Regional variation in tiger shark (Galeocerdo cuvier) abundance and habitat use

The purpose of this study was to investigate whether there is regional variation in the abundance and habitat use of tiger sharks (Galeocerdo cuvier) within in a model seagrass ecosystem. Abundance was determined with catch rates on drumlines and habitat preferences were investigated using acoustic tracking of large tiger sharks (n=4). I found spatiotemporal variation in the probability of catching at least one shark and in catch rates on days sharks were caught. In general, sharks were present throughout more of the year and in higher abundances in the northern region. Habitat use also varied between regions. In the northern region, sharks moved randomly with respect to habitat, while in the southern region sharks preferred shallow habitats. Although preliminary, these results suggest that large predator abundance and habitat use may vary over relatively small spatial scales and that such variation may be useful for elucidating their ecological role

Influence of Natural and Anthropogenic Light Levels on Female Preferences in Eastern Gray Treefrogs (hyla Versicolor)

Chapter 1: While the influence of environmental variables, particularly temperature and rainfall, on the breeding behavior of amphibians is widely recognized, relatively few studies have addressed how the moon affects amphibian behavior. Yet, the lunar cycle provides several rhythmic temporal cues that animals could use to time important group events such as spawning, and the substantial changes in light levels associated with the different moon phases may also affect the behavior of nocturnal frogs. Using seven years of field observation data, we tested for lunar effects on the reproductive activity of male and female Eastern gray treefrogs (Hyla versicolor). We found that chorusing and breeding activity was statistically more likely to occur around the first quarter of the moon and during intermediately bright nights, but that reproductive activity also occurred during various other times during the lunar cycle. We discuss these findings in relation to the two main hypotheses of lunar effects on animals: predator avoidance and temporal synchronization of breeding. Chapter 2: Nocturnal light levels vary throughout the course of the lunar cycle, being darkest during the new moon and brightest during the full moon. Many nocturnal animals change their behavior in response to this natural variation in moonlight intensity. Frequently, these behavioral changes can be attributed to the way in which moonlight affects the ability of predators to spot potential prey. Mate sampling females may expose themselves to predators, making mate choice a behavior likely influenced by moonlight. Because mate choice is an important cause of sexual selection, understanding the causes of variation in mate choice decisions can yield a better understanding of the strength and direction of sexual selection under natural conditions. We predicted that female Eastern gray treefrogs (Hyla versicolor) would prefer longer calls (i.e., more attractive males) and/or be choosier, under darker conditions, because cover of darkness may aid in predator evasion. However, light treatment did not affect how females responded to variation in call duration, nor did it affect female choosiness or aspects of their approach behavior. This suggests that in gray treefrogs, variation in light levels associated with the changing phases of the moon does not alter the sexual selection regime on male call traits. Chapter 3: Human activities are drastically changing the amount of artificial light entering natural habitats. Because light pollution alters the sensory environment, it may interfere with behaviors ranging from prey detection and vigilance to mate choice. Here we test the hypothesis that anthropogenic light pollution affects the mate choice behavior of female Eastern gray treefrogs (Hyla versicolor). We tested this hypothesis under two experimental light treatments that simulate the light pollution created by streetlights (i.e., expansion of lit areas and increased light intensity), and the light pollution created by headlights of passing vehicles (i.e., rapid fluctuations between bright and dark conditions). The hypothesis predicts that females tested under conditions simulating light pollution will show behavioral changes geared towards mitigating detection by predators, such as relaxed preferences, decreased choosiness for the normally preferred call, and differences in approach behavior (either more directional, faster, or stealthier movements, or no approach at all). Contrary to our prediction, we found that light pollution did not affect mate choice behavior in gray treefrogs, and should therefore neither interfere with population persistence nor affect the sexual selection regimes on male call traits of this species. However, we caution that this result does not imply that anthropogenic light pollution is of no concern for amphibian conservation, because behavioral responses to variation in nocturnal light levels (both in the natural as well as anthropogenically enhanced range) seem to be highly species-specific in anurans. We encourage additional studies to help gage the vulnerability of anurans to anthropogenic light pollution

Scheduling Flexible Demand in Cloud Computing Spot Markets

The rapid standardization and specialization of cloud computing services have led to the development of cloud spot markets on which cloud service providers and customers can trade in near real-time. Frequent changes in demand and supply give rise to spot prices that vary throughout the day. Cloud customers often have temporal flexibility to execute their jobs before a specific deadline. In this paper, the authors apply real options analysis (ROA), which is an established valuation method designed to capture the flexibility of action under uncertainty. They adapt and compare multiple discrete-time approaches that enable cloud customers to quantify and exploit the monetary value of their short-term temporal flexibility. The paper contributes to the field by guaranteeing cloud job execution of variable-time requests in a single cloud spot market, whereas existing multi-market strategies may not fulfill requests when outbid. In a broad simulation of scenarios for the use of Amazon EC2 spot instances, the developed approaches exploit the existing savings potential up to 40 percent – a considerable extent. Moreover, the results demonstrate that ROA, which explicitly considers time-of-day-specific spot price patterns, outperforms traditional option pricing models and expectation optimization

The ecology of venom use in the Javan Slow Loris (Nycticebus Javanicus) and its implications for conservation

The slow loris Nycticebus spp. belongs to the few venomous mammals. I aimed to explore sources for venom sequestration and the ecological function of slow loris venom, which has never been studied before. I examined the hypotheses that venom is used for intraspecific competition, predator defence and/or (ecto-) parasite avoidance. From April 2012 to June 2013 I observed 12 radio-collared and several uncollared wild Javan slow lorises (N. javanicus) at the rural agricultural field site Cipaganti in West Java, Indonesia. I collected behavioural observations including feeding and ranging data, examined faecal samples for diet remains and parasites, and regularly checked animals for ectoparasites. I also captured arthropods over five months. I monitored the coexistence with potential predator species using camera traps and by conducting forest surveys throughout Java. Venom may be sequestered from secondary plant metabolites and noxious arthropods, as the latter were abundant at the study site. Javan slow lorises fed extensively on gum (56 %) and 95 % of faecal samples contained arthropod remains. With regard to the ecological function, ranging patterns and social interactions indicated that the social system, with a monogamous social organisation and mating system with promiscuous tendencies, has potential for high sexual and non- sexual intraspecific competition. Camera trapping and forest surveys revealed the coexistence of Javan slow lorises with potential predators. However, predator avoidance could not explain the detected lunarphobia in Javan slow lorises. Additionally, animals were surprisingly ectoparasite-free. My results support all three hypotheses explaining the ecological function but should be enforced by analysing the venom composition in relation to various dietary and environmental factors, aided by (behavioural) experiments with potential predator and parasites. Finally, I applied my results to conservation of the Critically Endangered Javan slow loris, providing recommendations for the conservation of wild populations, husbandry of captive animals and reintroduction

The influence of illumination and moon phase on activity levels of nocturnal mammalian pests in New Zealand

New Zealand (NZ) hosts several introduced mammalian pests that threaten native flora and fauna. Substantial time and money is spent controlling these pest populations with some success, but in order to attain the dream of a predator free NZ we must increase our effectiveness. We already know that nocturnal mammals worldwide alter activity levels in response to moon phase; understanding this behaviour can allow better control of their populations. Little is known as to how NZ’s nocturnal mammalian pest activity levels change with moon phase or nocturnal illumination levels. If we can predict when pests will be most active then the deployment of pest control and monitoring could be more efficient and effective. The main goal of the current study was to determine how moon phase and illumination affect the activity levels of nocturnal mammalian pests. The first step in this process was to analyse two large camera trap data sets from the Blue Mountains (Otago) and Hawkes Bay to assess the response of the pests to moon phase (measured illumination data was not available for these data sets). Next, a highly sensitive light meter, a Sky Quality Meter (SQM), was tested in the dark conditions of rural Banks Peninsula (Canterbury) to assess whether it could differentiate illumination levels between moon phases and canopy covers. This device was then used in conjunction with indirect indices of activity, using Waxtags™ and camera traps, on three field sites over three months to assess activity levels. The Banks Peninsula data, as well as data from the Blue Mountains and Hawkes Bay, were analysed using a generalized linear mixed model with a binomial distribution and a logit link function. Moon phase was not able to fully explain the variation in pest activity within the camera trap data (from Hawkes Bay and the Blue Mountains), by including measured illumination levels in the Banks Peninsula study more of the variation in the data set was explained. Overall, the most interesting finding was that illumination does impact nocturnal mammalian pests and appears to affect activity levels more than moon phase or rain. These results suggest that as illumination levels decreased, pest activity levels increased. The second major finding was that SQM’s can detect, even under very dark conditions, significant differences in illumination between moon phases and under different canopy covers. This research has several practical applications. First, SQM’s were found to measure illumination in a biologically relevant way and would be useful in further ecological studies. Second, there was an implication for pest control in that monitoring these pests should be targeted during darker conditions, such as outside of the full moon and under canopy cover. Taking illumination into account may increase the efficiency and effectiveness of monitoring and control, bringing us one step closer to a predator free New Zealand

Endogenous Business Cycles and the Economic Response to Exogenous Shocks

In this paper, we investigate the macroeconomic response to exogenous shocks, namely natural disasters and stochastic productivity shocks. To do so, we make use of an endogenous business cycle model in which cyclical behavior arises from the investment–profit instability; the amplitude of this instability is constrained by the increase in labor costs and the inertia of production capacity and thus results in a finite-amplitude business cycle. This model is found to exhibit a larger response to natural disasters during expansions than during recessions, because the exogenous shock amplifies pre-existing disequilibria when occurring during expansions, while the existence of unused resources during recessions allows for damping the shock. Our model also shows a higher output variability in response to stochastic productivity shocks during expansions than during recessions. This finding is at odds with the classical real-cycle theory, but it is supported by the analysis of quarterly U.S. Gross Domestic Product series; the latter series exhibits, on average, a variability that is 2.6 times larger during expansions than during recessions.Business cycles, Natural disasters, Productivity shocks, Output variability

Fish behavior and its use in the capture and culture of fishes

Fishery management, Behaviour, Food fish, Fish culture, Conferences

The Nature of Phenotypes: Provoking and Measuring the Dynamic Processes of Swarm Expansion, Predation, and Antibiotic Resistance in Myxococcus Xanthus

The question of how genotype affects phenotype has fascinated and puzzled scientists for generations. Regardless of organism, the correlation between observation and underlying condition is necessary for scientists to understand the world around us. Myxococcus xanthus, a fascinating organism with a large genome (7,314 genes), is known for complex social behaviors and is an excellent model system for the study of this relationship. Upon starvation, M. xanthus cells condense into large multicellular aggregates to await renewed nutrient availability. M. xanthus cells swarm together on surfaces as a predatory biofilm, lysing and killing prey as a singular unit. During predation, swarms display dynamic multicellular patterns called ripples. Individual cells also retain the ability to move independently, leaving behind a slime trail for other cells to follow. This creates complex flare structures at the edge of multicellular swarms. The first part of this thesis addresses the problem of genotype-to-phenotype accuracy in complex organisms. Using 50 single gene knockout M. xanthus strains, I performed the traditional motility phenotype assay as well as a novel motility phenotype assay under magnification. Comparison of these results demonstrates not only that genes not related to motility machinery can induce a motility phenotype, but also that motility phenotypes are dynamic and can change over time. Additionally, I demonstrate that motility phenotype can change significantly when swarms move over prey, as opposed to simple agar surfaces. This more in-depth analysis allows for phenotypic classification of knockout strains previously thought to be without phenotype. The complexity of the M. xanthus genome is not only responsible for its incredibly complex multicellular phenotype, but for its potential use as a model for the study of antibiotic resistance and production of novel antibiotic compounds. The production of secondary metabolites like antibiotics is not ubiquitous in bacteria. The unique resources or building blocks required for their manufacture as well as their complicated molecular scaffolds restricts their production to more complex organisms like M. xanthus. The laboratory-friendly and non-pathogenic nature of M. xanthus adds another category to its list of interesting attributes. By sharing many qualities with pathogenic bacteria while remaining a biosafety level one organism, M. xanthus represents a unique opportunity to study how antibiotic resistance is obtained, maintained, and compensated for in a complex genome. The second part of this thesis studies M. xanthus\u27 usefulness in the fight against antibiotic resistance. I created strains of M. xanthus resistant to a wide variety of antibiotics. Some were exposed to initially low concentrations slowly building over time while others experienced higher antibiotic concentrations over a shorter period. The creation of these strains, simulating the manner in which pathogenic bacteria may gain resistance to antibiotics in vivo, allowed for a laboratory-friendly study of phenotypes and fitness costs associated with varying levels of resistance. I also supply preliminary proof of antibiotic-resistant M. xanthus\u27 utility as a general heterologous host for novel antibiotics. Upon introduction of the oxytetracycline gene cluster, resistant strains were significantly more likely to retain the plasmid than WT. These results represent an important step in both understanding how and why antibiotic resistance arises in complex bacteria as well as a potential mechanism for novel antibiotic discovery