The Pros And Cons Of Natural Selection

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Millstein, a scientists experimenting with species of beetles, argued that each of these positions could be right in one way, but wrong in another in that natural selection takes place at the level of populations, but it is a causal process when done this way (2006). Arguments between scientists are often if natural selection acts on a population level or an individual level (Millstein, 2006). Dealing with this issue of levels, the difference between the two arguments can be shown by an example of a person believing, in terms of the levels of selection, that selection acts on organisms (Millstein, 2006). This person may ask whether the selection process was acting on individual organisms or populations of organisms (Millstein, 2006). The second
Three of which can be a counterfactual account, a manipulability account, and a controlled experiment account (Millstein, 2006), but only the first two will be reviewed. For each of the three cases heritable differences in physical characteristics and differences in reproductive success can be seen (Millstein, 2006). With the counterfactual account, the heritable difference can be explained by saying that the differences in reproductive success do not occur (Millstein, 2006). Natural selection favors the counterfactuals because, if there were no heritable differences in characteristics among organisms in the population, then there would be no differences in reproductive success (Millstein, 2006). This would mean that natural selection had nothing to favor and all organisms would have the same genotype (Millstein, 2006). Referring to the manipulability account, if scientists would change the heritable differences in physical characteristics of the organism in a population, there would be a visible change of their reproductive success (Millstein, 2006). For example, in a population of beetles with varying abilities to withstand different temperatures, a new beetle genotype is introduced that can withstand a greater range of temperatures, and we would expect that the relative reproductive success of the other genotypes would decrease (Millstein,
Phylogenetic relationships among the four Radix species are inferred based on their genomes and nuclear loci (Feldmeyer, 2015). Three different tests to infer selection and changes in amino acid properties yielded a total of 134 genes with signatures of positive selection (Feldmeyer, 2015). The majority of these genes belonged to functional genes including reproduction, genitalia, development, and growth rate (Feldmeyer, 2015). This studied showed that the Radix species divergence may be primarily enforced by selection on life history traits such as larval development and growth rate (Feldmeyer, 2015). The scientists hypothesized that life history differences may hint toward advantages under the according climate regimes, and they might have a fitness advantage with fast developing life stages, which are more tolerant to habitat changes (Feldmeyer, 2015). This study showcases that natural selection can act on the gene level and that certain mechanisms in the evolution of the organism can lead scientists to believe that it

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