Cline (biology)
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In biology, a cline is a measurable gradient in a single characteristic of a species across its geographical range. Clines usually have a genetic, or phenotypic character. They can show either smooth,
Bergmann's Rule demonstrated showing the difference in size between a larger northern fox, whose range spans colder regions, and a smaller desert fox, whose range is primarily in hot regions
Ring species
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In biology, a ring species is a connected series of neighbouring populations, each of which interbreeds with closely sited related populations, but for which there exist at least two end populations i
Cline (biology)
…and selection too weak a force of differentiation, for speciation to take place. However, the existence of particular types of clines, such as ring species, in which populations did not differentiate in allopatry but the terminal ends of the cline nonetheless do not interbreed, cast into doubt whether…
Herring gull (Larus argentatus) (front) and lesser black-backed gull (Larus fuscus) (behind) in Norway: two phenotypes with clear differences
Ensatina salamanders, an example of a ring species