One easily visible example of a clinal distribution seen worldwide is the patterning of human variation in skin color. Whether in southern Asia, sub-Saharan Africa, or Australia, dark brown skin is found.
What does it mean to say variation is clinal?
Clinal Variation Definition
Clinal variation is a slight amount of change in the character or nature of a species in a population across a defined biogeographic location. The change in a single character is gradual in the case of a cline leading to a steady change in the species during evolution.
What causes clinal variation?
Clines are often cited to be the result of two opposing drivers: selection and gene flow (also known as migration). Selection causes adaptation to the local environment, resulting in different genotypes or phenotypes being favoured in different environments.
Is human variation clinal?
By the 1960s, scientists began to use a clinal approach to classify human variation. This approach maps variation in traits over geographic regions (such as continents) or even worldwide. Clinal models are a useful way of describing human variation that does not lead to discrete races or other categories of people.
What is the meaning of clinal?
n. A gradual change in a character or feature across the distributional range of a species or population, usually correlated with an environmental or geographic transition. [From Greek klīnein, to lean; see klei- in Indo-European roots.] clin′al (klī′nəl) adj.
What is clinal variation anthropology?
What are clines? In anthropology we talk about clinal variation. Cline is a term that was devised by the biologist Julian Huxley to represent a geographical gradient in a particular trait across a species.
What is clinal distribution?
Genetically inherited traits often have a clinal distribution. That is to say there is a continuous, progressive gradation moving from one geographic region to another. Such patterns can result when selective pressures differ from one region to another and when people mate mostly with their immediate neighbors.
What human traits have clinal distribution?
Many human traits are clinally distributed, but they often require laboratory testing to discover their various manifestations. The most easily perceived trait that has a clinal distribution is skin color.
What is cline and examples?
A cline is the specific set of traits in a population of a given species that have been influenced by the local environment. For example, a population of warm-blooded animals that lived in a cooler climate closer to the North Pole would have larger bodies, allowing them to better conserve heat.
Is hair type clinal distribution?
The covariation of hair form and skin color are an exception to the pattern of clinal discordance. Hair on the head varies, and for a biological reason—spiral and wooly hair insulates the head from ultraviolet radiation.
What is a cline race?
A cline is a gradual change of a character or feature (phenotype) in a species over a geographical area, often as a result of environmental heterogeneity. In population genetics, a cline could include a spectrum of subspecies.
What is discordant variation?
Nonconcordant variation and discordant variation are the phrases that have historically been used to describe the commonly found noncorrelative and nonassociated nature of variation between pairs of genetically controlled traits.
What is Deme in ecology?
deme, in biology, a population of organisms within which the exchange of genes is completely random; i.e., all mating combinations between individuals of opposite sexes have the same probability of occurrence.
What is the principle of discordance?
The principle of discordance
Montagu pointed out that human physical variation was discordant, thus the physical features found in populations were not consistently correlated with each other.
What does non concordant mean?
nonconcordant (not comparable) Discordant; inharmonious; disconsonant; not in keeping with; not agreeable with; disagreeing. The patient’s left leg symptoms were nonconcordant with the right leg symptoms. (mathematics) not preserving the sign; of opposite sign or zero.
