Allison's evolution blog

. I decided to research strokes to see investigate how lifestyle is associated with a rise in stroke cases. I am interested in researching strokes specifically because I am currently reading a book called My Stroke Of Insight, and I find strokes to be very intriguing. A stroke is a what occurs when the blood supply to part of the brain interrupted or reduced, which then prevents the brain from getting oxygen and nutrients. When stroke occurs brain cells begin to quickly die, and getting medical attention fast is the most important thing for the best stroke outcome. From my research, I have learned that there are many causes that can increase your risk of stroke from lifestyle choices one may make.  One of the major causes of stroke is an unhealthy diet. A diet high in cholesterol, sodium, processed foods, sugar, and not enough fresh fruits. and vegetables are all things that will increase risk of stroke. Being overweight/obese also greatly increases yo...

This weeks blog is all about species and the rate at which species evolve. The term species is a basic evolutionary unit.  It takes different amounts of time for a new species to form, and the speed is different for each type of species. I think that the speed of speciation does vary among different modes of speciation. Reproductive isolation tends to be a gradual process that occurs along the gradient. Reproductive isolation has multiple different mechanisms of how species evolve. The different mechanisms include pre-mating isolation, post-mating isolation/pre-zygotic isolation, and post-zygotic isolation.  The Pre-mating isolation has reproductive barriers such as members from different populations not meeting, they are not compatible for mating, or they do not recognize each other. Post mating has reproductive barriers that could come from sperm competition, cryptic female choice, or gametic incompatibilities. Post-Zygotic isolation mechanisms could come from reduced hybrid...

I believe this courtship of females courting males may have evolved to be this way because females may have been getting too  seriously injured during mating, resulting in no or very few offspring being produced. This would cause fitness levels to be very low for males and females. in turn, the fish may have adapted better ways to reproduce without the females being injured during an aggressive mating process. Pipefish are an example of a species where the female courts the male. This means that the roles are also reversed for males and females when it comes to attracting mates. Females are attracted to larger males in order to carry their offspring, and females do a dance to attract the males to choose them.  I do not think my hypothesis completely aligns with why females court males in the pipefish population. From the reading I have done, it seems that the females court the males because the males have pouches which allows the offspring be...

An organism that I have always been fascinated by is the great white shark. Don't get it twisted though, while I am fascinated I have always been scared of having an encounter when in the ocean. I have always been fascinated by these amazing creatures because of their size and power. Great white sharks usually grow to be an average of 15 feet long and 2.5 tons or greater. The really big great whites can even grow to be as long as 20 feet!! That's insane. Great white sharks mouths are lined with 300 serated, triangular teeth which are lined up in several rows. They even have organs that can detect electromagnetic fields generated by animals. Great white sharks have some amazing adaptations as well. Great whites boys have adapted into a torpedo shape in order to reduce the drag in the water. Great whites also have a fairly symmetrical body, and this is thought to allow them to move through what at a more efficient rate. Sources: https://oceantracks.org/library/spe...

Selection is often assumed to eliminate genetic variation. So, why is genetic variation then not eroded over time? Genetic variation has not eroded over time because there are many different factors that affect it other than selection. We have learned about a lot of different ways that genetic variation is maintained in class from the past few modules. For example, quantitative traits which are controlled by multiple traits and the environment. Not all quantitative traits are normally distributed because one trait may be dominant and the other may not be. Another factor that affects genetic variation is drift. If there is strong genetic drift, this will lead to small populations, and this swamps out selection. Genetic drift is very different than selection because it does not lead to adaptation unlike selection which increases the average fitness across populations. There is also a major difference in the selection on dominant vs. Recessive traits. Dominant alleles reap advantages righ...

So far I have learned so much in evolution class, and I have also really enjoyed the layout of this class. I have learned that I really enjoy the discussions in small groups because it helps me to better understand the topics.   I went back to my first blog post where I defined evolution, and I said that "evolution as a change over time in a species". I went into more details with what this meant to me and gave examples as well. Since the post, I have learned so much more about what evolution is and I would change my initial response by adding more details of other factors involved in evolution. I learned that the modern perception in evolution takes more factors into consideration such as how important the environment is to causing differences in fitness. The differences in fitness can then lead to change in the generations to follow. I would also add in that mutation is the main cause of variation that can cause evolutionary change. Evolution can be very small or very large...