Evidence That the Magnitude of the Trade-Off in a Dichotomous Trait is Frequency Dependent

Evolution ◽  
1994 ◽  
Vol 48 (5) ◽  
pp. 1650 ◽  
Author(s):  
Derek A. Roff
Keyword(s):  
Frequency Dependent ◽  
Trade Off ◽  
Dichotomous Trait

scholarly journals Parasite-mediated selection drives an immunogenetic trade-off in plains zebras ( Equus quagga )

2014 ◽  
Vol 281 (1783) ◽  
pp. 20140077 ◽  
Author(s):  
Pauline L. Kamath ◽  
Wendy C. Turner ◽  
Martina Küsters ◽  
Wayne M. Getz
Keyword(s):  
Immune System ◽  
Parasite Burden ◽  
Heterozygote Advantage ◽  
Host Immune System ◽  
Fluctuating Selection ◽  
Frequency Dependent ◽  
Trade Off ◽  
Mixed Support ◽  
And Function

Pathogen evasion of the host immune system is a key force driving extreme polymorphism in genes of the major histocompatibility complex (MHC). Although this gene family is well characterized in structure and function, there is still much debate surrounding the mechanisms by which MHC diversity is selectively maintained. Many studies have investigated relationships between MHC variation and specific pathogens, and have found mixed support for and against the hypotheses of heterozygote advantage, frequency-dependent or fluctuating selection. Few, however, have focused on the selective effects of multiple parasite types on host immunogenetic patterns. Here, we examined relationships between variation in the equine MHC gene, ELA -DRA , and both gastrointestinal (GI) and ectoparasitism in plains zebras ( Equus quagga ). Specific alleles present at opposing population frequencies had antagonistic effects, with rare alleles associated with increased GI parasitism and common alleles with increased tick burdens. These results support a frequency-dependent mechanism, but are also consistent with fluctuating selection. Maladaptive GI parasite ‘susceptibility alleles’ were reduced in frequency, suggesting that these parasites may play a greater selective role at this locus. Heterozygote advantage, in terms of allele mutational divergence, also predicted decreased GI parasite burden in genotypes with a common allele. We conclude that an immunogenetic trade-off affects resistance/susceptibility to parasites in this system. Because GI and ectoparasites do not directly interact within hosts, our results uniquely show that antagonistic parasite interactions can be indirectly modulated through the host immune system. This study highlights the importance of investigating the role of multiple parasites in shaping patterns of host immunogenetic variation.

A Frequency-Dependent Filter Design Approach for Norm-Optimal Iterative Learning Control and Its Fundamental Trade-Off Between Robustness, Convergence Speed, and Steady-State Error

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Xinyi Ge ◽  
Jeffrey L. Stein ◽  
Tulga Ersal
Keyword(s):  
Steady State ◽  
Model Uncertainty ◽  
Iterative Learning Control ◽  
Filter Design ◽  
Learning Control ◽  
Iterative Learning ◽  
Convergence Speed ◽  
Frequency Dependent ◽  
Trade Off ◽  
State Error

This paper focuses on norm-optimal iterative learning control (NO-ILC) for single-input-single-output (SISO) linear time invariant (LTI) systems and presents an infinite time horizon approach for a frequency-dependent design of NO-ILC weighting filters. Because NO-ILC is a model-based learning algorithm, model uncertainty can degrade its performance; hence, ensuring robust monotonic convergence (RMC) against model uncertainty is important. This robustness, however, must be balanced against convergence speed (CS) and steady-state error (SSE). The weighting filter design approaches for NO-ILC in the literature provide limited design freedom to adjust this trade-off. Moreover, even though qualitative guidelines to adjust the trade-off exist, a quantitative characterization of the trade-off is not yet available. To address these two gaps, a frequency-dependent weighting filter design is proposed in this paper and the robustness, convergence speed, and steady-state error are analyzed in the frequency domain. An analytical expression characterizing the fundamental trade-off of NO-ILC with respect to robustness, convergence speed, and steady-state error at each frequency is presented. Compared to the state of the art, a frequency-dependent filter design gives increased freedom to adjust the trade-off between robustness, convergence speed, and steady-state error because it allows the design to meet different performance requirements at different frequencies. Simulation examples are given to confirm the analysis and demonstrate the utility of the developed filter design technique.

scholarly journals Trade-off Geometries and Frequency-Dependent Selection

2004 ◽  
Vol 164 (6) ◽  
pp. 765
Author(s):  
de Mazancourt ◽  
Dieckmann
Keyword(s):  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Trade Off

scholarly journals Trade‐Off Geometries and Frequency‐Dependent Selection

2004 ◽  
Vol 164 (6) ◽  
pp. 765-778 ◽  
Author(s):  
Claire de Mazancourt ◽  
Ulf Dieckmann
Keyword(s):  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Trade Off

A Flow-Preserving Algorithm for the Time-Cost Trade-Off Problem

1982 ◽  
Vol 14 (2) ◽  
pp. 109-113 ◽  
Author(s):  
Suleyman Tufekci
Keyword(s):  
Time Cost ◽  
Trade Off

Dual Goals for Speed and Accuracy on the Same Performance Task

2012 ◽  
Vol 11 (3) ◽  
pp. 118-126 ◽  
Author(s):  
Olive Emil Wetter ◽  
Jürgen Wegge ◽  
Klaus Jonas ◽  
Klaus-Helmut Schmidt
Keyword(s):  
Memory Scanning ◽  
Performance Task ◽  
Performance Tasks ◽  
Trade Off ◽  
Test Experiment ◽  
Trade Offs ◽  
New Finding ◽  
Sternberg Paradigm ◽  
Speed Accuracy ◽  
Speed And Accuracy

In most work contexts, several performance goals coexist, and conflicts between them and trade-offs can occur. Our paper is the first to contrast a dual goal for speed and accuracy with a single goal for speed on the same task. The Sternberg paradigm (Experiment 1, n = 57) and the d2 test (Experiment 2, n = 19) were used as performance tasks. Speed measures and errors revealed in both experiments that dual as well as single goals increase performance by enhancing memory scanning. However, the single speed goal triggered a speed-accuracy trade-off, favoring speed over accuracy, whereas this was not the case with the dual goal. In difficult trials, dual goals slowed down scanning processes again so that errors could be prevented. This new finding is particularly relevant for security domains, where both aspects have to be managed simultaneously.

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