Elite Populations Research Articles

Weighing science and politics in local decision making about hazards

As a step towards understanding how local environemntal hazards policy is made, this article explores how Canadian local elected officials gained and assimilated scientific and technical information about the environmental hazards facing their communities. Consistent with previous work in the hazards field, three of Weiss’s (1979) meanings of research utilization were found to be directly applicable. The elected officials expressed the view that reconciling conflicting expert opinion and competing concerns was more difficult and more rightly their responsibility than gathering information. This research demonstrates the utility of focus groups for interviewing elite populations making community scale decisions.

The Effect of Interviewer Characteristics On Gatekeeper Resistance in Surveys of Elite Populations

This article focuses on the interviewer's role in obtaining access to an elite respondent through a gatekeeper and considers the characteristics of interviewers that may make some more successful than others in circumventing gatekeepers. Analysis of data from a national survey of physicians suggests that experienced interviewers have greater success than inexperienced interviewers in bypassing gatekeepers. These findings persist after taking into account the number of interviewing hours and the portion of the field period worked, two considerations that have been neglected in previous investigations of interviewer effects.

Analysis of genetic recombination in maize populations using molecular markers

Variation in recombination rate is important to plant breeders since a major objective is to obtain favorable recombinants of linked genes. The ability to increase recombination (R) in circumstances in which favorable and unvavorable genes are linked (Corn Belt x exotic populations) and to decrease recombination when many favorable genes are linked (narrow-based, elite populations) would be of immense value. However, the concept of variation in recombination frequencies between linked genes has received limited attention despite its implications in breeding and genetic linkage studies. Molecular techniques have allowed better estimations of this variation. In this study, attempts were made to characterize: (1) the R values in the Pgm1-Adh1 and Adh1-Phi1 adjacent regions of chromosome 1 and the Idh2-Mdh2 region of chromosome 6 in F2 families of three maize (Zea mays L.) populations; (2) the environmental effect on R values of F2s from two populations. One population, NSO, was a Corn Belt synthetic, and the other two populations, CBMEX3 and CBCAR5, were composites from crosses between Corn Belt and exotic germ-plams.Wide ranges of estimated recombination ([Formula: see text]) values were observed among families in each population for all three chromsomal regions. The distribution of [Formula: see text] values for the Pgm1-Adh1 region showed that the F2 families of each population fell into two broad categories: 0.30-0.50 and 0.02-0.20. No intermediates (0.21-0.29) were found. The distributions were almost normal for the Adh1-Phi1 and the Idh2-Mdh2 regions. It would appear that the major dispersion in the Pgm1-Adh1 region was controlled by the effects of a single gene, while the Adh1-Phi1 and Idh2-Mdh2 regions were only affected by polygenes. No correlation was found between recombination values of the two adjacent regions, indicating that the genes affecting recombination for the Pgm1-Adh1 region may be specific for that region.For the Pgm1-Adh1 region, no differences in [Formula: see text] values were found among the three populations. For the Adh1-Phi1 region, [Formula: see text] frequencies of CBMEX3 and NSO were not significantly different, but both had significantly greater [Formula: see text] values than CBCAR5. For the Idh2-Mdh2 region, CBMEX3 was significantly different from NSO. There were significant differences between some paired F2 families within each population for each chromosome region.No significant differences in response to the two environments were detected in CBMEX3 and NSO for either region in chromosome 1.

Morphological and Agronomic Variation in North African and Arabian Alfalfas

A long history of cultivation in desert regions of the Middle East has led to the evolution of diverse ecotypes of very nonwinterdormant alfalfa (Medicago sativa L.). However, relatively little is known about variation among alfalfa ecotypes from different regions of the Middle East. Relationships between extant Middle Eastern ecotypes and elite nondormant alfalfas are also not well understood. Both of these factors confound the use and conservation of this germplasm resource. The objective of this study was to develop and use practical numerical analysis procedures to describe variation in representative Middle Eastern alfalfa ecotypes and improved nondormant germplasm. Agronomic and morphological data were collected in southern Arizona over a 2‐yr period from 25 ecotypes from North Africa and the Arabian Peninsula and seven elite cultivars or populations bred in North America using primarily Middle Eastern germplasm. Data were taken on forage yield, stem elongation rate, maturity, response to salinity, aphid population, frost damage, leaf area and shape, internode number and length, and stem and leaf pubescence. These data were subjected to principal components and average linkage cluster analysis. This resulted in classification of the populations evaluated into six phenotypically distinct geographical groupings: northeastern Africa (including all elite populations), the central portion of the Arabian Peninsula, Oman, Yemen, southwestern Saudi Arabia, and the Siwa Oasis in Egypt. Eight country or regional clusters were resolved in further analysis. Significant regional variation was observed within the germplasm evaluated but ecotypes from neighboring countries were generally closely associated. All elite germplasm fell within one cluster and significant divergence from the phenotype common in elite nondormant cultivars and North African ecotypes was observed in germplasm from more isolated regions, especially in southern Arabia. This suggests that only a relatively small portion of the range of variability in Middle Eastern alfalfas has been used in formal breeding.

Theoretical value of estimates of general combining ability in the autotetraploid crop

The means of half-sib progenies have been indicated as selection criteria for intra-population improvement while the average of the means of full-sib progenies in diallel analyses have been proposed as predictors, in part, of the means of untested synthetic varieties. When these measures based on progeny means are expressed as deviations from a defined greater population of crosses, they are often termed the general combining ability (GCA). In this study the GCA estimates or a facsimile were theoretically investigated for the one locus, digene, autotetraploid model to verify the genetic basis and its value for selection and prediction in the presence of a naturally occurring phenomena of autopolyploids called gametic disequilibrium with three types of non-additive inheritance. Two breeding objectives were envisioned, the selection of best parents with recurrent selection based on GCA in the continued development of elite populations and the prediction of advanced generation synthetic variety performance. The first generation means of progenies with a potential bias due to gametic disequilibrium were compared to GCA estimation of same progenies in the absence of gametic disequilibrium. The results indicated that testcrossing plants to a population without gametic disequilibrium could be used for selection of best parents. The gametic disequilibrium in the cross may increase or depress selection response dependent on the array of genotypes which happen to be evaluated, on the type of genic action at the locus, and on the frequency of the desirable allele in the testor population. The GCA estimates for prediction of synthetic performance were potentially biased by gametic disequilibrium. An assumption of pollination by the same array of gametes was made for all plants, but obviously was unrealistic for GCA estimation with partial diallels, or with no selfing, and in other situations. The GCA estimate was shown to be an unreliable predictor of synthetic variety performance. When it was assumed that different plants were pollinated by different arrays of gametes, a more realistic situation, no genetic interpretation of GCA values was possible even with purely additive gene action at the locus.

Genetic diversity and genetic vulnerability—an appraisal

1. Plant germplasm is among the most essential of the world’s natural resources. Its conservation merits far greater attention than it is now receiving. 2. Total genetic diversity does not provide insurance against genetic vulnerability. To be of use to the breeder, sources of genetic diversity must include useful alleles not present in elite populations that carry resistance to pests and other stresses that adversely affect productivity and quality. 3. Breeding programs of the most important crops include only a small percentage of the total germplasm available within each crop. The major reason for this limited use of the stores of germplasm found in gene banks is the lack of evaluation data on such material. Until a gene bank’s accessions are evaluated and documented they will continue to be of limited value to the breeder. 4. The results of a recent survey indicate that the genetic base of several important crops has increased during the past decade. 5. Several criticisms of the Green Revolution (used in the broadest sense) are considered. Introductions of new, improved cultivars do tend to replace indigenous varieties containing potentially useful germplasm. Expanded efforts are needed to rescue such varieties before extinction. Research does not support the contention that modern, genetically-uniform cultivars are necessarily less stable and less dependable than genetically-variable cultivars. 6. With respect to the impacts of a changing seed industry on genetic diversity, it is suggested that these changes will not result in a concentration of fewer varieties used worldwide. The movement of pharmaceutical and chemical companies into the seed industry has occurred too recently to permit an evaluation of the effects of such moves. It will likely result in greater competition which, in turn, will stimulate more breeding and the introduction of a greater number of varieties than have been available in the past. Plant variety protection legislation in the United States has also served to stimulate additional breeding in self-fertilized species and has resulted in an increase in the amount of genetic diversity available to the farmer.

A Note on Who's Who in America as a Biographical Data Source in Studies of Elites

This article examines the comprehensiveness of Who's who in America coverage of elites and the extent of biographical data reported in Who's Who in America biographies using two business elite populations derived from standard sources. Who's Who in America coverage of the two business elite populations appeared fairly comprehensive when three editions were examined for each population. The extent of data reported in Who's Who in America biographies varied greatly by type of data, with more “sensitive” types less likely to be reported. These results are discussed.

Monogamy on trial

A discussion of the origins and subsequent developments of attitudes toward monogamy and its alternatives reveals marked variations and some similarities. A range of specific factors have impinged upon norms of intimacy in various historical periods, e.g., the Medieval Church stressed the ideal of celibacy and derogated monogamy. While external factors such as economics and religion tend to influence lifestyle preferences to produce noncumulative effects, there has been a more recent tendency toward democratization of options. Those patterns most closely associated with elite populations tend to be eventually adopted in an altered fashion by broader sectors of the populace.

Genetic Changes in Oat Bulk Populations under Winter Survival Stress1

Convergent crossing was used to produce 58 different winter oat (Avena by zantina K. Koch and A. sativa L.) bulk populations, and these populations were subjected to 4 years of winter survival stress in Pennsylvania. Two types of observations were subsequently made to determine the effect of natural selection on these populations. First, all populations were compared in the F8 and F7 generations to determine performance for juvenile growth habit, freezing resistance in a laboratory test, and winter survival in the field. Second, F8 and F7 individual plants were isolated from 12 populations and classified for juvenile growth habit, maturity, and plant height. Derived F1 and F8 lines from six of these populations were compared for freezing resistance.Thirty‐four of the 58 populations increased significantly in freezing resistance and changed similarly for winter survival in the field. The majority of the populations that changed greatly for these chadracteristics were low performers in the F3. Initially elite populations made small, nonsignificant changes under natural selection. Nonresponsiveness to natural selection in the latter populations did not reflect low genetic variability, since a wide range in freezing resistance was observed among derived lines, regardless of generation or population.In every population, the F3 growth habit ranged from intermediate to very erect. By the F7 generation, 28 populations were significantly more decumbent in juvenile growth habit. Plants from 10 out of 12 populations were significantly more decumbent by the F7 generation; and all populations were later in maturity. Plants with decumbent juvenile growth were latest in maturity, and these two characteristics were correlated within each generation of all populations. Five of 12 populations were taller by the F7 generation, and the others did not change in average plant height under natural selection. Changes in maturity and plant height were independent of natural selection on winterhardiness.If the bulk population approach is to be used for natural selection for winterhardiness, controlled selection pressure during one or more early generations may have to be applied so that the tendency to increase gone frequencies for lateness and tallness can be offset.

Why I'm Becoming a Marxist

For too long I had been hearing and reading that schools were failing. Books abounded that told me how these terrible places stunted children (and teachers) and robbed them of their potential and creativity. I was left with an empty feeling of sadness or depression. Friends of mine became so angered by the situation in public education that they began free schools—places where their children could grow up and become what they were meant to be (doctors, lawyers, teachers, social workers). These free schools, too, however, began to be criticized—for their class bias and elite populations. And the litany of criticism went on and on. As a teacher I read them all—always feeling a sense of frustration and guilt.This article can also be found at the Monthly Review website, where most recent articles are published in full.Click here to purchase a PDF version of this article at the Monthly Review website.