David Shenk talks about how if you were to clone someone, the clone would make different mistakes and collect different memories; he'd lead a different life (73). He'd also have a very different GxE landscape which can guarantee enormous differences between originals and their copies. An experiment with cloning cats has shown that the copy will not necessarily act or even look like the original even though they are genetic clones of each other. How does this relate to twin studies? And despite extraordinary stories of reunited identical twins, how does this affect the impact of environment on them?
(Mindy Shaw, mindyshaw95@yahoo.com)
The cat experiment with the original cat Rainbow and its clone Cc is a perfect demonstration of reasons why genes don’t necessarily always control traits. Even though they were genetically the same, they were “far from perfect copies of each other” (76 Shenk) because of the environment interacting with the genes. A reason for this may be that natural selection happens where the animal adapts to its environment in order to survive. Rainbow and Cc’s pictures were shown by Shenk during the skype session and he described that their personality and looks were very different due to adapting to different environments. While Rainbow’s fur color was bright and orange and he was very plump ,Cc’s fur color was much darker and more black and Cc was skinner. The reason for this is due to the X chromosome in the cats. A gene that determines coat color is on this chromosome. Since both Rainbow and Cc were female, they had 2 X chromosomes that had specifying colors, one black and one orange. So the reason for their fur color difference is that during early development, each of Rainbow’s cells “turned off on entire X chromosome-and therefore turned off either black color gene or the orange one” (http://learn.genetics.utah.edu/content/tech/cloning/cloningmyths/). So thanks to environmental differences, gene regulation occurred where a specific section of the DNA was turned off and transcription, RNA processing, translation, and protein formation was altered thanks to the environment. This proves the GxE paradigm, genes don’t solely determine our traits, rather it is the interaction of genes and their environment that determine our traits. The advantage to organisms developing differently due to their environment is to produce a variation of traits in order to survive and reproduce effectively in that specific environment. So maybe the changing of fur color enables the organism to camouflage into their environment and enhance their survival rate. The best trait, such as the best color produced to blend into environment, altered thanks to gene regulation, will help the organism survive in their environment and be able to reproduce, which is natural selection. Campbell further backs up this argument by stating that “genetic components of behavior evolve through natural selection for traits that enhance survival and reproductive success in a population” (Campbell 1132). Although some traits are consistently passed on from parent to child, other traits can be varied because of one’s environment. Twin studies are a perfect demonstration of this. Even though twins may look the same, which is the passing of the consistent trait, they might act completely different due to how their genes are interacting with the environment, or vice versa. So even though twins have same genes, because of their interaction with the environment due to natural selection, their still different traits. This proves the GxE equation of genes and environment interacting with each other in order to produce the best, most effective, and suitable traits for the environment of the organism due to natural selection.
ReplyDeleteBing Zhao (bingzhao9@yahoo.com)