Large Census Research Articles

Restricted dispersal in a long-distance migrant bird with patchy distribution, the great reed warbler.

In patchily distributed species dispersal connects local populations into metapopulations. Reliable quantifications of dispersal are therefore crucial to understanding the population dynamics and genetic structure of such metapopulation systems. The great reed warbler (Acrocephalus arundinaceus) inhabits eutrophic lakes and has a patchy breeding distribution. In this study we investigated the dispersal pattern of the great reed warbler based on an extensive capture-recapture effort covering a large census area (22,500km2). At two adjacent breeding sites (10km apart) in southern Central Sweden, the "main study area", we ringed the majority of adult and nestling great reed warblers between 1992 and 1999. In 1998 and 1999, we opportunistically searched for territorial males at the majority of the Swedish breeding sites, and were able to examine about 56% of all males in the region. Analyses of recaptured males demonstrated that philopatry predominated. Sixty-nine percent of the recruiting nestlings returned to breed in the main study area (their natal area), and 92% of the resighted adults were found at the same breeding locality in both study years. Breeding dispersal was significantly more restricted than natal dispersal. Additional data on natal and breeding dispersal within the main study area in 1992-1999 suggested that females were as philopatric as males. The overall high level of philopatry, with only occasional longer dispersal distances documented, yielded a root-mean-square dispersal distance of 33km per generation. High philopatry, short dispersal distances and similar dispersal patterns of male and female great reed warblers contrast the findings among birds in general, but conform to data of species having patchy breeding habitat and isolated populations. Restricted dispersal suggests limited gene flow even among several Swedish populations, which is in line with some previous findings of the population ecology of the great reed warbler: (1) structured mtDNA lineages among European populations; (2) small-scale population differences in song patterns; and (3) low genetic variation and occurrence of inbreeding depression in our main study population.

A propos de la corpulence des bovins en France durant les périodes historiques

Variations of the bovine size are examined from the Roman Conquest to the XVIIIth century in France, through a large census of osteometric data concerning the metatarsus. Results of the diachronic observations of the raw measures lead us to consider the biologic and breeding mechanisms before finding the socio-economic reasons of these variations. The hypothesis which suggests the import of large Roman bovines from Rome or another Italian centre, the presence of a little bovine during the Middle Ages who has growed up during the Renaissance, are confronted to results of this census which constitutes in himself a novelty for France.

Population extinction and recolonization in human demographic history

For over 30 years, a debate has raged among anthropologists about the origins of anatomically modern humans. At first the debate centered on fossil evidence, but in the past 10–15 years population geneticists have entered the fray. One model, the multiregional evolution model, posits a gradual transition from Homo erectus to anatomically modern humans throughout the Old World. In contrast, the recent African origin model hypothesizes that anatomically modern humans arose from a small, isolated population in Africa, spread out of Africa, and replaced indigenous H. erectus populations in Eurasia and Australasia. A primary objection, from a population genetics perspective, to the multiregional model is that the genetic data suggest a small effective population size for humans. This effective size is on the order of 10 000. Effective population size has a complex relationship with census size, but it has been argued that, assuming that effective size is roughly equal to the number of breeding individuals in human populations under standard demographic conditions, 10 000 breeding individuals could not have occupied much of the Old World throughout the Pleistocene and remained a cohesive species via gene flow. However, this argument is not valid if one considers population extinction and recolonization, which might have played an important role in human history during the Pleistocene. With population extinction and recolonization, the inbreeding effective population size can be small and the census size extremely large. In this paper, I will show that under conditions of population extinction and recolonization, an effective population size of 10 000 suggested by genetic data is compatible with a large census size consistent with the multiregional model.

Distributing Large Historical Census Samples on the Internet

A new project at the University of Minnesota will provide data extraction and distribution over the Internet of the Integrated Public Use Microdata Series – a database which integrates all existing national samples of the US census from 1850 to 1990 into a consistent format.

Interspecific Aggression and Habitat Selection by Amazonian Birds

We report that interspecific territoriality is a common spacing mechanism among closely related bird species distributed along a primary successional gradient in the meander belt of an Amazonian whitewater river. In the first phase of the research, we mapped the territories of more than 330 bird species in large census plots encompassing the complete successional gradient. We found species pairs in over 20 genera that showed contiguous but non-overlapping territories, such that early stages of the successional gradient were occupied by one member of the pair, and later stages by the other. Other species pairs showed additional types of spatial relationships, including partially overlapping and completely overlapping territories. Using reciprocal heterospecific playback experiments, we tested for the existence of aggressive interactions between the members of species pairs (usually congeners) showing all three types of spatial relationship. Among 12 species pairs showing contiguous, non-overlapping territories, 10 showed evidence of interspecific aggression (approach to the playback speaker). In eight of these 10 cases, the responses were markedly asymmetric. Target individuals of one species approached the speaker, whereas individuals of the other species remained in place or moved away. The heavier species was consistently the aggressor. In six species pairs showing partial territorial overlap along the successional gradient, only one species displayed statistically significant interspecific aggressiveness, although some individuals in all six pairs approached or avoided the speaker. In species pairs distributed with completely overlapping territories, we found interspecific aggression in only one of five genera tested. We suggest that spatial segregation of congeneric bird species on habitat gradients (presumably including elevational gradients), is commonly underpinned by interspecific territoriality mediated through directed, asymmetrical interspecific aggression. Aggressive asymmetry suggests a despotic model of habitat occupancy, in which the larger species occupies the more productive end of habitat gradients, and the smaller species occupies less productive habitats. The pronounced successional gradients characteristic of Amazonia may explain much of the increased species richness, especially within genera, of Amazonian bird communities.

Few V gene segments dominate the T cell receptor beta-chain repertoire of the human thymus.

We undertook a large sample census of the TCR-beta repertoire from a single human thymus (300 clones from an unamplified cDNA library), to establish the statistics of the rearranged V, D, J, and C gene segments. The assortments of all germ-line segments are subject to significant biases and thus critically reduce the effective germ-line contribution to beta-chain diversity. Thirty-two V genes characterize the whole sample, but surprisingly as few as seven genes from different families encompass half of the beta-chain repertoire. Furthermore, a Spearman rank order correlation test of the thymic V beta frequencies with those inferred in other studies using RNase protection assays shows a statistically significant similarity. Thus, in the establishment of thymic V beta frequencies in man, rearrangement preferences intrinsic to the progenitors of TCR-beta expressing cells override HLA- and Ag-dependent biasing factors. By implication, a large enough pool of direct progenitor cells (maybe as high as thousands) must exist to secure V beta frequencies against large random fluctuations. Uncorrelated with the V gene bias, the representation of D beta and J beta segments is also far from even. Notably, D beta 1 and J beta 2.1 and 1.2 predominate. Using the above mentioned rank order statistic, we also find that unlike V genes, the bias in the J segment usage carries over into the frequencies of peripheral T lymphocyte populations.

Rapid Loss of Genetic Variation in Large Captive Populations of Drosophila Flies: Implications for the Genetic Management of Captive Populations

Levels of variation in eight large captive populations of D. melanogaster (census sizes ∼ 5000) that had been in captivity for periods from 6 months to 23 years (8 to 365 generations) were estimated from allozyme heterozygosities, lethal frequencies, and inversion heterozygosities and phenotypic variances, additive genetic variances (VA), and heritabilities (h2) for sternopleural bristle numbers. Correlations between all measures of variation except lethal frequencies were high and significant. All measures of genetic variation declined with time in captivity, with those for average heterozygosities, VA, and h2 being significant. The effective population size (Ne) was estimated to be 185–253 in these populations, only 0.037–0.051 of census size (N). Levels of allozyme heterozygosities declined rapidly in two large captive populations founded from another wild stock, being reduced by 86% and 62% within 2.5 years in spite of being maintained at sizes of approximately 1000 and 3500. Estimates of Ne/N for these populations were only 0.016 and 0.004. Two estimates of Ne/N for captive populations of D. pseudoobscura from data in the literature were also low at 0.036 and 0.012. Consequently, the rate of loss of genetic variation in captive populations and endangered species may be more rapid than hitherto recognized. Merely maintaining captive populations at large census sizes may not be sufficient to maintain essential genetic variation.

Disability status and length of stay at a VA medical center.

In this study, patients who benefited financially from extended admissions had a significantly greater proportion of hospital stays exceeding 20 days. The system of monetary rewards for veterans with service connected partial disabilities appears to prolong inpatient stays. Costs indude not only the increased disability payments, but also the additional expenses for the protracted stay and larger census. It is unlikely that VA compensation rules will be changed. Physicians should be aware that patients with service-connected partial disabilities may have expectations for hospital stays different from their own. Taking appropriate discharge planning steps early in treatment is preferable to suddenly insisting on discharge on the 19th day of hospitalization, a measure not likely to be easily accepted by patients eligible for remunerated hospitalization.

Using the U.S. Bureau of the Census CD-ROM test disc 2: A note∗

Data on U.S. Census Bureau CD-ROM Test Disc 2 is accessible using dBASE III Plus ®. Different computer hardware configurations are used to determine the most efficient method of manipulating the data. Various software options for accessing Census CD-ROMs are also mentioned. Using the same dBASE commands with each system, comparisons are made between 8088 and 80386 configurations. The 80386 is found to be essential to the efficient searching of large census files. Libraries will need to invest in advanced computing capabilities and staff training to respond to the GPO's commitment to CD-ROM technology.

An assessment of computer technology in U.S. local governments

This paper presents a broad, current assessment of the use and impacts of computers and electronic data processing in the larger municipal and county governments of the United States. It is based on extensive data gathered by a major research project which has involved both case-studies in forty cities and a large census survey of urban local governments in cities with greater than 50,000 population and counties with greater than 100,000 population. Three general themes arc explored: (1) the current ‘state-of-the-art’ of computer technology in local government, including general profiles of the governments using EDP, the characteristic administrative arrangements for providing the EDP function, and the types of uses to which EDP has been applied; (2) the impact of computers on local governments, particularly in the areas of operational performance, coordination and control, and local planning; and (3) critical issues currently facing local government in the effective utilization of EDP, including development and management of computer technology, technology transfer and privacy protection.

Occupational Classification

The need for a common occupational classification system has begun to outweigh the importance of the precision of a multipurpose classification system. Recent multiplication, in government, of sources of occupational statistics, the variety of uses to which occupationally classified data are now put, and the theoretical dissatisfaction shown in recent literature make it desirable that a single, standard classification system be developed for all agencies.Work is now starting on a standard classification system (presently in the major group of professional, technical, and related workers). Although final results will not be available for use in the1970 Census, there is detailed effort to reduce the large residual census categories and to develop a more detailed list of classifications for that Census. The statistician should beaware that work is in progress on one of the classifications of growing importance to him.