Further, the two marker types exhibit largely differing mutation rates e. Mutations generating biallelic SNPs are usually considered to be unique events in the Y-chromosomal phylogeny, which makes them ideal candidates for the analysis of events dating deeply back in human history and evolution . When investigated at the level of these slowly evolving markers, the Y-chromosomal landscape in Europe is largely shaped by the markedly differing and complementary dispersal patterns of two major clades R1a and R1b R-M  , .
Haplogroup R1b reaches its modal frequency in the west and north-west of Europe and shows a decline toward the east and the Balkans, whereas Y chromosomes belonging to haplogroup R1a and here especially to the dominant R-M17 R1a1a lineage complement this picture by reaching the highest frequencies in the east of the continent  — . In this study, the proportion of Y chromosomes carrying the derived M17 allele was Haplogroup R-M R1b accounted for Even more pronounced differences became evident when analyzing regions A and B separately.
In regions A and B haplogroup R-M reached frequencies of North Tyrol. The opposite applied to the sub-sample from region B. At a higher haplogroup resolution, the distribution pattern within R-M became more complex. None of these differences proved statistically significant Table S7.
At the probands and fathers level of analysis region A featured approximately fourfold higher frequencies of these chromosomes than region B. These contrasts remained statistically significant after correcting for multiple comparisons  at the fathers and grandfathers analysis level. The significance of these findings for an understanding of the phylogeographic variation of human Y chromosomes in East Tyrol remains unclear. Y chromosomes exhibiting the derived base state at the M locus constituted one of the major groups in East Tyrol. In this study, Obviously, this balanced frequency distribution did not provide easy to interpret information in respect of our attempt to shed light on the significance of historical events on the present-day Y chromosome variation in East Tyrol.
Y-STRs are evolving at a much higher rate than Y-SNPs and are therefore considered the better choice for the population genetic investigation of more recent historical events  , . In an initial attempt to test for spatial genetic structuring in the distribution of the East Tyrolean Y-STR haplotypes, a spatial autocorrelation analysis  ,  was performed using present-day road distances as geographic and F ST as well as S H UA as genetic distance measures.
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This picture, however, was probably obscured by the low number of individuals sampled for the majority of municipalities. However, for both genetic distance measures visual inspection of the correlograms failed to provide evidence for non-random spatial genetic patterning Fig. Hence, in contrast to the Y-SNP haplogroup data this haplotype based approach did not yield convincing data in favor of a segmentation of East Tyrol's present-day Y-chromosomal landscape.
Nevertheless, additional attempts were undertaken at the Y-STR haplotype level to test for a potential geographic segmentation pattern of East Tyrol's Y chromosomes that still might bear an imprint of East Tyrol's early history. Aside from being convenient, the use of a commercially available and widely used kit for Y-STR typing made it easier to find suitable haplotype data sets for comparisons as well. Principal coordinates analysis was performed to map the relationships among the genetic distances. The reference populations clearly clustered by language along principal coordinate 1 and the combined East Tyrolean data set closely matched with the Germanic group Fig.
Analysis of the partitioned East Tyrolean sample, however, allocated the region A subsample to the Romance speaking populations and the region B Y chromosomes to the Germanic cluster, regardless of the applied distance measure Fig. Subdividing the East Tyrolean sample showed an astonishingly clear effect on the subsample from the former Romance main territory region A. However, a major part of the Y-SNP signal that differentiated the two subsets from regions A and B came from haplogroup R-M17, which constituted one of the most frequent clades in East Tyrol.
Hence, an overrepresentation of R-M17 chromosomes should be expected for the small sample from region A rather than their complete lack in this area. However, too optimistic population frequency estimates for haplogroup R-M and its subgroups can not be fully excluded for region A. Yet, the overall frequency of R1b chromosomes appeared too high to be solely explained by random ascertainment error.
Marked genetic drift due to a small effective population size is a factor that is known to cause population differentiation. Thus, we set out to roughly assess its significance for the Y-chromosomal distribution pattern we observed in region A. The sample numbers were particularly low for the Gail and the Villgraten valleys. Therefore, this approach allowed only for the exclusion of a pronounced effect of genetic drift acting differently in the three valleys. However, a more differentiated picture was gained by the analysis of the differences in allelic variability among the three major R1b sub-haplogroups.
R-M exhibited on average in both regions only about 2 different Y-STR alleles per locus haplotype.
An equivalent picture was obtained for these three R1b subgroups when looking at of the average number of multiple-step neighbors per pairwise haplotype comparison. Again, the differences between the two East Tyrolean sub-samples were small. However, neither of them convincingly explained the marked geospatial structuring of modern Y chromosomes.
Therefore, we suggest that the question of whether or not the segmentation of East Tyrol during its early history of settlement, as deduced by the frequency distribution of the Romance and Slavic etymons of pasture names, still correlates with the Y-chromosomal landscape in present-day East Tyrol, can be positively answered for the region of ancient Roman main settlement region A , even centuries after the Romance language was completely replaced by the Bavarian dialect brought to East Tyrol by the Germanic speaking people.
For Y chromosomes from region B area of ancient Slavic main settlement , however, no indication for a clustering with the Slavic speaking reference populations was detected. Beyond these findings, the results obtained for the Y chromosomes sampled in region A, in particular, demand an explanation. Does the lack of haplogroup R-M17 still relate to the outcome of the battle of Aguntum in the year , which stopped the westbound Slavic settlement in East Tyrol ?
How can we explain the striking clustering of the haplotypes from region A with the reference samples from Romance speaking populations? The clear phylogeographic differentiation between regions A and B takes place at the microgeographic scale. For instance, the average pairwise road distances among municipalities in the lower Drau, Virgen, and Defereggen valley all region B , and in the Puster and Gail valley both region A amount to about 40 km and 22 km, respectively Table S6.
Onomastic analysis of the probands' family names revealed no indication of significant immigration to East Tyrol from the Romance speaking neighbouring areas since the common usage of surnames in the 14 th century. This is corroborated by the high degree of patrilocality that can be deduced from the personal information regarding the fathers and paternal grandfathers provided by the blood donors and dating back to the 19 th century.
Thus, significant migrational events that took place within the last years can be excluded as an explanation for our findings. The phylogeographic signal therefore must root deeper in time. Demographic conditions limiting the effective population size are known to have been a factor in Tyrol until the beginning of the 20 th century. For instance, in the 's the average annual rate of marriages was about 0.
In , tight restrictions became effective that precluded all persons without a secure income from marriage. This regulation was particularly strict for non-residents. As a consequence, the average annual number of marriages per residents dropped to less than five until . Due to an exceptionally low illegitimacy rate of about 0. The typical age at marriage was high for both sexes and both the annual birth rates and the infant mortality rates were relatively low in Tyrol . In the 19 th century the birth rates approximated over time the mortality rate, which caused, in combination with a latent outflow of people, a reduction in population growth rates.
The sparse historical facts covering the early times of settlement in East Tyrol and later on, allow us only to speculate about the demographic processes that shaped the Y-chromosomal landscape in East Tyrol. However, linguistic science provides strong support for a long-term seclusion of the East Tyrolean area, since the archaic structure of the indigenous vernacular reflects only little influence from the surrounding dialects .
It seems reasonable to assume that in a small, agriculturally dominated alpine area, philopatric men e.
Our results suggest cultural diffusion rather than population replacement as the underlying mechanism for the complete transition from a Romance to a Germanic speaking population in the southwestern part of East Tyrol. Further, the outcomes of this study formidably demonstrate how largely differing disciplines can complement each other. Here, the toponomastic analysis of pasture names provided essential and otherwise unavailable information for the detection, analysis, and interpretation of a marked substructuring in a population of human Y chromosomes initially considered homogeneous.
Binary Y-SNP haplogroup tree. Phylogenetic tree depicting the relationships among the binary Y-chromosomal haplogroups defined by the 27 SNPs analyzed in this study. Intergenerational migration distances. Year of birth statistics. Box-and-Whiskers plots summarizing the probands', their fathers', and paternal grandfathers' year of birth statistics.cajas2.barrica94.cl/map15.php
The whiskers depict the lowest highest datum falling within the 1. Data points outside the 1. Spatial autocorrelation analysis. Correlograms plotting the spatial autocorrelation coefficient r as a function of geographical distance class. Spatial structuring is inferred when the measured r value for a particular distance class falls outside this belt. Geographical distances represent present-day road distances between municipalities. Principal coordinates analysis at the fathers-level.
Principal coordinates analysis at the grandfathers-level. Y-SNP marker related information. Supporting information regarding the binary Y-chromosomal markers analyzed in this study. The sequences of the primers used for PCR amplification and sequencing were either taken from the literature  ,  —  or designed in-house. Oligonucleotides used for plex single nucleotide primer extension.
The primer sequences were either taken from the literature  —  ,  or designed in-house. Amplicon sequences. Overview of the sequences of all PCR products generated for genotyping the haplogroup diagnostic Y-SNPs  ,  ,  ,  ,  — . PCR primer binding regions are depicted by upper case, bold face letters, those for single base extension primers are underlined.
SNP positions are shown in parentheses. Sampling statistics.
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