Shenk discusses genetic clones and cites the case of
Rainbow the cat and its clone, Cc, whose physical features and personalities
revealed them to be “far from
perfect copies of each other” despite sharing the same genetic code
(74). Furthermore, a hypothetical Ted Williams clone would not necessarily
possess the same baseball skill set as the original and would also not produce
an exact replica. Considering the extent to which genes can control an
organism’s potential, might Shenk’s position on genetic clones be used to
support or refute the theory of natural selection in the context of evolution?
Refer your answer to the ecology units from the beginning of the year.
David Ribot (ribotdavid@gmail.com)
Although Rainbow and CC have the same genes because they’re clones, their environmental interactions cause the change in their appearance and ultimately their traits. Therefore, the theory of natural selection where organisms with the best traits survive and reproduce is supported because even though Rainbow and CC have the same genes, they are “far from perfect copies of each other” (76) because the environment interacts with genes so that clones are not perfect copies with different traits suited or not suited to survive. Genes only control the potential of an organism to a certain extent concerning characteristics, but when genes interact with the environment that can regulate genes. For example, DNA methylation is a form of gene regulation where DNA becomes inactive by methylating the X chromosome. In cats, the Barr body in the cats of perhaps Rainbow or CC results in the change in color of the fur coat. In communal ecology, even the color of fur can attribute to a trait that can result in elimination in the case of adaptive coloration. The result of the genes and the environment interacting in the GxE model explains how some organisms are naturally selected to survive due to the traits and characteristics they were born with or acquired. Other forms of gene expression regulation takes place in transcription, RNA processing, translation, and protein processing which all allow the variation of traits of eukaryotes to survive and reproduce based on their effectiveness in the environment. In the context of evolution, those with the best traits will survive and reproduce and therefore evolve the species to be better adapted to the environment. Identical twins is another perfect example of how similar organisms still have different traits based on their interaction with the environment and perhaps natural selection will select for survival based on the traits they acquire.
ReplyDeleteIn relation to the development of behaviors, which is another ecology unit related subject, both genetic makeup and the environment interact to affect behavior which is another important trait in evolution. The selection for individual survival and reproductive success can explain most behaviors. The genetic components of behavior evolve through natural selection for traits that enhance survival and reproductive success in a population (Campbell 1133). For example, the optimal foraging model shows how natural selection would favor a foraging behavior that minimizes the cost of foraging and maximizes the benefits. An organism’s traits along with behavior relate to the natural selection theory which consists of “Variation. Organisms (within populations) exhibit individual variation in appearance and behavior. These variations may involve body size, hair color, facial markings, voice properties, or number of offspring. On the other hand, some traits show little to no variation among individuals—for example, number of eyes in vertebrates.” (http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html) and “Inheritance. Some traits are consistently passed on from parent to offspring. Such traits are heritable, whereas other traits are strongly influenced by environmental conditions and show weak heritability.” The other steps of high population growth and differential survival and reproduction will entail and therefore evolution will take place over time selecting the organisms which are most fit. In twins and clones, genes can only play a partial role in natural selection and evolution because the environment is also vital in determining acquired behaviors and traits that will differential the clones or twins into the process of natural selection and evolution based on the effectiveness of their behaviors and traits in the environment.
(Kirk Chiu- krkpchiu@gmail.com)
I found the study of cloning to strongly support Shenk's statements and beliefs that the environment around us dictates our end development and gene expressions. The genes an organism possessed is influenced by the interactions with other organisms, but most importantly by the factors around the organism developing throughout life.
ReplyDeleteI believe that the theory that Shenk states, how it is very unlikely to produce clones with the "same behaviors and same looks" when communicating through Skype with us. He made a clear point that genes are not just instructions, but they are specific to what stresses and situations the organism is surrounded by and therefore selectively and uniquely expressed. For example, the cat Rainbow's clone named Cc shows very little similarity between personality and looks as Shenk showed photographs during the Skype meeting.
Referring to natural selection, I feel that the inability to create exact copies of organisms works in favor of natural selection. This in turn provides a variety of organisms and species that have different genes turned "on" and "off", thus increasing diversity, creating a stronger population that can withstand more and greater environmental pressures. Natural selection is defined as the, "process in which individuals that have certain heritable characteristics survive and reproduce at a higher rate than other individuals" (459).
For example in the article titled "Ecological Genetics and Natural Selection in Molluscs" that there is a positive association between mean summer temperatures and, "the gene frequencies at the shell color locus". The article describes the color variations of the 500,000 C. nemoralis snails used in the study. In the end, Shenk's statements on how our environment "dictates our end development and gene expressions" supports the need for diversity in organisms in order for the population to evolve over time and possess the most favorable genes.
Also, natural selection is said to be always "operating", so although genes may be the same the environment will also dictate where and why an organism should occupy the niche and habitat that it does currently. This carries onto the theme of evolution throughout Biology. Organisms are going to strive to be the best and pass on their genes. Unfortunately, those with unfavorable genes, or those who can't fight a pathogen for example will not survive to reproduce and pass on their genes.
(Weronika Dudkiewicz wpd1414@gmail.com)