W8

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American Public University *

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133

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Anthropology

Date

Oct 30, 2023

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docx

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Uploaded by natthy

Part A Three C's (Content, Concern, Connection) The impact of the parasitoid fly, Ormia ochracea, on the evolution of the cricket population was intriguing, particularly how it led to the dominance of flatwing, silent males as an adaptive response. It was fascinating seeing how a specific predator could make such a drastic difference in the behavior and characteristics of the crickets. After reviewing this case study, one question I have is what will be the long-term effects of the changes in the cricket's population due to the parasitoid fly? I am curious to see the flatwing, silent males' effect on the ecosystem's overall dynamics and other interconnected species in the long run. This case study highlights the relationship between predator-prey interactions and evolutionary adaptation, focusing attention on the delicate balance within ecosystems. It emphasizes the significance of understanding the complex dynamics within an ecosystem, where the presence of a single species can have far-reaching influence for the entire community. Part B Part I: question 1 One difference between the typical male and the flatwing male is the outline in the wings. The typical male wing has a harp and mirror needed to create the cricket songs whereas the typical male does not. They also differ in size, the flatwing male is larger in all aspect from antennas to leg size. Being that the flatwing male doesn’t have the same wing anatomy as the typical male, this leaves the flatwing male with no call or song. Part I: question 2 One of the possibilities for the population of crickets’ wings to change so dramatically is where they fall on the food chain. In a study from Berkely university of California there's an article on “quick evolution leads to quiet crickets,” where they explain perfectly how the cricket's possibility mutated. Flies are attracted to the chirping of a calling cricket, leading to droppings of maggots onto the crickets back. The maggots burrow into the cricket and appear a week later killing the cricket. Later, biologists Marlene Zuk, John Rotenberry, and Robin Tinghitella discovered that in just a few years the crickets have evolved a strategy to avoid being a maggot. The evolution would come down to change in a single mutation affecting the wing shape in male cricket. We can then tell that the mutual male aka the flatwing male, have wings more like those of a female who cannot chirp to attract mates. This study was based in Hawaiian island of Kauai, where the offspring of a fly, Ormia ochracea, invaded Hawaii from Northen America.

Another possibility for the population of the crickets' wing to change is climate change. Climate change often leads to an increase in the frequency and intensity of extreme weather events. These events can directly impact the habitat and food availability, potentially influencing their evolutionary pathways including changing their wings. References: https://evolution.berkeley.edu/evo-news/quick-evolution-leads-to-quiet-crickets/ https://www.kcur.org/2023-07-21/heat-crickets-chirp-hot-high-temperatures https://www.kcur.org/2023-07-21/heat-crickets-chirp-hot-high-temperatures Part I: question3 Evolution is often defined as a change in a population’s genetic composition over time. Is this, therefore, an example of evolution? Or do we need additional information to decide? Why or why not. Being that evolution is often defined as a change in populations genetic composition, I do believe this would be an example of evolution. For the flies not to be attracted to the crickets, the mutant wing needed to be created to avoid the attraction of the flies; the typical male genetic structure. Part II: 4A and 4B The male crickets lost the ability to make calls or songs because of the parasitoid fly, Ormia ochracea. The typical male would produce the mating calls making them more vulnerable to being located by the fly. Due to this, the flatwing has an advantage to surviving because they're less likely to attract the attention of parasitoid flies. The absence of the mating call reduced the risk of parasitic infestation and subsequent death, promoting the survival. This can also help with reproductivity of the silent males within the population. The target on typical males from the parasitoid fly creates favor for the flatwing males in the population. The parasitoid fly would locate the cricket through the sound of their call leading to increased death in the typical male. As a result, male crickets with mutations lead to reduced or no callings having a survival advantage. Over time, more crickets stopped singing, and the silent ones became more common. This happened because being silent helped them stay away from the fly and increase the survival rate. Part III: question 6 Based on the framework for natural selection, it is expected that the survival rate for crickets would decrease if there had never been variation in the wing shape. Part III: question 9

In a different study, Dr. Zuk and colleagues investigated mating requirements in the female Hawaiian T. oceanicus cricket populations. They found that the females did prefer normal, stridulating males compared to a silent male. However, unlike female crickets from other Pacific Island populations of this same species, they would still mate with a silent male about 50% of the time. This information is important because it shows that while female crickets generally prefer the mating sound, they were still willing to mate with the silent males, flatwing male. This suggest that even though the flatwing male became common, it didn’t take away completely from the mating process. This can suggest that other factors might have contributed to the spread of the flatwing male in the population. Part VI: question 11-part A&B Males with the new purring call might be more attractive to females for mating compared to silent, flatwing males. By producing a unique mating call, these males could have an increased chance of reproduction, thereby improving their overall fitness in the population. Males with the new purring call might be more appealing to females compared to males with the ancestral call, potentially leading to increased mating success and higher reproductive fitness. If the purring call is better acclimated to the current environmental conditions, males with the new call could experience increased mates and higher reproductive fitness compared to those with the older call. This could result in the spread of the purring trait over time within the community. Part VI: questions 12-part A&B Based on the earlier response, we can predict that female crickets would be most attracted to the purring call, followed by the ancestral call, and then show the least response to the white noise. Thus, in the study, we would expect to collect data showing a higher rate of female cricket approach or mating behavior toward the speakers playing the purring call, a moderate response to the ancestral call, and minimal to no response to the white noise. According to the earlier explanation, we can predict that O. ochracea parasitoid flies would be least attracted to the purring call, followed by the ancestral call, and most attracted to the white noise. Therefore, the data from the study should indicate a lower rate of approach or attraction to the speakers playing the purring call, a moderate response to the ancestral call, and a higher rate of approach or attraction to the white noise.

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