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PubMed1998

On the theory of partially inbreeding finite populations. V. The effective size of a partially selfing age-structured population.

Consider a large population, with the same age distribution at times 0, 1, 2, ..., in which there is reproduction by selfing with probability beta and by random mating with probability 1-beta. An individual between i and i + 1 units of age at time t is said to be in age group i at that time. Let L be the mean, among copies of an allele A in genotypes of offspring in age group 0, of ages of parents when the inbreeding coefficient has attained an equilibrium value. Then if there is no selection and allele A is originally present in one heterozygote, the probability that it is ultimately fixed is 1/(2N0L), where N0 is the number of individuals in age group 0 at any time. The effective population size can then be derived. It turns out to be the same as for a population with discrete generations having the same mean and variance of the number of successful gametes produced during a lifetime and the same number of individuals entering the population per generation.

Age Distribution↗
PubMed2000

Correlates of blood pressure in an urban Zimbabwean population and comparison to other populations of African origin.

We have evaluated the relationship between systolic blood pressure (SBP) and age, body mass index (BMI), waist circumference, sodium to potassium ratio (Na/K), and tobacco use in an urban African population. We conducted a random, population-based, cross-sectional survey of people 25 years and older in Marondera, Zimbabwe, with over-sampling in older age groups (n = 775), using a method comparable to that used in International Collaborative Study on Hypertension in Blacks (ICSHIB). The age-adjusted prevalences of hypertension in Marondera (SBP >/=140/DBP >/=90/antihypertensive medication) were 30% for women and 21% for men. The average BMI was 26.3 kg/m2 for women and 21.4 kg/m2 for men. The prevalence of hypertension had a steep association with age and in women ranged from 15% (25-34 years) to 63% (55 years and over) and in men from 9% to 47%. No tobacco use in women and greater Na/K ratio in spot urines in men were significantly associated with an increased SBP. In both men and women the levels of hypertension and SBP were strongly positively associated with BMI, although the relationship appeared to plateau in women with a BMI greater than >/=25 kg/m2. At a given BMI, men and women had similar SBPs and prevalences of hypertension. There is a very high prevalence of hypertension among urban Zimbabweans, particularly among women. Under the assumption the studies are comparable, the prevalence of hypertension in Zimbabwean women (41%) and men (26%) after age adjustment to the ICSHIB populations, appeared higher than almost all of the ICSHIB populations, including those with higher average body mass indexes. Journal of Human Hypertension (2000) 14, 65-73.

Adult↗
PubMed1999

Maximum-likelihood estimation of migration rates and effective population numbers in two populations using a coalescent approach.

A new method for the estimation of migration rates and effective population sizes is described. It uses a maximum-likelihood framework based on coalescence theory. The parameters are estimated by Metropolis-Hastings importance sampling. In a two-population model this method estimates four parameters: the effective population size and the immigration rate for each population relative to the mutation rate. Summarizing over loci can be done by assuming either that the mutation rate is the same for all loci or that the mutation rates are gamma distributed among loci but the same for all sites of a locus. The estimates are as good as or better than those from an optimized FST-based measure. The program is available on the World Wide Web at http://evolution.genetics. washington.edu/lamarc.html/.

Animals↗
PubMed2000

Empirical Bayes procedure for estimating genetic distance between populations and effective population size.

We developed an empirical Bayes procedure to estimate genetic distances between populations using allele frequencies. This procedure makes it possible to describe the skewness of the genetic distance while taking full account of the uncertainty of the sample allele frequencies. Dirichlet priors of the allele frequencies are specified, and the posterior distributions of the various composite parameters are obtained by Monte Carlo simulation. To avoid overdependence on subjective priors, we adopt a hierarchical model and estimate hyperparameters by maximizing the joint marginal-likelihood function. Taking advantage of the empirical Bayesian procedure, we extend the method to estimate the effective population size using temporal changes in allele frequencies. The method is applied to data sets on red sea bream, herring, northern pike, and ayu broodstock. It is shown that overdispersion overestimates the genetic distance and underestimates the effective population size, if it is not taken into account during the analysis. The joint marginal-likelihood function also estimates the rate of gene flow into island populations.

Algorithms↗
PubMed1999

Frequent occurrence of hypoalphalipoproteinemia due to mutant apolipoprotein A-I gene in the population: a population-based survey.

To determine the frequency of familial hypoalphalipoproteinemia in the general population due to mutation of the apolipoprotein A-I (apo A-I) gene, we analyzed sequence variations in the apo A-I gene. The subjects were 67 children with a low high-density lipoprotein (HDL) cholesterol level (</=38 mg/dl, below the fifth percentile in the population of this study) who were screened from 1254 schoolchildren through a school survey. Four different mutations with deleterious potential, three frameshifts and one splice site mutation, were identified in four of the subjects. The plasma apo A-I levels of the four children with apo A-I gene mutations were reduced to approximately half of the normal levels and were below the first percentile of the general population distribution (80 mg/dl). Thus, the frequency of hypoalphalipoproteinemia due to a mutant apolipoprotein A-I gene was estimated at 6% (95% CI: 2.4-14. 4%) in the subjects with low HDL cholesterol levels and 0.3% (95% CI: 0.1-0.8%) in the Japanese population. This suggests that familial hypoalphalipoproteinemia due to apo A-I gene mutations is relatively common.

Adolescent↗
PubMed2005

Estimation of effective population size and detection of a recent population decline coinciding with habitat fragmentation in a ground beetle.

We assess the impact of habitat fragmentation on the effective size (N(e)) of local populations of the flightless ground beetle Carabus violaceus in a small (<25 ha) and a large (>80 ha) forest fragment separated by a highway. N(e) was estimated based on the temporal variation of allele frequencies at 13 microsatellite loci using two different methods. In the smaller fragment, N(e) estimates ranged between 59 and a few hundred, whereas values between 190 and positive infinity were estimated for the larger fragment. In both samples, we detected a signal of population decline, which was stronger in the small fragment. The estimated time of onset of this N(e) reduction was consistent with the hypothesis that recent road constructions have divided a continuous population into several isolated subpopulations. In the small fragment, N(e) of the local population may be so small that its long-term persistence is endangered.

Animals↗
PubMed1999

Population based assessment of diabetic retinopathy in an urban population in southern India.

AIM: To assess the prevalence of diabetic retinopathy and the visual impairment caused by it in an urban population in southern India in order to determine its public health significance. METHODS: 2522 subjects (85.4% of those eligible), a representative sample of the population of Hyderabad city in southern India, underwent interview and detailed dilated eye examination during 1996-7 as part of the Andhra Pradesh Eye Disease Study. RESULTS: 124 subjects, all >/=30 years old, reported that they had diabetes, an age-sex adjusted prevalence of 7.82% (95% confidence interval (CI) 5.76-9.88%) in this age group. Diabetes was diagnosed at age >/=30 years in all but two subjects. The duration since diagnosis of diabetes was <10 years in 75.6% and >/=15 years in 6.7%. Diabetic retinopathy was present in 28 subjects, 1.78% (95% CI 1.09-2.48%) of those >/=30 years old. Most of the diabetic retinopathy was of the mild (50%) or moderate (39.3%) non-proliferative type; one subject (3.6%) had proliferative retinopathy. Multiple logistic regression revealed that the odds of having diabetic retinopathy were significantly higher in those >/=50 years than in those 30-49 years old (odds ratio 7.78, 95% CI 2.92-20. 73). Three subjects had visual impairment between 6/12 and 6/38 in either eye due to diabetic retinopathy, 0.19% (95% CI 0-0.41%) of those >/=30 years old. CONCLUSION: Visual impairment due to diabetic retinopathy was relatively uncommon in this urban Indian population in 1996-7. However, this could change in the near future with an increase in duration of diabetes because of the anticipated aging of India's population and the recent suggestion of increase in diabetes prevalence in urban India, and therefore should be monitored.

Adult↗
PubMed2006

Eye care utilization patterns in Tehran population: a population based cross-sectional study.

BACKGROUND: The aim of this study is to determine eye care visits which are an indicator of eye care service utilization by Tehran population and its determinants. METHODS: Through a population-based, cross-sectional study, 6497 Tehran citizens were sampled. All participants had complete eye examinations and an interview regarding demographic and socioeconomic status variables, past medical and eye history, and their previous and last eye care visits. RESULTS: Among those sampled, 4565 people participated in the study (response rate of 70.3%). Among these participants, 34.7 % had never visited an ophthalmologist or optometrist (95% confidence interval [CI]: 32.4 to 36.9) and 43.2% had not seen an eye care provider in the last 5 years. Multivariate logistic regression revealed that men (OR = 1.30), younger participants (each year increase in age: OR = 0.98) and the less educated (each year increase in education: OR = 0.93) were more likely, and the visually impaired were less likely (OR = 0.41) to have neglected eye care. CONCLUSION: A large proportion of the population, including those in the high risk group who require eye care, has never utilized any eye care service. These data suggest that efforts have to be made to better understand the causes and to optimize the utilization of the available eye care services in the population.

Adolescent↗
PubMed2005

Relating results of chronic toxicity responses to population-level effects: modeling effects on wild Chinook salmon populations.

Standard toxicity tests assess the physiological responses of individual organisms to exposure to toxic substances under controlled conditions. Time and space restrictions often prohibit the assessment of population-level responses to a toxic substance. Compounds affecting various toxicity endpoints, such as growth, fecundity, behavior, or immune function, alter different demographic traits and produce different impacts on the population. Chronic effects of immune suppression, reproductive impairment, and growth reduction were examined using life history models for Chinook salmon (Oncorhynchus tshawytscha). Modeled immune suppression acted through reductions in age-specific survival, with first- and second-year survival producing the greatest changes in the population growth rate (lamda). A 10% reduction in various reproductive parameters all produced a similar lamda, but different sensitivity and stable age distributions. Growth reduction models incorporated effects to both survival and reproduction and produced additive effects. Overall, model output indicated that for Chinook salmon, alteration of first-year survival has the greatest relative impact on lamda. Results support the importance of linking toxicity endpoints to the demographic traits that they influence and help generate toxicity tests that are more relevant for the species. Life history modeling provides a useful tool to develop testable hypotheses regarding specific and comparative population-level impacts.

Animals↗
PubMed1999

[Genetic-demographic processes in urban populations of the Ukraine in the 90's. The marital structure of the Poltava population].

Analysis of records of the marriages that were contracted in the city of Poltava revealed an increase in outbreeding between 1960 and 1985 in the Poltava population. This was expressed in increased ethnic diversity, proportion of interethnic marriages, migration range, and the parent-offspring and average marital distances, whereas the proportion of the indigenous ethnic group (Ukrainians) decreased. By 1995, outbreeding decreased: the ethnic composition of the population became more homogeneous (98% Slavic), the proportion of Ukrainians and the frequency of monoethnic marriages increased, and the migration range decreased. During the period studied, the population became more panmictic with respect to ethnicity and birthplace, with the social and professional subdivisions of the population remaining unchanged.

Demography↗
PubMed1996

[Assimilation and bending over the nationality of the Czechoslovak population in light of population censuses, 1950-1991].

"The annual balances of population by nationality (live births by mother's nationality, deceased and migrants by their nationality) [allow us] to calculate the volume of nationality assimilation after each population census as well as so called ¿bending over of nationality' [declaring a nationality not one's own] when we compare the balance and the results of population census by nationality.... The author analyzes probable causes of assimilation processes among individual population censuses in Czechoslovakia on the basis of such processes in the Czech and in the Slovak part of the previous Czechoslovak federation...." (SUMMARY IN ENG)

Acculturation↗
PubMed1990

[Comparison of parameters and factors affecting the differences in obesity among urban population of Warsaw and the rural agricultural-industrial population of the Tarnobrzeg province].

Comparison of the parameters of obesity between two populations, urban from Warsaw and agricultural-industrial from Tarnobrzeg province revealed that skinfolds thickness, Quetelet index and body fat index, and per cent of overweight were statistically significantly higher in men from urban population. In the group of women these parameters were also statistically higher in Warsaw population with the exception of triceps skinfold and Quetelet index--differences of no statistical significance. There were also differences in the set of variables which correlate with the parameters of obesity between these two tested populations.

Adipose Tissue↗
PubMed1980

[Population studies of hypertension in 2 populated areas].

A population-genetic study on the population of the mountainous villages, in the Rhodopes, was carried out, aiming at the elucidation of the incidence of hypertonic disease (HD), depending on the effect of hereditary factors and risk environmental factors. The values of systolic and diastolic arterial pressure among the population from both villages are distributed in Gauss--Laplacian curves, as a result from the effect of multiple poligens. In one of the villages, the mode of life of the population is considerably close to that of a modern town, hence the risk environmental factors, originated by technization and urbanization, have a stronger effect and as a consequence HD incidence observed is higher--10.05 per cent, whereas in the other village--in the absence of those factors--its incidence is 7.18 per cent. The same are the reasons, in the first village, that affect the females more often than the males (p less than 0.001) and a tendency is obvious for a considerable shift of the disease to an earlier age. In both villages a very low percentage of patients with HD were found that were insensitive to the bitter taste of phenylthiocarbamide.

ABO Blood-Group System↗
PubMed1997

Intercensal population change in the Belfast urban area 1971-91: the correlates of population increase and decrease in a divided society.

"This paper analyses population change in the Belfast Urban Area (BUA) [of Northern Ireland] between 1971 and 1991 in its socio-economic context to understand the nature of urban social change. Although considering religious factors as a cause of population change, the research compares the BUA with other urban areas and relates developments in Belfast to some literature on sociospatial polarisation and the ¿underclass'.... The results suggest that population change is not driven by explicitly religious factors, the relationship between religion and socio-economic well-being has changed, and that changes in religious mixing and segregation occur in many contexts. The BUA is like other urban areas, albeit with unique features arising from the influence of religion."

Demography↗
PubMed1986

[Three projections of population decline for Quebec: characteristics and implications for the working population].

"After a brief review of various projections of population decline for Quebec, the author analyses some previous examples of depopulation, and emphasizes that public opinion will have to change much if immigration is to be used as a tool for avoiding population decline. He then investigates four implications of the projected decline: the size of the working population, its age and sex structure, the labor force participation ratio, and the economic dependency ratio." (SUMMARY IN ENG AND SPA)

Age Factors↗
PubMed1992

[Dynamics of numerical changes in human population in terms of animal population ecology].

The author uses data concerning the natural regulation of population size and growth among animals to consider possible future scenarios for human population growth. Four possible variants are considered: "numerical stabilization and its consequences connected with density effect; sharp slump caused by a global ecological catastrophe; limited slump brought about by exhaustion of resources and environmental pollution; numerical decrease through birth regulation. It has been shown that only the last variant can, in [the] case of the human population being 1.2-1.5 billion people, ensure restoration of [the] biosphere with keeping [the] existing tempo of scientific-technological progress." (SUMMARY IN ENG)

Demography↗
PubMed1976

Training public school teachers in population dynamics: An evaluation of the urban life-population education workshops in Baltimore.

Nine population education workshops were held for city school teachers in Baltimore, Maryland during the 1972-73 academic year. The original program schedule was modified two times, at the end of the third workshop and the sixth. Each change resulted in fewer formal presentations, more teacher discussions and greater teacher involvement in the workshop program. From the ideas generated by the workshops, curriculum units suitable for elementary and secondary school students were produced. An evaluation of the program showed that teachers' knowledge of selected demographic concepts and facts increased between the pre-workshop period and the post-workshop period. The changes were greater in the later workshops. The changes in knowledge were statistically significant. While there was some regression to pre-test levels, the teachers retained a substantiol portion of the knowledge they received when measured a second time after the workshop. High school teachers showed greater effective changes in knowledge than lower grade teachers. However, interest in population education appears to be wide-spread among all teachers including lower grade teachers. It is suggested that in the future, programs in population education consider conducting separate workshops for teachers of the same or similar grade level.

Curriculum↗
PubMed2006

mtDNA variation in Inuit populations of Greenland and Canada: migration history and population structure.

We examined 395 mtDNA control-region sequences from Greenlandic Inuit and Canadian Kitikmeot Inuit with the aim of shedding light on the migration history that underlies the present geographic patterns of genetic variation at this locus in the Arctic. In line with previous studies, we found that Inuit populations carry only sequences belonging to haplotype clusters A2 and D3. However, a comparison of Arctic populations from Siberia, Canada, and Greenland revealed considerable differences in the frequencies of these haplotypes. Moreover, large sample sizes and regional information about birthplaces of maternal grandmothers permitted the detection of notable differences in the distribution of haplotypes among subpopulations within Greenland. Our results cast doubt on the prevailing hypothesis that contemporary Inuit trace their all of their ancestry to so-called Thule groups that expanded from Alaska about 800-1,000 years ago. In particular, discrepancies in mutational divergence between the Inuit populations and their putative source mtDNA pool in Siberia/Alaska for the two predominant haplotype clusters, A2a and A2b, are more consistent with the possibility that expanding Thule groups encountered and interbred with existing Dorset populations in Canada and Greenland.

Canada↗