Dobzhansky T, Sturtevant AH

Genetics. 1938 Jan;23(1):28-64. doi:10.1093/genetics/23.1.28

Inversions in the Chromosomes of Drosophila Pseudoobscura.

Observation of polytene chromosomes in salivary glands of hybrid D. pseudoobscura crossed form different populations showed lage-scale inversions in the 3rd chromosome. The collection of haplotypes can be represented as a graph linking single inversion events. Multiple haplotypes may coexist in the same geographical region.