18 research outputs found
Population genomics of post-glacial western Eurasia.
Western Eurasia witnessed several large-scale human migrations during the Holocene <sup>1-5</sup> . Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes-mainly from the Mesolithic and Neolithic periods-from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a 'great divide' genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 BP, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 BP, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a 'Neolithic steppe' cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations
Spatial autocorrelation of tree attributes in naturally regenerated managed beech (Fagus sylvatica) forests in the Beskid Niski Mountains, southern Poland
European beech (Fagus sylvatica L.) is a widely distributed forest tree species in central, southern
and western Europe. In Poland it reaches the eastern limit of its natural range. The three forest stands
selected for the analysis presented here are located in the Dukla Forest Inspectorate, southern Poland in
the Beskid Niski Mountains. The measurement plots were rectangular, 0.35 ha each, established under
homogenous conditions. The origin of all stands is natural and up to now they were thinned several times
according to selective thinning method. The main tree species on each plot is European beech. In each stand
(x, y) coordinates, the species, total heights of trees and their diameters at breast height were recorded.
Total tree height, diameter, basal area and tree volume were considered as marks in statistical analysis. The
aim of this paper is to find out the differences in the spatial autocorrelation of different tree marks as well
as to explain the reasons for differences if they were observed. The empirical mark correlation functions indicated
that there is a negative spatial correlation of all these marks in all three forest stands, i.e. trees close
together tend to have smaller marks than the average in the stand. No significant spatial correlation was
found for the tree heights. Diameter, basal area and volume show some correlation, but only in one stand
a deviation test showed that the detected spatial correlation is significant. The mark variograms indicated
that neighboring trees tended to have similar sizes
HEALTH-RELATED QUALITY OF LIFE OF PEOPLE ATTENDING SCREENING FOR DIABETIC RETINOPATHY WITHIN A TRIAL SETTING
Poster presented at EASDec 201
The greater growth rate of male over female of the dioecious tree Juniperus thurifera only in worse habitat conditions
Dioecy is a mating system in which a greater reproductive effort has been observed in one sex than
the other. This is expressed in differences between the sexes in growth rate and spatial segregation. The spatial
structure of Juniperus thurifera subsp. thurifera and Juniperus communis subsp. communis and growth rate of
tree-ring width of J. thurifera were tested in different habitat conditions in Santo Domingo de Silos in northern
Spain. We analyzed junipers growing on the eastern slope, with better habitat conditions, and the western,
with poorer habitat conditions. The studies found that males of J. communis were taller when compared to the
females, both on the eastern and the western slope. J. thurifera females were taller on the eastern slope (the
better habitat), but shorter on the western slope as compared to males. J. thurifera males and females on the
eastern slope had the greater tree-ring width in comparison with those on the western slope. The annual
tree–ring width of males dominated over females on both slopes at first, probably from the time of sexual
maturation. However, these differences persisted to the end of the analyzed period only on the poorer western
slope. The growth rate of females and males after several years was equal on the eastern slope. Spatial segregation
has not been shown, probably due to the homogeneity of the habitat on both slopes. Studies have
shown that the decrease of growth rate in J. thurifera females can occur only in the poorer habitat conditions