Geographic Divergence in Mortality in the United States

The United States trails other developed countries in adult mortality, a process that has become more pronounced over the past several decades. However, comparisons are complicated by substantial geographic variations in mortality within the United States. The second half of the twentieth century was characterized by a substantial divergence in adult mortality between the South and the rest of the United States. The article examines trends in US geographic variation in mortality between 1965 and 2004, in particular the aggregate divergence in mortality between the southern states and states with more favorable mortality experience. Relatively high smoking‐attributable mortality in the South explains 50–100 percent of the divergence for men between 1965 and 1985 and up to 50 percent for women between 1985 and 2004. There is also a geographic correspondence between the contribution of smoking and other factors, suggesting that smoking may be one piece of a more complex health‐related puzzle.     

Habitat fragmentation promotes fluctuating asymmetry but not morphological divergence in two geckos

The process of species formation is often ignored in discussions on the conservation of biodiversity. Yet the clearance of vegetation may promote divergence among populations of a species through isolation, providing conditions for rapid genetic drift and novel selection pressures. Here, stepwise discriminant function analysis and fluctuating asymmetry are used to examine variation in morphology within and among non fragmented and recently fragmented populations of two species of gecko,Oedura reticulata andGehyra variegata. High reclassification error rates using discriminant function analysis, indicate that fragmentation has had no detectable effect on morphological differentiation among populations of either species. In contrast, remnant populations of both species exhibit higher mean levels of fluctuating asymmetry than do populations in undisturbed habitat. ForOedura reticulata, levels of fluctuating asymmetry are negatively correlated with the log of adult population size. These results suggest that the changes following habitat clearance have been severe enough to cause increased developmental instability in populations of both species but not detectable morphological divergence. Given the high rate of extirpation of gecko populations in the study region and the extreme vulnerability of the remaining populations, it is unlikely that species formation will be significant in maintaining reptile diversity in that region.     

Resolution of evolutionary conflict: a general theory and its applications

While many cases in which conflict over the evolution of social behavior exists even between closely related individuals (e.g., parent-offspring conflict) have been pointed out, little attention has been paid on the problem of where such conflict should lead. A general theory of conflict resolution, however, has recently been developed. The key idea of the theory is the incorporation of conflict costs in the inclusive fitness evaluation. The theory shows that if both sides engaged in the conflict can potentially control the other at a cost, the coevolutionary game of escalating the fight with increased conflict costs always leads either side to give in to the other, resolving the conflict. Here we examine the logical basis of the theory in terms of a simplest example, donor-recipient conflict over the evolution of altruism, and to show its different types of application we review two more specific examples: reproductive-worker conflict over true (sterile) worker evolution in termites and insider-outsider conflict over group size determination. The latter exemplifies the resolution of conflict over the value of a variable (group size in this case) rather than a behavior, suggesting extended applicability of the basic theory.     

Establishing trends in atsic regional council populations using census data: A cautionary note

This paper points out that limitations in official census data for Aborigines and Torres Strait Islanders draw into question the validity of trend analysis based on time series data for Aboriginal and Torres Strait Islander Commission (ATSIC) regional council areas. Accordingly, the meaningful application of projection techniques to estimate future population profiles using existing census data is severely restricted. Among the difficulties encountered in reconstructing council area populations are census boundary changes over time, changes in enumeration techniques and coverage, the problems posed by self-identification and associated population growth, and, in some cases, the difficulty of matching ATSIC regional council boundaries with census geography. Following discussion of these problems, detailed figures showing changes in the size of the Aboriginal and Islander populations and labour force in each council area are presented using 1976 as the base year. As expected, geographic patterns of population and labour-force change are difficult to discern and exact reasons for comparative growth or decline are impossible to determine. The paper concludes that reverse projections for regional council areas using 1991 Census data would provide a more reliable basis for establishing demographic trends. Although not entirely adequate, these reconstructions for ATSIC regional councils are the only estimates of these populations that have been undertaken to date.     

Shifts in Reproductive Patterns in China

The People's Republic of China, during the second half of the twentieth century, has been repeatedly affected by social and political upheavals associated with government policies. These have produced strong but unexpected impacts on Chinese demographic patterns. Many of these policies are of the sorts that alter reproductive costs and benefits. This study examines patterns in Hebei, Shaanxi, and Shanghai, three provinces with differing ecological, geographic, and economic characteristics. Government policies affected the three populations differentially; this was evident at both aggregate and individual levels. The Great Leap Forward and subsequent famine created higher birth deficits and mortality among the largely rural populations of Hebei and Shaanxi than the more urban Shanghai. In contrast, the Cultural Revolution and family planning resulted in lower fertility levels for women in Shanghai. The population history of China during the second half of last century thus reflects strong state interventions in the lives of its citizens. Government policies, along with regional variations in geographic, social, and economic conditions, strongly influence individual access to resources in China. Variations in timing and intensity of women's reproductive patterns reflect differential access to resources and subsequent trade-offs.     

(Un)natural disaster: vulnerability,long-distance displacement,and the extended geography of neighborhood distress and attainment after Katrina

After Hurricane Katrina, socioeconomically vulnerable populations were slow to return to their poor and segregated pre-disaster neighborhoods. Yet, very little is known about the quality of their post-disaster neighborhoods. While vulnerable groups rarely escape neighborhood poverty, some Katrina evacuees showed signs of neighborhood improvement. The current study investigates this puzzle and the significance of long-distance moves for neighborhood change among participants in the Resilience in the Survivors of Katrina Project. Seven hundred low-income, mostly minority mothers in community college in New Orleans before Katrina were tracked across the country a year and a half later. The findings show that respondents’ immediate and extended neighborhoods and metropolitan areas after Katrina were less disadvantaged, less organizationally isolated, and more racially and ethnically diverse compared to their pre-hurricane environments, and to the environments of those staying or returning home. Counterfactual analyses showed that more than within-neighborhood changes over time, between-neighborhood mobility and long-distance migration decreased respondents’ exposures to distress in their neighborhood, extended geographic area, and metropolitan area.     

AN INVESTIGATION OF GENERALIZED RAKINGIN THE SYNTHETIC ESTIMATION OFPOPULATION SIZE

The problem of counting a population that is cross-classified with respect to demographic and geographic attributes is considered. A census is conducted in which individuals are “captured” with probabilities that are believed to be relatively constant within demographic categories. The census is followed by a random sample in which individuals are “recaptured” independently of the census. Using the two counts, capture-recapture estimates of the demographic category populations are obtained. A synthetic estimate of population size for a geographic entity is obtained by summing the corresponding adjustment factors (capture-recapture estimates divided by census counts) across all individuals captured by the census in the entity. The use of generalized raking is considered as a method for smoothing adjustment factors. It is found that generalized raking differs little from a class of weighted least squares regression models. This suggests that generalized raking does not offer an improvement over regression for smoothing adjustment factors. The efficiency loss of generalized raking relative to the best regression-based procedures can be substantial.     

The population dynamics of the voleClethrionomys rufocanus in Hokkaido, Japan

Population dynamics of the gray sided-vole,Clethrionomys rufocanus, in Hokkaido, Japan were described on the basis of 225 time series (being from 12 to 31 years long); 194 of the time series have a length of 23 years or longer. The time series were classified into 11 groups according to geographic proximity and topographic characteristics of the island of Hokkaido. Mean abundance varied among populations from 1.07 to 21.07 individuals per 150 trap-nights. The index of variability for population fluctuation (s-index) ranged from 0.204 to 0.629. Another index for population variability (amplitude on log-10 scale) ranged from 0.811 to 2.743. Mean abundance and variability of populations were higher in the more northern and eastern regions of the island. Most populations, except for the southernmost populations, exhibited significant direct density-dependence in population growth. Detection rate for delayed density-dependence varied among groups from 0% to 22.6%. Both direct and delayed density-dependence tended to be stronger in the more northern and eastern populations. The proportion of cyclic populations was higher in the northern-eastern areas than that in the southern-western areas. There was a clear gradient from the asynchronous populations in southwest, to the highly synchronized populations in the northeast.     

On the Decline of Marriage in Rural Ireland 1851–1911: The Role of Ecological Constraints and/or Developing Philopatry

The proportion of people who never married and the age at first marriage increased in rural Ireland after the famine (1845–1847). In 1851, 11% of the population were never married at 45–54 years and this percentage increased steadily over time to 34% for men and 25% for women in 1936. The period from 1851 to 1911 was marked by economic progress, and despite some bad years, production, incomes and standards of living increased steadily. Ownership of land, passing from landlord to tennant, thus fixed the population to specific geographic locations and made the rural population increasingly philopatric. The Ecological Constraints Hypotheses (E.C.H.). has been used to explain the low marriage rate. It asserts that delayed dispersal and reproduction are caused by constraints such as a lack of access to resources such as land or mates. However in rural Ireland, wealthy heads of households were more likely to be celibate than occupiers of small holdings. The low nuptiality that developed after the famine appeared first in the more prosperous parts of Ireland and was accompanied by a substantial rise in living standards. The increasingly secure tie after the famine between the rural population and its geographic location reflected a new ecological situation which facilitated a change in reproductive strategy that was characterised by delayed marriage and an increase in celibacy. This strategy is adaptive in a stable ecology without major threats to survival. The data are consistent with evidence from animals and human populations showing associations in a stable ecology between long life expectancy, low population turnover and low fecundity, yet a rate of reproduction that is sufficient to maintain the population in its environment.     

[An analysis of the sex ratios at birth of China].]

The sex ratio at birth in China is analyzed using data from the 1982 census. The focus is on geographic differentials in sex distribution and the impact of population density on those differentials. Findings indicate that the sex ratio at birth was lower in urban populations than in rural populations.     

A probability model for census adjustment

The census can be adjusted using capture‐recapture techniques: capture in the census, recapture in a special Post Enumeration Survey (PES) done after the census. The population is estimated using the Dual System Estimator (DSE). Estimates are made separately for demographic groups called post strata; adjustment factors are then applied to these demographic groups within small geographic areas. We offer a probability model for this process, in which several sources of error can be distinguished. In this model, correlation bias arises from behavioral differences between persons counted in the census and persons missed by the census. The first group may on the whole be more likely to respond to the PES: if so, the DSE will be systematically too low, and that is an example of correlation bias. Correlation bias is distinguished from heterogeneity, which occurs if the census has a higher capture rate in some geographic areas than others. Finally, ratio estimator bias and variance are considered. The objective is to clarify the probabilistic foundations of the DSE, and the definitions of certain terms widely used in discussing that estimator.     

Estimating Mortality Level for Small Populations: An Evaluation of a Pair of Two-Census Methods

A pair of two-census methods of estimating mortality levels are tested with simulated census data. The populations considered range in size from 250 to 1500 individuals of each sex; censuses were taken at intervals of five and ten years. In general, the methods are resistant to bias, and yield variances similar in magnitude to those obtained using vital registration data and life table techniques for censored data. The two-census methods represent a substantial improvement over the techniques of mortality estimation previously available for small populations, since two reliable censuses are more likely to be available for these populations than complete vital registration.     

Risk-Taking Behaviors of Gay and Bisexual Men in New York City Post 9/11

Until now, the reactions of gay and bisexual populations have been largely overlooked in response to terror and disaster. This study assesses risk-taking behaviors in gay and bisexual men two weeks before and after the 9/11 attacks in Manhattan. For the purposes of this study, risk-taking behaviors include drug use and unprotected anal sex. These behaviors and associated desires were examined in relation to race/ethnicity, age, geographic location, and HIV status, within and across time. The results of this study demonstrate that HIV status may be a pivotal demographic feature in understanding risk-taking behaviors post disaster. No changes in drug use were reported pre and post 9/11. However, there was an increase in risky sexual behaviors in relation to serostatus, with HIV-positive men reporting a higher number of sexual partners post 9/11. In contrast, the number of sexual partners remained constant in HIV-negative men. There was also an interaction effect, demonstrating that HIV-positive men were more likely than HIV-negative men to act on their desire for sex. Thus, as a population already faced with the prospect of death, HIV-positive men may be a population more vulnerable in the face of terror and disaster.     

Stability of environment and of insect populations

Summary The abundance of moths was monitored with light-traps in two sites in southern Bohemia, České Budějovice for 22 years and in Černiš for 9 years. In these sites, that are vastly different in environmental stability and predictability, stability of insect populations was studied. The amplitude of fluctuations in abundance of the insect populations, as measured by the coefficient of variation (CV), varied a great deal between species so that there was a large overlap between the two sites. Nevertheless there was a highly significant tendency for species at Černiš, the more stable site, to have smaller values of CV, i.e., to be less fluctuating. Also in species co-occurring in the two sites, the CV at Černiš tended to be smaller. Trends in abundance of individual species over time, both increases and decreases, were common in both sites and did not differ between habitats. Environmental stability begets insect population stability in terms of the amplitude of the fluctuations, but trends in time occur irrespective of stability of the habitat.     

An individual-based model for competingDrosophila populations

An individual-based model forDrosophila is formulated, based on competition amongst larvae consuming the same batch of food. The predictions of the model are supported by data for single speciesDrosophila populations reared in the laboratory. The model is used to build a simple discrete model for the dynamics ofDrosophila populations that are kept over a number of generations. The dynamics of a single species is shown to give either a stable equilibrium or fluctuations which can be periodic or chaotic. When the dynamics of a species in the absence of the other is periodic or chaotic, we found coexistence or two alternative states, on neither of which the species can coexist.     

Dynamics ofSitotroga cerealella (olivier) (lepidoptera: gelechiidae) andSitophilus zeamais motschulsky (Coleoptera: Curculionidae) populations in a small bulk of stored corn

Summary The dynamics of Angoumois grain moth,Sitotroga cerealella (Olivier), and maize weevil,Sitophilus zeamais Motschulsky, populations breeding in a small bulk (initially 5.36 t) of shelled corn were studied over an 8-year period by monthly sampling. The weevil population showed wide fluctuations in density superimposed on a general decline with time. The moth population showed no upward or downward trend for the first 60 months, although it fluctuated widely. Following a decline that occurred between 56 and 60 months, the moth population fluctuated within a much narrower range, and there was a general decrease in density with time. The decline of the weevil population paralleled deterioration of the corn as did that of the moth population after ca 60 months, and the decline of both species probably resulted from increasing scarcity of suitable breeding sites. Both populations exhibited seasonal variation in density with minima in late summer and early fall, following periods of adversely high temperatures in the storage shed. The populations increased during the fall, leveled off or declined slightly during the winter months, and then increased to maximum levels in late spring or early summer. It thus appears that high temperatures had a greater adverse effect on the populations than low temperatures. The grain moth and the maize weevil both tended to be randomly dispersed at low population levels and moderately aggregated at intermediate and high levels, although the degree of aggregation was not correlated with population density when low population levels were considered separately, and the maize weevil showed a greater tendency for aggregation than did the grain moth. Analysis of individual samples at fixed points in time showed a conspicuous bias for negative correlation between numbers of the two species within sampling quadrats, suggesting a tendency for the two species to segregate within the grain mass. This process could have resulted from behavioral differences or from the destruction of one species by the other. Competitive displacement of the grain moth by the maize weevil has been demonstrated in laboratory experiments but has rarely been observed under natural conditions, and in our study the two species coexisted for 8 years in a relatively small grain bulk.     

1990年以来中国各民族人口教育发展研究——来自人口普查和人口抽样调查数据的分析

运用人口普查和人口抽样调查数据,研究1990年以来各民族人口教育发展状况,考察7～16岁儿童在校率的影响因素。在实证分析的基础上,针对如何促进少数民族人口的教育发展提出政策建议。研究发现,在过去几十年中,少数民族与汉族人口的教育都取得了长足发展。少数民族人口中,未受过初中教育的人口比例高于汉族。不论对少数民族还是汉族,与城镇地区相比,乡村地区初中教育的缺失更加严重。在城镇地区,少数民族与汉族7～16岁儿童在校率相差很少,但在乡村地区仍然存在一些差距。在考虑了地区影响因素后,少数民族与汉族儿童的在校概率差异或者缩小,或者消失,只有满族除外。     

Smoking and Variation in the Hispanic Paradox: A Comparison of Low Birthweight Across 33 US States

The Hispanic Paradox in birth outcomes is well documented for the US as a whole, but little work has considered geographic variation underlying the national pattern. This inquiry is important given the rapid growth of the Hispanic population and its geographic dispersion. Using birth records data from 2014 through 2016, we document state variation in birthweight differentials between US-born white women and the three Hispanic populations with the largest numbers of births: US-born Mexican women, foreign-born Mexican women, and foreign-born Central and South American women. Our analyses reveal substantial geographic variation in Hispanic immigrant–white low-birthweight disparities. For example, Hispanic immigrants in Southeastern states and in some states from other regions have reduced risk of low birthweight relative to whites, consistent with a “Hispanic Paradox.” A significant portion of Hispanic immigrants’ birthweight advantage in these states is explained by lower rates of smoking relative to whites. However, Hispanic immigrants have higher rates of low birthweight in California and several other Western states. The different state patterns are largely driven by geographic variation in smoking among whites, rather than geographic differences in Hispanic immigrants’ birthweights. In contrast, US-born Mexicans generally have similar or slightly higher odds of low birthweight than whites across the US. Overall, we show that the Hispanic Paradox in birthweight varies quite dramatically by state, driven by geographic variation in low birthweight among whites associated with white smoking disparities across states.     

Methods for the analysis of mortality risks across heterogeneous small populations: examination of space-time gradients in cancer mortality in North Carolina counties 1970–75

A method of analyzing mortality rates in heterogeneous populations is presented. This method, appropriate for the investigation of mortality rates in small geographic areas (e.g., counties) where the forces of mobility operate to selectively “package” persons, is applied to the determination of whether a spatial west-east gradient in cancer mortality rates existed in North Carolina over the period 1970 to 1975. A significant gradient (as well as a significant temporal trend) is determined to exist in the data, though only for particular race, age and sex-specific demographic groups. Several alternate hypotheses are presented to explain the existence of the spatial gradient in these particular demographic groups.     

Extinction of populations due to inbreeding depression with demographic disturbances

The process of population extinction due to inbreeding depression with constant demographic disturbances every generation is analysed using a population genetic and demographic model. The demographic disturbances introduced into the model represent loss of population size that is induced by any kind of human activities, e.g. through hunting and destruction of habitats. The genetic heterozygosity among recessive deleterious genes and the population size are assumed to be in equilibrium before the demographic disturbances start. The effects of deleterious mutations are represented by decreases in the growth rate and carrying capacity of a population. Numerical simulations indicate rapid extinction due to synergistic interaction between inbreeding depression and declining population size for realistic ranges of per-locus mutation rate, equilibrium population size, intrinsic rate of population growth, and strength of demographic disturbances. Large populations at equilibrium are more liable to extinction when disturbed due to inbreeding depression than small populations. This is a consequence of the fact that large populations maintain more recessive deleterious mutations than small populations. The rapid extinction predicted in the present study indicates the importance of the demographic history of a population in relation to extinction due to inbreeding depression.