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Sex allocation of a cosexual wind-pollinated species, Quercus dentata (Fagaceae), was analyzed using biomass, carbon, nitrogen and phosphorus as currencies based on data accumulated for 61 individuals from 1997–2004. Strongly female-biased sex allocation was indicated when measured in terms of biomass and carbon, but no significant bias was detected when measured in terms of nitrogen or phosphorus. From an adaptive viewpoint, there is little support for strong female-biased sex allocation, suggesting that sex allocation in terms of nitrogen or phosphorus is closer to the real picture. The relative sex allocation considerably varied from year to year, but the relative femaleness of individuals in the population was rather constant across years. No significant correlation was observed between relative sex allocation and fecundity or tree height, but individuals that showed very low fecundity tended to produce only acorns. [ABSTRACT FROM AUTHOR]

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To evaluate the responses of Quercus crispula and Quercus dentata to herbivory, their leaves were subjected to simulated herbivory in early spring and examined for the subsequent changes in leaf traits and attacks by chewing herbivores in mid summer. In Quercus crispula, nitrogen content per area was higher in artificially damaged leaves than in control leaves. This species is assumed to increase the photosynthetic rate per area by increasing nitrogen content per area to compensate leaf area loss. In Quercus dentata, nitrogen content per area did not differ between artificially damaged and control leaves, while nitrogen content per mass was slightly lower in artificially damaged leaves. The difference in their responses can be attributable to the difference in the architecture of their leaves and/or the severeness of herbivory. The development of leaf area from early spring to mid summer was larger in artificially damaged leaves than in control leaves in both species, suggesting the compensatory response to leaf area loss. Leaf dry mass per unit area was also larger in artificially damaged leaves in both species, but the adaptive significance of this change is not clear. In spite of such changes in leaf traits, no difference was detected in the degree of damage by chewing herbivores between artificially damaged and controlled leaves in both species. [ABSTRACT FROM AUTHOR]

The spatial genetic structure was assessed by amplified fragment length polymorphism (AFLP) technique for Quercus crispula Blume (37 individuals) and Q. dentata Thunberg (54 individuals) growing along a 550-m transect in Ishikari, Hokkaido, northern Japan. The simple Mantel test revealed significant negative correlation between genetic similarity and geographic distance in Q. dentata and negative but insignificant correlation in Q. crispula . Spatial autocorrelation analysis revealed that Mantel's r generally decreased from positive to negative values with the increase of spatial distance in both oak species with significant deviation from zero for the 50–100-m (positive) and 250–300-m classes (negative) in Q. dentata . Thus, significant spatial genetic structure was revealed at least in Q. dentata [ABSTRACT FROM AUTHOR]

Quercus crispula and Q. dentata (Fagaceae) am dominant members of cool-temperate forests of Japan and are assumed to hybridize in nature. To characterize and discriminate these two species and their hybrids, we carried out multivariate analysis using several morphological traits and principal coordinate analysis using molecular (amplified fragment length polymorphism [AFLP]) data. Further, we examined the composition of Phyllonorycter species (leafmining insects) on individuals from a mixed forest. Morphological traits and Phyllonorycter composition differ enough in these two oak species to be useful for identification of species and hybrids. AFLP data, however, are less informative because the degree of molecular differentiation between the two species is low. Nine out of 105 individuals from a mixed stand had intermediate morphologies according to the multivariate analysis, and eight out of the nine individuals had intermediate Phyllonorycter composition in either one or both of the two study years. These eight individuals were tentatively assigned as hybrids or backcross individuals, and the remaining individual with intermediate morphologies was assigned as Q. dentata according to its Phyllonorycter composition and the AFLP analysis. [ABSTRACT FROM AUTHOR]

Abstract: Population dynamics of leafminers on a deciduous oak Quercus dentata, were studied for 9years in northern Japan. Most leafminers in the study site were bivoltine, while a gregarious Stigmella species was univoltine. Many leafminers showed species-specific patterns of population fluctuations. In the major bivoltine leafminers (Phyllonorycter, solitary Stigmella and Caloptilia species), the densities of autumn generation mines were highly correlated with those of summer generation mines when analysed on the basis of the densities at the early developmental stage. Thus, their mortality and egg productivity in this phase (i.e., from late June to early September) varied only a little from year to year. In Phyllonorycter, however, correlation of densities between these two generations became lower when analysed on the basis of the densities at the tissue-feeding stage, suggesting that their mortality from the early developmental stage to the tissue-feeding stage in the autumn generation varied from year to year. Regression analyses suggest that yearly variation in precipitation in July and August was responsible for this variation. Correlations of densities between the autumn generation and the summer generation of the next year in the major leafminers were not high. Thus, their mortality and/or egg productivity in this phase (i.e., from September to June of the next year) varied from year to year. Regression analyses suggest that climatic factors that affected the population dynamics in this phase varied among the leafminers, except some factors have been suggested to be commonly effective in the two Phyllonorycter species. Density-dependent effects were not explicit in the population dynamics of the present leafminers. [Copyright &y& Elsevier]