Effects of Traffic Noise on the Social Behavior of Tufted Titmice (Baeolophus bicolor).

The presence of traffic noise and its potential effects on wildlife is a burgeoning topic of research within the fields of conservation behavior, animal behavior, ecology and wildlife management. Accumulated data from these efforts, mostly correlative and rarely-experimental, suggest that traffic noise induces a myriad of species-specific changes to population dynamics, breeding behavior and acoustic structure of avian song. However, the degree of generalizability of these findings is confounded by the limited variety of behaviors studied within a relatively small sample of species. This original research provides experimental evidence of the effects of simulated and real traffic noise on previously unstudied social and vocal behavior in tufted titmice (Baeolophus bicolor). First, titmice were exposed to simulated traffic noise for 8 hours per day to determine whether traffic noise caused changes in social and vocal behavior as had been suggested by previous research. This stimulus, background noise mimicking the duration of exposure, amplitude and frequency parameters of traffic noise, significantly affected several aspects of social behavior. Analyses on the vocal behavior of these subjects suggests that noise only affects call use of the most vocally-productive bird, who also happens to be the most dominant group member. A second study broadcasted recordings of traffic noise to titmice for 2.5 hours per day to test for the effects of the temporary rise in background noise levels resulting from \u27rush hour\u27 on the same social behavior found to be effected in study one. Results of Study 2 corroborated those of Study 1 and indicated that characteristics of traffic noise itself influence its effects. Among the first of its kind, this research demonstrates a direct link between traffic noise and survival-relevant social and vocal behavior

Mixed-species Flock Members’ Reactions to Novel and Predator Stimuli

Novel stimuli are ubiquitous. Few studies have examined mixed-species group reactions to novelty, although the complex social relationships that exist can affect species’ behavior. Additionally, studies rarely consider possible changes in communication. However, for social species, changes in communication, including rates, latencies, or note-types within a call, could potentially be correlated with behavioral traits. As such, this research aimed to address whether vocal behavior is correlated with mixed-species’ reactions to novel objects. I first tested the effect of various novel stimuli on the foraging and calling behavior of Carolina chickadees, Poecile carolinensis, and tufted titmice, Baeolophus bicolor. Chickadees and titmice both had longer latencies to forage in the presence of novel stimuli. Chickadees also modified their vocal behavior, having shorter latencies to call and using more ‘D’ notes in their calls in the presence of novel stimuli compared to titmice. Chickadees and titmice reacted to the novel stimuli similarly to how I would expect them to react to a predator. Therefore, a second experiment was conducted directly comparing chickadee and titmouse reactions to a novel (Mega Bloks®) stimulus and a predator (Cooper’s hawk) stimulus. Chickadees and titmice had an intermediate latency to forage in the presence of a novel stimulus compared to control and predator contexts. Again, chickadees had shorter calling latencies across contexts compared to titmice. As a final experiment, using semi-naturalistic aviaries, I tested whether chickadee flock size and the presence or absence of titmice influenced reactions to novel and predator stimuli. Chickadees called more in smaller chickadee flocks compared to larger chickadee flocks, and also when titmice were absent compared to when they were present. These results were stronger in predator contexts compared to novel contexts. This suggests that conspecific flock size influences calling behavior, such that smaller flocks, which may experience higher stress levels and may be required to exhibit more anti-predatory behavior, call more than larger flocks. Taken together, this work has important implications for the complexity of social relationships in mixed-species groups, the social roles species play within the group, and how group size influences vocal behavior and reactions to various degrees of threat

Determining the effect of temperature on species interactions in microcosms: a QPCR approach

A thesis submitted to the Institute of Biomedical, Environmental Science and Technology, University of Bedfordshire, in fulfilment of the requirements for the degree of Masters by Research.Predicting the impact of environmental change is a major goal and challenge in ecology. With climate change threatening the biodiversity and ecosystem functioning of our natural ecosystems, understanding the effects of such change and how these are mediated through a community is of critical importance. Community stability could be severely affected by temperature through extinctions, alterations in species dominance and species-specific responses. One approach to testing the consequences of climate change on a community is to manipulate experimental aquatic microcosms. However, investigating community-level responses to change in experimental microcosms has been limited by the ability to accurately monitor the basal trophic level of bacteria. Here I develop a molecular approach to monitoring bacteria by using qPCR. The qPCR approach was successful for three bacterial species and produced sensitivity to the single cell. The qPCR approach was implemented in an experimental setting to aid the investigation of the relationships between temperature, species interactions and community properties. Direct temperature response was species-specific, but indirect interactions strongly mediated temperature through the community, altering competitor and predator response. Therefore, predicting species and community response to environmental change is dependent on knowledge of specific-species response, indirect pathways of interaction and the effects of community composition

Exploring the Links Between Seasonal Variation and Spider Foraging

According to optimal foraging theory, generalist predators, such as spiders, are thought to feed indiscriminately on prey according to its availability, especially when food is scarce. In contrast, generalists can display selective feeding decisions under regimes of high prey abundance, but few studies have tracked changes in prey choice on a seasonal basis under open field conditions. Additionally, adaptations to surviving winter have been largely ignored in the research of foraging behavior. To elucidate this, I monitored prey availability and collected common forest-dwelling wolf spiders for molecular gut-content analysis, in parallel for 18 months, to assess the temporal changes occurring in spider preferences of common leaf litter prey. In addition, to determine if any physiological improvements to resisting low temperature mortality were affecting spider foraging, I also collected spiders monthly to track changes in spider supercooling points. The results revealed that spiders do exhibit selective feeding throughout the year, and appear to do so in a way that diversifies their diets. Also, despite low litter temperatures putting them in severe freezing risk, cold tolerance in these spiders remained unchanged throughout the winter, which suggests opportunity for growth during this uncompetitive period is paramount to accumulating survivorship-increasing, but also mobility-decreasing, cryoprotectants

The dimensions of personality in humans and other animals: A comparative and evolutionary perspective

This paper considers the structure and proximate mechanisms of personality in humans and other animals. Significant similarities were found between personality structures and mechanisms across species in at least two broad traits: Extraversion and Neuroticism. The factor space tapped by these personality dimensions is viewed as a general integrative framework for comparative and evolutionary studies of personality in humans and other animals. Most probably, the cross-species similarities between the most broad personality dimensions like Extraversion and Neuroticism as well as other Big Five factors reflect conservative evolution: constrains on evolution imposed by physiological, genetic and cognitive mechanisms. Lower-order factors, which are more species- and situation-specific, would be adaptive, reflecting correlated selection on and trade-offs between many traits

Is the Hyporheic Zone Relevant beyond the Scientific Community?

Rivers are important ecosystems under continuous anthropogenic stresses. The hyporheic zone is a ubiquitous, reactive interface between the main channel and its surrounding sediments along the river network. We elaborate on the main physical, biological, and biogeochemical drivers and processes within the hyporheic zone that have been studied by multiple scientific disciplines for almost half a century. These previous efforts have shown that the hyporheic zone is a modulator for most metabolic stream processes and serves as a refuge and habitat for a diverse range of aquatic organisms. It also exerts a major control on river water quality by increasing the contact time with reactive environments, which in turn results in retention and transformation of nutrients, trace organic compounds, fine suspended particles, and microplastics, among others. The paper showcases the critical importance of hyporheic zones, both from a scientific and an applied perspective, and their role in ecosystem services to answer the question of the manuscript title. It identifies major research gaps in our understanding of hyporheic processes. In conclusion, we highlight the potential of hyporheic restoration to efficiently manage and reactivate ecosystem functions and services in river corridors. View Full-Tex

Selective Forces That Shape the VLS Antigenic Variation System in Borrelia Burgdorferi

Evolutionary success of microbial pathogens requires survival within hosts, despite the rapidly changing and lethal immune response. Pathogens such as the Lyme disease bacteria Borrelia burgdorferi have evolved antigenic variation systems that are necessary for survival within the adverse immune environment. Although antigenic variation systems are essential to both microbial pathogenesis and microbial evolution, it is largely unclear what selective forces have influenced the evolution of antigenic variation systems. In this thesis, we investigate evolution of the vls antigenic variation system in B. burgdorferi by asking two major questions: First, what traits relevant to the vls antigenic variation system have natural selection acted on? Second, how did the selective forces shape the genetic sequences of the vls antigenic variation systems? We characterize sources of natural selection using mathematical modeling, computational simulation and mutagenesis experiments. Our findings show that natural selection has promoted diversity among VlsE variants on both sequence and structure by organizing the variable sites in the vls unexpressed cassettes. We also show that the level of diversity among the VlsE variants may strongly influence the within-host dynamics of Bb, an important fitness component of B. burgdorferi. Finally, our results indicate that diversity among VlsE variants might be constrained by purifying or stabilizing selections on translational efficiency and structural stability of the VlsE variants