Matching Items (4)
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- All Subjects: Evolution & development
- Creators: Cohen, Adam B.
- Creators: Collins, James P.
Description
During the 1960s, the long-standing idea that traits or behaviors could be
explained by natural selection acting on traits that persisted "for the good of the group" prompted a series of debates about group-level selection and the effectiveness with which natural selection could act at or across multiple levels of biological organization. For some this topic remains contentious, while others consider the debate settled, even while disagreeing about when and how resolution occurred, raising the question: "Why have these debates continued?"
Here I explore the biology, history, and philosophy of the possibility of natural selection operating at levels of biological organization other than the organism by focusing on debates about group-level selection that have occurred since the 1960s. In particular, I use experimental, historical, and synthetic methods to review how the debates have changed, and whether different uses of the same words and concepts can lead to different interpretations of the same experimental data.
I begin with the results of a group-selection experiment I conducted using the parasitoid wasp Nasonia, and discuss how the interpretation depends on how one conceives of and defines a "group." Then I review the history of the group selection controversy and argue that this history is best interpreted as multiple, interrelated debates rather than a single continuous debate. Furthermore, I show how the aspects of these debates that have changed the most are related to theoretical content and empirical data, while disputes related to methods remain largely unchanged. Synthesizing this material, I distinguish four different "approaches" to the study of multilevel selection based on the questions and methods used by researchers, and I use the results of the Nasonia experiment to discuss how each approach can lead to different interpretations of the same experimental data. I argue that this realization can help to explain why debates about group and multilevel selection have persisted for nearly sixty years. Finally, the conclusions of this dissertation apply beyond evolutionary biology by providing an illustration of how key concepts can change over time, and how failing to appreciate this fact can lead to ongoing controversy within a scientific field.
explained by natural selection acting on traits that persisted "for the good of the group" prompted a series of debates about group-level selection and the effectiveness with which natural selection could act at or across multiple levels of biological organization. For some this topic remains contentious, while others consider the debate settled, even while disagreeing about when and how resolution occurred, raising the question: "Why have these debates continued?"
Here I explore the biology, history, and philosophy of the possibility of natural selection operating at levels of biological organization other than the organism by focusing on debates about group-level selection that have occurred since the 1960s. In particular, I use experimental, historical, and synthetic methods to review how the debates have changed, and whether different uses of the same words and concepts can lead to different interpretations of the same experimental data.
I begin with the results of a group-selection experiment I conducted using the parasitoid wasp Nasonia, and discuss how the interpretation depends on how one conceives of and defines a "group." Then I review the history of the group selection controversy and argue that this history is best interpreted as multiple, interrelated debates rather than a single continuous debate. Furthermore, I show how the aspects of these debates that have changed the most are related to theoretical content and empirical data, while disputes related to methods remain largely unchanged. Synthesizing this material, I distinguish four different "approaches" to the study of multilevel selection based on the questions and methods used by researchers, and I use the results of the Nasonia experiment to discuss how each approach can lead to different interpretations of the same experimental data. I argue that this realization can help to explain why debates about group and multilevel selection have persisted for nearly sixty years. Finally, the conclusions of this dissertation apply beyond evolutionary biology by providing an illustration of how key concepts can change over time, and how failing to appreciate this fact can lead to ongoing controversy within a scientific field.
ContributorsDimond, Christopher C (Author) / Collins, James P. (Thesis advisor) / Gadau, Juergen (Committee member) / Laubichler, Manfred (Committee member) / Armendt, Brad (Committee member) / Lynch, John (Committee member) / Arizona State University (Publisher)
Created2014
Description
Infectious diseases have been a major threat to survival throughout human history. Humans have developed a behavioral immune system to prevent infection by causing individuals to avoid people, food, and objects that could be contaminated. This current project investigates how ambient temperature affects the activation of this system. Because temperature is positively correlated with the prevalence of many deadly diseases, I predict that temperature moderates the behavioral immune system, such that a disease prime will have a stronger effect in a hot environment compared to a neutral environment and one's avoidant behaviors will be more extreme. Participants were placed in a hot room (M = 85F) or a neutral room (M = 77F) and shown a disease prime slide show or a neutral slide show. Disgust sensitivity and perceived vulnerability surveys were used to measure an increased perceived risk to disease. A taste test between a disgusting food item (gummy bugs) and a neutral food item (gummy animals) measured food avoidance. There was no significant avoidance of the gummy and no significant difference in ratings of disgust sensitivity or perceived vulnerability as a function of temperature conditions. There were no significant interactions between temperature and disease. The conclusion is that this study did not provide evidence that temperature moderates the effect of disease cues on behavior.
ContributorsOsborne, Elizabeth (Author) / Cohen, Adam B. (Thesis advisor) / Kwan, Sau (Committee member) / Neuberg, Steven (Committee member) / Arizona State University (Publisher)
Created2012
Description
Primary production in aquatic ecosystems is often limited by the availability of nitrogen (N) and/or phosphorus (P). Animals can substantially alter the relative availability of these nutrients by storing and recycling them in differential ratios. Variation in these stoichiometric traits, i.e., the elemental phenotype, within a species can link organismal evolution to ecosystem function. I examined the drivers of intraspecific variation in the elemental phenotype of aquatic consumers to test for the generality of these effects. Over a thermal gradient in Panamá, I found that average specific growth grate and body P content of the mayfly Thraulodes increased with environmental temperature, but that these patterns were due to site-specific differences rather than the direct effects of warmer temperature. In a meta-analysis of published studies, I found that in fishes intraspecific variation in dietary N:P ratio had a significant effect on excretion N:P ratio, but only when accounting for consumption. I tested for the effects of variation in consumption on excretion N:P ratio among populations of the fish Gambusia marshi in the Cuatro Ciénegas basin in Coahuila, Mexico. G. marshi inhabits warm groundwater-fed springs where it often co-occurs with predatory fishes and cool runoff-dominated wetlands which lack predators. Using stoichiometric models, I generated predictions for how variation in environmental temperature and predation pressure would affect the N:P ratio recycled by fishes. Adult female G. marshi excretion N:P ratio was higher in runoff-dominated sites, which was consistent with predators driving increased consumption rates by G. marshi. This result was supported by a diet ration manipulation experiment in which G. marshi raised on an ad libitum diet excreted N:P at a lower ratio than fish raised on a restricted diet ration. To further support the impacts of predation on phenotypic diversification in G. marshi, I examined how body morphology varied among habitats and among closely related species. Both among and within species, predation had stronger effects on morphology than the physical environment. Overall, these results suggest that predation, not temperature, has strong effects on these phenotypic traits of aquatic consumers which can alter their role in ecosystem nutrient cycling through variation in consumption rates.
ContributorsMoody, Eric Kellan (Author) / Elser, James J (Thesis advisor) / Sabo, John L (Thesis advisor) / Angilletta, Michael J (Committee member) / Capps, Krista A (Committee member) / Collins, James P. (Committee member) / Arizona State University (Publisher)
Created2017
Description
The present study tested the hypothesis that women dress modestly to signal to other women that they pose no mate poaching threat and are sexually restricted, and that this is especially true for religious women. Participants were 392 Muslim women living in the United States. They read two passages describing fictional situations in which they met with a potential female friend and then indicated what kind of outfit they would wear in both situations. In one situation, the participant obtained a reputation for promiscuity; in the other situation, reputation was not mentioned. I predicted that participants would choose more modest outfits for the promiscuous reputation passage, because if women dress modestly to signal sexual restrictedness, then they should dress more modestly around women with whom they have a reputation for promiscuity—to counteract such a reputation, women may wish to send a strong signal that they are not promiscuous. The hypothesis was partially supported: Less religious women chose more modest outfits for the promiscuous reputation situation than they did for the no reputation situation. This suggests that some women dress modestly to signal sexual restrictedness to other women, but that this is especially true for women who are less religious, not more. More religious women dress more modestly than less religious women, but they may not dress modestly to signal sexual restrictedness. Two important goals for this area of research are to determine the proximate reasons that more religious women dress modestly and to investigate modest dress among non-Muslim religious women.
ContributorsNorthover, Stefanie Blair (Author) / Cohen, Adam B. (Thesis advisor) / Neuberg, Steven L. (Committee member) / Kenrick, Douglas T. (Committee member) / Lieberman, Debra (Committee member) / Arizona State University (Publisher)
Created2020