however, the term " ecotone ".

Examples

• In many mammals and birds, the body size increases with increasing latitude to ( Bergmann's rule )
• When veined White wing coloration varies from light to dark. The further you get in Scandinavia to the north, the darker the wings.