bluuebunny/crossref_metadata_2025 huggingface dataset:
On the mathematical basis of the variance‐mean power relationship
Authors: Tokeshi Mutsunori
Published: November 2006

The mathematical basis of a widely‐known variance‐mean power relationship of ecological populations was examined. It is shown that the log variance (S2)—log mean, (m) plot is virtually delimited by two lines log S2=log n+2 log m and log S2=log m, thus increasing the chance that a linear regression line can be successfully fitted, without a profoundly behavioural background. This makes difficult the task of interpreting a successful fit of the power law regression and its parameter b in a biologically meaningful manner. In comparison with the power law regression, Iwao'sm*‐m regression is structurally less constrained, i.e. has a wider spatial region in which data points can scatter. This suggests that a comparison between the two methods in terms of how good a fit is achieved for a particular data set is largely meaningless, since the power law regression may inherently produce a better fit due to its constrained spatial entity. Furthermore, it could be argued that a successful fit in Iwao's method, when found, is less taxed with mathematical arterfacts and perhaps more clearly linked to some biological mechanisms underlying spatial dispersion of populations.
The evolutionary significance of wing dimorphism in carabid beetles (Coleoptera: Carabidae)
Authors: Aukema Berend
Published: November 2006

A review of data on the background of wing dimorphism in carabid beetles (Coleoptera: Carabidae) and especially of the closely related Calathus cinctus and C. melanocephalus is given. In both Calathus species wing dimorphism is inherited in a simple Mendelian fashion with the brachypterous condition dominant, but in C. melanocephalus the expression of the long winged genotype is under environmental control as well. The development of long winged phenotypes in the latter species is favoured by relatively favourable environmental conditions, such as high temperatures and a high food‐supply. The higher fecundity of the larger and heavier long winged females of both species may compensate for losses of long winged phenotypes by flight activities. The evolutionary significance of both types of inheritance is discussed in relation to dispersal. The ‘fixed type’ as found in C. cinctus is considered an opportunistic short term ‘between sites strategy’, whereas the ‘dynamic type’ of C. melanocephalus represents a flexible long term ‘within sites strategy’.
Variability in wing form of crickets
Authors: Masaki Sinzo , Shimizu Toru
Published: November 2006

Loss of functional hindwings is observed in most subfamilies of Japanese crickets. Habitat, behaviour, body size and phylogenetic factors might be involved, but interactions among them may obscure the general trend. Wing dimorphism is common among the relatively small‐sized members of Gryllinae, and the two small‐sized subfamilies, Nemobiinae and Trigonidiinae. Both environmental cues (e. g. photoperiod) and genetic factors affect the wing form. In Dianemobius fascipes (Nemobiinae), the percentage macroptery was drastically changed by selection for macroptery or microptery. Crossing experiments indicated polygenic control of wing form as well as X‐chromosomal and maternal effects. Neither the long‐winged nor short‐winged line bred true after 40 generations of selection. Full‐sib families revealed a large genetic variation in frequency of macropterous forms within a population. The genetic determination of the propensity for macropterism did not seem to be directly coupled to the mechanism performing the photoperiodic time‐measurement.
Losses of workers and reproductives in colonies of the paper wasp Polistes riparius (Hymenoptera: Vespidae) due to the parasitic wasp Latibulus sp.
Authors: Makino Shun'ichi
Published: November 2006

Losses in workers and reproductives due to the ichneumonid parasitoid Latibulus sp. were determined in a haplometrotic, temperate paper wasp, Polistes riparius, during a 5‐year study.

Fifty‐four to 79% of pre‐emergence nests were parasitized on worker brood, resulting in a worker loss of 25–31% on average. Worker brood reared in outer cells were much more often parasitized than those in central ones, possibly because outer cells are more accessible to the parasitoid. Infestation of worker brood was not random but aggregated among nests.

Seventy‐eight to 100% of nests were parasitized on reproductive brood, and lost 10–34% of reproductives.

The number of emerged workers positively correlated with that of reproductives produced and that of cells made during the season. This suggests that worker loss reduces reproductive output of colonies. Hence, the parasitoid can reduce colonial reproductive output not only by killing reproductive brood but by reducing worker force.
Spatio‐temporal distribution patterns of two tachinid flies, Epicampocera succincta and Compsilura concinnata parasitizing Pieris
Authors: Iwao Keisuke , Sato Yoshibumi , Ohsaki Naota
Published: November 2006

Larvae of genus Pieris in the northern part of Kyoto City are parasitized by two tachinid flies:Epicampocera succincta, a specialist on genus Pieris, and Compsilura concinnata, a generalist with very wide host‐range. We surveyed the parasitism rates of Pieris by both flies for two years at six study areas. In these study areas, there lived three host species in the genus Pieris: P. rapae, P. melete, and P. napi, but neither tachinid parasitized P. napi to any significant extent. In the mountainous district, P. rapae and P. melete coexisted and their populations were relatively continuous, while in the lowland, only P. rapae larvae were abundant in spring and autumn, but even they disappeared in summer. Parasitisms by E. succincta occurred mainly in mountainous district and never in the lowland. C. concinnata parasitized Pieris in all the areas, but its parasitisms occurred mainly in autumn.

We analyzed the factors affecting the spatial and temporal patterns of parasitism rates and presumed that the temporal discontinuity of host population restricted the distribution of the specialist parasitoid.
Modelling and analyzing density‐dependent population processes: Comparison between wild and laboratory strains of the bean weevil, Callosobruchus chinensis (L.)
Authors: Kuno Eizi , Kozai Yoshitake , Kubotsu Koji
Published: November 2006

Three models were constructed for analyzing the population characteristics of C. chinensis on stored beans; model A describing the whole reproductive process with a single equation, model B describing the three age‐specific processes (oviposition, egg survival and larval survival) with separate equations, and model C which describes all these processes not for the whole habitat but for the individual beans comprizing it. The logit equation was employed here as a common basis to describe the density‐response relationship involved. All three models showed very good fit to the experimental data obtained for both laboratory and wild strains of the weevil. The parameter values characterizing the population dynamics were, however, widely different between the two strains; the laboratory one which had been reared for some 500 generations showed significantly higher reproductive capacity, less sensitive and gentler response to crowding in both adult and egg stages, and more uniform egg distribution among individual beans, as compared with the wild strain newly introduced. Sensitivity analyses using these models suggested that these changes in population characteristics have been attained by the process of domestication or adaptation to stable laboratory conditions through a long period of time. This process seemed in effect to have optimized the population's performances in the laboratory environment. Evolutionary significance of such optimization was discussed with reference to the selection pressure which may have acted upon individuals.
Interannual fluctuations in recruitment and growth of the sardine, Sardinops melanostictus, in the sea of Japan and adjacent waters
Authors: Hiyama Yoshiaki , Nishida Hiroshi , Goto Tsuneo
Published: November 2006

Recruitment and growth of the sardine Sardinops melanostictus fluctuated markedly in the Sea of Japan and adjacent waters between 1978 and 1993. Stock size was calculated using Virtual Population Analysis and average body length in each age class was determined by the number of annual rings on the scales. There is an inverse correlation between average water temperature at a depth of 50 m in the coastal area of the mainland of Japan in winter (January to March) and recruitment R defined as the number of individuals at 1 year old. There is also an inverse correlation between spawning stock size E and reproductive success in (R/E). A multiple regression model using spawning stock size and water temperature in winter as independent variables can explain 73% of variance in reproductive success. It suggests that both density‐dependent and density‐independent factors perform important roles determining reproductive success. There is an inverse correlation between body length and stock size and this suggests that there is a density‐dependent effect on the growth of the sardine.
Effect of organic rice farming on planthoppers 4. Reproduction of the white backed planthopper, Sogatella furcifera Horváth (Homoptera: Delphacidae)
Authors: Kajimura Tatsuto , Widiarta I Nyoman , Nagai Kazuya , Fujisaki Kenji , Nakasuji Fusao
Published: November 2006

The reproduction of Sogatella furcifera was investigated in a chemically fertilized rice field and an organically farmed field. In the latter, the density of immigrants was significantly higher, while the settling rate of female adults and the survival rate of immature stages of ensuing generations were lower. The number of eggs laid by a female of the invading and following generations was smaller, and the percentage of brachypterous females in the next generation was also lower. Consequently, the density of nymphs and adults in the ensuing generations decreased in the organically farmed field. For an experimental comparison, potted rice plants were cultivated using seedlings and soil from the chemically fertilized or the organically farmed fields. When Sogatella furcifera was reared on these plants, both the reproductive rate and the appearance rate of brachypterous female adults were lower in the organic treatment. Egg hatchability was also lower in the organic treatment. This experiment suggested that a specific nutritional condition in rice plants suppressed the population of S. furcifera in the organically farmed field.
Accumulation of phyllodulcin in sweet‐leaf plants of Hydrangea serrata and its neutrality in the defence against a specialist leafmining herbivore
Authors: Ujihara Mami , Shinozaki Masateru , Kato Makoto
Published: November 2006

Among wild plants of Hydrangea serrata (Hydrangeaceae) in Japan, there are sweet plants whose leave contain a kind of isocoumarin, phyllodulcin, which happens to be 350 times as sweet as sucrose to the human tongue. In a primary beech forest in Ashu, Kyoto, the spatial distribution of sweet plants and temporal and the spatial distribution of phyllodulcin within and among plants were investigated using a high performance liquid chromatograph. The distribution of sweet plants was confined within a valley and was parapatric with non‐sweet plants. A plant's characteristic phyllodulcin accumulation did not change, even when transplanted into the different habitats. The phyllodulcin content of the sweet plants varied greatly among plants, and the population mean peaked in July when the plants flowered. Within a plant, phyllodulcin content was elevated by partial defoliation. We examined the possible effect of phyllodulcin on herbivory by a specialist leafmining herbivore, Antispila hydrangifoliella (Lepidoptera: Heliozelidae). We transplanted sweet and nonsweet plants reciprocally between their original habitats, excluded attacks by parasitoids, and compared performance of the leafminer. Leafminer colonization and larval survivorship on transplanted and in situ plants was not significantly different between sites. The fact that accumulation of phyllodulcin did not augment a defensive function, at least against herbivory by the leafminer, and the sporadic distribution of phyllodulcin‐accumulating plants, suggest that the genotypes synthesizing phyllodulcin emerged independently at separate localities by mutation, and that the genotypes are almost adaptively neutral in defence against the specialist herbivore.
Influence of parental density on the distribution pattern of eggs in the common cabbage butterfly, Pieris rapae crucivora
Authors: Kobayashi Shiro
Published: November 2006

To investigate the relation between the distribution pattern of eggs and the parental density in the common cabbage butterfly, Pieris rapae crucivora, the countings of egg number per plant were made on both cabbage plants cultivated in the farm and planted in the net house in which the female butterflies were released at various densities.

The frequency distribution of eggs fits well to the negative binomial excepting the cases where they agree withPoisson series, and the degree of aggregation expressed as the reciprocal of the parameter, 1/k, tends to decrease as the egg or parental density increases. At the same parental density, however, the distribution of eggs can be described by the negative binomial with a common parameter, kc, regardless of the difference in the density of laid eggs.

In the case where a single female butterfly lays eggs, the spatial pattern of egg distribution is always lean, while its frequencies conform toPoisson or the negative binomial series. This lean changes toward patchy with increasing the parental density.

From these results, it is concluded that the degree of aggregation in the distribution of eggs decreases with the increase of the parental density.
An index of spatial distribution
Authors: Lefkovitch L. P.
Published: November 2006

The index , which takes the value of −1 for a perfectly regular distribution, +1 for a highly aggregated distribution and 0 for the distribution implied by the theoretical varianceσ2, is proposed and a significance table provided.
Application of Iδ‐index to sampling techniques
Authors: Morisita Masaaki
Published: November 2006

Conclusion and Summary

An advantage in the Iδ method which utilizes the Iδ‐index for the description and analysis of population structure is that the values obtained through the use of this method indicated the degrees of non‐randomeness of the distribution of individuals so that they are comparable directly with each other. In this paper, equations representing some basic relations between the Iδ‐values of sample and population and those between the inter‐group Iδ and intra‐group Iδ were described and an example of their application to the field data was presented. Though the equations and methods may still have such a weakness as to be supplemented or corrected from mathematical point of view, they seem to be useful at least as the basis for the the future study for the development of the Iδ method.
The fitting of the logistic equation to the rate of increase of population density
Authors: Morisita Masaaki
Published: November 2006

Conclusion and Summary

Though there are many problems on the usefulness of the logistic curve, it may be necessary to examine before discussing these problems whether or not the actual data fit to the theoretical values. It has been clarified in this paper that the relation between the population density and its rate of increase per individual described by the differential equation (1) is represented by a straight line on a finite difference diagram on which Ni+1−Ni/Ni values are plotted against Ni+1. Utilizing this linear relation we may examine the fittness of the logistic curve to the actual data and when it is fitted we may estimate the parameters of the logistic equation by (5) and (6). The result of the application of this method to the experimental populations of azuki bean weevil indicates that the relation between parent and progeny densities fits well to the logistic type as has been proved byFujita andUtida (1953) who utilized the linear reltion between 1/R+2σ and parent density where R is the apparent rate of reproduction and σ is a constant dependent primarily upon the length of adult life (0≦σ≦1).
Adaptive parental feeding as a factor influencing the reproductive rate in the grey starling
Authors: Kuroda Nagahisa
Published: November 2006

Adaptive parental feeding of chicks is one of the factors influencing the reproductive rate of a local population.

The food resources in the rural and urban colonies in Tokyo were entirely different as proved by collar experiments of the chicks.

In the rural habitat the mole‐cricket of fair size (1 g) and of a high nutritive value was the ‘key food' to all broods and only a few other items were added for larger broods.

In the urban habitat the food consisted of both animal and plant (fruits) items of various kinds, but the animal matter was mostly small and of poor nutritive value, and fruits are much less nutritive than animal matters as experimentally proved with captive chicks by using cherries which are the most abundant and favoured fruit.

Thus the food preference and the feeding ability of parents had more important effect upon growth rate and flying success of chicks in the urban colony than in the rural, especially in larger broods.

In the rural colony, the adaptive reaction of parents to a large brood size (experimentally increased) was evident in a pair which adequately switched the normal food, the secretive mole‐cricket, to an easily obtainable kind, the small white pupae and caterpillars.

Such focussed or concentrated foraging was also shown to some other food items to be found in clustered condition and selection for large size was also suggested, since such large foods as the gecko or lizard were brought though they were disgorged by chicks in some cases.

Subject to various factors, there is the maximum possible feeding frequency for the parents and therefore, however hard the parents might work, there were limits of brood size they could successfully raise.

Such limits were 6 chicks for some parents or 7 for others, and a single parent could raise not more than 3 chicks.

Thus in the grey starling the broods of 5–6 chicks are of the most efficient size in reproductive rate and are most common, though are subject to difference of local food situation.
Mortality process in relation to aggregation in the southern green stink bug
Authors: Hokyo Nibuhiko , Kiritani Keizi
Published: November 2006

A simple experiment of simulation was done to analyze the natural mortality process of young larval colonies and egg masses of the southern green stink bug. In this experiment, a degree of contagiousness was allowed in regard to the action of a mortality factor, and was defined as the mean number killed per a colony or an egg mass by the mortality factor within a unit time and the number killed per a colony was assumed to follow the Poisson series with the mean . Thus each component of the Poisson series was opposed to each colony or egg mass which was taken at random from 162 egg masses, 135 and 117 colonies of the first and the second instar larvae, respectively.

It was revealed that mortality factors in the field did not act with a small degree of contagiosness, e. g., on all colonies or egg masses, but acted with a large degree of contagiousness, e. g., on some of the colonies or egg masses. Thus differential survival somewhat in all or none way occurred among the insect colonies irrespective of their initial sizes. These results were well explained by taking actual mortality factors into account.
Spatial distribution of eggs by ovipositing Indian meal moths, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)
Authors: Arbogast Richard T. , Mullen Michael A.
Published: November 2006

A series of increasing egg densities was obtained by releasing various numbers of female Plodia interpunctella (Hübner) in rooms where dishes of moth rearing medium were evenly spaced on the floor. The number of larvae produced in each dish was taken as an indication of the number of eggs that had been laid. At all egg densities, the eggs were aggregated, and most of the distributions conformed quite well with the negative binormial, but the degree of aggregation denreased as mean egg density increased. The implications of the results for the development of ware‐house sampling strategies are discussed.
A preliminary simulation model of movement of larvae of Culex pipiens molestus (Diptera: Culicidae) (Experimental studies on the dispersal of insects, II)
Authors: Sirota Yasuyuki
Published: November 2006

Experiments for analyzing the movement and dispersal of larvae of C. pipiens molestus were made and preliminaly simulation models were constructed. The models were based on two distributions, the distance and direction of movements between 1 minute intervals. The distribution of distance is represented by a unimodal curve, and that of angle by a bimodal one. The results of simulation reasonably depicted the actual process of movements. Nevertheless, the simulated time‐dispersal curves overestimated the number of dispersed individuals. This might be due to mutual attraction among the larvae.
On the problem of trap‐response types of small mammal populations
Authors: Tanaka Ryo
Published: November 2006

Conclusions

So far as the population data thus far amassed go, commensal rats in residential habitats are of type II; house mice may be of type I or III in fields but might show type II in residences, and fieral species or subspecies may range from type I to III. Altogether alloresponsive populations seem to be much commoner than the isoresponsive.

It is as yet little disclosed to what degree the differentiation of the type is correlated with speciation or subspeciation, even if only a proof that a subspecific population would hold type III as its fixed feature is given.

The response types are supposed to be associated with the levels of population shyness. Hence some characters reflected in those may possibly be connected with sexual isolation provoking speciation.

Some awkward respects due to the heterogeneous trappability, depending upon the trap‐response type, among a mixed population of marked and unmarked animals have been confirmed regarding the methodology for estimating parameters.
Mark‐recapture estimates of overwintering survival of the Queensland fruit fly, Dacus tryoni, in field cages
Authors: Sonleitner Frank J.
Published: November 2006

Four groups of 75 pairs each of marked adult Dacus tryoni that had emerged from field‐collected guavas were liberated into cage‐covered guava trees at the end of May, 1960 and sampled at weekly intervals to estimate the overwintering survivorship.

Estimates of numbers were made using three different methods as described byLeslie (1952) and one byJolly (1965). The Method A, approximate Method B andJolly models gave quite similar results although the Method A model was shown to be more sensitive to stochastic changes in the R/r ratios. The complete Method B model produced much smaller variances, due to its full utilization of the information in the data but it was very sensitive to small biases—even those caused by the restriction that recaptures must be whole numbers—and thus could not quite approach the exact expectations.

Although in some instances, statistical tests (Leslie, 1958) showed some significant deviations from randomness in recapture, these were not appreciable and did not affect the estimates.

When sufficient food was available, the flies in the field cages exhibited survival rates during the winter months of 1960 quite comparable to those of laboratory flies kept at room temperature with several exceptions: (a) there was a high mortality among the newly emerged flies during the initial week after release, (b) a high mortality during the last week of June and (c) a high mortality during the third week in July and the end of August which can be correlated with lack of rain, low humidity and warm daytime temperatures. Low temperatures apparently had little effect on survival.

There was no difference in the survival of males and females.

One replicate cage, whose flies had been anesthetized with carbon dioxide prior to release, exhibited significantly higher mortality rates than the other replicates.

Data from a fifth cage indicated that females were not inseminated during the winter months and did not produce mature eggs until the beginning of September.
Computing a population budget from sequentially sacrificed, replicated cultures
Authors: Sokal Robert R. , Bryant Edwin H.
Published: November 2006

When a population budget must be obtained from censuses based on replicated, sacrificed cultures, it is difficult to obtain estimates of transition probabilities and of the errors of such estimates, because there is no logical basis for pairing successive census counts. In a study of this nature estimating a population budget of immature stages of the housefly, the problem was solved by a randomization treatment of the original census results obtained at two densities. One hundred randomly generated census matrices over all census times for each density were smoothed to remove the effects of sampling error and a population budget constructed according to defined rules. Transition probabilities computed from the population budget were plotted on triangular coordinate paper and mean probabilities, 95% confidence regions for these means, and 95% equal frequency ellipses computed. All computations and the graphing of the results were carried out on a digital computer. The computer program, available from the authors, is written in FORTRAN IV and could be easily modified for similar studies.
A model of the plant‐to‐plant movement of aphids I. Description of the model
Authors: Shiyomi Masae
Published: November 2006

The plant‐to‐plant movement of insects in one of the factors determining the distribution of individuals in insect populations. In this report the movement of barley aphids was analyzed by a statistical model.

The model is represented as the convolution of three probability functions:

The probability that s individuals are found on a plant at time t0:Q(s);

The probability that i individuals leave the plant and remain on the ground from time t0 to t1:sCipiqs−i and p+q=1, where p and q are the proportions of individuals which do not leave a plant and which leave it once or more, respectively;

The probability that j individuals climb a plant between time t0 to t1 and stay there at time t1:e−λλj/λ!, where λ is the mean of the individuals.

The probability that l individuals are located on a plant at time t1 is represented by the following equation
urn:x-wiley:14383896:pope0053:equation:pope0053-math-0001

It was shown by simple experiments that the experimental populations were well fitted to the model.
Growth characteristics of Nelumbo nucifera Gaertn. in response to water depth and flooding
Authors: Nohara Seiichi , Kimura Makoto
Published: November 2006

Three experiments on the effects of water depth and flooding on Nelumbo nucifera Gaertn. were made in the artificial environment of concrete ponds. First, plants were harvested in autumn after growing under seven different water levels ranging from 0.2–3 m The number of floating leaves, the total number of leaves and the leaf area index of emergent leaves were greatest in the tanks at 0.5 m depth. The petiole dry weight per unit length of emergent leaves and the ratio of aboveground to belowground biomass rose with increasing water depth up to 2 m. In contrast, that of floating leaves was constant at about 10 mg dry weight cm−1. The proportion of biomass in tubers fell from 20% at 0.2 m to 6% at 2 m. Second, petiole elongation responses to the amplitude of flooding were investigated in early summer. The maximum rate of petiole elongation was 25 cm per day at 2.4 m water depth. This was the maximum depth at which N. nucifera could grow. No petioles could elongate from 3 m to 5 m depth. Finally, the effects of timing of flooding on growth were investigated. At the end of growing season, the belowground biomass of plants in the flooding treatment in late summer was smallest among the flooding treatment plants (P<0.05), and was most severe when flooding occurred in this season. Based on the results of these experiments, the growth characteristics of N. nucifera in relation to petiole elongation, biomass allocation, and flooding tolerance were discussed.
Can the tortoise beat the hare? A possible mechanism for the coexistence of competing mosquitoes in bamboo groves
Authors: Sunahara Toshihiko , Mogi Motoyoshi
Published: November 2006

We studied interspecific competition between the larvae of the two mosquitoes Aedes albopictus and Tripteroides bambusa, which are predominantly found in water‐filled bamboo stumps in northern Kyushu, south‐western Japan, using microcosms with dead bamboo leaves in the laboratory. We compared short‐term competition between single cohorts of the two species and long‐term competition involving four cohorts of each species, which were introduced at 6‐day intervals. In the single cohort experiment, A. albopictus grew faster than T. bambusa. However, in the multiple cohort experiment, although the first cohort of A. albopictus grew faster and began to pupate earlier than that of T. bambusa, molting rates of later cohorts of A. albopictus, that were introduced on the 12th and the 18th day, were lower than those of T. bambusa. The survival rate of A. albopictus became lower than that of T. bambusa after the 18th day. The cumulative number of the pupated T. bambusa individuals exceeded that of A. albopictus on the 96th day. The final pupation success was higher in T. bambusa than in A. albopictus, especially when additional leaves were supplied on the 48th and the 96th days. The reversed outcomes between short‐ and long‐term interspecific competition and the variation in the lifespans of small aquatic sites may contribute to the coexistence of the two mosquito species in bamboo groves.
Distribution and regeneration strategies of major canopy dominants in species‐rich subtropical/warm temperate rainforests in south‐western Japan
Authors: Takyu Masaaki , Ohsawa Masahiko
Published: November 2006

The distribution and regeneration strategy of the major canopy dominants in species‐rich subtropical/warm temperate rainforests in south‐western Japan was studied in a hilly zone below 1100 m a.s.l. Using the patch sampling method, four dominance‐community types were numerically identified and they corresponded to four habitats which represented a combination of topography and altitude (i.e. ridges vs slopes, and below vs above 500 m a.s.l.) Seven major canopy dominants had their respective distributional core in one of these topo‐altitudinal habitats. The seven canopy dominants could be classified into three species groups according to their size structure and growth habits. Group A (Tsuga sieboldii and Quercus gilva) and group B (Quercus acuta, Quercus salicina, Machilus thunbergii) were restricted to the emergent and canopy layer, respectively. These two groups had only a few subcanopy trees and saplings. Saplings of group B showed a rapid growth rate in canopy gaps. Group C (Distylium racemosum) was characterized by many subcanopy trees and saplings that grew steadily under the closed canopy. Castanopsis sieboldii showed intermediate characteristics between group B and C in the size structure and growth habit of its saplings. The density of D. racemosum canopy trees was markedly reduced on ridges and slopes above 500 m and on slopes below 500 m. In these marginal habitats, the three species groups coexisted by sharing different strata within a community. This situation was possible due to the differences in regeneration strategies among the canopy species.
Relatedness among females in a peak phase population of Japanese field voles
Authors: Mashima Hiroshi , Satoh Toshiyuki , Obara Yoshiaki
Published: November 2006

Spatial and genetic relationships among females in a peak population of Microtus montebelli were studied by live‐trapping and DNA fingerprinting. In the early period of the spring breeding season, a close genetic relationship was not observed between neighboring overwintered females, while in the late period, a proximity among highly related females and a dispersed distribution among intermediately related females was observed. These associations among relatives did not last very long, however, as female pairs who remained in the neighborhood for more than 150 days, covering two breeding seasons were not relatives. The possibility of cooperation among relatives in this species may thus be low, except among philopatric females in the late period of a single breeding season.
Nutrient‐uptake and nutrient‐use efficiency ofPinus thunbergiiParl. along a topographical gradient of soil nutrient availability
Authors: Enoki Tsutomu , Kawaguchi Hideyuki , Iwatsubo Goro
Published: November 2006

To examine responses of a plant species to nutrient availability, we investigated changes in soil nutrient availability, litterfall production and nutrient content in litterfall along a topographic gradient in aPinus thunbergiiParl. plantation. Responses were evaluated in terms of three efficiency indices: (i) nutrient‐uptake efficiency (the ratio of nutrient return in litterfall to soil nutrient availability); (ii) nutrient‐use efficiency (the ratio of litterfall mass to nutrient return in litterfall); and (iii) nutrient‐response efficiency (the ratio of litterfall mass to soil nutrient availability). These indices can distinguish the ability of a species to acquire nutrients and its ability to use them in litterfall production. Nitrogen and phosphorus availabilities in soil were lower in upper slope positions. The three efficiencies were higher in upper slope positions and negatively correlated with soil nutrient availability for both nitrogen and phosphorus. An increase in nutrient‐response efficiency was achieved by both increases in nutrient‐uptake and nutrient‐use efficiencies.
Major substrates for microbial sulfate reduction in the sediments of Ise Bay, Japan
Authors: Fukui Manabu , Suh Jungin , Yonezawa Yoshitaka , Urushigawa Yoshikuni
Published: November 2006

To clarify the anaerobic microbial interactions in the process of carbon mineralization in marine eutrophic environments, the microbial sulfate reduction and methane production rates were examined in coastal marine sediments of Ise Bay, Japan, in autumn 1990. Sulfate reduction rates (51–210 nmol ml−1 day−1 at 24°C) were much higher than the methane production ones (<1.78 nmol ml−1 day−1) in the surface sediments (top 2 cm) at the six stations surveyed (water depth: 10.7–23.3 m). Substrates for sulfate‐reducing bacteria (SRB) were estimated after the addition of a specific inhibitor for SRB (20 mmol l−1 molybdate) into the sediment slurry, from the substrate accumulation rates. In the presence of the inhibitor, sulfate reduction was completely stopped and volatile fatty acids (mainly acetate) were accumulated, although hydrogen was not. Methane production occurred markedly accompanied by consumption of the accumulated acetate from the third day after the addition of molybdate. The maximum rate of methane production was 1.2–1.9 μmol ml−1 day−1, which was similar to those in highly polluted freshwater sediments such as the Tama River, Tokyo, Japan. These results show that acetate is a common major substrate for sulfate reduction and methane production, and SRB competitively inhibit potential acetoclastic methanogenesis in coastal sediments. Methanogens may potentially inhabit the sediments at low levels of population density and activity.
Measurement of non‐randomness in spatial distributions
Authors: Green Roger H.
Published: November 2006

The measurement of departure from randomness in spatial distributions has widespread application in ecological work. Several “indices of non‐randomness” are compared with regard to their dependence on sample number, sample size and density. Criteria for the best choice of index for specific situations are discussed. A new coefficient Cx is proposed for use with positively contagious distributions and tests of significance are given. When Cx and another index (S2/m−1) are used for positive and negative contagion respectively, values ranging from −1 through 0 (random) to +1 are obtained, regardless of sample number, sample size or density.
Validating Clusters with the Lower Bound for Sum-of-Squares Error
Authors: Steinley Douglas
Published: November 2006

Given that a minor condition holds (e.g., the number of variables is greater than the number of clusters), a nontrivial lower bound for the sum-of-squares error criterion in K-means clustering is derived. By calculating the lower bound for several different situations, a method is developed to determine the adequacy of cluster solution based on the observed sum-of-squares error as compared to the minimum sum-of-squares error.
Intron exclusion and the mystery of intron loss
Authors: Hu Kejin
Published: November 2006

Mechanisms for loss and gain of introns are elusive. Reported here is a new pattern of intron loss which features a random loss of a single intron in a multiple‐intron gene with its neighboring introns remained, which process is defined as intron exclusion. Intron exclusion is reminiscent of removal of a limited stretch of non‐homologous sequence in a homologous recombination (HR) triggered by a double strand break (DSB), and therefore lends further evidence for a theory of intron loss through HR between a cDNA and its genomic intron‐containing locus. Thus, a model for intron loss is formulated.
Mice deficient in Dmrt7 show infertility with spermatogenic arrest at pachytene stage
Authors: Kawamata Masaki , Nishimori Katsuhiko
Published: November 2006

Genes including DM domain regulate sexual development in diverse metazoan phyla. One of these genes, Dmrt7, was expressed only in testes of adult mice. To determine the role of Dmrt7 in mice, we generated Dmrt7‐knockout mice (Dmrt7
−/−). Although the Dmrt7
−/− showed normal growth, null males were infertile. No sperm was detected in the epididymis of Dmrt7
−/− adult males. Absence of spermatids in a histological analysis, decreased expression of Ccna1 mRNA and the accumulation of SCP3‐positive spermatocytes showed the arrest of spermatogenesis at the pachytene stage in the Dmrt7‐knockout mice.
Nek7 kinase is enriched at the centrosome, and is required for proper spindle assembly and mitotic progression
Authors: Yissachar Nissan , Salem Hagit , Tennenbaum Tamar , Motro Benny
Published: November 2006

Members of the NIMA‐related kinases (NRK) family are recently emerging as central regulators of various aspects of the cell cycle. However, the cellular roles of the mammalian NRK, Nek7, remain obscure. We show here that the endogenous Nek7 protein is enriched at the centrosome in a microtubule‐independent manner. Overexpression of wt or kinase‐defective Nek7 resulted in cells of rounder appearance, and higher proportions of multinuclear and apoptotic cells. Down‐regulation of Nek7 using a small interfering RNA approach resulted in a significant increase in mitotic cells presenting multipolar spindle phenotype. These results suggest a role for Nek7 in regulating proper spindle assembly and mitotic progression.
The aging feline kidney: A model mortality antagonist?
Authors: Lawler Dennis F , Evans Richard H , Chase Kevin , Ellersieck Mark , Li Qinghong , Larson Brian T , Satyaraj Ebenezer , Heininger Kurt
Published: November 2006

Traditional thinking views apparently non-programmed disruptions of aging, which medical science calls geriatric diseases, as separate from ‘less harmful’ morphological and physiological aging phenotypes that are more universally expected with passage of time (loss of skin elasticity, graying of hair coat, weight gain, increased sleep time, behavioral changes, etc). Late-life disease phenotypes, especially those involving chronic processes, frequently are complex and very energy-expensive. A non-programmed process of homeostatic disruption leading into a death trajectory seems inconsistent with energy intensive processes. That is, evolutionary mechanisms do not favor complex and prolonged energy investment in death. Taking a different view, the naturally occurring feline ( Felis silvestris catus) renal model suggests that at least some diseases of late life represent only the point of failure in essentially survival-driven adaptive processes. In the feline renal model, individuals that succumbed to failure most frequently displayed progressive tubular deletion and peritubular interstitial fibrosis, but had longer mean life span than cats that died from other causes. Additionally, among cats that died from non-renal causes, those that had degrees of renal tubular deletion and peritubular interstitial fibrosis also had longer mean life span than those cats with no changes, even though causes of death differed minimally between these latter two groups. The data indicate that selective tubular deletion very frequently begins early in adult life, without a clear initiating phase or event. The observations support a hypothesis that this prolonged process may be intrinsic and protective prior to an ultimate point of failure. Moreover, given the genetic complexity and the interplay with associated risk factors, existing data also do not support the ideas that these changes are simple compensatory responses and that breed- or strain-based ‘default’ diseases are inevitable results of increasing individual longevity. Emerging molecular technology offers the future potential to further evaluate and refine these observations. At present, the existence of plastic and adaptive aging programming is suggested by these findings.
Hand Transplantation: The State-of-the-Art
Authors: SCHUIND F. , ABRAMOWICZ D. , SCHNEEBERGER S.
Published: November 2006

The feasibility of hand transplantation has been demonstrated, both surgically and immunologically. Levels of immunosuppression comparable to regimens used in solid organ transplantation are proving sufficient to prevent graft loss. Many patients have achieved discriminative sensibility and recovery of intrinsic muscle function. In addition to restoration of function, hand transplantation offers considerable psychological benefits. The recipient’s pre-operative psychological status, his motivation and his compliance with the intense rehabilitation programme are key issues. While the induction of graft specific tolerance represents a hope for the future, immunosuppression currently remains necessary and carries significant risks. Hand transplantation should, therefore, only be considered a therapeutic option for a carefully selected group of patients.
Dynamics in coalescing critical layers
Authors: BALMFORTH N. J. , PICCOLO C. , UMURHAN O. M.
Published: November 2006

This article continues an exploration of instabilities of jets in two-dimensional, inviscid
fluid on the beta-plane. At onset, for particular choices of the physical parameters,
the normal modes responsible for instability have critical levels that coalesce along
the axis of the jet. Matched asymptotic expansion (critical layer theory) is used to
derive a reduced model describing the dynamics of these modes. Because the velocity
profile is locally parabolic in the vicinity of the critical levels the dynamics is richer
than in standard critical layer problems. The model captures the inviscid saturation of
unstable modes, the excitation of neutral Rossby waves, and the decay of disturbances
when there are no discrete normal modes. Inviscid saturation occurs when the vorticity
distribution twists up into vortical structures that take the form of either a pair of
‘cat's eye’ patterns straddling the jet axis, or a single row of vortices. The addition
of weak viscosity destroys these cat's eye structures and causes the critical layer
to spread diffusively. The results are compared with numerical simulations of the
governing equations.
Periodic motion embedded in plane Couette turbulence: regeneration cycle and burst
Authors: KAWAHARA GENTA , KIDA SHIGEO
Published: November 2006

Two time-periodic solutions with genuine three-dimensional structure are numerically
discovered for the incompressible Navier–Stokes equation of a constrained plane
Couette flow. One solution with strong variation in spatial and temporal structure
exhibits a full regeneration cycle, which consists of the formation and breakdown of
streamwise vortices and low-velocity streaks; the other one, of gentle variation,
represents a spanwise standing-wave motion of low-velocity streaks. These two solutions
are unstable and the corresponding periodic orbits in the phase space are connected
with each other. A turbulent state wanders around the strong one for most of the
time except for occasional escapes from it. As a result, the mean velocity profile and
the root-mean-squares of velocity fluctuations of the plane Couette turbulence agree
very well with the temporal averages of those of this periodic motion. After an
occasional escape from the strong solution, the turbulent state reaches the gentle periodic
solution and returns. On the way back, it experiences an overshoot accompanied by
strong turbulence activity like an intermittent bursting phenomenon.
The wind in confined thermal convection
Authors: NIEMELA J. J. , SKRBEK L. , SREENIVASAN K. R. , DONNELLY R. J.
Published: November 2006

A large-scale circulation velocity, often called the ‘wind’, has been observed in
turbulent convection in the Rayleigh–Bénard apparatus, which is a closed box with a
heated bottom wall. The wind survives even when the dynamical parameter, namely
the Rayleigh number, is very large. Over a wide range of time scales greater than
its characteristic turnover time, the wind velocity exhibits occasional and irregular
reversals without a change in magnitude. We study this feature experimentally in an
apparatus of aspect ratio unity, in which the highest attainable Rayleigh number is
about 1016. A possible physical explanation is attempted.
Wave-driven currents and vortex dynamics on barred beaches
Authors: BÜHLER OLIVER , JACOBSON TIVON E.
Published: November 2006

We present a theoretical and numerical investigation of longshore currents driven by
breaking waves on beaches, especially barred beaches. The novel feature considered
here is that the wave envelope is allowed to vary in the alongshore direction, which
leads to the generation of strong dipolar vortex structures where the waves are
breaking. The nonlinear evolution of these vortex structures is studied in detail
using a simple analytical theory to model the effect of a sloping beach. One of our
findings is that the vortex evolution provides a robust mechanism through which the
preferred location of the longshore current can move shorewards from the location
of wave breaking. Such current dislocation is an often-observed (but ill-understood)
phenomenon on real barred beaches.

To underpin our results, we present a comprehensive theoretical description of the
relevant wave–mean interaction theory in the context of a shallow-water model for the
beach. Therein we link the radiation-stress theory of Longuet-Higgins & Stewart to
recently established results concerning the mean vorticity generation due to breaking
waves. This leads to detailed results for the entire life-cycle of the mean-flow vortex
evolution, from its initial generation by wave breaking until its eventual dissipative
decay due to bottom friction.

In order to test and illustrate our theory we also present idealized nonlinear
numerical simulations of both waves and vortices using the full shallow-water equations with
bottom topography. In these simulations wave breaking occurs through shock
formation of the shallow-water waves. We note that because the shallow-water equations
also describe the two-dimensional flow of a homentropic perfect gas, our theoretical
and numerical results can also be applied to nonlinear acoustics and sound–vortex
interactions.