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1.
Anna Torn‐Noguera Xavier Arnan Anselm Rodrigo Jordi Bosch 《Ecology and evolution》2020,10(8):3696-3705
Species assemblages and their interactions vary through space, generating diversity patterns at different spatial scales. Here, we study the local‐scale spatial variation of a cavity‐nesting bee and wasp community (hosts), their nest associates (parasitoids), and the resulting antagonistic network over a continuous and homogeneous habitat. To obtain bee/wasp nests, we placed trap‐nests at 25 sites over a 32 km2 area. We obtained 1,541 nests (4,954 cells) belonging to 40 host species and containing 27 parasitoid species. The most abundant host species tended to have higher parasitism rate. Community composition dissimilarity was relatively high for both hosts and parasitoids, and the main component of this variability was species turnover, with a very minor contribution of ordered species loss (nestedness). That is, local species richness tended to be similar across the study area and community composition tended to differ between sites. Interestingly, the spatial matching between host and parasitoid composition was low. Host β‐diversity was weakly (positively) but significantly related to geographic distance. On the other hand, parasitoid and host‐parasitoid interaction β‐diversities were not significantly related to geographic distance. Interaction β‐diversity was even higher than host and parasitoid β‐diversity, and mostly due to species turnover. Interaction rewiring between plots and between local webs and the regional metaweb was very low. In sum, species composition was rather idiosyncratic to each site causing a relevant mismatch between hosts and parasitoid composition. However, pairs of host and parasitoid species tended to interact similarly wherever they co‐occurred. Our results additionally show that interaction β‐diversity is better explained by parasitoid than by host β‐diversity. We discuss the importance of identifying the sources of variation to understand the drivers of the observed heterogeneity. 相似文献
2.
Laís F. Maia André R. Nascimento Lucas D. B. Faria 《Studies on Neotropical Fauna and Environment》2018,53(2):132-142
Incomplete sampling is a major problem affecting data quality with respect to food webs. We described a host–parasitoid food web based on data from four years of sampling, evaluated the dataset robustness of the food web, and tested the hypothesis that different trophic levels require different sampling efforts. We sampled Senegalia tenuifolia fruits at eight sampling sites in three areas, during four years (2011–2014) in the Brazilian cerrado (savanna). We recorded 26 insect species in three trophic levels associated with S. tenuifolia. For species accumulation curves, all insect trophic levels, areas and years reached the asymptote, except for one area. The cumulative species richness in each trophic level suggested that the third level (primary parasitoid) should be sampled for a longer time than the second and fourth levels, supporting our hypothesis. In conclusion, the sampling effort employed was sufficient to assess most of the insect species richness, and provided a high-quality and well-represented host-parasitoid food web, even though trophic levels require different efforts. 相似文献
3.
We observed the first case of host‐behavioral manipulation of an orb‐weaver spider Argiope argentata induced by a parasitoid wasp of the genus Acrotaphus. The modified web is similar of those constructed by other orb weavers attacked by wasps of the close related genus Hymenoepimecis. The stick spirals and radii are absent and the web is composed of a three‐dimensional structure of non adhesive threads. The discovery of the ability to induce changes in host's web‐building behavior in Acrotaphus is indicative that this trait may be primitively present in the clade that includes the genus Hymenoepimecis. 相似文献
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5.
Christina M. Mozzon Gretchen L. Lescord Pascale-Laure Savage Thomas A. Johnston 《Journal of fish biology》2020,96(1):92-101
We compared the trophic niches of freshwater sculpins Cottus spp. with those of other co-habiting forage fishes in two groups of boreal lakes with distinct habitats and fish communities. Near North Lakes (45° 00′ to 47° 30′ N) were deeper, stratified and contained lake trout Salvelinus namaycush as the apex piscivore, whereas Far North Lakes (51° 10′ to 52° 20′ N) were shallower, did not stratify and contained pike Esox lucius and walleye Sander vitreus as the apex piscivores. Trophic niches of sculpins and other forage fishes were compared based on niche metrics calculated from muscle stable carbon (δ13C) and nitrogen (δ15N) isotope ratios. In Near North Lakes, sculpins were found almost exclusively in deep, offshore waters and their niche positions reflected a greater reliance on pelagic production (lower δ13C) and a higher trophic elevation (higher δ15N) compared with most other forage fishes. Furthermore, sculpins in Near North Lakes tended to have larger trophic niches (occupied greater area in δ13C– δ15N space), particularly in the food chain (δ15N) dimension, than other cohabiting forage fishes. In contrast, sculpins in Far North Lakes were commonly found in the nearshore and had trophic niche positions and sizes that were similar to those of the other cohabiting forage fishes. This study illustrates the flexibility in the realised trophic niches of sculpins in relation to habitat availability and fish community composition in boreal lakes. 相似文献
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7.
Sofia Gripenberg Yves Basset Owen T. Lewis J. Christopher D. Terry S. Joseph Wright Indira Simn D. Catalina Fernndez Marjorie Cedeo‐Sanchez Marleny Rivera Hctor Barrios John W. Brown Osvaldo Caldern Anthony I. Cognato Jorma Kim Scott E. Miller Geoffrey E. Morse Sara Pinzn‐Navarro Donald L. J. Quicke Robert K. Robbins Juha‐Pekka Salminen Eero Vesterinen 《Ecology letters》2019,22(10):1638-1649
The top‐down and indirect effects of insects on plant communities depend on patterns of host use, which are often poorly documented, particularly in species‐rich tropical forests. At Barro Colorado Island, Panama, we compiled the first food web quantifying trophic interactions between the majority of co‐occurring woody plant species and their internally feeding insect seed predators. Our study is based on more than 200 000 fruits representing 478 plant species, associated with 369 insect species. Insect host‐specificity was remarkably high: only 20% of seed predator species were associated with more than one plant species, while each tree species experienced seed predation from a median of two insect species. Phylogeny, but not plant traits, explained patterns of seed predator attack. These data suggest that seed predators are unlikely to mediate indirect interactions such as apparent competition between plant species, but are consistent with their proposed contribution to maintaining plant diversity via the Janzen–Connell mechanism. 相似文献
8.
Changes in abiotic factors along altitudinal and latitudinal gradients cause powerful environmental gradients. The topography of alpine areas generates environmental gradients over short distances, and alpine areas are expected to experience greater temperature increase compared to the global average. In this study, we investigate alpha, beta, and gamma diversity, as well as community structure, of vascular plant communities along altitudinal gradients at three latitudes in the Swedish mountains. Species richness and evenness decreased with altitude, but the patterns within the altitudinal gradient varied between sites, including a sudden decrease at high altitude, a monotonic decrease, and a unimodal pattern. However, we did not observe a decline in beta diversity with altitude at all sites, and plant communities at all sites were spatially nested according to some other factors than altitude, such as the availability of water or microtopographic position. Moreover, the observed diversity patterns did not follow the latitudinal gradient. We observed a spatial modularity according to altitude, which was consistent across sites. Our results suggest strong influences of site‐specific factors on plant community composition and that such factors partly may override effects from altitudinal and latitudinal environmental variation. Spatial variation of the observed vascular plant communities appears to have been caused by a combination of processes at multiple spatial scales. 相似文献
9.
The reproductive success of many insects is considered to be limited by two main factors: the availability of mature eggs to lay (termed egg limitation) and the time to locate suitable hosts (termed time limitation). High host density in the environment is likely to enhance oviposition opportunities, thereby selecting for higher investment in egg supply. In contrast, a shortage of food (e.g. sugar sources) is likely to increase the risk of time limitation, thereby selecting for higher allocation to initial energy reserves. To our knowledge, the combined effect of host and food availability on these optimal life‐history allocations has never been investigated. We thus modelled their simultaneous effects on a three‐dimensional trade‐off between initial investment in energy reserves, egg number and egg size, while focusing on insect parasitoids. The model was based on Monte Carlo simulations coupled with genetic algorithms, in order to identify the optimal life‐history traits of a single simulated parasitoid female in an environment in which both hosts and food are present in varying densities. Our results reproduced the simple predictions described above. However, some novel predictions were also obtained, especially when specific interactions between the different factors were examined and their effects on the three‐dimensional life‐history surface were considered. The work sheds light on long‐lasting debates regarding the relative importance of time versus egg limitation in determining insect life‐history traits and highlights the complexity of life‐history evolution, where several environmental factors act simultaneously on multiple traits. 相似文献
10.
JOHN O. STIREMAN PIERFILIPPO CERRETTI DANIEL WHITMORE S
NKE HARDERSEN DAMIANO GIANELLE 《Insect Conservation and Diversity》2012,5(5):346-357
Abstract. 1. We analysed the canopy and understorey communities of flies in the family Tachinidae, the most diverse group of parasitoid Diptera, in a small and isolated temperate plain forest in northern Italy. Our objective was to assess whether and how these communities differ from one another, and how species distribution relates to forest structure, host distribution, mating sites, and season. 2. The study was carried out in 2008 with 14 Malaise traps installed between April and November in an equal number of sites randomly selected inside the forest, seven on the ground and seven in the tree canopy. 3. Overall species richness, abundance, and turnover were greater in the understorey traps, but most diversity metrics indicate greater overall diversity and evenness in the canopy traps. Community ordination and estimates of beta diversity indicate that the two habitat‐associated communities are distinct and should both be considered in assessments of insect diversity and community structure. Indicator species values revealed the presence of a number of species that were effective indicators of canopy and understorey habitats. No strong male bias in canopy traps was observed across species; however, the only significant sex ratio biases in the canopy were towards males. Both male and female biases were observed in understorey traps, depending upon the species. 相似文献
11.
Buckee C Danon L Gupta S 《Proceedings. Biological sciences / The Royal Society》2007,274(1619):1715-1721
Community structure has been widely identified as a feature of many real-world networks. It has been shown that the antigenic diversity of a pathogen population can be significantly affected by the contact network of its hosts; however, the effects of community structure have not yet been explored. Here, we examine the congruence between patterns of antigenic diversity in pathogen populations in neighbouring communities, using both a deterministic metapopulation model and individual-based formulations. We show that the spatial differentiation of the pathogen population can only be maintained at levels of coupling far lower than that necessary for the host populations to remain distinct. Therefore, identifiable community structure in host networks may not reflect differentiation of the processes occurring upon them and, conversely, a lack of genetic differentiation between pathogens from different host communities may not reflect strong mixing between them. 相似文献
12.
SATOSHI YAMASHITA KIYOSHI ANDO HIDETO HOSHINA NOBORU ITO YUJI KATAYAMA MAKOTO KAWANABE MUNETOSHI MARUYAMA TAKAO ITIOKA 《Ecological Entomology》2015,40(4):390-400
1. If fungivorous insect diversity is maintained by host specialisation on particular fungi, it should be higher in the tropics than in temperate or boreal regions owing to high macrofungus species diversity. 2. To reveal the community and food web structure of fungivorous insects on bracket fungi, fungivorous insects were collected from 427 fruiting bodies belonging to 22 genera throughout the development and deterioration process in a 3‐ha plot of lowland dipterocarp tropical rain forest on Borneo Island. 3. Eight hundred and twenty‐nine individuals of 82 coleopteran species in 13 families from 111 fruiting bodies of 15 fungal genera were collected. Tenebrionidae and Staphylinidae were most common. Fifty‐three and 19 insect species were observed on Ganoderma and Phellinus, respectively. The numbers of insect species and individuals on a particular fungal genus were positively correlated with the abundance of that fungal genus. 4. Quantitative food web analysis revealed a high degree of specialisation at the whole‐community level. At least 65% of insect individuals were observed on Ganoderma at every stage of development and deterioration. Diverse insects coexist on one dominant fungal genus, Ganoderma, in contrast to our hypothesis. 5. The high abundance of Ganoderma fruiting bodies, which lack obvious defences against insect feeding, probably influences the bracket fungus–insect food web in this tropical rainforest. 相似文献
13.
TOMAS ROSLIN 《Ecological Entomology》2013,38(5):522-530
- Indirect interactions mediated by natural enemies shared among herbivorous insects have recently attracted much interest. While many studies have predicted a high potential for apparent competition, only a few have rigorously tested predictions derived from the food web structure in terms of realised population and community dynamics.
- In this study, a quantified food web was used to identify pairs of herbivore species potentially tied by strong parasitoid‐mediated interactions. The host populations and their parasitism rates over two consecutive years were then followed, during which time the abundance of one dominant host crashed. Following this natural experiment, imprints of asymmetrical, long‐term apparent competition among hosts were sought in population growth rates.
- The population growth revealed no signs of apparent competition as mediated by parasitoids: the abundance and parasitism rates of less abundant herbivores were uncorrelated with the relative growth rate of four dominant herbivore species with which they shared a major part of their parasitoids. Likewise, the population crash of the dominant herbivore, Cynips longiventris, did not detectably affect the abundances or parasitism rates of other herbivores with which it shared a major fraction of its parasitoids.
- Overall, this case study fails to add evidence to previous suggestions that apparent competition may constitute a major force in structuring natural communities. However, it suggests that dynamics should not be inferred from static food web structure alone, but rather that predictions based on structure should be verified by empirical observations of realised population dynamics.
14.
Food webs typically quantify interactions between species, whereas evolution operates through the success of alleles within populations of a single species. To bridge this gap, we quantify genotypic interaction networks among individuals of a single specialized parasitoid species and its obligate to cyclically parthenogenetic aphid host along a climatic gradient. As a case study for the kinds of questions genotype food webs could be used to answer, we show that genetically similar parasitoids became more likely to attack genetically similar hosts in warmer sites (i.e. there was network‐wide congruence between the within‐species shared allelic distance of the parasitoid and that of its host). Narrowing of host‐genotype‐niche breadth by parasitoids could reduce resilience of the network to changes in host genetic structure or invasion by novel host genotypes and inhibit biological control. Thus, our approach can be easily used to detect changes to sub‐species‐level food webs, which may have important ecological and evolutionary implications, such as promoting host‐race specialization or the accelerated loss of functional diversity following extinctions of closely related genotypes. 相似文献
15.
KENT M. DAANE 《Ecological Entomology》2015,40(6):805-813
1. Predator interactions are often driven by size differences, with larger predators consuming smaller ones. Cannibalism is widespread among predators, and can be more intense than antagonistic interactions between different predator species. 2. In a series of greenhouse experiments and a field experiment, we investigated the role of size structure in shaping the impacts of a top predator (the wandering spider Cheiracanthium mildei L. Koch) on an insect herbivore in vineyards of Napa County, California. 3. In greenhouse cages, survival of small C. mildei was lower when large C. mildei were present, and the combined effects of small and large C. mildei on leafhopper numbers and grape leaf damage were non‐additive. The frequency of cannibalism in C. mildei did not change when the abundance of leafhoppers was manipulated. However, in the field experiment small and large C. mildei combined additively to reduce leafhopper numbers. 4. Results show that cannibalism has the potential to dampen the cascading effects of C. mildei in a vineyard food web, but that it may be less important than other mortality factors in the field. Nonetheless, C. mildei substantially impacted leafhoppers in both the greenhouse and the field, suggesting that mortality caused by cannibalism or other factors may not compromise its overall predatory impacts. 相似文献
16.
Quantitative real‐time PCR (qPCR) is a powerful tool to study species of cryptic organisms in complex food webs. This technique was recently developed to detect and quantify several species of entomopathogenic nematodes (EPNs), which are widely used for biological control of insects, and some natural enemies of EPNs such as nematophagous fungi and the phoretic bacteria Paenibacillus sp. and Paenibacillus nematophilus. A drawback to the use of primers and TaqMan probes designed for Paenibacillus sp. is that the qPCR also amplified Paenibacillus thiaminolyticus and Paenibacillus popilliae, two closely related species that are not phoretically associated with EPNs. Here, we report that the detection of Paenibacillus sp. DNA in nematode samples was two orders of magnitude greater (P < 0.001) when the bacterium was added to soil together with its EPN species‐specific host Steinernema diaprepesi than when it was added concomitantly with other EPNs or with species of bacterial‐feeding nematodes. Just 6% of samples detected trace amounts of P. thiaminolyticus and P. popilliae exposed to the same experimental conditions. Thus, although the molecular assay detects Paenibacillus spp. DNA in nonphoretic associations, the levels are essentially background compared to the detection of Paenibacillus sp. in association with its nematode host. 相似文献
17.
Research on the structure of ecological networks suggests that a number of universal patterns exist. Historically, biotic specialization has been thought to increase towards the Equator. Yet, recent studies have challenged this view showing non‐conclusive results. Most studies analysing the geographical variation in biotic specialization focus, however, only on the local scale. Little is known about how the geographical variation of network structure depends on the spatial scale of observation (i.e. from local to regional spatial scales). This should be remedied, as network structure changes as the spatial scale of observation changes, and the magnitude and shape of these changes can elucidate the mechanisms behind the geographical variation in biotic specialization. Here we analyse four facets of biotic specialization in host–parasitoid networks along gradients of climatic constancy, classifying the networks according to their spatial extension (local or regional). Namely, we analyse network connectance, consumer diet overlap, consumer diet breadth, and resource vulnerability at both local and regional scales along the gradients of both current climatic constancy and historical climatic change. While at the regional scale none of the climatic variables are associated to biotic specialization, at the local scale, network connectance, consumer diet overlap, and resource vulnerability decrease with current climatic constancy, whereas consumer generalism increases (i.e. broader diet breadths in tropical areas). Similar patterns are observed along the gradient of historical climatic change. We provide an explanation based on different beta‐diversity for consumers and resources across the geographical gradients. Our results show that the geographical gradient of biotic specialization is not universal. It depends on both the facet of biotic specialization and the spatial scale of observation. 相似文献
18.
Niche differentiation depends on body size in a cichlid fish: a model system of a community structured according to size regularities 总被引：1，自引：0，他引：1
Kohda M Shibata JY Awata S Gomagano D Takeyama T Hori M Heg D 《The Journal of animal ecology》2008,77(5):859-868
1. Communities of different species are often structured according to niche differentiation associated with competitive interactions. We show that similar principles may apply on an ecological time-scale when individuals of a species having a wide size variation compete for resources, using the Lake Tanganyika cichlid Lobochilotes labiatus (5-30 cm). This species has a mouth especially adapted to suck up invertebrates from rock crevices. 2. Individuals defended feeding territories against similar-sized conspecifics, but not against different-sized ones. Thus, territories of similar-sized fish rarely overlapped, but up to a total of seven individuals (of seven size-ranks) had broadly overlapping territories with dissimilar-sized individuals. Comparison with expectation from the null model demonstrated clearly that observed size ratios between adjacent size rank were determined non-randomly regardless of sexual combinations. 3. Larger individuals took larger prey types of larger average size, but more importantly used wider rock crevices from which to suck food than smaller individuals. We calculated pairwise values of Schoener's index of diet overlap C(d) and the values of Levin's index of diet breadth B(d) (prey type and prey size) and the same for the width of the rock crevices used for foraging (C(r) and B(r)). C(d) remained high among all combinations of the seven ranks. In contrast, C(r) declined strongly in combinations of adjacent ranks (to 0.27), and was low or zero among further different size ranks. This shows that fish with overlapping territories divided the food resources largely through foraging site partitioning. Accordingly, B(d) did not depend on the size difference to the nearest two coinhabiting fish, whereas B(r) did. 4. We conclude that this L. labiatus community is structured non-randomly: body size-dependent effects on foraging site usage result in competition with, and territorial exclusion of, similar-sized individuals, but not of dissimilar-sized individuals that were accepted as coinhabitants. Accordingly, mean body size ratios (large/small) between two adjacent ranks were consistently approximately 1.28 [standard deviation (SD) = 0.07, n = 104], while approximately 1.34 from the null model (SD = 0.34, n = 10 400 simulations). We discuss our results as an example of Hutchinson's rule, applied originally to size ratios of different species. 相似文献
19.
Yao‐Guang Qin Qing‐Song Zhou Fang Yu Xu‐Bo Wang Jiu‐Feng Wei Chao‐Dong Zhu Yan‐Zhou Zhang Alfried P. Vogler 《Ecology and evolution》2018,8(16):7879-7893
Host specificity of parasitoids may be measured by various specialization indices to assess the variation of interaction strength among species and the structure of the wider interaction network. However, the conclusions from analyses at the species and network levels may differ, which remains poorly explored. In addition, the recovery of cryptic species of hosts and parasitoids with molecular data may affect the structure of inferred interaction links. We quantified host specificity of hymenopteran parasitoids (family Encyrtidae) on armored scale insects (Hemiptera: Diaspididae) from a wide geographic sampling range across the Chinese Mainland based on both morphological and molecular species delimitation. Mitochondrial COI and nuclear 28S markers detected high cryptic species diversity in the encyrtids and to a lesser degree in the diaspidids, which divided generalist morphospecies into complexes of specialists and generalists. One‐to‐one reciprocal host–parasite links were increased in the molecular data set, but different quantitative species‐level indices produced contrasting estimates of specificity from various one‐to‐multiple and multiple‐to‐multiple host–parasite links. Network indices calculated from DNA‐based species, compared to morphology‐based species definitions, showed lower connectance and generality, but greater specialization and compartmentalization of the interaction network. We conclude that a high degree of cryptic species in host–parasitoid systems refines the true network structure and may cause us overestimating the stability of these interaction webs. 相似文献
20.
Stacey A. McCormack Jessica Melbourne‐Thomas Rowan Trebilco Julia L. Blanchard Ben Raymond Andrew Constable 《Ecology and evolution》2021,11(1):227-241
Understanding regional‐scale food web structure in the Southern Ocean is critical to informing fisheries management and assessments of climate change impacts on Southern Ocean ecosystems and ecosystem services. Historically, a large component of Southern Ocean ecosystem research has focused on Antarctic krill, which provide a short, highly efficient food chain, linking primary producers to higher trophic levels. Over the last 15 years, the presence of alternative energy pathways has been identified and hypotheses on their relative importance in different regions raised. Using the largest circumpolar dietary database ever compiled, we tested these hypotheses using an empirical circumpolar comparison of food webs across the four major regions/sectors of the Southern Ocean (defined as south of 40°S) within the austral summer period. We used network analyses and generalizations of taxonomic food web structure to confirm that while Antarctic krill are dominant as the mid‐trophic level for the Atlantic and East Pacific food webs (including the Scotia Arc and Western Antarctic Peninsula), mesopelagic fish and other krill species are dominant contributors to predator diets in the Indian and West Pacific regions (East Antarctica and the Ross Sea). We also highlight how tracking data and habitat modeling for mobile top predators in the Southern Ocean show that these species integrate food webs over large regional scales. Our study provides a quantitative assessment, based on field observations, of the degree of regional differentiation in Southern Ocean food webs and the relative importance of alternative energy pathways between regions. 相似文献