Aubree's Evolution Blog

  Something that makes me feel good is my families pup Maverick! 

  What genetic drift IS: Genetic Drift is RANDOM. In the case shown above there is a population of pink, blue, and purple bugs. A portion of that population got squashed by a shoe. That portion happened to be 2 purple bugs and a blue bug. There was only 2 purple bugs in the population to begin with so now there is not any more purple bugs in the population at all because these bugs randomly died.   What Genetic Drift is NOT:  Genetic Drift is not when a species has a phenotype that will allow them to better survive their environment. The green bugs above all get eaten by the lizard because their color stands out to the lizard against the dark bark of the tree. The brown bugs are not seen by the lizard so they are not eaten. This is not Genetic Drift, this is Natural Selection.

 Phenotypic Plasticity is the ability of an organism to change their phenotype in relation to the environment that they are in.  In the paper " The Genetic Basis of Adaptation following Plastic Changes in Coloration in a Novel Environment"  a study was done on lizards that live on these lava rocks. The lizards living on the dark lava rocks have a dark phenotype that enables them to blend into the rocks. These researches found that when you remove these lizards from the dark rocks and place them on a much lighter substrate, then these lizards become much lighter in color in order to blend in with the substrate. They also compared the lizards already living on the lava rocks to lizards nearby who were living off of the lava rocks. They found that when exposed to the dark colored substrate that both groups of lizards had a much darker phenotype, however, the researchers observed that the lizards already living on the lava rocks had darker phenot...

  My figure describes stabilizing and disruptive selection. We have also learned about directional selection and balancing selection.  Directional selection is when you have a population where one of the extreme traits are going to be favored above all of the other traits. This causes the allele frequency to shift toward to the favored allele.  Balancing selection is when there are multiples alleles in a population that have their frequencies continuing to shift with one another. When one allele goes up one goes down and then vice versa. 

       When the allele that we are focused on increases its relative fitness then we can expect to see an increase in the allelic frequency . If this allele decreases its relative fitness we expect to see a decrease in the allelic frequency seen in the population.      The relative fitness of the other alleles in the population can influence how quickly the allelic frequencies change .       Genetic drift acts on a population randomly. There is a possibility that drift can completely take the allele that we are focused on out of the population . This was shown using a smaller population size during the simulation. Genetic drift has a much larger effect on a smaller population compared to a larger population.