Giardia are a group of widespread intestinal protozoan parasites in a number of vertebrates. By means of genome-wide analysis about gene duplication patterns in the protozoan parasite Giardia lamblia, we found that 40% of its genes were identified as duplicated genes, although the whole genome is very compact. Furthermore, evolutionary distance analyses of these duplicated genes indicated two rounds of large scale duplication events had occurred in G. lamblia genome. Functional annotation of them further showed that the majority of recent duplicated genes are VSPs (Variant-specific Surface Proteins), which are essential for the successful parasitic life of Giardia in hosts. Based on evolutionary comparison with their hosts, it was found that the rapid expansion of VSPs in G. lamblia is consistent with the evolutionary radiation of placental mammals. Therefore professor Wen jianfan and his team (Kunming Institute of Zoology) proposed a hypothesis that the increment of Giardia hosts might be the driving force for the rapid expansion of VSPs. Here, we revealed an important mechanism underlying the parasitism the light of genomic evolution.

Sun J, Jiang HF, Flores R, Wen JF*. Gene duplication in the genome of parasitic Giardia lamblia. BMC Evol Biol. 2010 10:497.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2829556/pdf/1471-2148-10-49.pdf