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 … See more

According to Huxley, clines can be classified into two categories; continuous clines and discontinuous stepped clines. These types of clines … See more

Although the term "cline" was first officially coined by Huxley in 1938, gradients and geographic variations in the character states of species … See more

The steepness, or gradient, of a cline reflects the extent of the differentiation in the character across a geographic range. For example, a steep cline could indicate large variation in the colour of plumage between adjacent bird populations. It has been previously … See more

It was originally assumed that geographic isolation was a necessary precursor to speciation (allopatric speciation). The possibility that clines … See more

Clines can be portrayed graphically on maps using lines that show the transition in character state from one end of the geographic range to the other. Character states can however additionally be represented using isophenes, defined by Ernst Mayr as … See more