bluuebunny/crossref_metadata_2025 huggingface dataset:
Canadian Supportive Care Recommendations for the Management of Anemia in Patients with Cancer
Authors: Mikhael J. , Melosky B. , Cripps C. , Rayson D. , Kouroukis C. T.
Published: December 2007

Anemia is a common finding in cancer patients, most often as a result of chemotherapy. Management of anemia requires a comprehensive approach of appropriate diagnosis, exclusion of reversible causes, use of erythropoiesis-stimulating agents (esas), and iron supplementation. Recently, consensus guidelines on the management of chemotherapy-induced anemia were published in Europe and the United States. The present review is intended to be a practical guide for Canadian physicians, based on published guidelines, but specifically tailored to the Canadian environment. Recommendations for the use of esas are presented, including initiation, target hemoglobin, dosing and adjustments, monitoring, and re-initiation. Issues of safety are also addressed, including thromboembolic risk, impact on survival, and tumour progression. The importance of iron metabolism and the use of iron supplementation (both oral and parenteral) is discussed.
Homeopathy: Does a Teaspoon of Honey Help the Medicine Go Down?
Authors: Sagar S. M.
Published: December 2007

Homeopathic remedies are undergoing a resurgence of popularity because the patient can administer them without a prescription, and they are alleged to have no adverse side effects [...]
Die schönste falsche Theorie der Biochemie. Aus 4 mach' 20, oder 21, oder 22, oder ....
Authors: Roth Klaus
Published: December 2007

Das Wettrennen bei der Entschlüsselung des genetischen Codes, also der Umwandlung eines mit vier verschiedenen Zeichen geschriebenen Endlostextes in einen aus 20 Zeichen, gipfelte schließlich in den brillanten kommafreien Code von Crick, Griffith und Orgel. Für manche war und ist es enttäuschend, dass Experimente zeigen, dass die Natur einen anderen, weniger elegant erscheinenden chemischen Weg einschlägt. Erst vor kurzem konnte gezeigt werden, dass der natürliche im Vergleich zu alternativen genetischen Codes viel fehlertoleranter ist. Die Natur strebt eben nicht nach Eleganz, Effizienz oder oberflächlicher Schönheit, sondern nach Zuverlässigkeit und erlaubt Änderungen mit der Chance zur Verbesserung durch Dazulernen.
Are the dysfunctional beliefs that predict worry different from those that predict obsessions?
Authors: Belloch Amparo , Morillo Carmen , García‐Soriano Gemma
Published: December 2007

Chronic worry present in Generalized Anxiety Disorder (GAD) and obsessions characteristic of the Obsessive–Compulsive Disorder (OCD) are cognitive phenomena that share some features, but they also differ on others. Based on current cognitive approaches, dysfunctional meta‐cognitive beliefs underlie the development and/or maintenance of both GAD and OCD. However, to date, there has been little empirical evidence about the differences between the beliefs that predict the occurrence of obsessions and those that predict worry. This study focuses on the search for these differences and examines to what extent worry and obsessions are associated with a similar or different pattern of dysfunctional cognitive contents. One hundred and seventy‐five community subjects completed measures of worry and obsessional intrusive thoughts, as well as questionnaires assessing obsession‐related and worry‐related meta‐cognitive beliefs. Results showed that beliefs about uncontrollability and danger, as well as cognitive self‐consciousness, play a central role in predicting worry, whereas the beliefs concerning the importance of thoughts and Thought–Action Fusion probability are relevant in accounting for the frequency of obsessive intrusive thoughts. Copyright © 2007 John Wiley & Sons, Ltd.
Bewehrungsanschlüsse mit nachträglich eingemörtelten Bewehrungsstäben
Authors: Feistel Georg
Published: December 2007

Anschlüsse an bestehende Stahlbetonbauteile durch nachträglich eingemörtelte Bewehrungsstäbe kommen immer mehr zum Einsatz. Solche Bewehrungsanschlüsse können durch geeignete Injektionssysteme realisiert werden, wenn eine fachgerechte Verarbeitung auf der Baustelle erfolgt. Da für diese Anschlüsse keine allgemein anerkannten Bemessungsregeln in den Betonnormen DIN 1045 bzw. Eurocode 2 vorliegen, schreiben die Landesbauordnungen vor, dass die Anwendung über eine allgemeine bauaufsichtliche Zulassung oder eine Zustimmung im Einzelfall zu regeln ist.

Dieser Artikel informiert über die Grundlagen bei der Verwendung nachträglich eingemörtelter Bewehrungsstäbe.

Es wird über die bestehenden allgemeinen bauaufsichtlichen Zulassungen für diesen Bereich berichtet und die erforderlichen Maßnahmen zur Qualifikation des Baustellenfachpersonals und der ausführenden Betriebe werden vorgestellt.

Die Besonderheiten bei der Anwendung von solchen Systemen mit europäischer technischer Zulassung (ETA) werden dargestellt und es werden die Anwendungsregeln bei der Verwendung von Mörteln nach der europäischen Norm EN 1504‐6 zur Verankerung von Bewehrungsstäben erläutert.
Synthesis of Soluble and Size‐Controlled SnO2 and CeO2 Nanocrystals: Application of a General Concept for the Low‐Temperature, Hydrolytic Synthesis of Organically Capped Oxide Nanoparticles
Authors: Epifani Mauro , Arbiol Jordi , Andreu Teresa , Morante Joan R.
Published: December 2007

Metal oxide (CeO2, SnO2) sols were prepared in such a way as to hinder the inorganic condensation reactions. Acetylacetone was added to cerium nitrate solutions before hydrolysis with ammonia solution, while solvolysis of anhydrous tin chloride with methanol was used for preparing SnO2 sols. The sols were then injected into dodecylamine at 160 °C, followed by heating at the resulting temperature for 1 h. A clear sol was obtained, from which the products were extracted by precipitation with methanol and dried. Analysis by X‐ray diffraction and TEM demonstrated the presence of CeO2 and SnO2 nanocrystals, whose size depended on the metal concentration in the starting sol, ranging from 2.6 to 3.5 nm for CeO2 and from 1 to 1.9 nm for SnO2. The nanocrystals were soluble after the synthesis and redispersable in organic solvents, forming stable suspensions. The process appears to be easily generalizable to systems having similar hydrolytic chemistry.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Determination of gentisin, isogentisin, and amarogentin in Gentiana lutea L. by capillary electrophoresis
Authors: Citová Ivana , Ganzera Markus , Stuppner Hermann , Solich Petr
Published: December 2007

A novel, fast, and simple capillary electrophoresis method has been developed for the analysis of gentisin, isogentisin, and amarogentin in roots of Gentiana lutea (yellow gentian), an herb traditionally used as gastric stimulant. Gentisin and isogentisin are xanthones showing potent inhibition of monoamine oxidase type A and B, amarogentin represents one of the bitter principles of Gentiana, responsible for its gastric‐roborant effects. Optimal CE‐separation conditions comprise a 100 mM sodium tetraborate buffer of pH 9.3, containing 10 mM β‐cyclodextrin as additive; optimum temperature and applied voltage were found to be 30°C and 25 kV, respectively. Direct diode array detection at 260 nm (gentisin, isogentisin) and 242 nm (amarogentin) was performed, and the required analysis time was only 11 min. The developed method was validated for linearity, sensitivity, precision, and accuracy, and utilized to assay several commercially available G. lutea samples. Quantitative data obtained with the developed CE method are compared with HPLC results, and the advantages of each approach are discussed.
Frontiers in population ecology of microtine rodents: A pluralistic approach to the study of population ecology
Authors: Stenseth Nils Chr , Saitoh Takashi , Yoccoz Nigel G.
Published: December 2007

Current challenges for the study of population ecology of microtine rodents are reviewed. Comparisons with other taxonomic groups (other mammals, birds and insects) are given throughout. A major challenge is to link patterns and processes (i.e. mechanisms) better than is the case today. Other major challenges include the furthering of our understanding of the interaction between deterministic and stochastic processes, and as part thereof, the interaction between density‐dependent and density‐independent processes. The applicability of comparative studies on populations exhibiting different temporal dynamical patterns is, in this connection, emphasized. Understanding spatiotemporal dynamical patterns is another major challenge, not the least from a methodological point of view. Long‐term and large‐scale ecological data on population dynamics (in space and time) are critical for this purpose. Looking for consistency between hypothesized mechanisms and observed patterns is emphasized as a good platform for further empirical and theoretical work. The intellectual feedback process between different approaches to the study of microtine population ecology (observational studies, experimental manipulative studies, statistical modeling and mathematical modeling) are discussed. We recommend a pluralistic approach (involving both observational and experimental as well as theoretical studies) to the study of small rodent ecology.
The biology of the voleClethrionomys rufocanus: A review
Authors: Kaneko Yukibumi , Nakata Keisuke , Saitoh Takashi , Stenseth Nils Chr , Bjørnstad Ottar N.
Published: December 2007

The biology of the gray‐sided voleClethrionomys rufocanusin Hokkaido, concerning taxonomy, morphology, phylogeny, distribution, and natural history, is reviewed. Applied issues in forest management (damage, control and census) are also mentioned. AlthoughClethrionomys rufocanusof Hokkaido was originally identified as a distinct species,Evotomys(=nowClethrionomys) bedfordiaeThomas, 1905, current literature generally refers to the gray‐sided vole of Hokkaido asClethrionomys rufocanusor asC. rufocanus bedfordiae(vernacular name, the Bedford's red‐backed vole). The gray‐sided vole is the most common small mammal in Hokkaido. It inhabits open areas as well as forests, and mainly feeds on green plants. The gray‐sided vole has a high reproductive potential; litter size: 4–7; gestation period: 18–19 days; maturation age: 30–60 days old. Although spring‐born individuals usually attain sexual maturity in their summer/fall of birth, their maturation is sometimes suppressed under high densities. The breeding season is generally from April to October, but with some regional variation.Clethrionomys rufocanushas a rather specialized diet (folivorous), particularly during winter when it feeds on bamboo grass. Many predators specialize on the grey‐sided vole in Hokkaido; even the red fox, which is a typical generalist predator, selectively feeds on this vole. Damage by voles’ eating bark used to be sever on forest plantations in Hokkaido. Censuses of small rodents have been carried out for management purpose since 1954.
Social organization of the vole Clethrionomys rufocanus and its demographic and genetic consequences: A review
Authors: Ishibashi Yasuyuki , Saitoh Takashi , Kawata Masakado
Published: December 2007

Recent findings on the relationship between social interaction and demographic process in the gray‐sided vole Clethrionomys rufocanus are reviewed with reference to the findings in other microtine rodents. Social behavior was particularly focused on spacing and dispersal, and their effects on population dynamics are discussed. Female territoriality can limit a population abundance as a density‐dependent factor, although its regulatory effect is controversial. Female philopatry and male‐biased dispersal should bring about the clumped distribution of female relatives and genetically random distribution of males during the breeding season. The sexual difference in dispersal patterns can contribute to the mating behavior of the vole; promiscuous mating and low frequency of incestuous mating. However, effects of social structure, including kinship, on reproduction and survival of individuals still remains to be clarified. Molecular markers may help to solve these issues and provide new field of population ecology in microtine rodents.
Kin‐related social organization in a winter population of the vole Clethrionomys rufocanus
Authors: Ishibashi Yasuyuki , Saitoh Takashi , Abe Syuiti , Yoshida Michihiro C.
Published: December 2007

Kinship among Clethrionomys rufocanus was investigated during the winter of 1992/93 in a 3‐ha enclosure using both molecular and catch‐mark‐release techniques. Forty‐six adult voles (22 males and 24 females) having high heterozygosities, which were collected from several natural populations, were released into the enclosure on 29 September 1992. Most fall‐born individuals of both sexes stayed in their natal site during the non‐breeding period (December–March), although reproductively active females dispersed during the fall breeding season (October–November). These philopatric individuals aggregated and formed an maternal family in the winter. Several females which failed to reproduce were solitary during this season. Some individuals which were derived from several families also aggregated into a mixed lineage group. Survival rate of fall‐born voles from earlier litters was higher than that from later ones. Maternal families broke up soon after the onset of spring reproduction. Most females established a territory near the wintering site and made a kincluster, in which close relatives neighbored each other. Maternal families in winter bring about female kin‐clusters in spring, which may influence reproductive output in the breeding season.
The population dynamics of the vole Clethrionomys rufocanus in Hokkaido, Japan
Authors: Saitoh Takashi , Stenseth Nils Chr , Bjørnstad Ottar N.
Published: December 2007

Population dynamics of the gray sided‐vole, Clethrionomys rufocanus, in Hokkaido, Japan were described on the basis of 225 time series (being from 12 to 31 years long); 194 of the time series have a length of 23 years or longer. The time series were classified into 11 groups according to geographic proximity and topographic characteristics of the island of Hokkaido. Mean abundance varied among populations from 1.07 to 21.07 individuals per 150 trap‐nights. The index of variability for population fluctuation (s‐index) ranged from 0.204 to 0.629. Another index for population variability (amplitude on log‐10 scale) ranged from 0.811 to 2.743. Mean abundance and variability of populations were higher in the more northern and eastern regions of the island. Most populations, except for the southernmost populations, exhibited significant direct density‐dependence in population growth. Detection rate for delayed density‐dependence varied among groups from 0% to 22.6%. Both direct and delayed density‐dependence tended to be stronger in the more northern and eastern populations. The proportion of cyclic populations was higher in the northern‐eastern areas than that in the southern‐western areas. There was a clear gradient from the asynchronous populations in southwest, to the highly synchronized populations in the northeast.
Mapping the regional transition to cyclicity inClethrionomys rufocanus: Spectral densities and functional data analysis
Authors: Bjørnstad Ottar N. , Stenseth Nils Chr , Saitoh Takashi , Lingjærde Ole Chr
Published: December 2007

We study the regional transitions in dynamics of the gray‐sided vole,Clethrionomys rufocanus, within Hokkaido, Japan. The data‐set consists of 225 time series of varying length (most from 23 to 31 years long) collected between 1962 and 1992 by the Forestry Agency of the Japanese Government. To see clearly how the periodic behavior changes geographically, we estimate the spectral density functions of the growth rates of all populations using a log‐spline method. We subsequently apply functional data analysis to the estimated densities. The functional data analysis is, in this context, analogous to a principal component analysis applied to curves. We plot the results of the analysis on the map of Hokkaido, to reveal a clear transition from relatively stable populations in the southwest and west to populations undergoing 3–4 year cycles in the northeast and east. The degree of seasonality in the vegetation and the rodent demography appear to be strongest in the cyclic area. We briefly speculate that the destabilization of the rodent dynamics is linked to increased seasonalforcing on the trophic interactions in which the gray‐sided voles are involved.
Seasonal forcing on the dynamics of Clethrionomys rufocanus: Modeling geographic gradients in population dynamics
Authors: Stenseth Nils Chr , Bjørnstad Ottar N. , Saitoh Takashi
Published: December 2007

We interpret gradients in population dynamics of the gray‐sided vole from the southwestern part of the island of Hokkaido to its northeastern part within the framework of a phenomenological model involving the relative length of summer and winter. In Hokkaido, as in other northern regions, both spring and fall is considered as short transition periods between the two main seasons — summer (the primary breeding season) and winter (the non‐reproductive or secondary breeding season). We show that the geographic transition in dynamics may be understood as the combined consequence of different patterns of density‐dependence during summer and winter, and geographically varying season lengths. Differences are shown to exist between summer and winter with respect to strength of density‐dependence. Direct density‐dependence, in particular, is stronger during winter than during summer. A model is presented to show how relative lengths of seasons can induce both stable and periodically fluctuating population dynamics. The results are compared and contrasted with what is otherwise known about the gradient in rodent dynamics in Fennoscandia.
The role of vole populations in prevalence of the parasite (Echinococcus multilocularis) in foxes
Authors: Saitoh Takashi , Takahashi Kenichi
Published: December 2007

Effects of population fluctuation of the gray‐sided vole (Clethrionomys rufocanus) on the prevalence (infection rates) of the parasite Echinococcus 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.
The demography ofClethrionomys rufocanus: From mathematical and statistical models to further field studies
Authors: Yoccoz Nigel G. , Nakata Keisuke , Stenseth Nils Chr , Saitoh Takashi
Published: December 2007

Until recently, most studies on microtines have focused on patterns in population dynamics or demography without providing a quantitative assessment of the robustness of the inferred patterns as well as a link between demography and population dynamics. Developments in statistical time‐series analysis on the one hand and in capture‐recapture statistical modelling on the other hand, now allow for improved analyses. We review some of the recent developments in the capture‐recapture statistical methodology — restricting ourselves to methods most relevant to the demography of small mammals. A 5‐years study of the gray‐sided voleClethrionomys rufocanusin Hokkaido, Japan was used as an example to explore some models. We then provided a framework for further demographic analysis of microtine populations, includingC. rufocanus.Investigating the relative importance of the different demographic parameters (e.g. survival, maturation, dispersal) will require studies done on larger scale than is commonly done today, with more effort devoted to the low density phase. Special emphasis is given to study‐design, and to experimental designs tailored to the study of specific demographic mechanisms.
The population biology of coevolution
Authors: Thompson John N.
Published: December 2007

New populational approaches to the study of coevolution among species are confronting two major problems: the geographic scale at which coevolution proceeds, and the long‐standing issue of how species may coevolve with more than one other species. By incorporating the ecological structure of life histories and populations into analyses of the coevolutionary process, these studies are indicating that coevolutionary change is much more ecologically dynamic than indicated by earlier work. Rather than simply a slow, stately process shaping species over long periods of time, parts of the coevolutionary process may proceed rapidly (sometimes observable in less than a decade), continually molding and remolding populations and communities locally and over broad geographic scales.
Receptivity of female remating and sperm number in the sperm storage organ in the bean bug, Riptortus clavatus (Heteroptera: Alydidae)
Authors: Sakurai Tamito
Published: December 2007

This study examines the relationship between the number of sperm in the seminal receptacle (spermatheca) and the receptivity of female remating in the bean bug Riptortus clavatus Thunberg. On the 21 st day after the first mating when receptivity to remating was > 70%, females receptive to remating had significantly fewer sperm (< 40 on average) in the spermathecae than females reluctant to do (about 150 on average). However, averages of the number of eggs laid by receptive and reluctant females within 21 days were almost same. The proportion of fertilized eggs for receptive females at 15–21 days after copulation was significantly lower than that for reluctant females. Spermatozoa transferred from a male to a female's spermatheca were detected 5 min after copulation and then increased continuously to about 500 with the first hour. When copulation durations were manipulated artificially, the shorter the copulation period (=females had less sperm in their spermathecae), the higher the remating rate became. Females may perceive the number of sperm in their seminal receptacles and then determine whether they copulate or not. These results support the hypothesis that females mate multiply in order to replenish inadequate sperm supplies to fertilize all eggs produced.
Natural enemies for the cabbage webworm, Hellula undalis (Fabr.) (Lepidoptera: Pyralidae) in Malaysia
Authors: Sivapragasam A. , Chua T. H.
Published: December 2007

Four species of larval parasitoids were reared from larvae of the cabbage webworm (CWW),Hellula undalis (Fabr.) (Pyralidae: Glaphyriinae) collected from various cruciferous plants and a capparidaceous weed, Cleome rutidosperma (DC). On cabbage, only two species were recorded, viz, Bassus sp. (Braconidae) and Trathala flavoorbitalis (Cam.) (Ichneumonidae). The other parasitoids were braconids, Chelonus sp. and Phanerotoma sp. Egg or pupal parasitoids were not recorded. The parasitoids were not an important mortality factor of CWW on cabbage because they were usually present at the end of the crop season and their numbers were generally low. On the other hand, predator‐exclusion experiments indicated that predators were important in determining the density of CWW on cabbage and the within‐generation survival in the field. The major predator was the fire‐ant, Solenopsis geminata (F.), which foraged on the prepupae and pupae.
Possible influences of habitat characteristics on the evolution of semelparity and cannibalism in the hump earwigAnechura harmandi
Authors: Kohno Katsuyuki
Published: December 2007

The possible influences of life history and habitat characteristics on the evolution of semelparity and cannibalism in the hump earwigAnechura harmandiwere studied. This species is univoltine and overwinters as an adult. Females laid single egg‐batches during winter in nests under stones at a riverside in a valley. They took care of the eggs which hatched in early spring and the offspring ate their mother before dispersing. The valley was sometimes flooded in summer. Nymphs emerged as adults and dispersed to elsewhere before the rainy season arrived. They returned to the riverside after the rainy season. The flooding and/or summer heat seemed to be the selective force for the evolution of dispersal behavior and semelparity in this species. The cannibalism of the female parent by her offspring seemed to have readily evolved after the evolution of semelparity. The unfavorable environmental conditions seemed to have a large effect on the evolution of semelparity and cannibalism in this species.
Deme formation in gall‐making aphids Adelges japonicus (Homoptera: Adelgidae)
Authors: Ozaki Kenichi , Itahana Naoei
Published: December 2007

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 of Picea 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 (q1,q2 and q3). 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 on q1 (fecundity of gallicolae multiplied by survivorship of fundatrices while feeding on needles) and q3 (fecundity of fundatrices multiplied by survivorship of gallicolae before emergence from the galls), suggesting genetic differences in resistance among clones. The two‐fold difference in q3 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 in q1 seemed to be caused by different survivorship of larval fundatrices while feeding on needles.
An island biogeographical approach to the analysis of butterfly community patterns in newly designed parks
Authors: Kitahara Masahiko , Fujii Koichi
Published: December 2007

We analyzed the butterfly communities in the newly designed city parks (area C), “newly opened habitat islands”, of Tsukuba City, central Japan. The area constituted a natural ecological experiment on the mainland for clarifying the pattern and process of faunal immigration. We compared butterfly communities in area C with those in two other areas in the light of the theory of island biogeography and the concept of generalist/specialist. Our results showed the following: (1) Fewer species were found in area C than in other areas, due largely to the absence of many specialist types, restricted and habitat specialists, and/or low density species in the area. Generalist types, widespread and habitat generalists, and/or high density species predominated in area C. (2) The difference in the species numbers among the three sections within area C could be explained by the habitat structure in and around the respective sections. (3) The densities of many species were low in area C, probably due to its man‐modified habitat structure. In particular, several species occurred at extremely low densities in area C, but at high densities in other areas. (4) The internal structure of the habitat island butterfly community in area C was almost perfectly consistent with that of “quasi‐equilibrium” communities that appear during the colonization of an island. Our results demonstrate that the synergetic application of the generalist/specialist concept and the island biogeography theory is effective for the understanding of the patterns and structures of habitat island communities.
Population stability in relation to resource availability in an introduced population of an herbivorous lady beetle
Authors: Ohgushi Takayuki , Sawada Hiroichi
Published: December 2007

Mechanisms responsible for population stability in relation to resource availability were studied in an introduced herbivorous lady beetle, Epilachna niponica. The introduced population was relatively constant over a seven‐year study period. Egg density was related to the variation in host‐plant abundance in different years, and was highly stabilized during the period from reproductive adult to egg stage. Two density‐dependent processes were identified in the reproductive season: (1) density‐dependent reduction in fecundity and (2) density‐dependent increase in female mortality and/or emigration, all of which operated early in the season. As a result, temporal variability in cumulative egg density was greatly reduced by mid‐May, by which time approximately 40% of total eggs were laid. A field cage experiment demonstrated that egg‐laying of individual females was largely limited by resource availability even at low levels of leaf herbivory. Since movement activity of ovipositing females increased in a density‐dependent manner, inter‐plant movement is more likely to cause density‐dependent reduction in fecundity and female loss, due to enhanced energy expendiditure. The introduced population was less stable than the source population, probably because of decreased inter‐plant movement of females and the unlikelihood of egg resorption, both of which contribute significantly to the temporal stability of E. niponica population densities.
Extinction of populations due to inbreeding depression with demographic disturbances
Authors: Tanaka Yoshinari
Published: December 2007

The process of population extinction due to inbreeding depression with constant demographic disturbances every generation is analysed using a population genetic and demographic model. The demographic disturbances introduced into the model represent loss of population size that is induced by any kind of human activities, e.g. through hunting and destruction of habitats. The genetic heterozygosity among recessive deleterious genes and the population size are assumed to be in equilibrium before the demographic disturbances start. The effects of deleterious mutations are represented by decreases in the growth rate and carrying capacity of a population. Numerical simulations indicate rapid extinction due to synergistic interaction between inbreeding depression and declining population size for realistic ranges of per‐locus mutation rate, equilibrium population size, intrinsic rate of population growth, and strength of demographic disturbances. Large populations at equilibrium are more liable to extinction when disturbed due to inbreeding depression than small populations. This is a consequence of the fact that large populations maintain more recessive deleterious mutations than small populations. The rapid extinction predicted in the present study indicates the importance of the demographic history of a population in relation to extinction due to inbreeding depression.
Competition and evolutionary stability of plants in a spatially structured habitat
Authors: Takenaka Yasuto , Matsuda Hiroyuki , Iwasa Yoh
Published: December 2007

We modelled the population dynamics of two types of plants with limited dispersal living in a lattice structured habitat. Each site of the square lattice model was either occupied by an individual or vacant. Each individual reproduced to its neighbors. We derived a criterion for the invasion of a rare type into a population composed of a resident type based on a pair‐approximation method, in which the dynamics of both average densities and the nearest neighbor correlations were considered. Based on this invasibility criterion, we showed that, when there is a tradeoff between birth and death rates, the evolutionarily stable type is the one that has the highest ratio of birth rate to mortality. If these types are different species, they form segregated spatial patterns in the lattice model in which intraspecific competitive interactions occur more frequently than interspecific interactions. However, stable coexistence is not possible in the lattice model contrary to results from completely mixed population models. This clearly shows that the casual conclusion, based on traditional well mixed population models, that different species can coexist if intraspecific competition is stronger than interspecific competition, does not hold for spatially structured population models.
Maintenance of diapause variability in the two‐spotted spider mite, tetranychus urticae, in a heterogeneous and stochastic environment
Authors: Tsuda Yoshio , Takafuji Akio , Kuno Eiji
Published: December 2007

A simple nongenetic mathematical model analyzed the processes responsible for the variations in the diapause percentage among populations of the two‐spotted spider mite, Tetranychus urticae Koch. This model incorporates the following assumptions. 1) Mites have diapause (DD), non‐diapause (NN), and “plastic” (DN) populations (plasticity exists in the phenotypic expression of diapause in response to habitat conditions at the time of diapause induction). 2) A heterogeneous mite habitat consists of microhabitat L, in which all the non‐diapausing mites die during the winter due to the lack of winter host plants, and microhabitat O with winter hosts capable of supporting some of the non‐diapausing mites overwinter. 3) Temporal fluctuation of winter conditions which affect the survival and reproduction of non‐diapausing mites. Using these assumptions, we compared the fitness functions of the three populations and analyzed the conditions under which each population is favoured over the other two, thereby elucidating the processes involved in the maintenance of variability in diapause. Our analysis revealed: 1) frequent mild winters are of primary importance for the non‐diapause trait to be maintained, 2) the existence of winter hosts is also important for the nondiapause trait to be favoured, and this importance depends greatly on the degree of the adaptive diapause expression in the DN mites in response to habitat conditions, i.e., the better the phenotypeenvironment matching in DN, the higher the probability that DN will be favoured, 3) The combined effect of the temporal and spatial variation enhances the maintenance of variablity in the diapause trait of the mites.
Shoot growth dynamics and size‐dependent shoot fate of a clonal plant, Festuca rubra, in a mountain grassland
Authors: Hara Toshihiko , Herben Tomas
Published: December 2007

The relation of the within‐season and between‐season patterns of shoot growth were compared in a clonal grass with long‐lived shoots, Festuca rubra, in a mown mountain grassland. The growth rate of shoot length from spring to summer in a year was almost constant for each shoot irrespective of spring shoot length each year. The annual shoot growth rate from spring to spring was negatively correlated with the shoot length in the first spring. Shoots of different length and age therefore tended to converge over time to a population of identical shoot size, suggesting an equalizing effect of growth pattern on size structure. Shoot size (shoot length and number of leaves) influenced the fates of shoots. Larger shoots showed an increased incidence of both flowering and formation of intravaginal daughter shoots and a decreased incidence of death in the subsequent time period. The fates of shoots were independent of their age. Although the negatively size‐dependent springto‐spring annual shoot growth rate acted to decrease shoot size variation, the remaining variation within the shoot population was still sufficient to generate different fates of shoots. These fates were not related to the previous life history of individual shoots. There was a significantly positive effect of the shoot size at initiation on its life expectancy. This was mainly attributable to the positively size‐dependent survival rate of shoots in the early stage (<1 year old) of shoot life history. Later on (> 1 year old), shoot size had little effect on the survival rate of shoots. Once small young shoots have survived this early stage (< 1 year old) in life history, they can grow vigorously, little affected by competition regardless of shoot size, and converge to a stable size structure of shoots of similar size. Only shoot size in the early stage (< 1 year old) of life history is important for the persistence of a shoot population.
Silique burst of Cardamine scutata (Cruciferae) as a physical inducible defense against seed predatory caterpillars
Authors: Yano Shuichi
Published: December 2007

Matured seeds of bitter cress, Cardamine scutata Thumb, are scattered by the bursting of siliques. They also burst in response to chewing by seed predatory caterpillars even when seeds are immature. In this case, the caterpillars are frequently expelled, or killed when their bodies become enswathed by the released pericarps. Consequently, many seeds escape from the attack. The plant trait is explained as an immediate induction of a physical defense against seed predators. The germination rate of scattered immature seeds was significantly lower than that of mature ones, which is a direct demonstration of trade‐off between anti‐herbivore defense and reproduction of the plant.
A method for the estimation of parameters for natural stage‐structured populations
Authors: Manly Bryan F. J.
Published: December 2007

A relatively simple method is proposed for the estimation of parameters of stage‐structured populations from sample data for situation where (a) unit time survival rates may vary with time, and (b) the distribution of entry times to stage 1 is too complicated to be fitted with a simple parametric model such as a normal or gamma distribution. The key aspects of this model are that the entry time distribution is approximated by an exponential function with p parameters, the unit time survival rates in stages are approximated by an r parameter exponential polynomial in the stage number, and the durations of stages are assumed to be the same for all individuals. The new method is applied to four Zooplankton data sets, with parametric bootstrapping used to assess the bias and variation in estimates. It is concluded that good estimates of demographic parameters from stagefrequency data from natural populations will usually only be possible if extra information such as the durations of stages is known.
Selection and reproductive success in males of the dragonfly, Orthetrum japonicum (Odonata: Libellulidae)
Authors: Kasuya Eiiti , Edanami Kaori , Ohno Ikuko
Published: December 2007

Reproductive success, copulation success, and mating success were measured for a population of male dragonflies, Orthetrum japonicum. Copulation success explained the greatest variation in reproductive success. The proportion of copulations followed by oviposition was positively correlated with the number of oviposited eggs per mating. Directional selection on four morphological characters was estimated. The effect of selection on correlated traits was comparable to that of direct selection. Directional selection varied between traits and between episodes in a single trait. The probability that the observed directional selection on the four morphological traits was expected under the condition of the selective neutrality of traits was not smaller than 5%.
δ15N examination of the Lindeman‐Hutchinson‐Peters theory of increasin omnivory with trophic height in aquatic foodwebs
Authors: France Robert L.
Published: December 2007

The advent of stable nitrogen isotope analysis in ecological research has at last enabled precise identification of trophic position and omnivory due to the differential enrichment of15N over14N with progressive assimilation up the foodweb. I compiled literature data on δ15N values in freshwater and marine foodwebs to search for qeneral patterns in omnivory, specifically the supposition originally proposed by Lindeman (1942) and most recently advanced by Peters (1977), that omnivory should increase with trophic height or position. Omnivory, measured as average intraspecific variability in δ15N, was indeed found to increase with trophic height, such that species at the top of foodwebs were comprised of animals relying, on average, on energy originating from a mixture of different trophic categories.
Evolution of condition‐dependent dispersal: A genetic‐algorithm search for the ESS reaction norm
Authors: Ezoe Hideo , Iwasa Yoh
Published: December 2007

Many insects produce two types (winged and wingless) of offspring that greatly differ in dispersal ability. The ratio of the two types often depends on the quality of the local habitat and the crowding experienced by the mother. Here we studied the condition‐dependent dispersal that is evolutionarily stable. The model is also applicable to annual plants that produce two types of seeds differing in dispersal rates. The model assumptions are: the population is composed of a number of sites each occupied by a single adult. The total number of offspring produced by a mother depends on the environmental quality of the site that varies over the years and between sites. The ESS fraction of dispersing type as a function of the quality of the habitat (or ESS reaction norm) states that dispersers should not be produced if habitat quality m is smaller than a critical value k. If m is larger than k, the number of dispersers should increase with m and that of nondispersers should be kept constant. Second, we developed an alternative way of searching for the ESS: the reaction norm is represented as a three‐layered neural network, and the parameters (weights and biases) are chosen by genetic algorithm (GA). This method can be extended easily to the cases of multiple environmental factors. There was an optimal (relatively wide) range of mutation rates for weights and biases, outside of which the convergence of the network to the valid ESS was likely to fail. Recombination, or crossing‐over, was not effective in improving the success rate. The learned network often shows several characteristic ways of deviation from the ESS. We also examined the case in which the quality of different sites was correlated. In this case the ESS fraction of dispersers increases both with the quality of the site and with the average quality of the whole population in that year.
Optimal age‐dependent sustainable harvesting of natural resource populations: Sustainability value
Authors: Yamauchi Atsushi , Matsumiya Yoshiharu , Iwasa Yoh
Published: December 2007

We studied the optimal age‐dependent harvesting of a natural resource population that achieves a maximum income under the constraint of sustainability, i.e. the reproductive adults numbers must exceed a given minimum. The resource species is assumed to be semelparous (a single reproduction over a life). The economic value and natural mortality coefficient can vary with age. The optimal age‐dependent harvesting under the sustainability constraint is obtained using Pontryagin's maximum principle. The constraint of resource sustainability can be treated as an additional term measured in the same units as economic income. Specifically, three terms: (1) current harvesting value, (2) future harvesting value, and (3) sustainability value, are calculated for each age, and the resources should be harvested at the maximum rate when their current harvesting value is greater than the sum of future harvesting value and sustainability value, and should not be harvested otherwise. Numerical analyses of several cases demonstrated that the optimal harvesting schedule depends critically on the natural mortality coefficient and the functional form of the economic value of the resource.
Differences in adult and reproductive lifespan in the two male forms of Mnais pruinosa costalis selys (Odonata: Calopterygidae)
Authors: Tsubaki Yoshitaka , Hooper Rowan E. , Siva‐Jothy Michael T.
Published: December 2007

The damselfly Mnais pruinosa costalis (Odonata: Calopterygidae) is unusual in that males are dimorphic, existing as clear‐winged non‐territorial ‘sneaks’ and orange‐winged territorial ‘fighters’. Here we report the results of population census data and behavioural observations in the field and laboratory, and present estimates of emergence period, reproductive period, total lifespan, and reproductive success of each morph. Clear‐winged males are smaller and have lower daily reproductive success than orange‐winged males, but live for longer in the field and laboratory. We accounted for the difference in the ‘operational reproductive life’ of the two morphs and estimated lifetime reproductive success: there was no difference between clear‐winged and orange‐winged males. We discuss possible mechanisms for the maintenance of the two forms.
Biogeographical history of northeastern Asiatic soricine shrews (insectivora, mammalia)
Authors: Ohdachi Satoshi , Masuda Ryuichi , Abe Hisashi , Dokuchaev Nikolai E.
Published: December 2007

A hypothetical biogeographical history of northeastern Asiatic soricine shrews in the late Quaternary was developed by integrating their present distributions, fossil records, a hypothetical phylogeny, and geological investigations. First, a biological area cladogram of the northeastern Asiatic region was constructed by applying the vicariance hypothesis to the phylogeny of the caecutiens/shinto group, a monophyletic group proposed by Ohdachi et al. (1997). Comparing the biological area cladogram with a geological hypothesis by Ohshima (1990,1991,1992), we hypothesized a geographical history of northeastern Asia. Species were then located on the dendrogram of the geographical history, referring to the present distributions, fossil records, and phylogeny of shrews. According to our hypothesis, higher species diversity of the northern region of northeastern Asia (Hokkaido, Sakhalin, and Eastern Siberia) was achieved by several series of colonizations and habitat expansion. On the other hand, the shrew communities of the southern region (Honshu, Sado, Shikoku, and Kyushu) were created by extinction and isolation followed by speciation.
Life history traits of pest and non‐pest populations in the phytophagous ladybird beetle, Epilachna niponica (coleoptera, coccinellidae)
Authors: Shirai Yoichi , Morimoto Naotake
Published: December 2007

Life history traits of the phytophagous ladybird beetle, Epilachna niponica were compared between a non‐pest population feeding on wild thistle and a pest population feeding on cultivated solanaceous crops, mainly potato. The pest population had larger females, a higher population growth rate, a more continuous oviposition schedule, and a shorter developmental period in the immature stages, compared with the non‐pest population. The two populations showed no clear differences in phenology from spring to autumn, egg mass size, hatchability, and larval survival rate. Significant differences were found in number of eggs laid per female during the first and second periods, and in the developmental period of the immature stages. These life history traits were influenced primarily by food plant. A higher fecundity and shorter immature period appear to be readily altered by the host shift from thistle to potato.