A Method for the Estimation of Parameters for Natural Stage-structured Populations
Bryan F. J. MANLY
Department of Mathematics and Statistics, University of Otago, P.O. Box 56, Dunedin, New Zealand
E-mail: bmanly@maths.otago.ac.nz
Abstract. 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 stage-frequency data from natural populations will usually only be possible if extra information such as the durations of stages is known.
Key words: bootstrap, maximum likelihood, stage-frequency data, stage-structure, zooplankton
Selection and Reproductive Success in Males of the Dragonfly, Orthetrum japonicum (Odonata: Libellulidae)
Eiiti KASUYA1), Kaori EDANAMI and Ikuko OHNO
Laboratory of Biology, Faculty of Education, Niigata University, 2-8050 Ikarasi, Niigata City, 950-21 Japan
1) To whom correspondence should be addressed.
Present address: Department of Biology, Faculty of Science, Kyushu University, 812-81 Fukuoka, Japan; E-mail: ekasuscb@mbox.nc.kyushu-u.ac.jp
Abstract. 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%.
Key words: dragonfly, Orthetrum japonicum, reproductive success, selection
d15N Examination of the Lindeman-Hutchinson-Peters Theory of Increasing Omnivory with Trophic Height in Aquatic Foodwebs
Robert L. FRANCE
Harvard University, Graduate School of Design, 48 Quincy Street, Cambridge, Massachusetts 02138, USA
E-mal: rfrance@mars.gsd.harvard.edu
Abstract. 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 of 15N over 14N with progressive assimilation up the foodweb. I compiled literature data on d15N values in freshwater and marine foodwebs to search for general 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 d15N, 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.
Key words: foodwebs, omnivory, d15N variability, trophic position.
Evolution of Condition-Dependent Dispersal: A Genetic-Algorithm Search for the ESS Reaction Norm
Hideo EZOE and Yoh IWASA*
Department of Natural Science, Osaka Women's University, Daisen-cho, Sakai 590, Japan; E-mail: hezoe@center.osaka-wu.ac.jp
* Department of Biology, Faculty of Science, Kyushu University, Fukuoka 812-81, Japan; E-mail: yiwasscb@mbox.nc.kyushu-u.ac.jp
Abstract. 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.
Key words: density-dependent dispersal, ESS, genetic algorithm, neural network, reaction norm.
Optimal Age-dependent Sustainable Harvesting of Natural Resource Populations: Sustainability Value
Atsushi YAMAUCHI 1), Yoshiharu MATSUMIYA, and Yoh IWASA *
Population Dynamics of Marine Organisms Ocean Research Institute, University of Tokyo, Minamidai 1-15-1, Nakano, Tokyo 164, Japan
* Department of Biology, Faculty of Science, Kyushu University, Fukuoka 812-81, Japan
1) To whom all the correspondence should be addressed. Present address: Faculty of Fisheries, Nagasaki University, Bunkyo 1-14, Nagasaki 852, Japan. E-mail: a-yama@net.nagasaki-u.ac.jp
Abstract. 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 spawning 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.
Keywords: age-dependent harvesting, maximum principle, semelparity, sustainability
Differences in Adult and ReproductiveLifespan in the Two Male Forms of Mnais pruinosa costalis Selys (Odonata: Calopterygidae)
Yoshitaka TSUBAKI, Rowan E. HOOPER and Michael T. SIVA-JOTHY*
Laboratory of Wildlife Conservation, National Institute for Environmental Studies, Tsukuba 305, Japan; E-mail: tsubaki@nies.go.jp
* Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
Abstract. The damselfly Mnais pruinosa costalis (Odonata: Calopterygidae) is unusual in that males are dimorphic, existing as clear-winged non-territorial (IT(Jsneaks(IU(J and orange-winged territorial (IT(Jfighters(IU(J. 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 (IT(Joperational reproductive life(IU(J 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.
Key words: alternative reproductive tactics; dimorphism; Odonata; reproductive success; Mnais pruinosa costalis.
Biogeographical History of Northeastern Asiatic Soricine Shrews (Insectivora, Mammalia)
Satoshi OHDACHI1), Ryuichi MASUDA*, Hisashi ABE** and Nikolai E. DOKUCHAEV
Institute of Low Temperature Science, Hokkaido University, Kita-ku, Sapporo 060, Japan; E-mail: ohdachi@bio.hokudai.ac.jp
*Chromosome Research Unit,Faculty of Science, Hokkaido University, Kita-ku, Sapporo 060, Japan
**Laboratory of Applied Zoology, Faculty of Agriculture, Hokkaido University, Kita-ku, Sapporo 060, Japan
Institute of Biological Problems of the North, 68510 Magadan, Russia
Abstract. 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.
Key words: biogeography, Eurasia, phylogeny, Soricinae, species diversity.
Life History Traits of Pest and Non-pest Populations in the Phytophagous Ladybird Beetle, Epilachna niponica (Coleoptera, Coccinellidae)
Yoichi SHIRAI and Naotake MORIMOTO*
National Institute of Agro-Environmental Sciences, Tsukuba 305-0856, Japan
E-mail: flight@niaes.affrc.go.jp
* Faculty of Agriculture, Shinshu University, Ina 399-4511, Japan
Abstract. 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.
Key words: host shift, host suitability of potato, oviposition schedule, wild thistle.
Distributions of Larval Mosquitoes among Bamboo-stump Pools which Vary in Persistence and Resource Input
Toshihiko SUNAHARA1) and Motoyoshi MOGI
Division of Parasitology, Department of Microbiology, Saga Medical School
1) E-mail: sunahara@smsnet.saga-med.ac.jp
Abstract. We 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.
Key words: Aedes albopictus, bamboo stump, mosquito, coexistence, habitat persistence, Tripteroides bambusa.
Effects of Spatio-Temporal Intervals between Newly-Hatched Larvae on Larval Survival and Development in Monochamus alternatus (Coleoptera: Cerambycidae)
Hisashi ANBUTSU1) and Katsumi TOGASHI
Department of Environmental Studies, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739, Japan
1) E-mail: anbutsu$B!w(Jipc.hiroshima-u.ac.jp
Abstract. The 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.
Key words: conspecific bites, intraspecific competition, larval mortality, Monochamus alternatus, oviposition scar.
Speciation and Evolutionary Dynamics of Asymmetric Mating Preference
Jin YOSHIMURA1) and William T. STARMER*
NERC Centre for Population Biology, Imperial College at Silwood Park, Ascot, Berkshire SL5 7PY United Kingdom; Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210 USA
*Department of Biology, Syracuse University, Syracuse, NY 13244 USA
1) Present address: Department of Systems Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, 432-8011 Japan; E-mail: jin@sys.eng.shizuoka.ac.jp
Abstract. Asymmetric mating preferences occur in two closely related species, if females of one species are highly selective against males of the second, while females of$B!!(Jthe 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 arizonae-mojavensis species cluster also support the hypothesis.
Key words: Drosophila arizonae (arizonensis), Drosophila mojavensis, interspecific sexual selection, sexual competition, sexual character displacement, sexual character release.
Changes in Searching Responses with Temperature of Cyrtorhinus lividipennis Reuter (Hemiptera: Miridae) on the Eggs of the Brown Planthopper, Nilaparvata lugens (Stal.) (Homoptera: Delphacidae)
Y. H. SONG1) and K. L. HEONG*
Department of Agricultural Biology, Gyeong-Sang National University, Chinju 660-701, South Korea
* Entomology and Plant Pathology Division, International Rice Research Institute, Los Banos, Laguna, Philippines
1) E-mai: yhsong@nongae.gsnu.ac.kr
Abstract. The functional response of Cyrtorhinus lividipennis Reuter attacking the brown planthopper (Nilaparvata lugens (Stal.), BPH) eggs on rice was determined at six constant temperatures of 20 oC, 23 oC, 26 oC, 29 oC, 32 oC and 35 oC. 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 oC and 32 oC. However, at 35 oC, a negative handling time (Th = -0.0029) was produced. The effect of temperature was incorporated into Rogers' equation by making the attack rate (a) and handling time (Th) functions of temperature within the range 20 oC to 32 oC. The attack rate and handling time were fitted as hyperbola and reciprocal hyperbola functions of temperature respectively. The temperature incorporating four-parameter composite model fitted the combined data as well as did separate Rogers' equations based on the parameter estimates.
Key words : Cyrtorhinus lividipennis, functional response, Nilaparvata lugens, temperature.
The Effect of Vegetation Patterns on Oviposition Habitat Preference: A Driving Mechanism in Terrestrial Chironomid (Diptera: Chironomidae) Succession?
Jan FROUZ
Institute of Soil Biology ASCR, Na s$BaE(Jk$BaD(Jh 7, (IH(JeskqBudejovice, CZ - 37005, Czech Republic; E-mail: frouz@upb.cas.cz
Abstract. Relationships between changes of two species of terrestrial chironomids (Smittia cf. aterrima and Bryophaenocladius 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.
Key words: plant - animal interaction, secondary succession, soil fauna, source-sink populations.
An Individual-Based Model for Competing Drosophila Populations
Vincent A. A. JANSEN1) and Jan G. SEVENSTER*
NERC Centre for Population Biology, Imperial College at Silwood Park Ascot, Berks, SL5 7PY, U.K.
* Institute of Evolutionary and Ecological Sciences, Leiden University, P.O. Box 9561, NL-2300 RA Leiden, The Netherlands
1) Present address: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K. E-mail: vincent@lyapunov.zoo.ox.ac.uk
Abstract. An 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.
Key words: coexistence, competitive exclusion, mathematical model, population dynamics, single resource competition.
Loss of Genetic Variability in a Fragmented Continuously Distributed Population
Masakado KAWATA
Biological Institute, Graduate School of Science, Tohoku University, Aoba, Sendai, 980-77, Japan; E-mail: kawata@mail.cc.tohoku.ac.jp
Abstract. An 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 (HI , HS 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 HI had three stages. During the first stage, HI decreased with the rates predicted by Wright's neighborhood size. During the second stage, HI 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 HI, HS, 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.
Key words: effective population size, fragmentation, genetic variability, heterozygosity, individual-based model, subdivision.
A Population Size Estimate of the Finless Porpoise, Neophocaena phocaenoides, from aerial sighting surveys in Ariake Sound and Tachibana Bay, Japan
Hideyoshi YOSHIDA, Kunio SHIRAKIHARA*, Hirohisa KISHINO** and Miki SHIRAKIHARA***
National Research Institute of Far Seas Fisheries, 5-7-1 Orido, Shimizu, Shizuoka 424, Japan; E-mail: hideka@enyo.affrc.go.jp
*Faculty of Bioresources, Mie University, 1515 Kamihama, Tsu, Mie 514, Japan
**Department of Social and International Relations, Universi-ty of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153, Japan
***Takada Junior College, 195 Toyono, Isshinden, Tsu, Mie 514, Japan
Abstract. We estimated the population size of the finless porpoise (Neophocaena phocaenoides) in Ariake Sound and Tachibana Bay of the western Kyushu, southwestern Japan, from aerial sighting surveys using line transect methods. All the 12 surveys were conducted from May 1993 to May 1994 (8 in Ariake Sound and 4 in Tachibana Bay). In addition to them, 14 surveys were also carried out to obtain information on porpoise occurrence in Tachibana Bay (5 surveys) and in neighboring Sumo Nada (5) and Yatsushiro Sound (4). In Ariake Sound, 225 porpoise groups (369 animals) were detected during all the flights of 1694.4 km. In Tachibana Bay, a total of 997.8 km was surveyed and 55 groups (290 animals) were sighted. However, no sightings were recorded in Sumo Nada (distance searched = 148.7 km) and Yatsushiro Sound (208.4 km). In Ariake Sound, few sightings were recorded at waters shallower than 5 m in depth. In Tachibana Bay all the animals were detected at waters less than 50 m. The population size was estimated as 1983 animals in Ariake Sound (95% CI = 1382 - 2847), 1110 in Tachibana Bay (95% CI = 642 - 1920), and 3093 in the 2 waters (1.3 individuals/km2, 95% CI = 2278 - 4201).
Key words: aerial sighting survey, Ariake Sound and Tachibana Bay of Japan, line transect sampling, Neophocaena phocaenoides, population size estimation,.
The Effects of Spatial and Temporal Environmental Heterogeneities on Persistence in a Laboratory Experimental Community
Takayuki MITSUNAGA1) and Koichi FUJII2)
1) Graduate School of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, Japan; E-mail: aeiou@moumou. biol. tsukuba. ac. jp
2) Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, Japan; E-mail: fujiiko@sakura. cc. tsukuba. ac. jp
Abstracts. Among many stabilizing factors for community dynamics, spatial and temporal heterogeneities have been widely considered as two of the most important properties in recent years. However, the difference of the two types of heterogeneities have not been studied except Clark and Yoshimura (1993). We evaluated experimentally the effect of temporal and spatial heterogeneities on persistence of biological community. The experimental communities were consisted of one parasitic wasp, one bean weevil, and two kinds of bean. Temporal and spatial heterogeneities of experimental communities were generated by kinds and timing of bean supply. In all experimental communities, the most persistent community was temporally and spatially homogeneous community with Red Kidney as primary resource. Compared to spatially heterogeneous communities, temporally heterogeneous community was 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 the community persistence, we have to measure the degree of environmental heterogeneity as the rate of change of the strength of interspecific interactions.
Key words: bean weevil, biological interaction, community persistence, parasitic wasp, spatial heterogeneity, temporal heterogeneity.