scholarly journals Investment in sensory structures, testis size, and wing coloration in males of a diurnal moth species: trade‐offs or correlated growth?

2015 ◽  
Vol 5 (8) ◽  
pp. 1601-1608 ◽  
Author(s):  
Brett P. Shiel ◽  
Craig D. H. Sherman ◽  
Mark A. Elgar ◽  
Tamara L. Johnson ◽  
Matthew R. E. Symonds
Keyword(s):  
Testis Size ◽  
Trade Offs ◽  
Sensory Structures ◽  
Moth Species ◽  
Diurnal Moth ◽  
Wing Coloration

scholarly journals Sperm competition leads to functional adaptations in avian testes to maximize sperm quantity and quality

Reproduction ◽  
2011 ◽  
Vol 141 (5) ◽  
pp. 595-605 ◽  
Author(s):  
Stefan Lüpold ◽  
Joachim Wistuba ◽  
Oliver S Damm ◽  
James W Rivers ◽  
Tim R Birkhead
Keyword(s):  
Sperm Competition ◽  
Relative Number ◽  
Cell Types ◽  
Sperm Length ◽  
Testis Size ◽  
Trade Offs ◽  
Competition Level ◽  
Selection For ◽  
Sperm Output

The outcome of sperm competition (i.e. competition for fertilization between ejaculates from different males) is primarily determined by the relative number and quality of rival sperm. Therefore, the testes are under strong selection to maximize both sperm number and quality, which are likely to result in trade-offs in the process of spermatogenesis (e.g. between the rate of spermatogenesis and sperm length or sperm energetics). Comparative studies have shown positive associations between the level of sperm competition and both relative testis size and the proportion of seminiferous (sperm-producing) tissue within the testes. However, it is unknown how the seminiferous tissue itself or the process of spermatogenesis might evolve in response to sperm competition. Therefore, we quantified the different germ cell types and Sertoli cells (SC) in testes to assess the efficiency of sperm production and its associations with sperm length and mating system across 10 species of New World Blackbirds (Icteridae) that show marked variation in sperm length and sperm competition level. We found that species under strong sperm competition generate more round spermatids (RS)/spermatogonium and have SC that support a greater number of germ cells, both of which are likely to increase the maximum sperm output. However, fewer of the RS appeared to elongate to mature spermatozoa in these species, which might be the result of selection for discarding spermatids with undesirable characteristics as they develop. Our results suggest that, in addition to overall size and gross morphology, testes have also evolved functional adaptations to maximize sperm quantity and quality.

Comparative Study of the Fine Morphology of Sensory Receptors in Aspidogaster conchicola and Cotylaspis insignis

1972 ◽  
Vol 30 ◽  
pp. 150-151
Author(s):  
Venita F. Allison ◽  
J. E. Ubelaker ◽  
J. H. Martin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nervous System ◽  
Osmic Acid ◽  
Sensory Receptors ◽  
Transmission Electron ◽  
Sensory Structures ◽  
Fine Morphology ◽  
Scanning Electron

It has been suggested that parasitism results in a reduction of sensory structures which concomitantly reflects a reduction in the complexity of the nervous system. The present study tests this hypothesis by examining the fine morphology and the distribution of sensory receptors for two species of aspidogastrid trematodes by transmission and scanning electron microscopy. The species chosen are an ectoparasite, Cotylaspis insignis and an endoparasite, Aspidogaster conchicola.Aspidogaster conchicola and Cotylaspis insignis were obtained from natural infections of clams, Anodonta corpulenta and Proptera purpurata. The specimens were fixed for transmission electron microscopy in phosphate buffered paraformaldehyde followed by osmic acid in the same buffer, dehydrated in an ascending series of ethanol solutions and embedded in Epon 812.

Novel players fine-tune plant trade-offs

2015 ◽  
Vol 58 ◽  
pp. 83-100 ◽  
Author(s):  
Selena Gimenez-Ibanez ◽  
Marta Boter ◽  
Roberto Solano
Keyword(s):  
Ubiquitin Ligase ◽  
Feedback Loop ◽  
Molecular Level ◽  
26S Proteasome ◽  
Signalling Molecules ◽  
Transcriptional Reprogramming ◽  
Trade Offs ◽  
Jaz Proteins ◽  
Regulatory Feedback Loop ◽  
Fine Tune

Jasmonates (JAs) are essential signalling molecules that co-ordinate the plant response to biotic and abiotic challenges, as well as co-ordinating several developmental processes. Huge progress has been made over the last decade in understanding the components and mechanisms that govern JA perception and signalling. The bioactive form of the hormone, (+)-7-iso-jasmonyl-l-isoleucine (JA-Ile), is perceived by the COI1–JAZ co-receptor complex. JASMONATE ZIM DOMAIN (JAZ) proteins also act as direct repressors of transcriptional activators such as MYC2. In the emerging picture of JA-Ile perception and signalling, COI1 operates as an E3 ubiquitin ligase that upon binding of JA-Ile targets JAZ repressors for degradation by the 26S proteasome, thereby derepressing transcription factors such as MYC2, which in turn activate JA-Ile-dependent transcriptional reprogramming. It is noteworthy that MYCs and different spliced variants of the JAZ proteins are involved in a negative regulatory feedback loop, which suggests a model that rapidly turns the transcriptional JA-Ile responses on and off and thereby avoids a detrimental overactivation of the pathway. This chapter highlights the most recent advances in our understanding of JA-Ile signalling, focusing on the latest repertoire of new targets of JAZ proteins to control different sets of JA-Ile-mediated responses, novel mechanisms of negative regulation of JA-Ile signalling, and hormonal cross-talk at the molecular level that ultimately determines plant adaptability and survival.

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.

Traits and trade-offs are insufficient for evolutionary personality psychology.

2007 ◽  
Vol 62 (9) ◽  
pp. 1073-1074 ◽  
Author(s):  
Kennon M. Sheldon ◽  
Melanie S. Sheldon ◽  
Charles P. Nichols
Keyword(s):  
Personality Psychology ◽  
Trade Offs

Trade-offs Between Economic and Social Goals

2007 ◽  
Author(s):  
Poonam Arora ◽  
David H. Krantz ◽  
David Hardisty ◽  
Nicole Peterson ◽  
Kavita Reddy
Keyword(s):  
Social Goals ◽  
Trade Offs

Trade-offs for equitable climate policy assessed

Nature ◽  
2020 ◽  
Vol 588 (7837) ◽  
pp. 225-226
Author(s):  
Wei Peng
Keyword(s):  
Climate Policy ◽  
Trade Offs

A Political Economy Model of a Research University

2009 ◽  
pp. 132-143
Author(s):  
K. Sonin ◽  
I. Khovanskaya
Keyword(s):  
Organizational Structure ◽  
Information Structure ◽  
Research University ◽  
Hiring Decisions ◽  
Voting Rules ◽  
Economy Model ◽  
Trade Offs ◽  
Political Economic ◽  
Optimal Incentives

Hiring decisions are typically made by committees members of which have different capacity to estimate the quality of candidates. Organizational structure and voting rules in the committees determine the incentives and strategies of applicants; thus, construction of a modern university requires a political structure that provides committee members and applicants with optimal incentives. The existing political-economic model of informative voting typically lacks any degree of variance in the organizational structure, while political-economic models of organization typically assume a parsimonious information structure. In this paper, we propose a simple framework to analyze trade-offs in optimal subdivision of universities into departments and subdepartments, and allocation of political power.

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