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1. In order to increase the trichome number on Brassica rapa, I would do the following: grow a population of Brassica rappa (BRG0). Take the top X percent of hairiness (for example, ten percent) of BRGO, then breed that selected population to produce BRG1. Take the top ten percent of BRG1, then the top ten percent of BRG1, etc. This will produce a gradual increase of average hairiness over the course of generational selection. 2. The properties of the original population: 63 had 0-4 trichomes. 23 had 5-9 trichomes. 8 had10-14 trichomes. 5 had 15-19 trichomes. 12 had 20-24 trichomes. The ten selected original plants which then became the parents of the following generation had a mean number of 16 trichomes. The distribution of the offspring generation will probably be greater than the orginial unselected population mean of 3, but slightly smaller than selected mean of 16: it will increase toward the selected average but will not be equal to the average of the selecteds. If h2=1.0, that would mean that the phenotype variation was solely dependent upon genetic variation [Vp=VG] and Xp1=16. If h2=0, then the phenotype variation solely depends upon environmental variation and Xp1=3. Therefore, I believe h2 will be between 0 and 1, leaning towards the 1 side (therefore be closer to 16 trichomes than 3) because I think the genetic factor will be stronger than the envirnomental factor. This slow trend toward a different mean corresponds with a "soft sweep" effect on a population. The results support this hunch for the following reasons: the Xp0 = 3, Xs=16 and Xp1=11. So the breeded generation mean trichome count is 11, which leans on the 16 side but is between 3-16. Therefore, h2=R/S=(11-3)/(16-3)= 61.5% realised heritability. Yay! 3. As mentioned in number 2, h2=R/S=(11-3)/(16-3)= 61.5% realised heritability. So the VG influence on the offspring was about 2/3, while the Vp is about 1/3. This goes to show that genotypes have more influence, IN THIS SCENARIO, than environment. 4. The realized heritablitliy varies from generation to generation because the "breeders" of a given generation will be different from the preceeding generation precisely because it is a different generation. Also, the environmental factor will be different because the second generation cannot be born in the same circumstances and at the same time as the first generation. These differences are influence the realised heritability because the "magnitude of selection force" changes, and the response to the selection force can be influenced by environmental factors. 5. I predict that G6 would have a mean trichome number of 39.5%. This is assuming that the realized heritability would remain relatively stable at around 61.5%. If so, then h2=R/S=.615=(X-21)/(51-21). In this case, X = .3945 or approximately 39.45%. 6. The original range of Brassica rapa is 0-24 trichomes. So for microevolution, this range would not change. But it doesn't stay within this range. However, it can't really be classified as macroevolution either because the range is only partially exceed. Therefore, this Brassica rapa study is somewhere in between micro and macroevolution. Brassica rapa Trichome Range Trend over Generations G5-6 G4-5 No Trichomes G3-4 Trichome Range G2-3 G1-2 0 20 40 60 X-axis= # of trichomes Y-axis= Generation number This show that the range of trichomes changes over time, so in a way it's macroevolution, but it changes gradually and much of the data stays withing the original range, making it also microevolution. Therefore, it's somewhere between the two: 'micmac' evolution. Week 2 Prompts: #2 Describing experiment in NY Times article: This expriment studied fruit flies over 600 generations, studying approximately 250 whole genomes of flies in order to better understand what genetic changes had occured during the 600 generations. They bred them in populations of about 2,000, and selected the earliest hatching flies to be the parents of the next generation. Overall, the hatching time by the end of the experiment was 20% shorter than at the beginning. #3: hard vs. soft sweep A hard sweep is one in which a mutation in a gene takes over the entire population, so that every memeber has that mutation, thereby elimination all other possible "competitive" mutations. A soft sweep is when a trait is influenced by many genes and a tendency toward one gene in particular happens slowly and is not necessarily complete within that population. By this definition, a soft sweep more accurately describes our Brassica rapa data because the change in trichome number is happening slowly, over several generations (although I'm not completely happy with this answer because "slow" and "fast" are relative terms. Compared to the fruit fly study, our Brassica rapa change is extremely fast: their data only shifted by 20% over 600 generation while our range almost doubled in only 6). So I suppose microevolutiona and macroevolution can only be correctly applied to a situation by first defining the context. Otherwise, all results will always be micro compared to some and macro compared to others. REFLECTION: Once again the importance of defining a system makes itself very evident to me with the micro vs. macro debate. This is frustrating, because it would be a lot easier to be able to simply classify any given experiment as micro or macro and be done with it. By extention, this necessity to always define a system might be helpful in the long run, but in the short run (e.g. with questions like these) it complicates the process by adding in another step. This brings me back to the discussion on "is there truth," because we can't easily state anything as being relative to a truth that might not exist. Therefore nothing is easily defined. Luckily, most people don't think like this, which makes everyday conversation possible, otherwise we would be so caught up in trying to define everything before we moved forward that we would get nowhere. Quite a learning paradox. I would also like to explore the idea of bioethics as or if they apply elsewhere (e.g. ideas).