GeneticistsIntroFeedback

Main corrections: Sterile Hybrids The aim of the field trip is to discern the underlying processes for the differences in phenotypes of snails, not that it is due to different environmental factors. Need to say more about the samples being taken, too vague to say three separate areas will be sampled. Why will selecting 2 grassland areas and a shrub area give a broad spread of samples. Need to specify collecting 40 samples of snails. How do you know that the phenotypes in the snails aren’t different due to genetic drift or selection if the environments are different, and not due to the environmental differences. The differences in the snails are probably not due to mutation, as mutations are thought to be random in response to need. How will you tell genetic drift, natural selection or the founder effect apart. Need evidence for saying that snails will be studied because they have a less complex phenotypic expression, in comparison to humans for eye or skin colour, as evidence shows that only a few loci affect these characters. Need to say how the generations between snails are going to be compared. Jennifer’s group Studying snails doesn’t only benefit the understanding of human evolution. Snails, as well as humans, have genes that are unclear or affected by more than one gene. Need to explain what discrete meta-populations are and whether they really are discrete. Need to make a distinction between the words ‘product’ or ‘driver’ when saying that colour or banding can cause selection pressures, genetic drift or gene flow. Evidence for saying that predation, luck, geography and the ability to absorb light rays can affect phenotypes. Need to explain logic in comparing dead and living snails. How do you know if the results are due to a founder event. Why would you keep the samples in a habitat close to each other. How do you know if a snail has adapted or not. How will you know what the snail’s cause of death was. Joshua’s Group Explain what the difference is between prominence and frequency. All species have many possible morphs, not just snails. Need a reference for saying that rich polymorphism can be seen in the shell pattern, and what the implication of this is. Humans are not the only species of interest, so snails are not only studied because they have no ethical considerations, but because snails are also relevant to humans. Cant say ‘dominance’ to mean high frequency as this has a different meaning in genetics. How will you link the prominence of a certain phenotype to an environment, as both drift and selection can cause this, who will you tell them apart. How will you determine whether there is gene flow or migration by studying the areas between two environments. Why would you compare the ratio of dead and live snails in each location. How would you determine the rate of mortality of snails due selection disadvantage. How will you tell apart processes that you are studying. How will you know which process is operating if all of them can change allele frequencies. ME+Tripple S    Polymorphism is defined on the basis of the phenotype. The aim of the experiment is to study how the evolutionary processes have an effect on the distribution of alleles, not the polymorphic distribution of snails. Snails are not being used because they are hermaphrodites, nor to do with the complexity of the organism. Both snails as well as humans can have allelic differences that are subtle, and in both some traits are determined by only a few loci. Need evidence for saying why simpler organisms will be easier to distinguish between the effects of gene flow, genetic drift and selection on allele frequencies. How will you be able to tell which of the evolutionary processes has the strongest effect on snail phenotype distribution. Why do the samples between each habitat need to be adequately spaced apart to reduce the effects of gene flow. Why does performing three repeats in each habitat increase the accuracy and validity of the results. Can’t say that if the allele frequencies are similar in both localities it would be due to gene flow, as gene flow would cause a difference in allele frequency between the two localities. How will you distinguish the effect of genetic drift from the effect of selection. ** Group 7  ** · Good points have been made, but not in enough detail. More description needed of terms used and statements made. · Where some points have been made, it will be useful to give examples · There are some good points; however there is a lack of evidence in proving the point. · There is no reasoning as to why that type of particular study is carried out · “If genetic drift is the sole cause of differentiation among populations then the pattern would be...”- explain this statement further · There have been misunderstandings between stating results and the actual explanation of results · Elaboration is needed on how the study method enables you to distinguish between the possible explanations of the patterns observed ** Charlotte’s Group  ** · The action of selection is not known as polymorphism- Need to look up and understand what the action of selection is known as. · The existence of alleles at a locus is..- Elaborate on this point · Explain why //Cepaea // studies have been so informative. · Points have been made, but are they realistic enough? · How does large family size increase polymorphism? · The logic made is sometimes unclear. More reading around the subject might be required. · What will tell you whether its drift or selection? Any form of evidence? · The concluding sentence needs to be finalised and explained more clearly. ** Selection  ** · More explanation needed in terms of drift and how it affects population size · Is bottleneck a mechanism? · When gene flow occurs it hinders genetic drift- Explanation of this statement is needed · There is a slight misunderstanding of the term “species” · Some good points have been made, but not enough evidence or research to back up the statements made · What is the reasoning for the difference in allele frequency being due to genetic drift? ** Rakhee’s Group  ** · Could have a better opening sentence. One is which is more informative and constructed. · Explain why there is a difference in populations. Has gene flow got an effect? · What does “reduced locomotion” mean · There have been good statements made, but is there evidence to back these statements? · Why are snails better to be used for this experiment? · Statements, which may not be true, have been made. Maybe provide with references? How do you know that you sample size is big enough? Humus & Peter
 * Population is polymorphic and not the variants
 * Many of the introductions did not explain how the results gathered would help us distinguish between genetic drift and natural selection. More detailed explanation of what we would expect. Common corrections would be to include how the hypothesis made would be supported.
 * Aisha’s group – Mapping of genotypes onto phenotypes and describing how this occurs
 * Single gene that was responsible – some confusion
 * The fact that existence of different alleles explains variation in phenotype.
 * Also referring to previous studies more when explaining what we are trying to find out. e.g. there have been studies on the Cepaea and the evolutionary processes occuring but no direct answer

First sentence is very dull and states the obvious. A well structured introductory sentence would have been more appealing to the reader. Cepaea Nemoralis does not have to be stated continuously, can be abbreviated to C.Nemoralis. How can the effects of selection show it has an effect on the snails? Overall, good introduction but few changes can be made to make it strong. Geneticists A very good introduction with minimal changes needed. Something to add would be: how does the mapping of the genotype shown in the phenotype? The causes of evolution of C.Nemoralis cannot be pinpointed so make sure you state that what you will be finding will only be a theory. Group 6 Good sample size. Lots of vague sentences have been incorporated. There are few sentence with wrong logic and lack of evolutionary understanding. More reasoning needed with evidence Very poor introduction with no sense of understanding or grasp of the whole case study. Ayesha’s Group Very boring introductory sentence, If terms or sentence have been copied from elsewhere, make sure you reference it. A lot irrelevant information have been included How can snails drift according to different environments? Some good sentences have been added Good introduction