October 17, 2005

21 populations, 5 loci, 3 clusters

Forensic STR loci have high variability and mutation rate. This makes them useful in forensic applications, because the large number of different alleles make it very easy to distinguish between different individuals. On the other hand, the high variability of forensic STR loci results in the same alleles being the result of homoplasy, or convergent evolution, and not of common descent. So, there is some controversy as to whether they can be used in phylogenetic studies about human population history.

BMC Genetics 2005, 6:47

Reconstructing recent human phylogenies with forensic STR loci: A statistical approach

Suraksha Agrawal and Faisal Khan

Abstract (provisional)


Forensic STR loci are effective for the purpose of individual identification, and other forensic applications. Most of these markers have high allelic variability and mutation rate because of which they have limited use in the phylogenetic reconstruction. In the present study, we have carried out a meta-analysis to explore the possibility of using only five STR loci (TPOX, FES, vWA, F13A and Tho1) to carry out phylogenetic assessment


Phylogenetic analysis based on two different approaches - genetic distance and maximum likelihood along with statistical bootstrapping procedure involving 1000 replicates was carried out. The ensuing tree topologies and PC plots were further compared with those obtained in earlier phylogenetic investigations. The compiled database of 21 populations got segregated and finely resolved into three basal clusters with very high bootstrap values corresponding to three geo-ethnic groups of African, Orientals, and Caucasians.


Based on this study we conclude that if appropriate and logistic statistical approaches are followed then even lesser number of forensic STR loci are powerful enough to reconstruct the recent human phylogenies despite of their relatively high mutation rates.


No comments: