Blog Post Module 6

 Inbreeding is the mating of individuals that are closely related through common ancestry. A cost of inbreeding is that it can facilitate adaption by bringing together alleles that would usually never interact. It can also provide a sort of exit mechanism. However, there are many more costs to inbreeding than benefits I would say. A cost of inbreeding is that it increases the probability that individuals will be homozygous for a recessive deleterious allele. This is because if a parent is heterozygous and has one recessive deleterious allele that they pass on to their offspring, and two of those offspring mate, there is a possibility for them each to contribute that mutated allele to their offspring meaning the mutation would be expressed (as they are now homozygous recessive). We all have deleterious alleles, but they are not expressed due to their heterozygous nature. It only becomes an issue when two of these recessive deleterious alleles combine. Additionally, increased probability of combining deleterious alleles reduces the average fitness in a population. So inbreeding affects not only individuals, but also the populations those individuals make up. Due to the costs of inbreeding some species have even evolved inbreeding avoidance mechanisms. Additionally, inbreeding can have varying impacts on survival depending on population density (as seen in Soay sheep). 

In terms of the phenotypic distribution for the water snakes, it makes sense that Ontario has a high striped frequency because mainland snakes typically look like this to blend in with leaf litter in forest streams. For Kelley's island you have the highest frequencies of reduced striping rather than stripe-less. I think this is because this island is still fairly near Ohio which is a mainland where striped snakes could have come from. So there is still adaptation as well as some flexibility depending on location going on. The Middle and Pelee islands are the furthest away from any mainland and therefore most likely have more interaction with species directly from the surrounding islands. So it makes sense that they have the highest frequency of A (gray color) because it would be adaptive and favorable to blend in with rocks in that location. Migration can introduce new genetic variation to places. Part of a population migrating elsewhere can change allele frequencies in both locations. If speckled lizards from a diverse lizard population happened to migrate leaving behind their solid colored friends, then that newly colonized place is going to have a greater frequency of alleles that lend a speckled phenotype. Introducing a set of alleles to a new environment can also lead to adaptation and natural selection depending on the conditions of the new place.