Introduction . A frequent need in comparative genomic studies is the accurate identification of homologous genes on different chromosomes (or segments) that are arranged in similar linear order (colinearity)1 , 2 , 3 , 4. The identification of these so-called ‘colinear blocks’5on a genome scale can shed light on ancient polyploidy events1 , 6 , 7, genomic rearrangements8 , 9and gene duplications, as well as provide inferences of gene orthology relation...