Modern soybean cultivars in the U.S. are highly related within the northern and within the southern maturity groups and they trace their genetic constitution to a small number of ancestral lines. On the other hand, there is much less genetic relationship between northern cultivars and southern cultivars. Examples of this can be seen in Figure 1, which shows the ancestral relationships among selected lines and cultivars developed from the northern and southern germplasm pools, respectively.
Allen, F. L. and Bhardwaj, H. L.
"Research Notes : United States : Measured and predicted yield response of soybeans to simulated acid rain,"
Soybean Genetics Newsletter: Vol. 13
, Article 42.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol13/iss1/42