Parasites: Site Selection Process

Parasites have evolved in a very specific and selective way throughout generations. Specific parasites have specific factors that influence their site selection process and that work in favor for the parasites. One important component that influences the parasite to become site specific is being host specific, which in turn affects the ability of extracting resources. The more efficient it is in extracting resources the better the chance of reproducing, which then increases the fitness of the parasite. Fitness plays a huge role in determining how successful the parasite may be. Few other factors that contribute to the site selection process are transmission, survival and reproduction. Since the parasites are in a very predictable environment
As the parasite becomes host specific it allows the parasite to have morphological changes that will aid in the extraction of resources from the host. “ It has often been notes that the site selection process often has a connection with the biology of the parasite. We can often relate to this by looking at the strigeoid tremaatodes and the specific sites they tend to occupy in the fish” (Matisz 2010). In order to further test the site selection process a group of research tried to infect different types of fish with metacercariea and see how long it would take them to actually get to the brain. After monitoring the fish and the metacercarie for 24 hours, they were able to confirm that they migrated to specific places in the brain via spinal cord and then cranial nerves. More specifically they were able to find a lot of the metacercaire in the optic lobe of the fish via an electronic microscope. However, the bigger question is why would the parasites participate in such migration and what benefits does this give the parasite. The major answer behind this phenomenon tends to be the idea of fixed action patterns. “Certain stimuli often offer fairly predictable condition within an environment”(sukhdeo 1997). These predictable behaviors often become fixed over time and offer a huge fitness advantage. Due to the genetically fixed patterns, parasites have become site specific. This
One factor that is commonly not taken into consideration when talking about site specificity and the behavior of the parasite is the parasites perspective. A few factors that can affect behavior of the parasite can be age of infection, immune response, increase in size of parasite population or simply a change in the host diet. A lot of the times it is thought that parasites take a certain pathway that lead to their specific site, and it is often misunderstood for that fact that they have two different paths to choose and they end up taking one that becomes fixed. However, there is more involved in this than just simply making a decision. It can be the environment made the parasite choose that path or because it there was a higher reproductive success in that specific path. I believe there is a lot more involved in the path that parasites take. Furthermore, a important concepts that need to be taken into consideration when talking about reproductive success is specific trade off the parasite has to give. Although the parasite wants to produce more eggs, there is often more pathology also involved with the bigger body. Due to these specific tradeoff that are involved with the increased fitness of the parasite there may be more involved with the specific site and behavior of the parasite. Next, when it comes to choosing the specific resources within