Evolution Spring 2021

For this blog, I have chose diabetes. Diabetes is prevalent all across the United States and its numbers are... alarming.  Sure, Type 1 Diabetes in unavoidable and is not contributed to lifestyle. But, Type 2 Diabetes (T2D) is another story.  We see T2D on the rise here in America and world-wide, actually. This can be due to an increased sedentary lifestyle, as well as the nutrition habits of the patient. In Asians, we see an increase in T2D if they consume excessive amounts of carbohydrates and/or have very little physical activity (Hu, 2001).  In this 2004 article, Klein and colleagues touch on the fact that BMI has an incredible impact on the likelihood of developing T2D. A patient with a BMI of greater than 35 is twenty times more likely to develop T2D (Klein et al., 2004). Cue the head-exploding emoji. That is just WILD. How to people develop a BMI over 35? Well, fast food, soda, junk food, and everything unhealthy that is advertised online and in stores. American's ...

All through my schooling, I have thought that it take so long for a new species to form. I mean, from Darwin's ideas on speciation, he pointed out that it is a long, drawn out process in order for speciation to occur. But, I don't think that's the full story here. We can see reproductive isolation in environments that are spatially separated (Hendry et al., 2007). This 2007 article examines the speed of speciation in relation to contemporary evolution and ecological speciation. This article aims to show the reader that speciation can occur in 100 generations or less (which is relatively fast!). This article also points out that speciation is a  process , not an endpoint (Hendry et al., 2007). Darwin also addressed this. But what most scientists classify as speciation is reproductive isolation, a.k.a the lack of interbreeding.  I believe this lack of interbreeding can occur very quickly, unlike what Darwin postulated. In this 2007 article, they point out that  Helianthus a...

We can see in the pipefish example that the female has striking colors, helping her to court the male. Normally, we see the male exhibiting these fancy displays in order to attract the females. This is because the females have eggs, which are seen as far more valuable than what the male has to offer. The most obvious example I can think of is peacocks and their exuberant fans. This female pipefish is displaying her coloring in order to attract a rather boring-looking male, which is extremely unique.  In Microphis deocata (pipefish), it is actually the male that carries the fertilized egg, not the female. This could explain why the female is required to have such a display; she needs to attract a male that will carry the fertilized egg for her. The males, in this case, have more value than the females. Therefore, they are sought after by females. My hypothesis is that female courtship arose due to the fact that the females in this species need a male to carry the fertilized offsprin...

This blog post is allowing me to dig deep into my current and past knowledge of evolutionary forces. Looking back on what I have learned so far, I can apply some concepts to this question of why genetic variation is not eroded over time due to selection.  Although selection may eliminate genetic variation, we will still see mutations occurs in an organisms genome. Just because selection eliminates some, doesn't mean more won't arise. This can be due to environmental factors, or simply mistakes made during DNA replication. A wide array of things can cause genetic variation, so just because selection "eliminates" the variation, is not to say that it will not continue to occur through these processes.  We can also see that selection is not the only force that acts on genetic variation. Say selection did eliminate variation, we will can still see gene flow and genetic drift occur and introduce variation into individuals and therefore the population. Selection is not alway...

The neutral theory of evolution states that evolutionary changes at the molecular level are due to random genetic drift of selectively neutral nucleotide substitutions (Tong, Ranganathan, 2013). The mutations that occur under the neutral theory are the result of genetic drift. We can see these mutations become fixed over many, many generations. Although they are neutral mutations, they are able to be fixed due to genetic drift. Kimura's theory really differs from the original theory of natural selection due to the fact that Kimura's theory emphasized that these are random mutations. We also do not see much about fitness or environmental influences in Kimura's theory of neutral evolution. I believe that this basically contradicts the whole theory of evolution by natural selection, where the most fit individuals survive and reproduce as a result of having advantageous genes. The key differences are that Kimura's theory relies on random genetic mutations and lack of select...

What are some benefits of inbreeding that may lead to the evolution of assortative mating? What are some of the costs of inbreeding that may have prompted to evolution of inbreeding avoidance (disassortative mating)? Inbreeding can be seen in a few species, such as Mangrove Killfish, some plants, and endangered species. Inbreeding can lead to assortative mating, where individuals with similar genotypes mate to produce offspring. I could see this as being potentially beneficial if the traits that the individuals have are favorable, and allow the species to survive and thrive in the environment they're in. Assortative mating can evolve as more and more individuals are produced from inbreeding, therefore the offspring simply do not have anyone else to mate with, since all the possible mates have similar genotypes. We can see inbreeding in endangered species, which in turn could continue to produce that species and help fight endangerment. But, it's not a given that these offspring...