Statistics problems with genetic analysis

hi everyone,

I'm having a bit of trouble trying to find out what to do with some results I've got in my research project. I've found 2 different groups of DNA sequences which I would expect to be different on their composition, so I got the results for the composition in both groups, the sample number is small (< 50) but apparently they don't follow a normal distribution, so I couldn't use an ordinary t-test using R. What I'd like to find is the statistical validation to confirm that these 2 groups either differ or are statistically the same.

Thank you very much for your help!

What is it that you have measured in this experiment? Is it some sort of sequence allignment? Some sort of score of similarity? If this measure is simply a quantitative score that identifies the composition of the sequence, then perhaps you could use a non-parametric procedure to test for a difference in the medians of the two groups. These types of tests are distribution-independent, and therefore do not require normality. If these data are a set of sequence allignments, other, more powerful (and complex) procedures have been developed to manange these situations.