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PubMed1996

[Geography of effective size of rural populations of Northern Eurasia. Geographic correlation between effective size and level of heterozygosity of populations].

A significant geographical correlation (r = 0.719) was found between the logarithm of effective size (InNe) and heterozygosity level (H) in populations under the assumption of the Hardy-Weinberg equilibrium. The area of highest positive correlation was positioned meridionally between the Ob and Yenisei rivers, from the Arctic coast of Taimyr Peninsula to eastern Sayans and the southern Cis-Baikal region, i.e., in the same region where the highest distribution density of mean Ne values was found. Two additional areas of high correlations were found on the northern Black Sea coast and in the lower Lena river region. Analysis and mapping of correlation ratios eta H/lnNe2 and eta lnNe/H2 revealed that effective size substantially influenced heterozygosity level (as could be expected in the case of an intense gene drift), and heterozygosity level influenced effective size to the same extent. The latter relationship indicated an intense adaptation, and changes in diversity of the gene pool caused substantial demographic changes. However, this might be accounted for by direct gene migration into a population prevailing over reverse migration, i.e., mechanical population growth prevailing over natural growth.

Adaptation, Physiological↗
PubMed1996

Genetics, geography, and culture: the population of S. Pietro Island (Sardinia, Italy).

An interesting aspect of the island of Sardinia (Italy) is the wide range of genetic variability within the island itself. The variability is widened by the presence of some populations of different ethnic origin who speak a language other than Sardinian. This work deals with the study of the genetic structure of the Carloforte population which inhabits the tiny island of S. Pietro 4 km off the southwest coast of Sardinia. S. Pietro was first populated in 1738 by emigrants coming from the island of Tabarka (Tunisia) who spoke an archaic form of the Ligurian dialect. Data on genetic polymorphisms in the Carloforte population are presented and discussed in relation to some Sardinian and Italian populations. Data on demographic and matrimonial structure are also presented. The genetic analyses show the Carloforte population as being clearly separated from both Sardinians and continental Italians. The isolation of Carloforte, highlighted by language diversity, endogamy, and consanguinity levels and marriage area, supports the idea of genetic diversity linked to cultural peculiarity.

Alleles↗
PubMed1982

The contribution of time and local geography to craniofacial variation in Nubia's Batn el Hajar.

While the history of Lower Nubia has traditionally been explained in terms of racial migrations and mixture, recent studies of craniofacial variation have emphasized the biological continuity in Lower Nubia over the past 12,000 years. Carlson and Van Gerven for example have demonstrated a trend among the populations for changes in craniofacial form that are best explained by changing masticatory function and in situ evolution independent of major racial migrations. The purpose of the present research is to extend the analysis of craniofacial variation in Lower Nubia to a culturally and geographically distinctive region to the south known as the Batn el Hajar. Data for Lower Nubia were obtained in the field from 44 Meroitic, 94 X-Group, and 36 Christian crania during the 1964 Colorado Expedition to Nubia. Data from the Batn el Hajar were obtained from 188 crania excavated in 1979 at the Christian site of Kulubnarti which spans the entire Christian era from 550 to 1450+. Analysis of 12 metric variables using discriminant function revealed two sources of variation. The first is temporal and reflects the pattern of facial reduction previously reported for Lower Nubia. The second is geographic and suggests a morphological convergence between the people of Kulubnarti and Lower Nubia during late Christian times. This convergence reflects the southward migration of Lower Nubian Christians following the annexation of Lower Nubia by Islamic Egypt in the middle 15th century.

Biological Evolution↗
PubMed1985

Genetic variation in North Amerindian populations: the geography of gene frequencies.

Ten-level synthetic gene frequency maps derived from a principal component analysis of seven polymorphic loci are displayed for a large sample of North Amerindian populations. These maps are useful for assessing population affinities over broad geographical regions and perhaps, as others have argued, for inferring recent migrations. The influence of European admixture is investigated by deleting highly admixed populations and regenerating the maps. In broad outline the resultant geographic patterning, while appearing more homogeneous, preserves many features of the maps that include the highly admixed samples--especially with respect to the Eskimo/non-Eskimo dichotomy. Further, in an effort to evaluate how varying the number of display levels affects patterning as well as interpretation, the maps were replotted at 5 and 20 levels. The 5-level maps are found to accentuate differences between the full data set and the less admixed data set, while the 20-level maps tend to obscure these differences.

Gene Frequency↗
PubMed1989

Genetic variation within two linguistic Amerindian groups: relationship to geography and population size.

Nine Carib and eight Tupi groups were studied for a minimum of eight common polymorphic systems and compared in terms of genetic distances using the methods of Nei and Edwards. Two levels of genetic information were distinguished, one with a maximum of 20 loci and another with a maximum of 12 loci considered. The dendrograms produced consistent, reproducible results, independent of the method used, when a minimum of ten polymorphic systems were included in the analysis. Irrespective of the number of systems or the method used, the Tupi showed two to three times higher average interpopulation genetic distances than the Carib groups, which may be due to their lower average population sizes, allowing for the action of genetic drift and/or founder effects, as these two sets of populations do not differ significantly in geographic range, years of contact with non-Indians, or degree of acculturation.

Bolivia↗
PubMed1991

Dimensions of face in Asia in the perspective of geography and prehistory.

Data from 24 craniofacial dimensions were compiled for samples representing all the human populations of the world. These were converted into C scores and used to construct Euclidean Distance dendrograms. The populations of the world are best depicted as 8 major regional clusters representing: Africa, Amerind, Asia-Mainland, Australo-Melanesia, Eskimo-Siberia, Europe, India, and Jomon-Pacific. The mainland Asian cluster divided into northern and southern components. The Neolithic in both areas is less clearly associated with the northern or southern components and may represent the form of their undifferentiated precursors. This needs to be tested by the addition of further specimens and an adequate sample from South China. Mongols are peripheral members of the Asia-Mainland cluster and should not be thought of as typifying the region as a whole. The use of the term "Mongoloid" is inappropriate in both theory and practice.

Asia↗
PubMed1993

Gm haplotype distribution in Amerindians: relationship with geography and language.

A review is made of the Gm haplotype distribution in 60 groups of Eskimos, North, Central and South American Indians, totaling 22,808 individuals. Differences were observed in the shapes of the distribution of Gm*ag and the other markers. Nearly identical values for FST and average heterozygosities were obtained in the North+Central/South comparisons. North-South and Southwest/Northeast clinal differences were observed in the Americas using correspondence factorial analysis. The two haplotypes mainly responsible for these differences are Gm*axg and Gm*abOst. When the populations are classified by language groups, besides the recognized differences between Eskimos and Athabaskan (Na-Dene) speakers compared with Amerinds, others are found. For instance, Uto-Aztecan speakers of the United States and Mexico differ in Gm frequencies from the Nuclear Chibchan, Macro-Arawak, and Carib speakers of Central and South America. The notion of a homogeneous Amerind genetic pool does not conform with these and other results.

Computers↗
PubMed1992

The geography of non-ocular malignant melanoma in India: its association with latitude, ozone levels and UV light exposure.

Ultraviolet light from sunlight is implicated in the aetiology of non-ocular malignant melanoma, mostly from Western studies. This study reports the relation of such melanomas from 7 cancer registries in different parts of India with latitude, altitude, ozone levels and ultraviolet (UV) light exposure. A log linear model was fitted using GLIM, assuming Poisson errors in incidence; linear and non-linear regression techniques were also used. Results show slight negative associations of melanoma with latitude, chi 2 = -3.37, p = 0.07, and statistically non-significant ones with atmospheric ozone levels (r = -0.36, n.s.), and a positive association with UV (r = 0.30, n.s.). Melanoma incidence from 4 places relates in a parabolic curve with latitude (y = 1-0.09 chi 2 + 0.003 chi 2 in males and y = 1.73-0.17 chi 2 + 0.005 chi 2 in females). Patients originally from west coastal ethnic/linguistic communities predominate in Bombay. Geographic patterns of melanoma in Indians are similar with those in white Caucasians. Ultraviolet light exposure may also be involved in its aetiology in non-white Caucasians, such as Indians.

Atmosphere↗
PubMedDate not supplied

Primate hepatitis B viruses - genetic diversity, geography and evolution.

There are six well characterised genotypes (A-F) of human hepatitis B virus that have distinct geographic ranges which generally relate to chronic HBV infection. A seventh human genotype (G) has recently been described, but there is limited information on ethnic and geographic distribution. Despite the fact that early studies indicated that HBV antigens were present in other primates, the prevailing dogma that HBV was a human disease precluded alternative explanations. Within the past 5 years, hepatitis B viruses have been characterised from all the Old World great apes (orangutan, gibbons, gorillas and chimpanzees) and from a New World woolly monkey. Each group of non-human primates appears to have a distinct strain of hepatitis B virus that can be distinguished from human sequences based upon the nucleotide sequence and selected amino acid changes in the viral proteins. The woolly monkey HBV is most divergent from other primate and human sequences, while the great ape HBV sequences cluster together with separate branches for each group.

Animals↗
PubMed2006

The geography of power: statistical performance of tests of clusters and clustering in heterogeneous populations.

Heterogeneous population densities complicate comparisons of statistical power between hypothesis tests evaluating spatial clusters or clustering of disease. Specifically, the location of a cluster within a heterogeneously distributed population at risk impacts power properties, complicating comparisons of tests, and allowing one to map spatial variations in statistical power for different tests. Such maps provide insight into the overall power of a particular test, and also indicate areas within the study area where tests are more or less likely to detect the same local increase in relative risk. While such maps are largely driven by local sample size, we also find differences due to features of the statistics themselves. We illustrate these concepts using two tests: Tango's index of clustering and the spatial scan statistic. Furthermore, assessments of the accuracy of the 'most likely cluster' involve not only statistical power, but also spatial accuracy in identifying the location of a true underlying cluster. We illustrate these concepts via induction of artificial clusters within the observed incidence of severe cardiac birth defects in Santa Clara County, CA in 1981.

California↗
PubMed1994

Concerted evolution and RAPping in mitochondrial VNTRs and the molecular geography of cricket populations.

In recent years, many animal species have been shown to exhibit a variable number of tandem repeats (VNTR) in the control region of their mitochondrial DNA. To characterize the nucleotide polymorphism of a VNTR system, this region was sequenced in individuals from two species of crickets (genus Gryllus) collected at a mainland locality and an island locality within each species. The data reveal a clear pattern of concerted evolution: homogeneity among repeats within individuals and populations, but heterogeneity among the tandem arrays from divergent populations, and between species. The patterns of nucleotide polymorphisms within the arrays show several instances of partial homogenization where derived nucleotides have not swept through all the repeats in the array. These serve as examples of concerted evolution "caught in the act". Additional repeat associated polymorphisms (RAPs) shed light on the molecular basis of the insertion and deletion of repeat units and, with the concerted evolution of VNTRs, provide phylogeographic resolution of island and mainland populations within and between species. The polymorphisms within VNTRs also provide a simple system in which to examine the balance of mutation and drift and offer a unique view of the histories of genomic and organismal phenomena in the patterns and processes of molecular evolution.

Animals↗
PubMed1992

The geography of coracoclavicular joints.

On the basis of published anatomical and skeletal anthropological surveys supplemented by published and unpublished commissioned radiologic surveys, the distribution of coracoclavicular joints in the world is described. The findings are in keeping with a focus having developed in central Asia in Pleistocene times. Thus, this anatomical variant can serve, by regression, as a marker for population migration from prehistoric times to the present.

Anthropology, Physical↗