Community Genetic and Competition Effects in a Model Pea Aphid System

2014 ◽  
pp. 243-265 ◽  
Author(s):  
Mouhammad Shadi Khudr ◽  
Tomos Potter ◽  
Jennifer Rowntree ◽  
Richard F. Preziosi
Keyword(s):  
Pea Aphid ◽  
Community Genetic ◽  
Competition Effects

scholarly journals Self and non-self recognition affects clonal reproduction and competition in the pea aphid

2021 ◽  
Vol 288 (1953) ◽  
pp. 20210787
Author(s):  
Yang Li ◽  
Shin-ichi Akimoto
Keyword(s):  
Population Growth ◽  
Evolutionary Biology ◽  
Spatial Interaction ◽  
Pea Aphid ◽  
Self Recognition ◽  
Colour Mutant ◽  
Competition Effects ◽  
Clonal Organisms ◽  
Set Up ◽  
Aphid Clones

The spatial interaction of clonal organisms is an unsolved but crucial topic in evolutionary biology. We evaluated the interactions between aphid clones using a colour mutant (yellow) and an original (green) clone. Colonies founded by two aphids of the same clone and mixed colonies, founded by a green aphid and a yellow aphid, were set up to observe population growth for 15 days. We confirmed positive competition effects, with mixed colonies increasing in size more rapidly than clonal colonies. In mixed colonies where reproduction started simultaneously, green aphids overwhelmed yellow aphids in number, and yellow aphids restrained reproduction. However, when yellow aphids started to reproduce earlier, they outnumbered the green aphids. To test whether aphids have the ability to control reproduction according to the densities of self and non-self clones, one yellow aphid or one antennae-excised yellow aphid was transferred into a highly dense green clone colony. Intact yellow aphids produced fewer nymphs in crowded green colonies, whereas the fecundity of antennae-excised aphids did not change. Thus, we conclude that aphid clones can discriminate between self and non-self clones, and can regulate their reproduction, depending on whether they are superior or inferior in number to their competitors.

When an Industry Peer Is Accused of Financial Misconduct: Stigma versus Competition Effects on Non-accused Firms

2021 ◽  
pp. 000183922110206
Author(s):  
Ivana Naumovska ◽  
Dovev Lavie
Keyword(s):  
Competitive Dynamics ◽  
Negative Consequences ◽  
Competition Effect ◽  
Market Returns ◽  
Stock Market Returns ◽  
Fine Grained ◽  
Competition Effects ◽  
Financial Misconduct ◽  
Industry Peers ◽  
The U.S

Research on misconduct suggests that accusations against industry peers generate negative consequences for non-accused firms (a “stigma effect”). Yet, building on research on competitive dynamics, we infer that such accusations can benefit non-accused firms that compete with these peers (a “competition effect”). To reconcile these opposing perspectives, we posit that the negative stigma effect will increase with greater product market overlap between the non-accused firm and its accused peer, up to a point, beyond which the positive competition effect will counterbalance it. We further conjecture that the competition effect will be relatively more pronounced when the market classification used by investors for assessing the market overlap is more fine-grained. Accordingly, we suggest that more sophisticated investors, who rely on more fine-grained market classifications, increase their shareholdings in non-accused firms to a greater extent than less sophisticated investors as the market overlap between the non-accused firm and the accused peer increases. Using elaborate data on products and investments, we analyze investors’ shareholdings and stock market returns of non-accused firms in the U.S. software industry following accusations of financial misconduct by their industry peers, and we find support for our predictions. Our study elucidates the interplay between stigma and competition following misconduct by industry peers.

scholarly journals OXIDATION OF CARBOHYDRATES BY THE PEA APHID, MACROSIPHUM PISI (KLTB.)

1955 ◽  
Vol 214 (1) ◽  
pp. 37-45 ◽  
Author(s):  
R.W. Newburgh ◽  
Vernon H. Cheldelin
Keyword(s):  
Pea Aphid

scholarly journals Trehalose and glucose levels regulate feeding behavior of the phloem-feeding insect, the pea aphid Acyrthosiphon pisum Harris

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guang Wang ◽  
Jing-Jiang Zhou ◽  
Yan Li ◽  
Yuping Gou ◽  
Peter Quandahor ◽  
...  
Keyword(s):  
Feeding Behavior ◽  
Growth And Development ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Feeding Time ◽  
Electrical Penetration Graph ◽  
Glucose Content ◽  
Glucose Levels ◽  
Phloem Feeding ◽  
Trehalose Content

AbstractTrehalose serves multifarious roles in growth and development of insects. In this study, we demonstrated that the high trehalose diet increased the glucose content, and high glucose diet increased the glucose content but decreased the trehalose content of Acyrthosiphon pisum. RNA interference (RNAi) of trehalose-6-phosphate synthase gene (ApTPS) decreased while RNAi of trehalase gene (ApTRE) increased the trehalose and glucose contents. In the electrical penetration graph experiment, RNAi of ApTPS increased the percentage of E2 waveform and decreased the percentage of F and G waveforms. The high trehalose and glucose diets increased the percentage of E2 waveform of A. pisum red biotype. The correlation between feeding behavior and sugar contents indicated that the percentage of E1 and E2 waveforms were increased but np, C, F and G waveforms were decreased in low trehalose and glucose contents. The percentage of np, E1 and E2 waveforms were reduced but C, F and G waveforms were elevated in high trehalose and glucose contents. The results suggest that the A. pisum with high trehalose and glucose contents spent less feeding time during non-probing phase and phloem feeding phase, but had an increased feeding time during probing phase, stylet work phase and xylem feeding phase.

Electrophysiologic Correlates of Attention versus Distraction in Young and Elderly Listeners

2002 ◽  
Vol 13 (07) ◽  
pp. 383-391 ◽  
Author(s):  
Albert R. De Chicchis ◽  
Michael Carpenter ◽  
Jerry L. Cranford ◽  
Murvin R. Hymel
Keyword(s):  
Selective Attention ◽  
Evoked Potential ◽  
The Elderly ◽  
Auditory Evoked Potential ◽  
Competition Effect ◽  
Specific Target ◽  
Attention Effect ◽  
Competition Effects ◽  
Significant Attention ◽  
Versus Stimulus

This study examined the effects of selective attention versus stimulus competition on the late auditory evoked potential (LAEP) in 20 young and 20 elderly listeners. In a series of test runs, different oddball tonal sequences were presented to one or both ears, and listeners were instructed to attend to tones at a specific target ear. Peak amplitudes were recorded for the N1, P2, and the early and late N2 components of the LAEP. Significant attention effects were found for all four components. N1 amplitudes increased significantly when participants attended to the target stimuli, whereas the amplitudes of P2, N2e, and N2l decreased. For all LAEP components except N2l, the attention effect did not differ between young and elderly listeners. Significant competition effects also were found for all four components. Amplitudes were significantly larger in monaural than binaural conditions for all components except N2l. The magnitude of this competition effect also was significantly larger for the young listeners than the elderly for all components except N1. These results suggest that the ability to attend selectively to sounds may be more resistant to normal aging than are effects related to stimulus competition.

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