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1.
Abstract

Mortality rates by age and sex of American Indians living in reservation and non‐reservation counties were compared for 1970 and 1978. An apparent overcount in the 1980 census enumeration of American Indians curtails rigorous comparisons, but broad differences can be delineated. The main improvement in American Indian mortality during the decade was in age group 0–4. In 1970, non‐reservation death rates were not different from reservation rates. By the end of the decade, non‐reservation death rates had diverged downward from reservation deaths. An analysis of 1978 death rates by poverty status showed that non‐reservation death rates are sensitive to county poverty level, whereas reservation death rates are not.  相似文献   

2.
Abstract

During the 1800's, the population of Ireland underwent a rapid increase and subsequent decrease in population size. The effects of this change upon population structure were assessed using a simulation of the isolation by distance model and comparing the results to those obtained assuming constant population size. These results indicate that changes in within‐group genetic similarity (kinship) brought about by a rapid increase in population size are cancelled by the effects of a rapid decrease in population size. Parameters of the isolation by distance model are hardly affected by population size changes. These results suggest that violation of the assumption of constant population size for population structure models may not be that serious when population size changes rapidly and in both directions.  相似文献   

3.
Abstract

This report compares the 1977 genetic demographies of Colonsay and Jura, adjacent yet isolated islands of the Scottish Inner Hebrides. Completed family analyses demonstrated that the residents of Colonsay have higher fertility, shorter generation length, and longer female reproduction span than those of Jura. Based on oral genealogies of five to six generations, the natives of Jura had a higher inbreeding coefficient (f= 0.0044) than did those of Colonsay (f= 0.0023). Each set of natives mainly derives from small groups of “founding” ancestors. Founder effects in the populations are transitory phenomena dependent upon population decline and the periodic emigration of native families. With their small sizes, the maximum sampling errors due to random genetic drift are ±0.063 for Colonsay and ±0.059 for Jura per generation. An unusual finding was that the effective sizes of Colonsay and Jura exceed their respective breeding sizes. Today Colonsay and Jura are former geographical isolates in dissolution through an increasing marital admixture with immigrants. Human migration dictated in large part by Hebridean economics dominates the mi‐croevolutions of Colonsay and Jura.  相似文献   

4.
Migratory behaviour in insects correlates with reproductive development in females, and migration often occurs during the pre‐reproductive stage of adults. The relationship between ovarian development and population status of the white‐backed planthopper Sogatella furcifera (Horváth) and the brown planthopper Nilaparvata lugens (Stål) was evaluated. Females of both species were captured in rice fields and light traps and then dissected in double‐season rice‐farming regions of southern China. The ovarian development of S. furcifera and N. lugens was divided into five levels, following previous studies. The population statuses of both species were examined based on the ovarian development of female adults caught in rice paddies. The ovarian development in N. lugens females caught in light traps mostly ranged from level I to level II, whereas that in S. furcifera females caught in light traps mostly ranged from level I to level III. During peak immigration, ovarian development in N. lugens females was mainly at level II, whereas that in S. furcifera females was mainly at level II and sporadically at level III. During peak emigration, both S. furcifera and N. lugens showed level I ovarian development. The temporal dynamics of ovarian development in light trap catches revealed that (i) significant emigration and partial immigration periods occur in S. furcifera, with ovarian development mainly at level I and sporadically from level II to level III and (ii) numerous immigrants of N. lugens were detected during sedentary and local breeding periods. The temporal dynamics of ovarian development provides more information than does the paddy population. Thus, this study proposes another method for pest forecasting, which is more precise and efficient than conventional forecasting methods such as light trap catching and monitoring population dynamics in rice fields.  相似文献   

5.
《Plains anthropologist》2013,58(56):134-142
Abstract

Drinking parties in country Indian homes display a regular structure that does not seem to be necessarily related to the amount of alcohol consumed. Elements of this structure include changes in interpersonal behavior, focus of behavior, topics of conversation, and affect. Relating this structure to other aspects of reservation culture, notably dissonance between ideal models of social organization and day-to-day disruption of the model, point up the theoretical advantage of looking at drinking as institutionalized social behavior rather than individual deviant behavior.  相似文献   

6.
When colonies of swarm-founding wasps lose their nests to predation or accident, the entire adult population escapes, emigrates as an absconding swarm, and renests elsewhere. Such an event causes a reduction in the adult population due to losses during the emigration itself and to adult attrition without replacement during the subsequent preemergence growth period in the new nest. We addressed the first of these sources of mortality for 27 absconding swarms of Polybia occidentalis in Costa Rica. Adult mortality over the day that included swarm emigration averaged 0.044 ± 0.039 (SD) of the original population and was a weak positive function of distance moved, but not of swarm size. A larger data set showed that emigration distance increased with swarm size. This is the first study to measure mortality rates during emigration in a swarm-founding social insect.  相似文献   

7.
目的 分析预约挂号是否缩短门诊患者的等候时间。方法抽取医院某一周全部患者挂号记录49 147条,通过秩和检验方法,分析预约挂号与非预约挂号患者的候诊时间的差异,比较不同预约方式对患者候诊时间是否存在影响。结果 预约挂号平均候诊时间为50分钟,非预约挂号患者平均候诊时间为111分钟,不同预约方式的患者候诊时间存在统计学上的差异。结论 预约挂号能够有效缩短门诊患者的候诊时间,其中复诊预约患者候诊时间最短,应鼓励患者预约就诊,复诊患者应鼓励进行复诊预约。  相似文献   

8.
Abstract

Changes in rates of admixture on the Sells Papago Indian reservation over the last century are shown to reflect ethnohistorically recorded events of extra‐tribal contact. Three distinct strategies providing, in varying degrees, for the preservation of group identity were identified. It is argued that strategies favoring maximum preservation of ethnic identity have threatened the survival of the reservation breeding units because traditional patterns of mate selection are inconsistent with present settlement patterns and result in delay of mate selection and childbearing early in reproductive life.  相似文献   

9.
Abstract

A number of studies are reviewed to show that the mean level of measured intelligence in Scotland is approximately three to four IQ points lower than that in England. These results are a striking contrast with another set of findings showing that in the nineteenth century Scotland had a greater proportional output of people of intellectual distinction than did England. Evidence on Scottish‐English differences in education, parental attention, and per capita income suggests that none of these factors can explain the difference in mean IQ. It is suggested that the principal cause of the reduced mean intelligence in Scotland lies in the selective emigration of the more intelligent, and evidence is reviewed to show that this emigration has occurred for at least a century.  相似文献   

10.
Understanding movement of individuals between sites is necessary to quantify emigration and immigration, yet previous analyses exploring sex biases in site fidelity among birds have not evaluated remigration (the return of marked birds that moved to alternative areas from the site at which they were marked). Using novel Bayesian multistate models, we tested whether between‐winter emigration, remigration and survival rates were sex‐biased among 851 Greenland White‐fronted Geese Anser albifrons flavirostris marked at Wexford, Ireland. We found no evidence for sex biases in emigration, remigration or survival. Thus, sex biases in winter site fidelity do not occur in any form in this population; these techniques for modelling sex‐biased movement will be useful for a better understanding of site fidelity and connectivity in other marked animal populations.  相似文献   

11.
1. The relative effect of migration and local growth on the spatio‐temporal density‐distribution of two co‐existing herbivorous weevils, Cionus scrophulariae L. and C. tuberculosus Scop., in 32 host plant Scrophularia nodosa L. patches of varying sizes was investigated. 2. Predictions of the temporal development of the slope in the density‐patch size relationships were derived from a basic population model with scale‐dependent migration rates. The model indicated that the slopes in the density‐patch size relationships during the early season should be reflected by the net scaling of immigration and emigration rates, whereas the slopes during the later season should increase as a result of local growth. 3. Emigration rates of the weevils were estimated in a field experiment, were the weevils coexisted in space and time. These results were then combined with a previous estimate of immigration rates in order to determine the net scaling of migration rates. 4. The emigration rate differed between species, caused by different movement rates in small patches, which could explain differences in the general slope of the density‐patch size relationships of the weevils in the natural figwort patches throughout the summer. The slopes in the relationships in the early season were largely predicted by the net scaling of migration rates. The slope also increased in the later season for C. tuberculosus, whereas the slope decreased for C. scrophulariae. 5. It was concluded that the understanding of both inter‐ and intra‐specific variations in density‐patch size relationships of insect herbivores can be improved using population models incorporating scale‐dependent migration and local growth.  相似文献   

12.
1 The ability to quantify whitefly migration provides a tool that can contribute to an improved understanding of the epidemic development of whitefly‐transmitted viruses. 2 In an attempt to develop a protocol for estimating whitefly immigration and emigration rates in an annual crop, new traps and sampling devices were tested in the field and models for population dynamics were developed. 3 An estimate of immigration rate was derived from the growth of a natural population of Trialeurodes vaporariorum (Westwood) in the beginning of a crop cycle before offspring of immigrants contributed to population growth. 4 A model for changes in whitefly density during an entire bean (Phaseolus vulgaris L.) crop cycle, including an immigration parameter, was also developed. 5 Non‐attractant window traps surrounding an annual field crop were assumed to intercept whiteflies immigrating into and emigrating away from the crop. Captures on these traps could not categorically be identified as immigrants or emigrants, but the cumulated captures nevertheless explained 66% of the variation in population density found within the field. Hence, window traps may be used as an efficient and reliable alternative to yellow sticky traps, aspirator methods and leaf‐turn methods, etc., for estimating whitefly densities in field crops.  相似文献   

13.
Large‐scale climate modes such as El Niño Southern Oscillation (ENSO) influence population dynamics in many species, including marine top predators. However, few quantitative studies have investigated the influence of large‐scale variability on resident marine top predator populations. We examined the effect of climate variability on the abundance and temporary emigration of a resident bottlenose dolphin (Tursiops aduncus) population off Bunbury, Western Australia (WA). This population has been studied intensively over six consecutive years (2007–2013), yielding a robust dataset that captures seasonal variations in both abundance and movement patterns. In WA, ENSO affects the strength of the Leeuwin Current (LC), the dominant oceanographic feature in the region. The strength and variability of the LC affects marine ecosystems and distribution of top predator prey. We investigated the relationship between dolphin abundance and ENSO, Southern Annular Mode, austral season, rainfall, sea surface salinity and sea surface temperature (SST). Linear models indicated that dolphin abundance was significantly affected by ENSO, and that the magnitude of the effect was dependent upon season. Dolphin abundance was lowest during winter 2009, when dolphins had high temporary emigration rates out of the study area. This coincided with the single El Niño event that occurred throughout the study period. Coupled with this event, there was a negative anomaly in SST and an above average rainfall. These conditions may have affected the distribution of dolphin prey, resulting in the temporary emigration of dolphins out of the study area in search of adequate prey. This study demonstrated the local effects of large‐scale climatic variations on the short‐term response of a resident, coastal delphinid species. With a projected global increase in frequency and intensity of extreme climatic events, resident marine top predators may not only have to contend with increasing coastal anthropogenic activities, but also have to adapt to large‐scale climatic changes.  相似文献   

14.
Population genetic analyses based on both mitochondrial cytochrome b and the internal transcribed spacer 2 of recombinant (r)DNA genes were implemented to examine hypotheses of population differentiation in the angular angel shark Squatina guggenheim, one of the four most‐widespread endemic species inhabiting coastal ecosystems in the south‐western Atlantic Ocean. A total of 82 individuals of S. guggenheim from 10 sampling sites throughout the Río de la Plata mouth, its maritime front, the outer shelf at the subtropical confluence and the coastal areas of the south‐west Atlantic Ocean, were included. The analysis of molecular variance (AMOVA) based on the second internal transcribed spacer (its‐2) region supports that the samples from the outer shelf represent an isolated group from other sites. Historical gene flow in a coalescent‐based approach revealed significant immigration and emigration asymmetry between sampling sites. Based on the low level of genetic diversity, the existence of a long‐term population decline or a past recent population expansion following a population bottleneck could be proposed in S. guggenheim. This demographic differentiation suggests a degree of vulnerability to overexploitation in this endemic and endangered south‐west Atlantic Ocean shark, given its longevity and low reproductive potential.  相似文献   

15.
《Cytotherapy》2014,16(9):1220-1228
Background aimsAdult human subcutaneous adipose tissue harbors a multipotent stem cell population, the so-called human adipose tissue–derived mesenchymal stromal cells (AT-MSCs). These cells are able to differentiate in vitro into various cell types and possess immunomodulatory features. Yet procedures to obtain AT-MSCs can vary significantly. The two most extensively used AT-MSC purification techniques are (i) density gradient centrifugation using Ficoll and (ii) red blood cell (RBC) lysis buffer treatment of the stromal vascular fraction. In the context of potential clinical cell therapy, the stem cell yield after purification and upon consecutive passages, as well as the purity of the obtained cell population, are of utmost importance.MethodsWe investigated the expansion capacity and purity of AT-MSCs purified by both procedures immediately after isolation and upon consecutive passages. We also investigated possible purification-dependent differences in their expression of immune-inhibitory factors and cell adhesion molecules.ResultsWe found that RBC lysis buffer treatment is a more robust and easier method to purify AT-MSCs than density gradient fractionation. However, the resulting AT-MSC-RBC population contains a significantly higher number of CD34+ cells, particularly during the first passages after plating. From passage 4 onward, no significant differences could be observed between both populations with respect to the immunophenotype, expansion capacity and expression of immune inhibitory factors and cell adhesion molecules.ConclusionsOur data show that RBC lysis buffer treatment may be a good alternative to density fractionation, providing a faster, more robust and easier method to purify AT-MSCs with biologically preserved characteristics.  相似文献   

16.
Dozens of morphologically differentiated populations, subspecies and species of crossbills (genus Loxia) exist. It has been suggested that this divergence is due to variation in the conifer cones that each population specialises upon, requiring a specific beak size to efficiently separate the cone scales. If so, apparent survival should depend on beak size. To test this hypothesis, we undertook multievent capture–recapture modelling for 6844 individuals monitored during 27 years in a Pyrenean common crossbill L. curvirostra population in a forest of mountain pine Pinus uncinata. Apparent survival was indeed related to beak width, resulting in stabilizing selection around an optimum that was close to the observed mean beak width, indicating that local crossbill beak morphology is adapted to the conifer they feed upon. Both natural selection (selective mortality) and selective emigration of maladapted individuals may explain our findings. As is often the case in capture–recapture analyses but rarely recognised, we could not formally decompose apparent survival into selective mortality versus selective permanent emigration. Nonetheless, there are several indications that selective permanent emigration should not be fully excluded. First, natural selection by itself would have to be unusually strong compared to other empirical estimates to create the observed pattern of apparent survival. Second, the observed mean beak width was a bit lower than the estimated optimum beak width. This can be explained by immigration of crossbills with smaller beaks originating from southern populations, which may subsequently have left the study area permanently in response to low food intake. This is in line with a detected transient effect in the data, yet apparently little influx from crossbills from northern Europe. When permanent emigration is phenotypically selective this will have ecological and evolutionary consequences, so this possibility deserves more attention in general.  相似文献   

17.
While African leopard populations are considered to be continuous as demonstrated by their high genetic variation, the southernmost leopard population exists in the Eastern and Western Cape, South Africa, where anthropogenic activities may be affecting this population's structure. Little is known about the elusive, last free‐roaming top predator in the region and this study is the first to report on leopard population structuring using nuclear DNA. By analyzing 14 microsatellite markers from 40 leopard tissue samples, we aimed to understand the populations' structure, genetic distance, and gene flow (Nm). Our results, based on spatially explicit analysis with Bayesian methods, indicate that leopards in the region exist in a fragmented population structure with lower than expected genetic diversity. Three population groups were identified, between which low to moderate levels of gene flow were observed (Nm 0.5 to 3.6). One subpopulation exhibited low genetic differentiation, suggesting a continuous population structure, while the remaining two appear to be less connected, with low emigration and immigration between these populations. Therefore, genetic barriers are present between the subpopulations, and while leopards in the study region may function as a metapopulation, anthropogenic activities threaten to decrease habitat and movement further. Our results indicate that the leopard population may become isolated within a few generations and suggest that management actions should aim to increase habitat connectivity and reduce human–carnivore conflict. Understanding genetic diversity and connectivity of populations has important conservation implications that can highlight management of priority populations to reverse the effects of human‐caused extinctions.  相似文献   

18.
Abstract

Child mortality experience may affect subsequent fertility of couples by exerting the so‐called “physiological” and/or “replacement” responses. The influence of either effect should become apparent upon an examination of individual reproductive histories. The impact of infant and early childhood mortality on subsequent reproductive behavior of couples is analyzed for the presence and intensity of these effects. Historical data are derived from 1,261 families in two communities in western Massachusetts. Relationships of intervals between successive confinements, and parity progression ratios, according to the fate of previous births, are examined. While forms of family limitation have been employed by the study population, indicating that the capacity for replacement existed, the data do not reveal any significant attempt at child replacement.  相似文献   

19.
Abstract

This study examines the proximate determinants of fertility in China by making use of the data collected by the One‐per‐Thousand Sample Fertility Survey of 1982. The results indicate that the most important inhibitor of potential fertility is deliberate control. Its contribution to fertility change has been far greater than all other proximate determinants. The marital structure of the population is also an important factor, while lactational infecundability and induced abortion are relatively unimportant. Comparative results by using data from the In‐depth Fertility Survey conducted in Shanghai Municipality, Hebei and Shaanxi Provinces in April 1985 agree well in the ranking of the four intermediate factors. The findings point to successful family planning program and government population policies, which propelled the fertility transition to a substantial degree. Further research needs and policy implications of the results of the study are discussed.  相似文献   

20.
Insights into the ecology and natural history of the neotenic salamander, Eurycea tonkawae, are provided from eight years of capture‐recapture data from 10,041 captures of 7,315 individuals at 16 sites. Eurycea tonkawae exhibits seasonal reproduction, with peak gravidity occurring in the fall and winter. Size frequency data indicated recruitment occurred in the spring and summer. Open‐population capture‐recapture models revealed a similar seasonal pattern at two of three sites, while recruitment was dependent on flow at the third site. Females can reach sexual maturity within one year, and oviposition likely takes place below ground. The asymptotic body length of 1,290 individuals was estimated as 31.73 mm (at ca. two years of age), although there was substantial heterogeneity among growth trajectories. Longevity was approximately eight years, and the median age for a recaptured adult was 2.3 years. Abundance estimated from closed‐population and robust‐design capture‐recapture models varied widely within and among sites (range 41–834), although, surprisingly, dramatic changes in abundance were not observed following prolonged dry periods. Seasonal migration patterns of second‐year and older adults may help explain lower ratios of large individuals and higher temporary emigration during the latter half of the year, but further study is required. Low numbers of captures and recaptures precluded the use of open‐population models to estimate demographic parameters at several sites; therefore, closed‐population (or robust‐design) methods are generally recommended. Based on observations of their life history and population demographics, E. tonkawae seems well adapted to conditions where spring flow is variable and surface habitat periodically goes dry.  相似文献   

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