Biological Sciences
Phenotype
Phenotype refers to the observable physical and biochemical characteristics of an organism, resulting from the interaction between its genetic makeup (genotype) and the environment. These characteristics can include traits such as eye color, height, and behavior. Understanding phenotypes is crucial in studying how genetic information is expressed and how it influences an organism's traits and overall biology.
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3 Key excerpts on "Phenotype"
eBook - PDFInsect Phenotypic Plasticity
Diversity of Responses
- T N Ananthakrishnan, Douglas Whitman, T N Ananthakrishnan, Douglas Whitman, T N Ananthakrishnan(Authors)
- 2005(Publication Date)
- CRC Press(Publisher)
Gene products create a cellular environment that can be influenced by external factors, including heat, light, nutrition, pH, toxins, pathogens, etc. In some cases, the environment can directly influence gene expression. But more often 2 Insect Phenotypic Plasticity externally induced changes in the internal environments of developing organisms alter their development, physiology, or behaviour, producing different Phenotypes. Hence, the genotype does not give rise to the Phenotype, but to a range of Phenotypes. In other words, a Phenotype is a biological system constructed by successive interactions of the individual genotype with the environment, in which development takes place. The norm of the reaction (Schlichting & Pigliucci, 1998) is the entire range, the whole repertoire of the variant pathways in development, that may occur in the carrier of a given genotype in all environments, favourable or unfavourable, natural or artificiar' (Dobzhansky, 1971). Thus, Phenotypes are always the product of genes x the environment. Indeed, genes can never be separated from the environment, because even the chromosomes of an unfertilized egg reside in a cellular environment that was presumably influenced by the mother's physiological state, and continues to be influenced by prevailing environmental conditions. This leads to the realization that most traits or characteristics of organisms are plastic, i.e., they can be influenced by the environment. It also suggests that phenotypic plasticity functions in evolution, by initiating phenotypic variation, the raw product upon which natural selection acts. Natural selection selects among different Phenotypes, not genes, and variation is an indispensable prerequisite of evolution. When the environment induces a novel Phenotype, then natural selection can begin to act on that novelty. If that specific Phenotype never occurs, then it cannot be selected for. Phenotypic plasticity then comes to assume an important place in evolution.
- Alan R. Templeton(Author)
- 2021(Publication Date)
- Wiley-Blackwell(Publisher)
Part 2 Genotype and Phenotype 295 8 Basic Quantitative Genetic Definitions and Theory In Chapter 1, we introduced the three premises upon which population genetics is founded. In Chapters 2 through 7, we explored the roles of premise one, DNA replication, and premise two, DNA mutation and recombination, on the fate of genes through space and time. Many powerful evolutionary mechanisms were uncovered during this exploration of premises one and two, but our discussion of evolutionary mechanisms remains incomplete until we weave the third premise into this microevolutionary tapestry. The third premise is that the information encoded in DNA interacts with the environment to produce Phenotypes (measurable traits of an individual). Premise one, DNA replicates, tells us that genes have an existence in time and space that transcends the individual. This transcendent behavior of genes does not imply that individuals are not important. The evolutionary fate of genes does depend on the individuals that carry the genes. DNA cannot replicate except through the vehicle of an individual living and interacting with its environment. Therefore, how an individual interacts with the environment plays a direct role in the ability of DNA to replicate. As pointed out in Chapter 1, the fact that DNA replication is sensitive to how an individual interacts with its environment is the basis of natural selection and adaptive evolution. Premise three says that you inherit a response to an environment, not traits per se. Thus, the envi- ronmental context in which individuals live and reproduce cannot be ignored if we want a full understanding of evolution. In this chapter and the following two, we will lay the foundation for understanding the relationship between genotype and Phenotype, a relationship that is essential to understand before turning our attention to natural selection and adaptive evolution in the final chapters of this book.
eBook - PDFNetwork Medicine
Complex Systems in Human Disease and Therapeutics
- Joseph Loscalzo, Albert-László Barabási, Edwin K. Silverman, Joseph Loscalzo, Albert-László Barabási, Edwin K. Silverman(Authors)
- 2017(Publication Date)
- Harvard University Press(Publisher)
Parallel work in the common variant genetics of psychiatric disease has re-vealed a large number of loci that are shared across apparently very different Phenotypes (Cross-Disorder Group of the Psychiatric Genomics Consortium, Lee, et al. 2013; Solovieff, Cotsapas, et al. 2013). While this has been interpreted as evidence of a shared etiology, in the context of the known high heritability of many of the underlying disorders, it is likely to represent a downstream endo-pathoPhenotype that modulates much more generic neuropsychiatric outputs such as tuning contributions to the core disease modules. Ultimately, these in-sights have led the psychiatric community to drive toward more global ap-proaches to Phenotype firmly based in quantitative objective metrics. It is clear that as biology enters a more quantitative and holistic era, a rigorous reappraisal of all Phenotypes will be required. Next-Generation Phenotypes for Network Medicine Together these observations on the origins, evolution, and limitations of the Phenotype concept argue for a much more comprehensive approach, one that documents the fundamental genetic molecular and cellular architecture of physiological and pathophysiological traits, not only under baseline conditions, but also in response to a range of empirically tested perturbations. A consensus is emerging that such a phenotyping project is necessary, as holistic network concepts of biology and disease are being defined (Bilder, Sabb, et al. 2009). This Phenotype, PathoPhenotype, and Endo(patho)Phenotype 127 last section of this chapter will outline some of the basic principles that might inform these converging frameworks at a time when genetics, genomics, and other tools are being deployed in the clinical arena. When compared with the finite scope of the genome, the enormity of mea-suring the phenome is all too apparent.
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