scholarly journals Identifying important interaction modifications in ecological systems

2017 ◽  
Author(s):  
J. Christopher D. Terry ◽  
Michael B. Bonsall ◽  
Rebecca J. Morris
Keyword(s):  
Potential Interaction ◽  
Ecological Systems ◽  
Trophic Interaction ◽  
Additional Species ◽  
Individual Interaction ◽  
Important Interaction ◽  
Interaction Modifications ◽  
Underlying Network ◽  
Relationship Of ◽  
The Relationship

AbstractTrophic interaction modifications, where a consumer-resource link is affected by additional species, are widespread and significant causes of indirect effects in ecological networks. The sheer number of potential interaction modifications in ecological systems poses a considerable challenge, making prioritisation for empirical study essential. Here, we introduce measures to quantify the topological relationship of individual interaction modifications relative to the underlying network. We use these, together with measures for the strength of trophic interaction modifications to identify modifications that are most likely to exert significant effects on the dynamics of whole systems. Using a set of simulated food webs and randomly distributed interaction modifications, we test whether a subset of interaction modifications important for the local stability and direction of species responses to perturbation of complex networks can be identified. We show that trophic interaction modifications affecting interactions with a high biomass flux, those that connect species otherwise distantly linked, and those where high trophic-level species modify to interactions lower in the web have particular importance for dynamics. In contrast, the centrality of modifications in the network provided little information. This work demonstrates that analyses of interaction modifications can be tractable at the network scale and highlights the importance of understanding the relationship between the distributions of trophic and non-trophic effects.

scholarly journals Trophic interaction modifications disrupt the structure and stability of food webs

2018 ◽  
Author(s):  
J. Christopher D. Terry ◽  
Rebecca J. Morris ◽  
Michael B. Bonsall
Keyword(s):  
Trophic Interaction ◽  
Community Interactions ◽  
Additional Species ◽  
Trophic Effects ◽  
Trophic Networks ◽  
Empirical Information ◽  
Interaction Modifications ◽  
Underlying Network ◽  
The Stability ◽  
The Impact

AbstractTrophic interaction modifications, where a consumer-resource interaction is influenced by an additional species, are established as being prevalent throughout ecological networks. Despite this, their influence on the structure of interaction distributions within communities has not yet been examined. Although empirical information about the distribution of interaction modifications is currently sparse, the non-trophic effects they induce will be structured by the underlying network of trophic interactions. Here we test the impact of interaction modifications, introduced under a range of distributional assumptions to artificial and empirical trophic networks, on the overall structure of interactions within communities. We show that local stability and reactivity is critically dependent on the inter-relationship between the trophic and non-trophic effects. Depending on their distribution, interaction modifications can generate significant additional structure to community interactions making analyses of the stability of ecological systems based solely on trophic networks unreliable. Empirical information on the topological and strength distributions of interaction modifications will be a key part of understanding the dynamics of communities.

scholarly journals Identifying important interaction modifications in ecological systems

Oikos ◽  
2019 ◽  
Vol 129 (2) ◽  
pp. 147-157
Author(s):  
J. Christopher D. Terry ◽  
Michael B. Bonsall ◽  
Rebecca J. Morris
Keyword(s):  
Ecological Systems ◽  
Important Interaction ◽  
Interaction Modifications

scholarly journals Phylogenetic analysis of the Andean genus Brachycladium Luer (syn. Oreophilus Higgins & Archila) and closely related genera based on nuclear ITS sequencing

Lankesteriana ◽  
2011 ◽  
Vol 11 (3) ◽  
Author(s):  
Mark Wilson ◽  
Lou Jost
Keyword(s):  
Phylogenetic Analysis ◽  
Cryptic Species ◽  
Bootstrap Support ◽  
Its Sequencing ◽  
Morphological Similarity ◽  
Additional Species ◽  
Nuclear Its ◽  
High Level ◽  
Relationship Of ◽  
The Relationship

We previously reported that nrITS sequencing and phylogenetic analysis revealed at least four cryptic species within Brachycladium nummularium (syn. Oreophilus nummularius). Sequencing of additional species in the genus revealed two major clades within Brachycladium, the “nummularium”-complex plus B. stalactites and Luer’s section Amplectentes. Since the relationship of Brachycladium to Andinia had been noted earlier, a number of Andinia species were also included. Two clades were observed, a clade containing A. lappacea, A. pensilis, and A. vestigipetala that was closely related to Brachycladium and a second, more distantly related clade containing A. dalstroemii, A. pogonion, and A. schizopogon. Samples of two additional genera, Masdevalliantha Szlachetko & Margonska and Xenosia Luer, were included in the analysis based upon morphological similarity to Andinia. These two genera formed a clade that was sister to both Brachycladium and Andinia. Only the node subtending clades of all four genera had a high level of bootstrap support, whereas nodes subtending clades of Brachycladium plus Andinia, or Brachycladium alone, had much lower support. If future chloroplast sequencing produces phylogenies congruent with nrITS, this would indicate that Andinia, Brachycladium (syn. Oreophilus), Masdevalliantha, and Xenosia should all be placed in the same genus. 

Species of the genus Neoperla (Plecoptera: Perlidae) from Henan, China

Zootaxa ◽  
2011 ◽  
Vol 2735 (1) ◽  
pp. 57 ◽  
Author(s):  
WEIHAI LI ◽  
HONGLIANG WANG ◽  
WENYAN LU
Keyword(s):  
New Species ◽  
Henan Province ◽  
Additional Species ◽  
Relationship Of ◽  
First Time ◽  
The Relationship

The genus Neoperla is for the first time recorded for Henan Province, China. Herein, we illustrate with color photographs three species, including Neoperla yaoshana sp. nov. The relationship of the new species with closely related ones is discussed and notes for two additional species presented.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

1991 ◽  
Vol 49 ◽  
pp. 236-237
Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver
Keyword(s):  
Mast Cells ◽  
Protein A ◽  
Scattered Electron ◽  
Ige Receptor ◽  
Receptor Complexes ◽  
Ige Binding ◽  
Electron Imaging ◽  
Small Clusters ◽  
Relationship Of ◽  
The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

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