RE LD you can try Monte Carlo simulations: i.e. Nucleic Acids Res. 2011 Nov;39(21):e144. Epub 2011 Sep 14. Towards an accurate identification of mosaic genes and partial horizontal gene transfers. htp://www.ncbi.nlm.nih.gov/pubmed/21917854 full text link: htp://www.info2.uqam.ca/~makarenkov_v/makarenv/Article_NAR_2011.pdf