The Cost of Meristem Limitation in Polygonum arenastrum: Negative Genetic Correlations between Fecundity and Growth

Evolution ◽  
1990 ◽  
Vol 44 (4) ◽  
pp. 799 ◽  
Author(s):  
Monica A. Geber
Keyword(s):  
Genetic Correlations ◽  
The Cost ◽  
Meristem Limitation ◽  
Polygonum Arenastrum

scholarly journals Comparison of Methods to Measure Methane for Use in Genetic Evaluation of Dairy Cattle

Animals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 837 ◽  
Author(s):  
Philip C. Garnsworthy ◽  
Gareth F. Difford ◽  
Matthew J. Bell ◽  
Ali R. Bayat ◽  
Pekka Huhtanen ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Repeated Measures ◽  
Large Scale ◽  
Genetic Correlations ◽  
Alternative Methods ◽  
True Value ◽  
Accuracy And Precision ◽  
Expert Working Group ◽  
Genetic Evaluations ◽  
The Cost

Partners in Expert Working Group WG2 of the COST Action METHAGENE have used several methods for measuring methane output by individual dairy cattle under various environmental conditions. Methods included respiration chambers, the sulphur hexafluoride (SF6) tracer technique, breath sampling during milking or feeding, the GreenFeed system, and the laser methane detector. The aim of the current study was to review and compare the suitability of methods for large-scale measurements of methane output by individual animals, which may be combined with other databases for genetic evaluations. Accuracy, precision and correlation between methods were assessed. Accuracy and precision are important, but data from different sources can be weighted or adjusted when combined if they are suitably correlated with the ‘true’ value. All methods showed high correlations with respiration chambers. Comparisons among alternative methods generally had lower correlations than comparisons with respiration chambers, despite higher numbers of animals and in most cases simultaneous repeated measures per cow per method. Lower correlations could be due to increased variability and imprecision of alternative methods, or maybe different aspects of methane emission are captured using different methods. Results confirm that there is sufficient correlation between methods for measurements from all methods to be combined for international genetic studies and provide a much-needed framework for comparing genetic correlations between methods should these become available.

scholarly journals Quantifying maladaptation during the evolution of sexual dimorphism

2019 ◽  
Vol 286 (1908) ◽  
pp. 20191372 ◽  
Author(s):  
Genevieve Matthews ◽  
Sandra Hangartner ◽  
David G. Chapple ◽  
Tim Connallon
Keyword(s):  
Sexual Dimorphism ◽  
Environmental Changes ◽  
Genetic Correlations ◽  
Theoretical Expression ◽  
Evolutionary Divergence ◽  
Substantial Cost ◽  
Quantitative Genetic ◽  
Classical Models ◽  
Selection For ◽  
The Cost

Females and males have distinct trait optima, resulting in selection for sexual dimorphism. However, most traits have strong cross-sex genetic correlations, which constrain evolutionary divergence between the sexes and lead to protracted periods of maladaptation during the evolution of sexual dimorphism. While such constraints are thought to be costly in terms of individual and population fitness, it remains unclear how severe such costs are likely to be. Building upon classical models for the ‘cost of selection’ in changing environments ( sensu Haldane), we derived a theoretical expression for the analogous cost of evolving sexual dimorphism; this cost is a simple function of genetic (co)variances of female and male traits and sex differences in trait optima. We then conducted a comprehensive literature search, compiled quantitative genetic data from a diverse set of traits and populations, and used them to quantify costs of sexual dimorphism in the light of our model. For roughly 90% of traits, costs of sexual dimorphism appear to be modest, and comparable to the costs of fixing one or a few beneficial substitutions. For the remaining traits (approx. 10%), sexual dimorphism appears to carry a substantial cost—potentially orders of magnitude greater than costs of selection during adaptation to environmental changes.

The cost of phenotypic evolution

Paleobiology ◽  
1984 ◽  
Vol 10 (3) ◽  
pp. 319-327 ◽  
Author(s):  
Brian Charlesworth
Keyword(s):  
Genetic Correlations ◽  
Evolutionary Change ◽  
Stabilizing Selection ◽  
Gradual Change ◽  
Evolutionary Trends ◽  
Phenotypic Evolution ◽  
Single Character ◽  
Selective Elimination ◽  
Low Levels ◽  
The Cost

Formulae are developed for the fraction of the population that must be eliminated by selection in each generation in order to account for a given rate of evolution in a metrical trait. A combination of directional and stabilizing selection is assumed. The effects of competition based on phenotypic value are also considered. The formulae are applied to data on evolutionary rates and their variances. It is concluded that most selective elimination is due to stabilizing selection, and that even very rapid evolutionary change in a single character usually involves low levels of additional elimination. It is suggested that long-sustained evolutionary trends are unlikely to be caused either by gradual change of the optimum under stabilizing selection or by the effects of competitive selection in favor of extreme individuals. It is possible that genetic correlations between traits under selection may limit the response of a single trait to directional selection and hence produce very gradual change.

Genetic Correlations with Floral Display Lead to Sexual Dimorphism in the Cost of Reproduction

2005 ◽  
Vol 166 (S4) ◽  
pp. S31-S41 ◽  
Author(s):  
Lynda F. Delph ◽  
Janet L. Gehring ◽  
A. Michele Arntz ◽  
Maureen Levri ◽  
Frank M. Frey
Keyword(s):  
Sexual Dimorphism ◽  
Genetic Correlations ◽  
Cost Of Reproduction ◽  
Floral Display ◽  
The Cost

The IBM-PC in electron microscopy

1996 ◽  
Vol 54 ◽  
pp. 612-613
Author(s):  
James F. Mancuso
Keyword(s):  
Head Start ◽  
Image Acquisition ◽  
Cost Effective ◽  
Financial Applications ◽  
Number Of Factors ◽  
Instrument Control ◽  
The Cost ◽  
Training And Support ◽  
Control Image ◽  
Ibm Pc

IBM PC compatible computers are widely used in microscopy for applications ranging from control to image acquisition and analysis. The choice of IBM-PC based systems over competing computer platforms can be based on technical merit alone or on a number of factors relating to economics, availability of peripherals, management dictum, or simple personal preference.IBM-PC got a strong “head start” by first dominating clerical, document processing and financial applications. The use of these computers spilled into the laboratory where the DOS based IBM-PC replaced mini-computers. Compared to minicomputer, the PC provided a more for cost-effective platform for applications in numerical analysis, engineering and design, instrument control, image acquisition and image processing. In addition, the sitewide use of a common PC platform could reduce the cost of training and support services relative to cases where many different computer platforms were used. This could be especially true for the microscopists who must use computers in both the laboratory and the office.

New Feasible Concepts of Aberration Correction for Realizing High-Resolution Electron Microscopes

1990 ◽  
Vol 48 (1) ◽  
pp. 202-203
Author(s):  
H. Rose
Keyword(s):  
Spherical Aberration ◽  
Wave Length ◽  
Electron Wave ◽  
Optical Lens ◽  
Resolution Electron ◽  
Rotationally Symmetric ◽  
Electron Microscopes ◽  
The Cost ◽  
Imaging Performance ◽  
Acceleration Voltage

The imaging performance of the light optical lens systems has reached such a degree of perfection that nowadays numerical apertures of about 1 can be utilized. Compared to this state of development the objective lenses of electron microscopes are rather poor allowing at most usable apertures somewhat smaller than 10-2 . This severe shortcoming is due to the unavoidable axial chromatic and spherical aberration of rotationally symmetric electron lenses employed so far in all electron microscopes.The resolution of such electron microscopes can only be improved by increasing the accelerating voltage which shortens the electron wave length. Unfortunately, this procedure is rather ineffective because the achievable gain in resolution is only proportional to λ1/4 for a fixed magnetic field strength determined by the magnetic saturation of the pole pieces. Moreover, increasing the acceleration voltage results in deleterious knock-on processes and in extreme difficulties to stabilize the high voltage. Last not least the cost increase exponentially with voltage.

An application: the cost of clinic care by undergraduate dental students and its relationship to clinic fees

1994 ◽  
Vol 58 (11) ◽  
pp. 832-835 ◽  
Author(s):  
ES Solomon ◽  
TK Hasegawa ◽  
JD Shulman ◽  
PO Walker
Keyword(s):  
Dental Students ◽  
The Cost

The effect of heliotherapy on the cost of psoriasis, p. 288

1998 ◽  
Vol 138 (2) ◽  
pp. 205-205
Author(s):  
Snellman ◽  
Maljanen ◽  
Aromaa ◽  
Reunanen ◽  
Jyrkinen‐Pakkasvirta ◽  
...  
Keyword(s):  
The Cost
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