Evolution Blog

What is Genetic Drift?  Genetic drift is a shift in a population's allelic frequencies due to random chance events. It can lead to the loss of alleles and a decline in genetic diversity.  Until this week, I was uncertain about the mechanism of drift. I knew it was due to random chance but I wasn't able to fully wrap my head around the concept. The example of Northern Elephant Seals helped me to understand that drift is not as complicated as I thought. I also now understand how the bottleneck and founder effects contribute to genetic drift and the loss of certain alleles.   

  It Gets Complicated What is phenotype plasticity and how does it affect evolution and selection? Plasticity refers to the ability of an organism to change a characteristic of itself in response to environmental stimuli or disturbances.  When examining a trait and determining if it is plastic, it is good to start by seeing if the organism can change the trait. If they can modify a trait, can they do so when stimulated? Can they revert to their original trait expression? If the answer to most or all of these is yes, then you can determine if the trait exhibits plasticity. 

  Genotypes and Phenotypes How does selection act on the phenotype when its really the genotype that is passed to the next generation? Phenotype is the physical expression of a trait and genotype is the gene that causes the expression of the trait. The phenotype is very important to survive in an environment and can be one of the many factors that contribute to the overall success of the organism. For example, if we take a look at the anoles from Improbable Destinies we see that the physical expression or phenotype of each anole is what helps them to truly thrive in their niche. The twig anoles have short and stout legs that hold tightly to twigs and branches while hunting prey and hiding from predators. Garman's anole is larger and stronger, being able to easily navigate the tree trunks and upper branches of trees, even being able to consume other, smaller anoles.  These physical expressions of the genotype are what allows the gene to be successful or not. The genotype goes ...