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in biology, any gradual change in a particular characteristic of a population of organisms from one end of the geographical range of the population to the other. Gradients of characteristics usually accompany, and are responses to, environmental gradients; for example, a mountain range features gradients from top to bottom such as a temperature gradient (colder to warmer) and a humidity gradient (wetter to drier). They may also reflect patterns of individual migration or gene flow. In species of birds and mammals, there is usually a cline in body size, with smaller individuals in warm climates and larger individuals tending to be found in colder climates.



in biology, a gradual increase or decrease (quantitative gradient) of some character or property in populations in connection with marked change in physical geographic factors. A cline usually develops when a large area is more or less uniformly populated by a particular species and the populations and their groups are not separated by rigid isolating barriers. A cline provides an advantage in natural selection because it allows adjustment to any direction of change in the corresponding physical geographic factors.

A cline may also develop as a result of the rapid dispersal of a species.


Timofeev-Resovskii, N. V., N. N. Vorontsov, and A. V. Iablokov. Kratkii ocherk teorii evoliutsii. Moscow, 1969. Pages 163, 164, 171, 176.


A graded series of morphological or physiological characters exhibited by a natural group (as a species) of related organisms, generally along a line of environmental or geographic transition.


Patsy, original name Virginia Patterson Hensley. 1932--63, US country singer; her bestselling records include "Walking After Midnight", "I Fall to Pieces", and "Leavin' On Your Mind".
References in periodicals archive ?
Analysis of the shape of the male genitalia across the hybrid zones revealed that both transects were characterized by sigmoid curves with a steep clinal transition between the two adjacent taxa (Fig.
To a large extent, the distribution of parasites was clinal on the East and West coasts, with clear relationships to well-known provincial boundaries.
El primero de los rasgos diferenciales de Euglypha como genero diferente de Aristolochia (utriculo con una constriccion basal) ocurre en otras especies de Aristolochia, y es de variacion clinal (continua, no discreta) a nivel interespecifico (Fig.
Recent research (Anderson & Johnson 2008, 2009) has treated clinal trends relating to proboscis length and body size in the nemestrinid species Prosoeca ganglbaueri Lichtwardt, 1910, and suggests that flowertube length was a significant predictor of fly proboscis length, but that altitude and body size may also influence proboscis length.
Clinal variation at the aspartate minotransferase-2 in spotted seatrout, Cynoscion nebulosus (Cuvier), inhabiting the north-western Gulf of Mexico.
Thus there is no evidence for clinal variation that might bridge morphometric differences between the two species and lead us to synonymize them.
Evidence of clinal variation of genotypic and phenotypic characteristics, in which adjacent localities are not statistically different but at some increasing distance (cline width) two samples do differ significantly, may not be apparent outwardly, but is critical to sound management (Taylor and Dizon, 1999).
Nevertheless, an evocation of this theory to explain our findings could only be reassure if we had examined all the species distribution and found a clinal variation along the different latitudes occupied by M.
pleurospilus reveal a clinal north to south variation from conspicuous midlateral spots equal to or larger than pupil size to often, faint dots smaller than the pupil; likewise the black ventral markings barely noticeable in some of the Guatemalan specimens, are conspicuous in individuals from El Salvador and Nicaragua (Figs.
The present case study would be improved by a) refining the construction and occupation chronology for the fortifications through additional survey and excavation; b) further testing of the model by surveying in other areas with a variety of real or effective precipitation clinal densities; and c) collecting local palaeoclimatic proxy records to supplement global records.
This variation may be clinal because the species varies greatly among its wide distribution area.