Shift In Life Cycle Research Articles

Age and vote choice: Is there a conservative shift among older voters?

Ageing is often believed to induce a movement towards the right of the political spectrum. Yet, empirical evidence remains inconclusive due to a dearth of longitudinal datasets covering multiple cohorts. Using eleven rotating panels of the Norwegian Election Studies (1977–2017) and exploiting first-derivative properties of the vote choice function, our empirical approach identifies non-linear life-cycle effects while controlling for cohort and period effects. Our main findings indicate that shifting towards the left is more likely among the young (under 40 years) whereas shifting towards the right occurs at an older age (over 55 years). Evaluating potential mechanisms, we find that individuals’ income, retirement, family status and political interest explain only a small part of the observed ageing effect. Life-cycle shifts in (some) policy preferences may play a bigger role. Finally, aging effects are similar across women and men, and only marginally stronger among groups with lower education and income levels.

EVOLUTIONARY REDUCTION OF COMPLEX LIFE CYCLES: LOSS OF HOST-ALTERNATION IN PEMPHIGUS (HOMOPTERA: APHIDIDAE).

In a Utah canyon, the aphid, Pemphigus betae, exhibits two life cycles: a cycle involving host-alternation between cottonwood trees and roots of herbaceous plants and a secondarily reduced cycle, in which the cottonwood generations are eliminated so that wingless forms live year round on roots. Relative frequencies of the two life-cycle types vary along a 30-km stretch of the canyon, with the reduced cycle predominating at upper sites. Factors underlying this life-cycle variation were examined with common-garden and transfer experiments. Results showed 1) a facultative increase in production of alternating forms in response to crowding in root colonies, 2) a genetic component to both within- and between-site variation in tendency to produce alternating morphs, and 3) site-specific environmental effects on level of investment in the reduced versus alternating life cycles. Thus, the variation in frequency of life-cycle reduction in this aphid is dependent on a complex of interdependent factors. These include adaptive phenotypic plasticity, microgeographically variable cues affecting mechanisms of morph determination, and genetically based variation in tendency to show reduction versus alternation. Genetic variation between sites corresponds to microgeographic variation in success of life-cycle phases. Where cottonwood hosts are absent (lower elevations) or where the cottonwood phase has low survival (upper elevations), clones tend to produce fewer migrating morphs, as compared to clones from middle elevations, where the cottonwood phase is relatively favorable. Such independence between conditions in alternate phases is a general feature of complex life cycles and can generate strong site-specific selection for permanent life-cycle reduction. Such life-cycle shifts have sometimes been followed by extensive radiations in aphids and other groups.

Cohort Analysis of Party Identification Among Southern Whites, 1952-1972

Cohort studies generally find that different generations retain the same pattern of partisanship throughout their lifecycles. In contrast, this study finds that changes within generations contribute greatly to the decline in traditional Democratic affiliation among southern whites. Carol A. Cassel is Assistant Professor of Political Science at the University of Missouri-St. Louis. The author is indebted to Robert Erikson and Norman Luttbeg for their encouragement and helpful comments. POQ 41 (1977) 28-33 This content downloaded from 207.46.13.156 on Sat, 10 Sep 2016 05:02:00 UTC All use subject to http://about.jstor.org/terms COHORT ANALYSIS OF PARTY IDENTIFICATION 29 Table 1. Party Identification among Whites by Region, 1952 and 1972 South Nonsouth 1952 1972 1952 1972 Democrat 79% 47% 43% 35% Independent 10 34 25 37 Republican 10 19 33 28 NOTE: The data were made available by the Inter-university consortium for Political Research. Neither the Center for Political Studies nor the Consortium bear any responsibility for the analysis or interpretation presented here. 1971. He did not exclude interregional migrants to the South. While migrants are known to have made an important contribution to the changing distribution of partisans in the South (Converse, 1966; 1972), in a sixyear period, migrants would have little effect on the relative size of cohort shifts. Glenn found all age cohorts contributed to an increase of 24 percentage points in political Independence in the South from 1965 to 1969, although the oldest cohorts made somewhat smaller shifts. Three-fifths of this increase in Independents, however, was lost from 1969 to 1971 as cohorts shifted back to the parties, and Republicans made a net gain of approximately 5 percentage points. Although Glenn did not view increasing southern Independence as the first stage of a southern movement to the Republican party, he found evidence that older as well as younger cohorts were adopting the Republican label in the South. Glenn's study of short-term partisan shifts in the South leaves unanswered important questions about the long-term trend away from Democratic affiliation: (1) What is the relative impact of generational change and aggregate life-cycle shifts on the overall trend away from Democratic affiliation in the South? (2) Does the long-term trend include adoption of a new (Republican) party label or merely shifts to political Independence? (3) Is there a relationship between age and ability to make life-cycle shifts? To assess more clearly the extent of life-cycle and generational shifts, we must first isolate the native white population. Interregional migrants must be excluded so that the addition of nonsoutherners to the South is not confused with aggregate life-cycle shifts and generational differences. Likewise, inclusion of blacks would obscure shifts away from the traditional Democratic affiliation of the South. Blacks only recently emerged as participants in the southern electoral system and are overwhelmingly Democratic for different reasons from those of white southerners.