bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractMatured 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

AbstractA 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

AbstractReproductive 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

AbstractThe 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

AbstractMany 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

AbstractWe 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

AbstractThe 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

AbstractA 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

AbstractLife 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.
Distributions of larval mosquitoes among bamboo‐stump pools which vary in persistence and resource input
Authors: Sunahara Toshihiko , Mogi Motoyoshi 
Published: December 2007

AbstractWe studied the seasonal occurrence and the distribution patterns of larval mosquitoes in a bamboo grove in northern Kyushu, Japan. The number of pools was large from June to August and was small in winter. Deep stumps and semi‐closed‐type stumps held water more persistently than shallow and open‐type stumps, respectively. Open‐type stumps trapped more leaves than semi‐closed‐type stumps and the number of leaves trapped in the open‐type stump was positively correlated with the area of the pool. The incidences of Tripteroides bambusa and Aedes albopictus were low early in their breeding season and gradually increased thereafter. In August, the density of T. bambusa larvae per pool was higher in the old (>2 months) pools than in the new pools and was positively correlated with the depth of the stumps. In contrast, the density of A. albopictus did not differ significantly between the new‐and old pools and was not significantly correlated with the depth of the stump. The density of A. albopictus was positively correlated with the number of leaves that had been trapped in the stump, whereas the density of T. bambusa was not. In addition to the seasonal fluctuation in habitat‐patch availability, the variations in habitat persistence and resource input among bamboo stumps may facilitate the coexistence of the two mosquitoes that were differentially limited by these factors.
Effects of spatio‐temporal intervals between newly‐hatched larvae on larval survival and development in Monochamus alternatus (Coleoptera: Cerambycidae)
Authors: Anbutsu Hisashi , Togashi Katsumi 
Published: December 2007

AbstractThe effects of distance between hatching larvae on survival and development were investigated in Monochamus alternatus. Two newly‐hatched larvae were inoculated into Pinus densiflora bolts at a distance of 2.5 cm or 10 cm, simultaneously or at an interval of 2 weeks. Some larvae were inoculated singly as a control. When larvae were inoculated simultaneously, mortality of the closely‐inoculated larvae was significantly higher than that of distantly‐inoculated larvae. Such high mortality was identified as due to conspecific bites. When the two larvae were inoculated asynchronously, the first‐inoculated larvae killed some second‐inoculated larvae but were never killed by them. Consequently, mortality was higher in second‐inoculated larvae than in first‐inoculated larvae. In particular, there was a significant difference in mortality between them when the larvae had been inoculated closely. The mortality of second‐inoculated larvae was higher in the closely‐inoculated group than in the distantly‐inoculated group although there was no significant difference between them. In the case of two simultaneously‐inoculated larvae, the initial distance between them had no significant effect on the development and growth in the early larval stage. When the larvae were inoculated asynchronously, the first‐inoculated larvae grew more quickly than singly‐inoculated control larvae.
Speciation and evolutionary dynamics of asymmetric mating preference
Authors: Yoshimura Jin , Starmer William T. 
Published: December 2007

AbstractAsymmetric mating preferences occur in two closely related species, if females of one species are highly selective against males of the second, while females of the second show less selection against males of the first species. It has been suggested that such asymmetry is an indicator of common ancestry between the two species, but actual observations are contradictory and inconclusive. We developed a scenario of speciation history and asymmetric mating preference, incorporating invasion dynamics via frequency‐dependent interspecific sexual competition. A newly isolated (derived) species may form at the periphery of the ancestral species’ distribution by invading a new range. Only a few closely related species would be expected in the new area, while many related species are expected to coexist with the ancestral species. In a peripherally derived species, female mating preferences should be relaxed through sexual character release, owing to a lack of sympatric species and a scarcity of intraspecific mating opportunities. Secondary contacts may then happen as: 1. repeated invasions, i.e. subsequent invasion by the ancestral species into the new range or, 2. backward invasions, i.e. derived species incursions into the ancestral range. Repeated invasions could lead to the coexistence of both the derived species and the newly invading ancestor. Backward invasions by the derived species can succeed only when the derived females develop a strict mating discrimination against the ancestral males. We then expect strong character displacement in the derived species. Thus, peripheral isolation and repeated invasions lead to the relaxed female mating preferences in the derived species and backward invasions lead to stronger female mating preferences in the derived species. This agrees with Drosophila data from Hawaii and the continents. Experimental data of the Drosophila arizonaemojavensis species cluster also support the hypothesis.
Changes in searching responses with temperature of Cyrtorhinus lividipennis reuter (Hemiptera: Miridae) on the eggs of the brown planthopper, Nilaparvata lugens (Stål.) (Homoptera: Delphacidae)
Authors: Song Y. H. , Heong K. L. 
Published: December 2007

AbstractThe functional response of Cyrtorhinus lividipennis Reuter attacking the brown planthopper (Nilaparvata lugens (Stål.), BPH) eggs on rice was determined at six constant temperatures of 20°C, 23°C, 26°C, 29°C, 32°C and 35°C. Rogers’ (1972) random predator equations were fitted to the data for each temperature separately. The equation model adequately described a Holling's Type II functional response for C. lividipennis and produced biologically realistic estimates of attack rates and handling times at five experimental temperatures between 20°C and 32°C. However, at 35°C, a negative handling time (Th = ‐ 0.0029) was produced. The effect of temperature was incorporated in to Rogers’ equation by making the attack rate (a) and handling time (Th) functions of temperature within the range 20°C to 32°C. The attack rate and handling time were fitted as hyperbola and reciprocal hyperbola functions of temperature respectively. The temperature incorporating fourparameter composite model fitted the combined data as well as did separate Rogers’ equations based on the parameter estimates.
The effect of vegetation patterns on oviposition habitat preference: A driving mechanism in terrestrial chironomid (Diptera: Chironomidae) succession?
Authors: Frouz Jan 
Published: December 2007

AbstractRelationships between changes of two species of terrestrial chironomids(Smittia cf. aterrimaandBryophaenocladius cf. virgo)and changes of vegetation cover during succession were studied with respect to plant — chironomid interaction in particular stages of chironomid life cycle. Several vegetation types forming vegetation mosaics in suburban fallow were distinguished according to their spatial architecture (height; density etc.). Abundance of chironomid larvae in particular type of vegetation and an area covered by these vegetation types were studied for three years. During one year the effect of vegetation types on density of aerial drift, oviposition habitat preference and adult emergence was studied in detail. Aerial drift was studied using pan traps, oviposition using soil sampling and adult emergence using emergence trap. Main results were similar for both species. Chironomid larvae were abundant in soil in initial years of succession. They were concentrated in patches with open and low height vegetation. Later their abundance decreased corresponding to a reduction of open and low vegetation areas. Greater density of aerial drift and oviposition preference was observed in areas of open and low vegetation. The success of larval development agreed with oviposition preference for winter larval generation only. The less preferred habitats seemed to be more suitable for summer generation. The results indicated that successional changes of terrestrial chironomids can be explained by the effect of vegetation cover on oviposition habitat preference.
An individual‐based model for competing Drosophila populations
Authors: Jansen Vincent A. A. , Sevenster Jan G. 
Published: December 2007

AbstractAn individual‐based model for Drosophila is formulated, based on competition amongst larvae consuming the same batch of food. The predictions of the model are supported by data for single species Drosophila populations reared in the laboratory. The model is used to build a simple discrete model for the dynamics of Drosophila populations that are kept over a number of generations. The dynamics of a single species is shown to give either a stable equilibrium or fluctuations which can be periodic or chaotic. When the dynamics of a species in the absence of the other is periodic or chaotic, we found coexistence or two alternative states, on neither of which the species can coexist.
Loss of genetic variability in a fragmented continuously distributed population
Authors: Kawata Masakado 
Published: December 2007

AbstractAn individual‐based simulation model was used to examine the effect of population subdivision, dispersal distance of offspring, and migration rates between subpopulations on genetic variability (H1HS and HT) in a continuously distributed population. Some difficulties with mathematical models of a continuously distributed population have been pointed out. The individual‐based model can avoid these difficulties and can be used to examine genetic variability in a population within which individuals are distributed continuously and in which the dispersal of individuals is disturbed by geographical or artificial barriers. The present simulation showed that the pattern of decrease in H1 had three stages. During the first stage, H1 decreased at the rates predicted by Wright's neighborhood size. During the second stage, H1 decreased more rapidly when the migration rate decreased, while during the third stage, it decreased less rapidly when the migration rate decreased. Increasing the number of subdivisions increased the rate of decrease after the 200th generation. The pattern of decrease in HT was classified into 2 stages. During the first stage, the rates of decrease corresponded with those of a randomly mating population. During the second stage, a decrease in the migration rates of the subpopulations slowed the rate of decrease in HT. A uniform spatial distribution and a reduced total dispersal distance of offspring caused H1HS, and HT to decrease more rapidly. Habitat fragmentation in a continuously distributed population usually was detrimental to the genetic variability in the early generations. Other implications of the results for conservation are discussed.