Geographic Variation of Size in Feral Pigeons

Even though they originated from phenetically and genetically heterogeneous domestic stocks, feral pigeons (Columba livia) today show significant interlocality variation in size of skeletal elements. About 30% of the size variation in European feral pigeons is owing to interlocality effects, compared to about 20% for American ferals. Additionally, size varies positively with latitude. Owing to the independent origin and long-term geographic isolation of American and European feral pigeons, the organization of size variation necessarily was developed independently in the two stocks. This instance of replicate size clines is probably a result of natural selection by environmental variables on common heritable variation in size.