Muscles Serve as a Water Source for Egg Development in Children's Pythons (Antaresia childreni)

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Description
Water-balance is a critical but understudied consideration for animals reproducing in dry environments, as females invest a significant amount of water into their offspring. What makes water especially challenging, is that few animals are known to have true water storage,

Water-balance is a critical but understudied consideration for animals reproducing in dry environments, as females invest a significant amount of water into their offspring. What makes water especially challenging, is that few animals are known to have true water storage, whereas energy as fat storage is well-documented. Recent studies have suggested the possibility that, when drinking water is scarce, animals can catabolize their muscles, thereby extracting cellular water. In this study, the aim was to show this as a potential method used by animals reproducing in dry environments to cope with dehydration and still produce a clutch. Children's pythons (Antaresia childreni) were used to investigate this phenomenon due to the fact that they experience two, distinctive, reproductive phases- vitellogenesis (when protein and energy are mobilized and invested into the yolk) and gravidity (when the major water investment into the egg occurs, as well as egg shelling). Other factors that make them excellent candidates are that they are pure capital breeders (don't eat during the reproductive season) and can withstand periods of water deprivation that far outlast their reproductive gravid phase. Reproductive and non-reproductive females were deprived of water for the duration of gravidity, and their mass decrease, epaxial muscle shrinkage, blood osmolality, total protein, uric acid, triglycerides and ketones were measured at the onset of each reproductive stage; these values were compared to their water-provided counterparts. Water-deprived females experienced greater mass loss, epaxial muscle loss, blood plasma osmolality, and uric acid than water-provided females. These findings suggest that muscle catabolism is used as a method of dealing with water-deprivation during gravidity.
Date Created
2018-05
Agent

Flight Performance Under Temperature Extremes of Thermally Evolved Drosophila Melanogaster

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Description
Species survive by adapting to what is demanded by their environment. In constant and fluctuating environments, specialist and generalists should be favored, respectively. However, the costs and benefits of adaptation can depend on a variety of factors that alter the

Species survive by adapting to what is demanded by their environment. In constant and fluctuating environments, specialist and generalists should be favored, respectively. However, the costs and benefits of adaptation can depend on a variety of factors that alter the intensity of the specialist-generalist trade-off. We examined flight performance to determine how well flies that evolved in constant and fluctuating temperatures acclimated to hot and cold temperatures. We predicted that flies would perform best at temperatures most similar to the ones the flies evolved at. Best performance was found when rearing and testing temperatures aligned with the temperature at which a genotype had evolved, with the generalist sharing the best and worst performance combination with the constant thermally evolved flies. Interestingly, evolved and reared temperatures had equal impact on flight performance. It was also observed that rearing at 25°C resulted in flies with the best fitness. These results contribute to the specialist-generalist theory and the idea that long term cold development is restricting in terms of range for thermal performance.
Date Created
2016-05
Agent

Flight performance and thermal tolerance of flies acclimated to hypoxia or hyperoxia

Description
Animals are thought to die at high temperatures because proteins and cell membranes lose their structural integrity. Alternatively, a newer hypothesis (the oxygen and capacity limitation of thermal tolerance, or OCLTT) states that death occurs because oxygen supply becomes limited

Animals are thought to die at high temperatures because proteins and cell membranes lose their structural integrity. Alternatively, a newer hypothesis (the oxygen and capacity limitation of thermal tolerance, or OCLTT) states that death occurs because oxygen supply becomes limited at high temperatures. Consequently, animals exposed to hypoxia are more sensitive to heating than those exposed to normoxia or hyperoxia. We hypothesized that animals raised in hypoxia would acclimate to the low oxygen supply, thereby making them less sensitive to heating. Such acclimation would be expressed as greater heat tolerance and better flight performance in individuals raised at lower oxygen concentrations. We raised flies (Drosophila melanogaster) from eggs to adults under oxygen concentrations ranging from 10% to 31% and measured two aspects of thermal tolerance: 1) the time required for flies to lose motor function at 39.5°C at normoxia (21%), referred to as knock-down time, and 2) flight performance at 37°, 39°, or 41°C and 12%, 21%, or 31% oxygen. Contrary to our prediction, flies from all treatments had the same knock-down time. However, flight performance at hypoxia was greatest for flies raised in hypoxia, but flight performance at normoxia and hyperoxia was greatest for flies raised at hyperoxia. Thus, flight performance acclimated to oxygen supply during development, but heat tolerance did not. Our data does not support the OCLTT hypothesis, but instead supports the beneficial acclimation hypothesis, which proposes that acclimation improves the function of an organism during environmental change.
Date Created
2016-05
Agent

Testing Rational Choice Theory through Arizona's "Move Over Law"

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Description
States nationwide have implemented "Move Over Laws" to try and increase roadway safety, yet even with these laws, hundreds of people are killed each year while working in and roadways. In Arizona, the "Move Over Law" requires drivers approaching a

States nationwide have implemented "Move Over Laws" to try and increase roadway safety, yet even with these laws, hundreds of people are killed each year while working in and roadways. In Arizona, the "Move Over Law" requires drivers approaching a stopped vehicle displaying flashing lights to "move over" or "slow down." However, not everyone complies with this enacted law, and the purpose of this study is to observe how approaching drivers behave when presented with various scenarios. Scenarios involved the use of different police car types (marked or unmarked), light displays (no lights, hazards, or emergency lights), and the advertisement of Arizona's "Move Over Law" (signboard or no signboard). Associated risk varied with each scenario, and according to rational choice theory, a driver's behavior should minimize risks and maximize benefits. Under the hypothesis that police presence impacts driving behavior, the expectation was that driver compliance through "moving over" and/or slowing down would be highest when a marked police car or emergency lights were used. Also hypothesized was that awareness impacts compliance with the thought that increasing awareness by using a signboard would increase "move over" percentages and decrease speeds. From the test site along State Highway 260 in Payson, Arizona, the results indicate that car type and light display impact driving behavior. The use of the marked car or emergency lights generally had higher adjusted compliance, higher "move over" percentages, and lower speeds than when the unmarked car or no lights were tested. Looking at how awareness influences behavior, the use of the signboard had a greater impact when the unmarked car was used as opposed to the marked car. Based on the results, both hypotheses were supported.
Date Created
2017-05
Agent

The use of heart rate to estimate metabolic rate in the early embryonic stages of the Eastern Fence Lizard, Sceloporus undulates

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Description
There are numerous strategies for determining an organism's metabolic rate, one of which is the heart rate method. The heart rate method is based on a relationship between an organism's heart rate and its oxygen consumption (V(O2)). Although validations of

There are numerous strategies for determining an organism's metabolic rate, one of which is the heart rate method. The heart rate method is based on a relationship between an organism's heart rate and its oxygen consumption (V(O2)). Although validations of the heart rate method have focused on adult animals, researchers could benefit from applying this method to embryonic animals. In this study, the heart rate's reliability as an indicator of oxygen consumption in early stage embryos of reptiles (or more specifically, lizards) is evaluated. The focus is primarily on the earliest stages of cardiovascular detection. The results suggest that while it may be possible to use a reliable heart rate method to find an accurate value for oxygen consumption of a group of early embryos in lizards if the oxygen pulse can be accurately identified, it is more likely that in the earliest stages of cardiovascular development, the heart rate cannot serve as a reliable indicator of V(O2) because it may not be the primary manner in which oxygen is distributed in Sceloporus undulatus.
Date Created
2013-05
Agent

Listing the American Pika (Ochotona princeps): The role of science in a political world

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Description
In 2007, the Center for Biological Diversity (CBD) petitioned the United States Fish and Wildlife Service (USFWS) and the California Department of Fish and Wildlife (CDFW) to list the American pika (Ochotona princeps) as an endangered species. After several petition

In 2007, the Center for Biological Diversity (CBD) petitioned the United States Fish and Wildlife Service (USFWS) and the California Department of Fish and Wildlife (CDFW) to list the American pika (Ochotona princeps) as an endangered species. After several petition denials, the petition was evaluated during both 90-day, and 12-month reviews. Ultimately, both petitions were denied and the pika was not given protection under the Endangered Species Act (ESA). During the petitioning years, 2007 through 2013, there were many newspaper publications, press releases, and blog entries supporting the listing of the pika. Information published by these media ranged from misleading, to scientifically inaccurate. The public was swayed by these publications, and showed their support for listing the pika during the public comment period throughout the 12-month status review in California. While the majority of the public comments were in favor of listing the pika, there were a few letters that criticized the CBD for making a poster child out of a "cute" species. During the 12-month status review, the CDFW contacted pika experts and evaluated scientific literature to gain an understanding of the American pika's status. Seven years after the original petition, the CDFW denied listing the pika on the grounds that the species is not expected to become extinct in the next few decades. This case serves as an example where a prominent organization, the CBD, petitions to list a species that does not warrant protection. Their goal of making the pika the face of climate change failed when species was examined.
Date Created
2014-05
Agent

Cold populations of flies evolved larger bodies and larger wings made of larger cells

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Description
We examined the evolutionary morphological responses of Drosophila melanogaster that had evolved at constant cold (16°), constant hot (25°C), and fluctuating (16° and 25°C). Flies that were exposed to the constant low mean temperature developed larger thorax, wing, and cell

We examined the evolutionary morphological responses of Drosophila melanogaster that had evolved at constant cold (16°), constant hot (25°C), and fluctuating (16° and 25°C). Flies that were exposed to the constant low mean temperature developed larger thorax, wing, and cell sizes than those exposed to constant high mean temperatures. Males and females both responded similarly to thermal treatments in average wing and cell size. The resulting cell area for a given wing size in thermal fluctuating populations remains unclear and remains a subject for future research.
Date Created
2015-05
Agent

Handling the Heat: Plasticity of an Arthropod Pest in Response to the Urban Heat Island

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Description
In recent years, ecologists have begun to study the effects of urbanization on species diversity. While urban areas generally suffer decreased biodiversity, some species, termed “urban exploiters”, not only live in the city but depend on urban resources to thrive.

In recent years, ecologists have begun to study the effects of urbanization on species diversity. While urban areas generally suffer decreased biodiversity, some species, termed “urban exploiters”, not only live in the city but depend on urban resources to thrive. It is hypothesized that urban exploiters may succeed in part due to phenotypic plasticity, in which organisms rapidly adjust their physiology or behavior to adapt to novel environmental contexts. In the city, it may be adaptive to display thermal plasticity, as the urban heat island effect caused by concrete and asphalt infrastructure prevents cooling at night. In this study, we observed the decorated cricket Gryllodes sigillatus, an invasive urban exploiter found in metropolitan Phoenix, in two separate experiments. We hypothesized that heat tolerance and activity are both plastic traits in this species. In Experiment 1, we predicted that knock-down time, a measure of heat tolerance, would be negatively affected by acclimation to a laboratory environment. Our results suggest that heat tolerance is affected by recent thermal regimes and that laboratory acclimation decreases knock-down time. In Experiment 2, we predicted that activity would increase with temperature until a point of extreme heat, at which point activity would decline. Statistical analysis for the second experiment reveals that activity decreases at 33°C, a natural urban extreme. This suggests either that 33°C is a thermal limit to physiology or that G. sigillatus is able to alter its behavior to exploit local thermal heterogeneity.
Date Created
2015-05
Agent

The True Costs of Theft: An Evolutionary Psychology Study of Stealing Among Male ASU Students

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Description
Regular instances of employee and petty theft seem to suggest that stealing is common. Certain situations make stealing an advantageous opportunity, and studies show that most people will steal under the right conditions. However, these "right conditions" vary widely among

Regular instances of employee and petty theft seem to suggest that stealing is common. Certain situations make stealing an advantageous opportunity, and studies show that most people will steal under the right conditions. However, these "right conditions" vary widely among individuals and are a combination of biological, social, psychological, and situational factors. In an attempt to better understand the rationality of stealing, our research team applied evolutionary psychology principles to a social experiment involving gift card theft. To find trends in how people will steal when given the opportunity, we attempted to create these "right conditions" (which we believed would encourage theft by minimizing cost) so that we could measure how a random sample of subjects (male students on the Tempe campus of Arizona State University) responded to variation in benefit. We predicted that if the cost was kept low, and if some gift cards conferred greater advantages than others (by possession greater value or utility), then the more advantageous gift cards would be stolen at a higher frequency from the sample pool than less advantageous ones. The results show that our assumptions were wrong. Theft almost never occurred and the few cards that were stolen were not the more "rational" choices as predicted. The experimental design indicates a flawed understanding of how the subjects weighed the benefits and costs of stealing gift cards. One major issue is that we failed to consider pro-social behavior as the norm. We also neglected the evolutionary benefits of cooperative behavior while overemphasizing the evolutionary benefits of theft. A more thorough and nuanced examination of the literature must be performed to avoid these fundamental flaws in the experiment in the future. The experiment also suffered from issues which might have inadvertently discouraged theft including the location, population, presence of other students, and time given to contemplate theft. If we wish to truly examine trends in theft to see if there is a trend towards the rational theft model we proposed, we must work with a population in which individuals already have a propensity to steal, the benefit is sufficiently high, and social pressures to be cooperative are low.
Date Created
2015-05
Agent

An Examination of Citrate Synthase Activity in Experimentally Evolved Drosophila melanogaster

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Description
Three populations of experimentally evolved Drosophila melanogaster populations made up of high temperature (H, constant 25 ᵒC), low temperature (C, constant 16 ᵒC) and temporal homogeneity (T, environment changes between 16 ᵒC and 25 ᵒC) were prepared and assayed to

Three populations of experimentally evolved Drosophila melanogaster populations made up of high temperature (H, constant 25 ᵒC), low temperature (C, constant 16 ᵒC) and temporal homogeneity (T, environment changes between 16 ᵒC and 25 ᵒC) were prepared and assayed to determine difference in citrate synthase activity. Between the three groups, the results were inconclusive: the resulting reaction rates in units of nmol min-1mgfly-1 were 81.8 + 20.6, 101 + 15.6, and 96.9 + 25.2 for the hot (H), cold (C), and temporally homogeneous (T) groups, respectively. We conclude that the high associated variability was due to a lack of control regarding the collection time of the experimentally evolved Drosophila.
Date Created
2015-05
Agent