Intraspecific variation in Arabidopsis thaliana. (a) A. thaliana (area of distribution shaded in green) is found throughout the Northern Hemisphere. It is a native of Eurasia and has been introduced into North America, Australia and southern Africa. The provenances of the first 74 accessions that have been sequenced as part of the 1001 Genomes project are indicated by the red dots. (b) Vegetative rosettes illustrating genetically determined variation in morphology among A. thaliana accessions.