Tamil Nadu map showing the sampling location of the 12 tribal (squares) and 19 non-tribal (circles) populations.

<p>The majority of tribal populations are located in the mountains of the Western Ghats. The color codes are: Red – Hill Tribe Foragers (HTF); Turquoise – Hill Tribe Cremating (HTC); Green – Hill Tribe Kannada (HTK); Grey – Schedule Castes (SC); Pink – Dry-Land Farmers (DLF); Deep Blue – Artisan and Warriors (AW) and Yellow – Brahmin related (BRH). Population abbreviations are as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050269#pone-0050269-t001" target="_blank">Table 1</a>.</p

Description of the 31 tribal and non-tribal endogamous populations studied.

a<p>- 2001 Census, Government of India, <a href="http://censusindia.gov.in/" target="_blank">http://censusindia.gov.in/</a>.</p>b<p>-1981 Indian Census.</p>c<p>-1931 Indian Census.</p>d<p>- Estimated census size.</p>e<p>-1901 Indian Census.</p>f<p>- All Brahmin-related castes in Tamil Nadu,</p>g<p>-No information available.</p>h<p>-Population code used in PCA & MDS plots,</p>i<p>-Sanskrit is the language of scriptures and ceremonies, but populations quickly adopted local cultures and languages.</p>j<p>-Lower, Middle & Higher social ranks are self-perceived/assigned classifications.</p>k<p>-Approximate coordinates.</p><p>NTN (North Tamil Nadu),TNV (Tirunelveli).</p><p>DR (Dravidian), IE (Indo-European).</p

Y chromosome haplogroup frequencies (%) in the 31 populations from Tamil Nadu.

<p>SD (Standard Deviation).</p

Analysis of molecular variance (AMOVA).

a<p> <i>P</i><0.00001.</p>b<p> <i>P</i><0.001.</p>c<p> <i>P</i><0.01.</p>d<p> No Significant, <i>P</i><0.2.</p><p>TR (Tribes), HTF (Hill Tribe Foragers), BRH (Brahmins), HTK (Hill Tribe Kannada speakers), SC (Schedule Castes), DLF (Dry Land Farmers), AW (Artisan & Warriors).</p><p>HG, MID, LOW – High, Middle and Low caste-rank hierarchy as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050269#pone-0050269-t001" target="_blank">Table 1</a>.</p><p>Endogamous populations were grouped based on geography, tribe-caste dichotomy, caste-rank hierarchy, and socio-cultural features mainly reflecting subsistence (7 Major Population Groups, MPG). The maximal genetic variation among groups (<i>F_CT</i>) and the minimal variation among populations within groups (<i>F_SC</i>) was observed when populations were grouped based on the 7 MPG classification.</p

Plots representing the genetic relationships among the 31 tribal and non-tribal populations of Tamil Nadu.

<p>(A) PCA plot based on HG frequencies. The two dimensions display 36% of the total variance. The contribution of the first four HGs is superimposed as grey component loading vectors: the HTF populations clustered in the direction of the F-M89 vector, HTK in the H1-M52 vector, BRH in the R1a1-M17 vector, while the HG L1-M27 is less significant in discriminating populations. (B) MDS plot based on 17 microsatellite loci <i>R_st</i> distances. The two tribal groups (HTF and HTK) are clustered at the left side of the plot while BRH form a distant cluster at the opposite side. The colors and symbols are the same as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050269#pone-0050269-g001" target="_blank">Figure 1</a>, while population abbreviations are as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050269#pone-0050269-t001" target="_blank">Table 1</a>.</p

Haplogroup variances and age estimates based on 17 microsatellite loci.

<p>Var (Variance), SE (Standard Error), SD (Standard Deviation).</p><p>Haplogroup age estimates are given in years; groups with less than 5 STRs (samples) were excluded from calculations. Non-tribal groups (castes) displayed the oldest age estimates for most of the Y chromosome haplogroups.</p

Reduced median network of 17 microsatellite haplotypes within haplogroup F-M89.

<p>The network depicts clear isolated evolution among HTF populations with a few shared haplotypes between Kurumba (HTK) and Irula (HTF) populations. Circles are colored based on the 7 Major Population Groups as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050269#pone-0050269-g001" target="_blank">Figure 1</a>, and the area is proportional to the frequency of the sampled haplotypes. Branch lengths between circles are proportional to the number of mutations separating haplotypes.</p