The effect of population density on the growth of an animal population

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Contribution from the Department of Fisheries, Kyoto University.

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Contribution from the Entomological Laboratory, Kyoto University, No. 201.     

On the estimation of insect population by time unit collecting

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Contributions from the Entomological Laboratory, Kyoto University, No. 230.     

On the difference of the action between two parasitic wasps in the fluctuations of the host and parasite. (Preliminary)

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Contributions from the Entomological Laboratory, Kotyo University, No. 227.     

Experimental analysis of emergency curve

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Contributions from the Entomological Laboratory, Kyoto University, No. 200.     

On the action of population density in the population fluctuation of the flour moth,Ephestia cautella

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Contributions from the Entomological Laboratory, Kyoto University, No. 228.     

Interspecific competition between two species of the bean weevil

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Contributions from the Entomological Laboratory, Kyoto University, No. 110.     

Grassland dynamics under sheep grazing in an Australian Mediterranean type climate

Grassland dynamics in a degraded disclimax grassland dominated by Danthonia caespitosa Gaudich. are examined using both demographic and multivariate approaches in an experiment designed to determine the effect of grazing intensity and exclosure on pasture dynamics. The experiment ran for 20 years from 1949 to 1968, using permanent quadrats at 3 grazing intensities and within exclosures. Demographic studies of some perennial grass species demonstrated markedly different responses to grazing; Danthonia caespitosa was unaffected by grazing but responsive to seasonal rainfall differences. Enteropogon acicularis survived only on protected sites. Numerical classification of total species set (121 species) for six observation periods demonstrated that community types were sensitive to differences in winter rainfall, and time since the start of experiment. Principal component analysis of permanent quadrat observations for individual years demonstrates quadrat trajectories which confirm this and indicate progressive divergence of the successional trends of the grazed and ungrazed quadrats. Repeated analysis on grazed quadrats only, shows that three components of pasture dynamics can be recognized; these are trend (succession?) and seasonal differences, each of which account for about 20% of the variance, and differences due to soil heterogeneity in the experimental paddock (8% of variance accounted for). No effect of grazing intensity was detected. Multivariate techniques can provide a clear partitioning of types of dynamic behaviour present in grassland communities. It is concluded that partitioning of environmental heterogeneity prior to demographic studies would increase their sensitivity.

     

Basic unit of population observed in the distribution of the rice-stem borer,Chilo simplex,in a paddy field. Pattern of the spatial distribution of insect. 4th report

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Contributions from the Entomological Laboratory, Kyoto University, No. 231.     

Population fluctuation in the system of host-parasite interaction

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Contributions from the Entomological Laboratory, Kyoto University, No. 226.     

On the individual variation of several morphological and physiological characters under different environmental conditions

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Contributions from the Entomological Laboratory, Kyoto University, No. 229.     

Nocturnal playbacks reveal hidden differences in singing behaviour between populations of Robin Erithacus rubecula

Capsule Birds subjected to playbacks of conspecific song responded strongly by day in both Wales and Ireland, and strongly at night only in Wales.

Aims To test the responses of Robins to conspecific playbacks between Wales and Ireland and between day and night.

Methods We measured the responses of Robins to conspecific playbacks during daylight, and at night on territories illuminated by streetlights, and compared Robins in Wales and in Ireland.

Results Most Welsh Robins responded to playbacks at night, whereas Irish Robins rarely responded. Both populations responded equally during daylight.

Conclusion We show for the first time that different populations with similar daytime behaviours may differ in nocturnal behaviour. Such population differences in communication behaviour should be taken into account, for example when using acoustic playback to census populations.     

Hierarchical competition models with the Allee effect II: the case of immigration

ABSTRACT

This is part II of an earlier paper that dealt with hierarchical models with the Allee effect but with no immigration. In this paper, we greatly simplify the proofs in part I and provide a proof of the global dynamics of the non-hyperbolic cases that were previously conjectured. Then, we show how immigration to one of the species or to both would, drastically, change the dynamics of the system. It is shown that if the level of immigration to one or to both species is above a specified level, then there will be no extinction region where both species go to extinction.     

Nestbox orientation: a species-specific influence on occupation and breeding success in woodland passerines

Capsule Nestbox orientation has species-specific influences on nestbox occupation and breeding success for woodland passerines.

Aims To determine if nestbox orientation had an influence upon nestbox selection or breeding success for three co-occurring woodland passerines.

Methods We analysed 15 consecutive years of breeding data (1990–2004) from 295 nestboxes in the UK using circular statistical analyses to examine the influence of orientation upon nestbox occupation and breeding success for three species, Blue Tit Cyanistes caeruleus, Great Tit Parus major and Pied Flycatcher Ficedula hypoleuca.

Results The three species used nestboxes of all orientations during the 15-year period. The frequency of nestbox occupation by Great Tits correlated with orientation (the mean number of nests in boxes oriented south-southwest was lower than the mean number of nests in boxes facing other directions). There was no such relationship for Blue Tits or Pied Flycatchers. Nestbox orientation influenced the breeding success of Pied Flycatcher (the mean number of young to fledge from boxes oriented south-southwest was lower than from boxes facing other directions). There was no such relationship for Blue or Great Tits.

Conclusion Nestbox orientation can be an important influence on occupation and breeding success, but this differed between species. Intriguingly, although the directionality reduced nestbox occupation (Great Tit) and breeding success (Pied Flycatcher) was the same (south-southwest), there was a disparity in the influence of orientation for Great Tit (orientation influenced the frequency of occupation but not success) and Pied Flycatcher (orientation did not influence occupation but did affect success). We discuss these disparities, considering the possible influences of mating strategy, breeding phenology, nestbox microclimate and offspring quality.     

Nucleotide polymorphism and phylogeographic history of an endangered conifer species Pinus bungeana

Pinus bungeana Zucc. ex Endl. (Pinaceae), is an endangered conifer tree species and is endemic to western central China. In this study, we detected the nucleotide polymorphism and phylogeographic history of P. bungeana based on three nuclear genes. We collected 16 natural populations and covered the entire distributional ranges of P. bungeana. We found that this endangered species have extremely low level of nucleotide diversity (π_t = 0.00098, π_sil = 0.00229) compared with that of other conifers. Meanwhile, hierarchical AMOVA revealed that genetic variations of two nuclear loci (010054_01 and 0_12329_02) mainly occurred among populations (54% and 55%), and another locus (0_14221_01) existed within populations (64%). This finding may be caused by random fixation of nuclear genes. Neutrality tests and mismatch analysis suggested that P. bungeana may have experienced the recent range expansion. In addition, high genetic diversity and unique haplotypes were identified in the west areas of Qinling-Daba and Lvliang Mountains, and these areas may be the glacial refuges of P. bungeana. After the glaciation, the species expanded or migrated outward from these refuges, and the founder effect or bottleneck effect in this process may have resulted in the low level of nucleotide polymorphism of P. bungeana.     

Coupling-induced population synchronization in an excitatory population of subthreshold Izhikevich neurons

We consider an excitatory population of subthreshold Izhikevich neurons which exhibit noise-induced firings. By varying the coupling strength J, we investigate population synchronization between the noise-induced firings which may be used for efficient cognitive processing such as sensory perception, multisensory binding, selective attention, and memory formation. As J is increased, rich types of population synchronization (e.g., spike, burst, and fast spike synchronization) are found to occur. Transitions between population synchronization and incoherence are well described in terms of an order parameter $\mathcal{O}$ . As a final step, the coupling induces oscillator death (quenching of noise-induced spikings) because each neuron is attracted to a noisy equilibrium state. The oscillator death leads to a transition from firing to non-firing states at the population level, which may be well described in terms of the time-averaged population spike rate $\overline{R}$ . In addition to the statistical-mechanical analysis using $\mathcal{O}$ and $\overline{R}$ , each population and individual state are also characterized by using the techniques of nonlinear dynamics such as the raster plot of neural spikes, the time series of the membrane potential, and the phase portrait. We note that population synchronization of noise-induced firings may lead to emergence of synchronous brain rhythms in a noisy environment, associated with diverse cognitive functions.     

Population Dynamics of the Root-Knot Nematode Meloidogyne Triticoryzae under Five Rice-Based Cropping Systems

Population dynamics of M. triticoryzae in five rice-based cropping systems have revealed that rice was the main host. Most of the population growth which contributed to the peak population density in September occurred in the rice crop. The other crops in the Rabi and summer seasons had a profound influence on the height of the peak in the succeeding rice crop. Some level of reproduction occurred in wheat, greengram and berseem in Rabi which contributed to relatively higher equilibrium densities. The potato variety Pusa Bahar increased the population density while Pusa Badshah decreased it. The lower temperature during the Rabi season also limited the rate of population growth. The incorporation of organic matter into the soil, either as crop residues of greengram or berseem, reduced the population growth of M. triticoryzae .     

Density, climate and varying return points: an analysis of long-term population fluctuations in the threatened European tree frog

Experimental research has identified many putative agents of amphibian decline, yet the population-level consequences of these agents remain unknown, owing to lack of information on compensatory density dependence in natural populations. Here, we investigate the relative importance of intrinsic (density-dependent) and extrinsic (climatic) factors impacting the dynamics of a tree frog (Hyla arborea) population over 22 years. A combination of log-linear density dependence and rainfall (with a 2-year time lag corresponding to development time) explain 75% of the variance in the rate of increase. Such fluctuations around a variable return point might be responsible for the seemingly erratic demography and disequilibrium dynamics of many amphibian populations.     

The small-scale spatial distribution of an invading moth

We studied the spread of a small leaf-mining moth [Phyllonorycter leucographella (Zeller), Gracillariidae] after its accidental introduction into the British Isles. At large geographical scales, previous work had shown the spread to be well described by a travelling weve of constant velocity. Here, we report the pattern of spread at scales of 1 km². By locating all bushes of the insect's foodplant (Pyracantha spp.) within 1-km² quadrats, the precise pattern of colonisation at finer spatial scales could be established. Where the 1-km² site was colonised by moths from the main advancing front, no spatial pattern in the order that bushes were infested was found. If the source of colonisation was a single or small group of infested plants within the site, there was some evidence that nearby plants were colonised first. We found no evidence of population turnover after colonisation. We interpret the results in terms of a two-stage model of invasion that produces different patterns at small and large geographical scales.     

Beobachtungen an Nerven des Eierstockes

Summary The great veins of the ovary contain nerves that end subendothelially.

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Herrn Prof. Bargmann zum 60. Geburtstag gewidmet.     

Development and characterization of 29 microsatellite markers for Ligumia nasuta (Bivalvia: Unionidae) using an Illumina sequencing approach

Ligumia nasuta (Say, 1817; Eastern Pondmussel) is an imperiled freshwater mussel (Unionidae) in eastern North America. Population declines in the Laurentian Great Lakes resulting from the introduction of dreissenid mussels and habitat destruction in the 20th Century have greatly reduced and limited its distribution. To properly inform restoration and management efforts for L. nasuta, fine-scale genetic analyses must be performed on the remnant populations. This study used Illumina paired-end shotgun sequencing to identify potential microsatellite loci for L. nasuta, utilizing two samples to develop the Illumina paired-end shotgun library. Forty-eight primer pairs were tested on the remaining 24 samples. Twenty-nine of the 48 microsatellite primer sets screened were successfully amplified using 24 L. nasuta samples collected from the Great Lakes watershed. The estimated fragment size ranged from 167 to 445 base-pairs (bp) and the number of alleles per locus varied between 5 and 16 (mean = 9.7). Only five of the loci deviated significantly from Hardy–Weinberg expectations after Bonferroni corrections. The development of these new microsatellite loci will greatly facilitate future genetic studies on L. nasuta.