In order to evaluate whether microsatellites were over- or underrepresented in genome sequences of members of the Caulimoviridae, we compared the observed number of microsatellites (O) with the expected number of microsatellites (E) in the form of a ratio of O/E. Statistical significance of the microsatellite representation (O/E), was assessed using Z scores defined as (OE)/pE . The expected number of microsatellite composed of Mt (M is motif of the microsatellite with repeat number of t, and its length is L) in a genome of length G was calculated using the formula as given by De wachter:- ExpðMtÞ ¼ fðMÞ t ½1 fðMÞ½G0 ð1 fðMÞ þ 2L ð1Þ G0 ¼ G tL 2L þ 1 ð2Þ where Exp(Mt) is the expected number of Mt, and f(M) is the probability of M