Phenotypic adaptation

Bacterial resistance to biocides (Table 13.2) is usually considered as being of two types (a) intrinsic (innate, natural), a natural property of an organism, or (b) acquired, either by chromosomal mutation or by the acquisition of plasmids or transposons. Intrinsic resistance to biocides is usually demonstrated by Gram-negative bacteria, mycobacteria and bacterial spores whereas acquired resistance can result by mutation or, more frequently, by the acquisition of genetic elements, e.g. plasmid- (or transposon-) mediated resistance to mercury compounds. Intrinsic resistance may also be exemplified by physiological (phenotypic) adaptation, a classical example of which is biofilm production. 

Biofilm production Phenotypic adaptation Plasmid transfer may occur within biofilms... 

Table 2 Some functional genomic relationships of protein kinases to cancer phenotypes (adapted from [10]) ...

Figure 11.1. Demonstrates a unimodal and bimodal distribution of drug metabolism. The theoretical unimodal (single gaussian distribution) on the left is typical of a nonpolymorphic metabolism, and the bimodal distribution (mixture of two Gaussian distributions) on the right represents the results of phenotyping for a polymorphic substrate, debrisoquine. The intersection of the two bimodal distributions is the antimode, or the estimated cutoff point between the two phenotypes used to predict the PM phenotype. Adapted, in part, from Henthorn T. K., Benitez, J., Avram,M. J., Martinez,C., Llerena, A., Cobaleda, J., Krejcie,T., and Gibbons, R. D. Clin. Pharmacol. Ther. 45, 328-333,1989 and Kiipfer, A., and Presage, R. Ear. J. Clin. Pharmacol. 26 753-759,1984.

Brandon, R. (1990), Adaptation and Environment, Princeton University Press, Princeton, NJ. Cartwright, N. (1983), How the Laws of Physics Lie, Oxford University Press, Oxford, UK. Dawkins, R. (1982), The Extended Phenotype, Freeman, San Francisco, CA. 

Sarkar, S. (2002), From the Reaktionsnorm to the Evolution of Adaptive Plasticity A Historical Sketch, 1909-1999, in T. DeWitt and S. M. Scheiner (eds.) Phenotypic Plasticity Functional and Conceptual Approaches, Oxford University Press, New York. 

A core assumption of ultra-Darwinism is that if not all, then most observed characters must be adaptive, so as to provide the phenotypic material upon which natural selection can act. However, what constitutes a character - and what constitutes an adaptation - is as much in the eye of the beholder as in the organism that is beheld, as Gould and Lewontin pointed out in their famous paper on spandrels (Gould and Lewontin, 1979). Natural selection s continual scrutiny does not give it an a la carte freedom to accept or reject genotypic or phenotypic variation. Structural constraints insist that evolutionary, genetic mechanisms are not infinitely flexible but must work within the limits of what is physically or chemically possible (for instance, the limits to the size of a single cell occasioned by the physics of diffusion processes, the size of a crustacean like a lobster or crab by the constraints... 

The evolution of parasitic phenotypes in nematodes is a topic of active practical and theoretical research (Skorping el al., 1991 Read and Skorping, 1995a,b). Understanding the mode and tempo of acquisition of particular phenotypes associated with succesful parasitism will permit fuller appreciation of the evolutionary constraints experienced by organisms adapting to new hosts. 

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