Effects of gall volume on survival and fecundity of gall-making aphidsAdelges japonicus (Homoptera: Adelgidae)

Summary The number of larvae reaching maturity within the gall ofAdelges japonicus was positively related to gall volume, and the relationship between the number of mature larvae and gall volume did not change with different densities of colonized larvae. The population changes in the bud galls ofA. japonicus were surveyed by collecting the galls, which did not suffer predation or parasitism within the galls, from young artificial plantations ofPicea jezoensis over two years. In the year when the density of colonized larvae was high, they suffered a 42% mortality within the galls, whereas mortality was nearly zero in the low density year. The numbers of larvae per gall were positively correlated with gall volume. The regression lines of the number of colonized larvae on gall volume did not differ significantly in the regression coefficients between the two years, whereas the intercept was significantly higher in the year when the density of colonized larvae was higher. However, different within-gall mortality nullified this difference, and the regression lines of the number of mature larvae on gall volume had no significant difference both in the regression coefficients and the intercepts. This suggests that the number of mature larvae per gall was limited by available resources within the gall which were positively related to gall volume. In 25% of the galls in which mature larvae inhabited, the space within the galls were completely filled by the larvae, indicating that space was one of the limiting resources. Gall volume also affected the number of adults that emerged from the gall and the potential number of their progeny.     

Deme formation in gall-making aphidsAdelges japonicus (Homoptera: Adelgidae)

The deme formation hypothesis in herbivorous insects states that herbivores differentiate genetically into small demes, each specialized in the idiosyncratic traits of individual plants. We examined this hypothesis in gall-forming aphids,Adelges japonicus, by reciprocal transfers of aphids among three susceptible clones ofPicea jezoensis standing in proximity. Performance of aphids transferred to their natal clone was compared with that of aphids transferred to other novel clones. ANCOVA showed no significant donor (source of aphids) by receptor (recipient of aphids) interactions for both total aphid performance on the host tree over a life cycle and its three subdivisions(q ₁,q ₂ andq ₃). In addition, the total performance on the natal clone was lowest among those in the three clones, which was explicitly against the prediction from the local adaptation. In contrast, there were significant receptor effects onq ₁ (fecundity of gallicolae multiplied by survivorship of fundatrices while feeding on needles) andq ₃ (fecundity of fundatrices multiplied by survivorship of gallicolae before emergence from the galls), suggesting genetic differences in resistance among clones. The two-fold difference inq ₃ among clones was due to different gall size, which was highly correlated with the number of gallicolae that emerged from the gall. The two-fold difference inq ₁ seemed to be caused by different survivorship of larval fundatrices while feeding on needles.     

Cultural Hegemony of Singapore among ASEAN Countries: Globalization and Cultural Policy

Abstract: Singapore had been called a Cultural Desert since its independence in 1965, but from the beginning of 1990s, there has been a significant change. The Singapore Government started to call their city a “Global City for the Arts”, making numerous cultural policy changes. They also worked on various cultural experiments to establish their cultural leadership or hegemony among Association of South East Asian Nations (ASEAN) countries. The development of arts policies, cultural industries and people's positive commitment towards cultural exchanges are examples of this change. Singapore therefore is now playing the role of the cultural hub among the ASEAN countries. As an example of this, the present study discusses “Esplanade”, which opened as a huge cultural complex in October 2002. Then the paper will also discuss both bright and dark sides of the cultural development in Singapore. As a conclusion, this paper discusses the possibility of the cultural contribution of Singapore to ASEAN countries, in spite of having serious epistemological discontinuity among ASEAN.     

Measuring Information Behavior: A Time Budget Survey in Japan

This paper discusses the results of a time budget survey which was conducted nationwide in Japan in 1995 on ‘information behavior’, that is, the amount of time people spent communicating and using information media ranging from conversations to computers. We propose a three-dimensional time budget survey as a method for measuring information behavior in actual life. The method classifies information behavior into 24 categories and measures them with respect to three factors, i.e. time, location and purpose of behavior. Our survey revealed that the total time spent on information behavior was about seven hours per day, of which about 45% was spent watching TV. The displacement effect of PC use on TV watching was estimated by a “time-shift matching” design. The results demonstrated that use of a PC does not significantly affect TV viewing, despite a large difference in TV viewing time between PC users and non-users.     

Brief Report: Useful Information for Face Perception Is Described with FACS

When we perceive the emotions of other people, we extract much information from the face. The present experiment used FACS (Facial Action Coding System), which is an instrument that measures the magnitude of facial action from a neutral face to a changed, emotional face. Japanese undergraduates judged the emotion in pictures of 66 static Japanese male faces (11 static pictures for each of six basic expressions: happiness, surprise, fear, anger, sadness, and disgust), ranging from neutral faces to maximally expressed emotions. The stimuli had previously been scored with FACS and were presented in random order. A high correlation between the subjects' judgments of facial expressions and the FACS scores was found.     

Nonparametric Growth Curve Model with Local Linear Approximation

The growth curve model has been developed for longitudinal data, and its time trend is usually described by polynomials. However, it is difficult to interpret each coefficient of the polynomials with higher degrees, even when the number of repetitions is sufficiently large. We propose herein an alternative growth curve model having time-varying coefficients.     

The role of vole populations in prevalence of the parasite (Echinococcus multilocularis) in foxes

Effects of population fluctuation of the gray-sided vole(Clethrionomys rufocanus) on the prevalence (infection rates) of the parasiteEchinococcus multilocularis in red fox(Vulpes vulpes) populations was investigated from 1985 to 1992 in eastern Hokkaido (Abashiri, Nemuro, and Kushiro area), Japan. This parasite needs two hosts to complete its life cycle; the gray-sided vole as its intermediate host and the red fox as its final host. We found that: (1) Infection rates in foxes depended on the current-year abundance of voles in all three study areas, particularly in Abashiri. (2) In addition to this direct density-dependence, delayed density-dependence between the infection rate and the prior-year abundance of voles was detected in Nemuro and in Kushiro. (3) The regional differences in density-dependence pattern were related to regional differences in the winter food habits of red foxes: in Abashiri the proportion of voles in the fox’s diet greatly decreases in winter, while the proportion remains high in winter in Nemuro and in Kushiro, probably because of shallower snowpack. These results suggest that infection rates in foxes in Abashiri were less influenced by the prior-year prevalence, since the infection cycle might be interrupted in winter, when voles became less important in fox’s diet. In contrast, the state of the prevalence may carry over from year to year in Nemuro and in Kushiro, because red foxes continue to eat a considerable amount of voles throughout year. The regionally contrasted results for the relationship between infection rate in foxes and vole abundance were parallel to the regional difference in fluctuation pattern of vole populations, which are highly variable in Abashiri area, but less variable in Kushiro-Nemuro area. Drastic change in vole populations appears to affect the host-parasite system.     

Contrasting effects of urbanization on arboreal and ground-dwelling land snails: role of trophic interactions and habitat fragmentation

Urbanization generally reduces wildlife populations. Individual species responses, however, are often highly variable, and such variability can be explained by differences in species ecological traits. To examine this hypothesis, we focused on two co-occurring land snails, Ezohelix gainesi and Euhadra brandtii sapporo; the former is ground-dwelling and the latter is arboreal. We first estimated their population densities at nine sites distributed along an urbanization gradient: three were located in continuous natural forests, three at the edge of natural forests, and the rest in small isolated forests in urban areas. As a result, the ground-dwelling E. gainesi occurred at highest density in urban forests, followed by forest edges and continuous forests. By contrast, the arboreal E. b. sapporo occurred at highest density in continuous forests, but declined in forest edges and urban forests. We then conducted manipulative field experiments to quantify changes in predation pressure on these species. Ground-tethered E. gainesi and E. b. sapporo were repeatedly predated upon by forest-living mammals in continuous forests, but their survival rates increased in forest edges and urban forests. By contrast, canopy-tethered E. b. sapporo maintained high survival rates in all three forest types. The results indicate that a lack of mammalian predators enables ground-dwelling species to occur at high densities in urban forests, whereas the arboreal species was not affected by this predator relaxation effect. The combination of species-specific behavioural traits and changes in predator communities across an urbanization gradient has important effects on the biodiversity of urban ecosystems.

     

Educational Inequality

Abstract. This paper develops a theoretical model of the inequality in wages and salaries associated with differences in years of schooling (educational inequality, for short). Our model assumes that in the long run individual decisions to become more educated equalize the lifetime earnings of more educated workers and comparable less educated workers. Given this assumption, our model implies that innovations that increase the relative demand for more educated labor, and which cause short‐run increases in educational inequality, in the long run induce offsetting increases in the relative supply of more educated labor. But our model also has the novel implication that innovations that increase differences between the wages and salaries received by workers with the same years of education who are more or less able (ability premiums, for short) cause a smaller fraction of workers to choose to become more educated. Consequently, innovations that increase ability premiums in the long run also cause educational inequality to be larger than otherwise. In applying our theory to recent changes in educational inequality in the USA, we suggest that, to the extent that innovations that increase ability premiums are contributing to educational inequality, the increases in educational inequality during the 1980s and 1990s are unlikely to be reversed soon.     

Correction to: contrasting effects of urbanization on arboreal and ground-dwelling land snails: role of trophic interactions and habitat fragmentation

Urban Ecosystems - The original version of the article unfortunately contained mistakes in the legends of Fig. 3. The legends (1) Blue square: Euhadra brandtii sapporo, ground is changed...