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11.
Among many stabilizing factors for community dynamics, nonlinear biological interactions such as type III functional response
have been widely considered to be major characteristics. However, most experimental biological communities employed so far
had quite simple structures. Therefore, the possibility that the conclusions in earlier studies were dependent on simple community
structure is undeniable. In this study, using a multiple-species experimental community, we evaluated which combinations of
component species and what kinds of interspecific interactions allow communities to persist and how these contribute to community
persistence. We conducted experimental communities using two species of beans, the adzuki bean (Vigna angularis) and the red kidney bean (Phaseolus vulgaris), two species of bean weevils, the Mexican bean weevil (Zabrotes subfasciatus, Coleoptera: Bruchidae) and adzuki bean weevil (Callosobruchus chinensis, Coleoptera: Bruchidae), and two species of parasitic wasp, Heterospilus prosopidis (Hymenoptera: Braconidae) and Anisopteromalus calandrae (Hymenoptera: Pteromalidae). The outcome of multiple-generation experimental communities was explained by the characteristics
of component species obtained from short-term experiments. In our two resources–two herbivores–one carnivore system, the strong
density-dependent attack ability of one parasitic wasp species (A. calandrae) led to the extinction of C. chinensis. On the other hand, the weak density-dependent attack ability of the other parasitic wasp species (H. prosopidis) led to system persistence. Our overall results show that, in a multiple-species community, the combination of species itself
is more important for community persistence than are the characteristics of the particular species.
Received: September 29, 1997 / Accepted: October 5, 1998 相似文献
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We monitored nine butterfly communities with varying degrees of human disturbance by conducting a census twice a month during
1980 by the line transect method in and around Tsukuba City, central Japan. We analyzed the biodiversity and community structures
using the generalist/specialist concept. The site (community) order based on decreasing human disturbance was positively correlated
with butterfly species diversity (H′), species richness (the total number of species), and the number of specialist species in a community, but not with the number
of generalist species. The number of generalist species was rather constant, irrespective of the degree of human disturbance.
Thus, both the butterfly species diversity and species richness were more dependent on the specialists than the generalists.
Our analyses also showed that the generalist species were distributed widely over the communities, and they maintained high
population densities, resulting in high rank status in abundance in a community, with more spatial variation in density per
species. Specialist species showed the opposite trends. These results demonstrate that the generalist/specialist concept is
a powerful tool applicable to analyse the biodiversity and structure of natural communities. 相似文献
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Among many stabilizing factors for community dynamics, spatial and temporal heterogeneities have been widely considered in
recent years as two of the most important properties. However, the difference between the two types of heterogeneities have
not been studied, except for Clark and Yoshimura (1993). We evaluated experimentally the effect of temporal and spatial heterogeneities
on the persistence of a biological community. The experimental communities consisted of one parasitic wasp species, one bean
weevil species, and two kinds of bean. Temporal and spatial heterogeneities of experimental communities were generated by
kinds and timing of bean supply. Of all the experimental communities, the most persistent community was a temporally and spatially
homogeneous community with Red Kidney bean as primary resource. Compared to spatially heterogeneous communities, temporally
heterogeneous communities were more persistent. These results were easily explained by considering the attack rate of parasitic
wasps and the difference between arithmetic and geometric means. In order to discuss the relative importance of environmental
heterogeneity and the mode of biological interaction on community persistence, we have to measure the degree of environmental
heterogeneity as the rate of change of the strength of interspecific interactions. 相似文献
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The outbreak mechanisms of the green rice leafhopper,Nephotettix cincticeps Uhler, in northern Japan
Intraspecific regulatory processes keep the population ofNephotettix cincticeps stable at a low density in southern Japan. In northern Japan, however, the yearly population density of the insect fluctuates
violently, and large outbreaks occasionally take place. To clarify the difference in the population dynamics between the two
regions, we analyzed light-trap and sweep-net sampling records from prefectural and national agricultural experimental stations.
The survival rate of the overwintering population decreased with increases in the period of continuous snow cover (PCSC) in
the north, and initial population densities in the years of long PCSC were too low for populations to reach equilibrium density
by the end of the active breeding season. This made yearly population fluctuations in the north much larger than in the south.
The equilibrium density in the north was higher than in the south. The higher equilibrium density presumably permits the higher
population density and larger yearly population fluctuations in the north. A major factor responsible for the difference in
equilibrium densities between the two regions is the difference in heading dates of the host plant (rice). Qualitative differences
among rice plant varieties, and among biotypes ofN. cincticeps, may also be important. 相似文献
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Koichi Fujii 《Researches on Population Ecology》1978,19(2):155-169
Summary Under a set of assumptions, a mathematical model was constructed to investigate the effect of cannibalistic behavior and medium
renewal schedule onTribolium population dynamics, and the results of simulation analyses were presented to show how modelling can contribute to a better
understanding of experimental study.
The analyses of the present model, the main concern of which is the cyclicity inTribolium population. showed that there are two distinct factors which create cyclicity, the cannibalistic behavior inTribolium itself, and the medium renewal schedule. Cannibalismper se does not necessarily cause cyclicity, but the combinations of cannibalistic behavior among various life stages and their
relative intensities among them can cause cyclicity and can also determine the period of cycle. External factors also can
generate cyclicity, but their interaction with cannibalistic behavior has a more significant effect in modifying the period
of cycle.
Some discrepancies between the model and experimental results were discussed. 相似文献
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