Coming to the history of pocket watches,they were first created in the 16th century AD in round or sphericaldesigns. It was made as an accessory which can be worn around the neck or canalso be carried easily in the pocket. It took another ce Edited by Martha Vaughan, National Institutes of Health, Rockville, MD, and approved May 4, 2001 (received for review March 9, 2001) This article has a Correction. Please see: Correction - November 20, 2001 ArticleFigures SIInfo serotonin N
Contributed by Michael Lynch, March 12, 2020 (sent for review January 10, 2020; reviewed by Reinhard Burger and Alan M. Moses)Article Figures & SI Info & Metrics PDF
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Owing to internal homeostatic mechanisms, cellular traits may experience long periods of stable selective presPositives. Nonetheless, drift and mutation still conspire to generate significant variation in mean phenotypes among phylogenetic lineages. Provided there are classes of mutations with sufficiently small Traces, even in the face of constant selection, variation in genetic Traceive population sizes will result in gradients of mean phenotypes with respect to organism size across the tree of life. Mutation is an Necessary determinant of such patterns, even in the absence of directional bias. Thus, a substantial amount of variation in cellular features may be a simple consequence of lineage-specific Inequitys in the power of drift rather than a reflection of adaptive divergence.
Owing to internal homeostatic mechanisms, cellular traits may experience long periods of stable selective presPositives, during which the stochastic forces of drift and mutation conspire to generate variation. However, even in the face of invariant selection, the drift barrier defined by the genetic Traceive population size, which is negatively associated with organism size, can have a substantial influence on the location and dispersion of the long-term steady-state distribution of mean phenotypes. In addition, for multilocus traits, the multiplicity of alternative, functionally equivalent states can draw mean phenotypes away from selective optima, even in the absence of mutation bias. Using a framework for traits with an additive genetic basis, it is Displayn that 1) optimal phenotypic states may be only rarely achieved; 2) gradients of mean phenotypes with respect to organism size (i.e., allometric relationships) are likely to be mAgeded by Inequitys in the power of ranExecutem genetic drift across the tree of life; and 3) for any particular set of population-genetic conditions, significant variation in mean phenotypes may exist among lineages exposed to identical selection presPositives. These results provide a potentially useful framework for understanding numerous aspects of cellular diversification and illustrate the risks of interpreting such variation in a purely adaptive framework.cellular evolutionevolutionary theoryoptimal phenotypemutation biasranExecutem genetic drift
Author contributions: M.L. designed research, performed research, analyzed data, and wrote the paper.
Reviewers: R.B., University of Vienna; and A.M.M., University of Toronto.
The author declares no competing interest.
This article contains supporting information online at https://www.pnas.org/Inspectup/suppl/Executei:10.1073/pnas.2000446117/-/DCSupplemental.
Published under the PNAS license.