Furthermore, the demographic changes occurring in the Yakut population since the Russian colonization make it difficult to reconstruct the genetic history using present day samples.
Given an admixed population PC derived from two ancestral populations PA and PB, the number of individuals in the analysis (i.e., present day samples) is n = nA = nB + nC.
Pair-wise distances comparing the aboriginal and extant samples show that the southern aboriginal sample was strongly differentiated from the northern and from all present-day samples.
However, there is a lag between the time of historical events and the collection of present-day samples that are used to infer contemporary population structure.
Much higher standard deviations of the FCA-scores among the oldest compared to present-day samples showed that the distribution of genetic variation has been much wider historically.
Particularly, the dynamics are notably different when the ancient samples are directly ancestral to the present-day samples and when they belong to a sister population that diverged from the present-day population.
The TEQ levels reported in the present study may not be applicable to present-day samples since many of the PBDE mixtures have been phased out, and other brominated replacement chemicals are being used in commerce.
When all the aDNA analyses were finished, DNA was extracted, and the mtDNA HVRI region was analysed in present-day samples at a physically distant laboratory following a previously published protocol.
To see, if genetic variation patterns were significantly different between the temporal groups, we compared the means and variances of individual scores along the first and second FCA axis between the first and present-day samples.
