1,720,998 research outputs found
Phylogenetic and non-phylogenetic patterns in the richness, frequency and composition of links in a herbivore-parasitoid interaction network
No full textRevealing processes that structure species interactions is central to understanding community assembly and dynamics. Species interact via their phenotypes, but identifying and quantifying the traits that structure species-specific interactions (links) can be challenging. Where these traits show phylogenetic signal, however, link properties may be predictable using models that incorporate phylogenies in place of trait data. We analysed variation in link richness, frequency, and species identity in a multi-site dataset of interactions between oak cynipid galls and parasitoid natural enemies, using a Bayesian mixed modelling framework allowing concurrent fitting of phylogenetic effects of both trophic levels. In both link incidence (presence/absence) and link frequency datasets, we identified strong signatures of cophylogeny (related parasitoids attack related host galls) alongside patterns independent of either phylogeny. Our results are robust to simulations of substantially reduced sample completeness, and are consistent with the structuring of trophic interactions by a combination of phylogenetically conserved and convergently evolving traits in both trophic levels. We discuss our results in light of phenotypic traits thought to structure gall-parasitoid interactions and consider wider applications of this approach, including inference of underlying community assembly processes and prediction of economically important trophic interactions
SUPERSEDED - Structure and composition of tritrophic communities associated with Fagaceae-feeding cynipid gallwasps in Sichuan, China
No full text## This item has been replaced by the one which can be found at https://doi.org/10.7488/ds/7756 ##
A key question in the assembly of biological communities is the extent to which trophic links between higher trophic levels are structured by ‘bottom-up’ effects. Here we explore bottom-up host plant effects on the structure of communities of Fagaceae host plants, cynipid gall wasps and parasitoid natural enemies in western Sichuan, China. We use quantified interaction data to test the hypotheses that, relative to parasitoid-tree associations, links between cynipids and Fagaceae are (1) more specialised, resulting in (2) more modular networks and (3) stronger signatures of turnover than nestedness for plant-associated beta diversity. Because no Linnaean classification exists for this study system we developed a working taxonomy based on gall morphotypes and parasitoid morphospecies, supported by DNA barcoding of gall inducers. Rearing of nearly 43,000 cynipid gall specimens from 23 host plant species in Castanea, Castanopsis, Lithocarpus and four sections in the genus Quercus (Cerris, Cyclobalanopsis, Ilex and Quercus) yielded 176 morphologically distinct cynipid gall morphotypes. We reared over 4500 specimens of 64 parasitoid morphospecies in the families Braconidae, Cynipencyrtidae, Eulophidae, Eupelmidae, Eurytomidae, Megastigmidae, Ormyridae, Pteromalidae and Torymidae. Our predictions were confirmed. We highlight the challenges facing research on biodiverse communities with a substantial taxonomic impediment, and discuss our findings in light of the processes thought to structure tritrophic interactions centred on endophytic insect herbivores. We summarise compositional and structural parallels of our study communities with Fagaceae-associated cynipid communities elsewhere and avenues for future research
Food web structure changes with elevation but not rainforest strata
No full textChanges in species richness along elevational gradients are well documented. However, little is known about how trophic interactions between species and, in particular, the food webs that these interactions comprise, change with elevation. Here we present results for the first comparison of quantitative food webs in forest understorey and canopy along an elevational gradient. Replicate quantitative food webs were constructed for assemblages involving 23 species of cavity‐nesting Hymenoptera and 12 species of their parasitoids and kleptoparasites in subtropical rainforest in Australia. A total of 1589 insects were collected using trap nests across 20 plots distributed at sites ranging from 300 to 1100 m a.s.l. Insect abundance, insect diversity and parasitism rate generally decreased with increasing elevation. Food web structure significantly changed with elevation. In particular, weighted quantitative measures of linkage density, interaction evenness, nestedness (weighted NODF) and potential for enemy mediated interactions (PAC) decreased with increasing elevation, and network specialisation (H2′) increased with increasing elevation, even after controlling for matrix size; but there was no change in weighted connectance. Changes in forest type and temperature along the elevational gradient are likely to be, at least partly, responsible for the patterns observed. We found no significant differences in insect abundance, insect diversity or parasitism rate between canopy and understorey. Furthermore, there were no differences in food web structure between strata. These results contribute further evidence to studies revealing changes in food web structure along natural environmental gradients and provide information that can potentially be used for predicting how communities may respond to climate change.No Full Tex
Network structure and taxonomic composition of tritrophic communities of Fagaceae, cynipid gallwasps and parasitoids in Sichuan, China
No full textA key question in insect community ecology is whether parasitoid assemblages are structured by the food plants of their herbivore hosts.
Tritrophic communities centred on oak-feeding cynipid gallwasps are one of the best-studied tritrophic insect communities. Previous work suggests that host plant identity is a much stronger predictor of oak-cynipid interactions than of cynipid-parasitoid interactions. However, these relationships have not been formally quantified.
We reason that the potential for ‘bottom-up’ effects should increase with host plant phylogenetic diversity. We therefore generated quantified interaction network data for previously unstudied tritrophic cynipid communities in Sichuan, China, where, in addition to Quercus, cynipid host plants include Castanea, Castanopsis and Lithocarpus. We characterise these communities taxonomically, and compare the extent to which host plant taxonomy predicts plant-herbivore and plant-parasitoid associations.
We sampled 42,620 cynipid galls of 176 morphotypes from 23 host plant species, yielding over 4500 specimens of 64 parasitoid morphospecies. Many parasitoids were identifiable to chalcidoid taxa present in other Holarctic oak cynipid communities, with the addition of Cynipencyrtus (Cynipencyrtidae). As elsewhere, Sichuan parasitoid assemblages were dominated by generalists.
Gallwasp-plant interaction networks were significantly more modular than parasitoid-plant association networks. Gallwasps were significantly more specialised to host plants (i.e. had higher mean d’ values) than parasitoids. Parasitoid assemblages nevertheless showed significant plant-associated beta diversity, with a dominant turnover component.
We summarise parallels between our study and other Fagaceae-associated cynipid communities, and discuss our findings in light of the processes thought to structure tritrophic interactions centred on endophytic insect herbivores.Readme.doc
FIGURES 1–7 in A new genus of oak gallwasp, Cyclocynips Melika, Tang & Sinclair (Hymenoptera: Cynipidae: Cynipini), with descriptions of two new species from Taiwan
No full textFIGURES 1–7. Cyclocynips uberis, new species, female: 1–3, head: 1, anterior view, 2, dorsal view, 3, posterior view. 4, antenna. 5–6, mesosoma: 5, lateral view, 6, dorsal view, 7, metascutellum and propodeum, posterodorsal view.Published as part of Melika, George, Tang, Chang-Ti, Sinclair, Frazer, Yang, Man-Miao, Lohse, Konrad, Hearn, Jack, Nicholls, James A. & Stone, Graham N., 2013, A new genus of oak gallwasp, Cyclocynips Melika, Tang & Sinclair (Hymenoptera: Cynipidae: Cynipini), with descriptions of two new species from Taiwan, pp. 534-548 in Zootaxa 3630 (3) on page 539, DOI: 10.11646/zootaxa.3630.3.8, http://zenodo.org/record/21944
FIGURES 99–106. Cycloneuroterus lohsei, new species. 99–101 in Eight new species of Cycloneuroterus Melika & Tang gallwasps from Taiwan and mainland China (Hymenoptera: Cynipidae: Cynipini)
No full textFIGURES 99–106. Cycloneuroterus lohsei, new species. 99–101, head, female: 99, frontal view, 100, dorsal view, 101, posterior view. 102–103, head, male: 102, frontal view, 103, dorsal view. 104–105, antenna: 104, female, 105, male. 106, mesosoma, dorsal view, female.Published as part of Tang, Chang-Ti, Sinclair, Frazer, Hearn, Jack, Yang, Man-Miao, Stone, Graham N., Nicholls, James A., Schwéger, Szabina & Melika, George, 2016, Eight new species of Cycloneuroterus Melika & Tang gallwasps from Taiwan and mainland China (Hymenoptera: Cynipidae: Cynipini), pp. 451-488 in Zootaxa 4088 (4) on page 478, DOI: 10.11646/zootaxa.4088.4.1, http://zenodo.org/record/25966
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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