Plants show phenotype is influenced by genotype AND environment скачать в хорошем качестве

Plants show phenotype is influenced by genotype AND environment

A review of: Experimental studies on the nature of species. I. Effect of varied environments on Western North American plants. Clausen J, Keck DD, Hiesey WM. 1940.Carnegie Institute, Washington DC. Twitter:   / genetics_stuff   OTHER VIDEOS YOU MIGHT LIKE: • The discovery of RNAi – double-stranded RNA worms its way into gene regulation (Fire et al., 1998) -    • Видео   • White-eyed flies and the discovery of sex linkage (Morgan, 1910) -    • Видео   • Proving the linear structure of genes: Benzer shoots and scores a goal (Benzer, 1959) -    • Proving the linear structure of genes: Ben...   Clausen, Keck, and Heisey’s first publication, Effect of Varied Environments on Western North American Plants (1940) aimed to determine the effect of the environment on the morphology and physiology of ecotypes. This was achieved by performing reciprocal transplants between three experimental stations with highly variable climates along a transect across California. Stanford, the coastal station had a warm, temperate climate. Mather, the mid-altitude station experienced moderate temperatures, while Timberline, situated at the apex of the Sierra Nevada, experienced freezing temperatures during winter. Genetically identical cuttings of individuals from a range of ecotypes across the transect were transplanted into each of these gardens. The researchers reasoned that variation between plants in the same garden has a genetic basis, while variation between genetically identical individuals across gardens is due to environmental adaptation. Modifications or changes in morphology or physiological processes such as growth rate, size, and periods of dormancy were measured. Clausen’s team observed that individuals retained their defining characteristics such as flower colour and leaf shape throughout transplantation. Once transplanted individuals were returned to their native environment, their original traits were restored, suggesting that modifications are reversible. Ecotypes derived from regions of similar climate were observed to react similarly when transplanted to the same garden, whereas ecotypes from dissimilar climatic regions would display different reactions. Two different plants also showed no tendency to become identical when transplanted into the same garden. By crossing different ecotypes and examining the segregation of traits, Clausen’s team verified that most observed traits had a genetic basis. Furthermore, their observations of ecotype distribution suggested that ploidy number did not dictate an ecotype’s adaptability to extreme environments, contradicting popular claims in the literature. They proposed that an organism’s ability to adapt was due to its gene expression, which overshadows any potential effects of chromosome number. Clausen’s team concluded that a plant must be in equilibrium with its environment for it to succeed. The plant’s gene activity regulates the balance of proteins produced, which impacts its morphology and rate of physiological processes. If these processes occur at the ideal rate for survival in a particular environment, the plant will be successful. Otherwise, it is likely to be eliminated by natural selection. From these experiments, Clausen’s team proposed that speciation occurs gradually, and in stages. It is mediated by genetic changes such as mutation or polyploidy that disrupt the equilibrium between the plant and its native environment. As a result, its gene activity now regulates a different physiological rhythm that may form a stable equilibrium with a new environment. These locally adapted races are ecotypes. Climatic differences between regions provide a weak barrier that discourages gene exchange between ecotypes. Over time, reproductively isolated ecotypes may give rise to differentiated species, given that the precise equilibrium requirements are satisfied. Creator: Catherine Shen References: Clausen, J., D. D. Keck, and W. M. Hiesey. 1940 Conclusion, pp. 408-429 in Experimental Studies on the Nature of Plant Species. I. Effect of Varied Environments on Western North American Plants. Carnegie Institute, Washington. Clausen, J., D. D. Keck, and W. M. Hies1ey, 1941 Regional Differentiation in Plant Species. Am. Nat. 75: 231-250. French, C. S., 1989 Jens Christian Clausen, pp. 73-107 in Biographical Memoirs: Volume 58. National Academy Press, Washington. Lowry, D. B., 2011 Ecotypes and the controversy over stages in the formation of new species. Biol. J. Linn. Soc. 106: 241-257. Núñez-Farfán, J., and C. D. Schlichting, 2001 Evolution in the changing environments: the “synthetic” work of Clausen, Keck and Heisey. Q. Rev. Biol. 76: 433-457. Ruse, M., 1975 Charles Darwin's Theory of Evolution: An Analysis. J. Hist. Biol. 8: 219-241. Turrill, W. B., 1946 The Ecotype Concept. New Phytol. 45: 34-43.