DFSC Applet and Application Page


DFSC (D and F tests under Size Change) is a program for testing Tajima's D and Fu and Li's D, D*, F, and F* statistics under the assumption that population size has changed over time. This change is assumed to have occurred according to a two-epoch model, as described by Rogers (1995). Under this model, population history is specified by three parameters: theta0, the ancient theta value of the population, tau the time at which population size changed, and rho, the magnitude of population growth. Detailed information about these parameters can be found in the DFSC README file.

The tests performed by this program make all of the assumptions of the original tests as formulated by Tajima (1989) and Fu and Li (1993) (except the assumption that population size has remained constant). The most important assumptions are that recombination has not occurred between polymorphisms and that homoplasy is rare. If recombination has occurred, these tests are overly conservative. This means that it is okay to use them, but you might accidentally fail to reject the null hypothesis when it really is false.

The DFSC README file gives more details, including example analyses.


To visit the DFSC applet (i.e., the online version of the program), go to the DFSC Applet Page.


If you want to install DFSC on your own computer, click here to download DFSC_1.1.zip. After you download the file, read the README file for instructions.


Fu, Y.-X., Li, W.-H. 1993. Statistical tests of neutrality of mutations. Genetics 133:693-709.

Rogers, A. R. 1995. Genetic evidence for a Pleistocene population explosion. Evolution 49:608-615.

Tajima, F. 1989. Statistical method for testing the neutral mutation hypothesis by DNA polymorphism. Genetics 123:585-595.

Wooding, S., Kim, U.-k., Bamshad, M., Larsen, J., Jorde, L. B., Drayna, D. 2004. Natural selection and molecular evolution in PTC, a bitter-taste receptor gene. Am. J. Hum. Genet. 74:637-646.

Last modified: Mon Mar 21 08:59:54 MST 2005