Question about PCA chart?

[21993]

http://gen3553.pagesperso-orange.fr/ADN/K15V4.png
I have seen the chart above in the website http://gen3553.pagesperso-orange.fr/ADN/K15.htm . In this chart, the distances between populations' are shown. My question is, although the data points on the chart above is 15-dimensional, how cam they scale them on a 2-D plane?

[21993]

up

[Lucas]

http://gen3553.pagesperso-orange.fr/ADN/K15V4.png
I have seen the chart above in the website http://gen3553.pagesperso-orange.fr/ADN/K15.htm . In this chart, the distances between populations' are shown. My question is, although the data points on the chart above is 15-dimensional, how cam they scale them on a 2-D plane?

Generally for such plots there are plotted only first two PCA columns with PC scores.

But Tolan as always has his own way of doing statistical things and his plot is somewhat different (if I do PCA from K15 data in PAST programm it is different), you can ask him personally how.