Dissertations / Theses on the topic 'Declines'

Agrochemical exposure is one of the factors that contributes to worldwide amphibian declines. Most studies that examine agrochemicals and amphibian declines focus on toxicity. However, declines are more likely caused by the sub-lethal effects of agrochemical exposure. Past emphases on the lethal effects of agrochemical exposure have overshadowed the contribution of decreased recruitment in amphibian declines. Additionally, studies that examine agrochemicals and reproductive function tend to focus on the effects of single chemical exposures instead of the effects of ecologically relevant mixtures. To address these issues, this dissertation examined the effects of ecologically relevant agrochemical exposures on the stress response and the reproductive endocrinology, morphology, and behaviors of male amphibians in the laboratory and the wild.

Chapter 1 provides a general review of the factors implicated in amphibian declines and provides an overview of the previous research conducted on the effects of agrochemical exposure on recruitment.

Chapter 2 is a field study that examined whether agricultural run-off alters the stress response and reproductive function of male bullfrogs ( Lithobates catesbeianus). Bullfrogs were collected upstream and downstream of agricultural activity across three California river systems (Salinas, Sacramento and San Joaquin). Size, primary and secondary sex traits, sperm count, and corticosterone and testosterone levels were examined. Overall, bullfrogs living downstream of agricultural activity (i.e. exposure to agricultural run-off) were small and had elevated testosterone and corticosterone levels. In addition, downstream males from the Salinas and San Joaquin Rivers were also small in size and had elevated testosterone levels. However, only downstream males of the San Joaquin River had elevated corticosterone and exaggerated secondary sex traits. Together, these data suggest that living downstream of agriculture can alter size, hormone levels, and the expression of sexually dimorphic sex traits. Such changes to the reproductive endocrinology and morphology of male amphibians can be detrimental to the reproductive health and long-term reproductive success of amphibian populations.

In Chapter 3, I examined corticosterone, testosterone, and the reproductive clasping behaviors of adult male African clawed frogs (Xenopus laevis) exposed to field collected and simulated agricultural run-off. This experiment implemented a novel eco-relevant experimental design to mimic real-life agrochemical exposures. Male frogs were exposed to field water collected downstream (agricultural run-off) and upstream (negative control) of agricultural activity along the Salinas River, CA. In addition, a pesticide mixture containing the top agrochemicals used in the Monterey County was included to simulate agricultural run-off. Mating behavior was suppressed in males exposed to simulated agricultural run-off but enhanced in males exposed to field collected agricultural run-off. In addition, testosterone levels of clasping males were elevated in comparison to controls. Males immersed in simulated agricultural run-off had significantly lower testosterone levels than control males in 2010. These data suggest that agrochemical exposure (both field collected and simulated) can alter reproductive hormones and clasping behaviors. Altered sex hormones and behaviors in male amphibians may play a role in amphibian declines.

Lastly, this dissertation is summarized in Chapter 4. The applicability of this dissertation as a model for amphibian declines and other reproductive related human health concerns are also introduced.

The Greater Himalaya has been identified as a key conservation region that supports high levels of biodiversity but has exceptionally high proportions of threatened species. One taxonomic group that is thought to be of particular concern is the bird order Galliformes. The Greater Himalaya is home to 24 species of resident Galliformes with a variety of ecological characteristics, geographical distribution patterns and abundance levels. Our current knowledge of South Asian Galliformes and Himalayan species in particular, contains many gaps. For example, it is suspected that many Himalayan Galliformes have undergone marked population declines but as to what extent they have declined and even the current status of some species is not fully known. There is a similar paucity of knowledge regarding both the distributions of the rarest of Himalayan Galliformes species and how well the current protected area network represents such distributions. Here I provide new insights into the distribution of the rarest Himalayan Galliform, the Critically Endangered Himalayan Quail (Orphrysia superciliosa) by using two proxy species with similar habitat preferences to create an environmental niche model. I show that by calculating an estimate of extinction likelihood, we have good reason to believe that the Himalayan quail to be extant and that recent searches in Nepal would be better targeted in North East India. Moving from single species to multiple species, I then examine long-term population changes across all Himalayan Galliformes by using changes in geographic range size as a proxy. I show that population changes for this suite of species both within and outside the Himalaya can help us to set conservation priorities and baselines. In addition, it can help us to identify species that have undergone large population changes that are not reflected in contemporary IUCN Red List statues. Species with small geographic ranges are currently top priorities for conservation efforts because they are thought to be at a greater risk of extinction. However, because it is also easier to track long term population changes over smaller spatial scales, concern exists that we may have underestimated the declines and therefore the extinction risk of more i widespread species. I show that across the entire Galliformes taxon, geographic range size does not predict the rate of geographic range decline. Finally, I move from population declines across all Galliformes to distributions of Himalayan Galliformes and assess how well the current protected area network represents such species. Using a combination of species distribution modelling and spatial prioritisation software, I show that the current protected area network in the greater Himalayas could be improved to offer better coverage for Himalayan Galliformes. I conclude by discussing the generality of my results and how they can be applied to other taxa and localities. Finally I make a series of recommendations for future Galliformes research and conservation within the Himalaya.

Honeybees are used as a major agricultural input around the world and their pollination services have been valued at US$14.6 billion to the United States alone. Dramatic declines in honeybee populations around the globe, however, questioned the sustainability of this reliance on a single pollinator species. In this study, I investigated the response of wild pollinator communities to declining honeybee density and changing land use intensity to determine the potential of wild pollinators to compensate for honeybee loss in an increasingly human-modified environment. I generated a gradient of declining honeybee density using increasing distances from commercial bee hives, and conducted flower observations on experimentally-grown plants across this gradient. I investigate how declining honeybee densities and intensifying land use combine to influence the composition of the pollinator community as a whole, then go on to explore individual trends in the most common pollinator species. I then analyze how this impacts the transport of viable pollen by the pollinator community and determine how these changes alter seed set in several common plant species. I then change my focus away from the composition of the pollinator community, and instead investigate how declining honeybee densities and land-use intensification influence the structuring of interactions between plants and pollinators within the community. I identify the pollen species carried by pollinators, and use this to construct a network of pollination interactions. I then use this network to analyze how changes in the way species interact influences the pollination services delivered by the pollinator community to different plant groups (weeds, native plants, and crop species). My findings show that honeybee declines may have a large impact on community structure and interactions within pollination systems. I observed a significant shift in the wild pollinator community composition as honeybee densities declined, from a generally bee/hoverfly dominated community to one more dominated by large flies. This was associated with a significant decline in the total pollen load transported by the community, indicating that pollination services may suffer in the absence of honeybees. As honeybee densities declined, however, I also observed a shift toward greater specialisation of pollinators on abundant resources, increased pollinator constancy, and a higher viability rate of the pollen transported. These findings show that although the total amount of pollen transported by the community declined as honeybee densities decreased, the probability of this pollen transport resulting in effective pollination likely increased. Thus, I observed no decrease in seed set with honeybee declines in any of the three plant species tested, and one of these even showed a significant increase. Finally, I also demonstrated that this change differentially affected different plant types, and that the extent of changes to each plant species differed between land-use types. This reflected changes in the relative abundance of pollen types in different land uses, with greater specialisation in the absence of honeybees disproportionately benefiting common species. These findings have strong implications for several contemporary issues in pollination biology, both locally within New Zealand and on a global scale. These are discussed in the following sections. Finally, I conclude by discussing the implications of this research on several contemporary issues in pollination biology, namely the ability for wild pollinators to compensate for honeybee declines, the impact of honeybees on natural new Zealand ecosystems, the contribution of honeybees to invasive weed pollination and finally the management of surrounding land use types to maximize the effectiveness of wild pollinators.

This thesis is about understanding the processes that explain the patterns of extinction risk and declines that we see in amphibians, how we can use that understanding to set conservation priorities, and how we can convert those priorities into practical, hands-on research and management. In particular, I focus on the threat posed by the emerging infectious disease, chytridiomycosis, which is caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Amphibians display a non-random pattern of extinction risk, both taxonomically and geographically. In chapter two I investigate the mechanism behind the observed taxonomic selectivity and find that it is due to species biology rather than heterogeneity in either threat intensity or conservation knowledge. In chapter three I determine which biological and environmental traits are important in rendering a species susceptible to declines, focussing on susceptibility to Bd. I found that restricted range, high elevation species with an aquatic life-stage are more likely to have suffered a decline. Using these traits, I predict species and locations that may be susceptible in the future, and which should therefore be a high priority for amphibian research and conservation.

BACKGROUND Consanguinity - or marriage between close blood relatives, in particular first cousins - is widely practised and even socially encouraged in many countries. However, in the face of fertility transition where the number of cousins eligible to marry declines, how might such constraints on consanguinity develop in the future? OBJECTIVE Numerous studies have stated that the practice cannot continue at present levels and in its present form in the face of fertility transition. However, the future impact of fertility transition on availability of cousins to marry has not yet been quantified. METHODS We perform a simulation exercise using past and projected net reproduction rates (NRRs) derived from the UN. We calculate the average number of cousins of the opposite sex as a function of the average number of children, the average probability of an individual having at least one eligible paternal cousin of the opposite sex, and conclude with an examination of constraints on consanguineous marriage in selected countries under different fertility assumptions. RESULTS Current and projected fertility levels in Middle Eastern countries will create challenging constraints on the custom once today's birth cohorts reach marriageable age. CONCLUSIONS Either consanguinity prevalence will diminish significantly, or the institution will be forced to adapt by becoming more coercive in the face of reduced choice or at the expense of other social preferences (such as for an older groom wedding a younger bride). Fertility decline affects prospects for social change not only through its well-known consequences for mothers but also through shaping marriage conditions for the next generation.

Pacific chorus frog (Pseudacris regilla) hatchlings were translocated and placed in cages in sites (~2,200 m elevation) located in Lassen, Yosemite, and Sequoia National Parks. DDE was found in 97% of Yosemite National Park samples, 84% in Sequoia National Park samples, and 15% of Lassen Volcanic National Park samples in 2001 and 2002. Total endosulfans were detected in 3% of Sequoia samples, 9% of Lassen samples and 24% of Yosemite samples. Both pesticides were detected in tadpoles and metamorphs raised at the three parks regardless of origin. Because the tadpoles were translocated post hatching, this finding indicates that the pesticides, particularly DDE, were accumulated at the site, instead of through deposition in the egg mass. Liver cells from 108 newly metamorphosed frogs were examined with flow cytometry (FCM) techniques for evaluation of chromosome breakage as measured by the half-peak coefficient of variation (HPCV) of the G1 peak. Regardless of origin, experimental groups raised at Lassen, the reference site, had significantly less chromosomal breakage (p=0.04) than metamorphs raised at the other two parks. This is the first documented evidence of DNA damage in juvenile frogs in the Sierra Nevada Mountains. Cholinesterase (ChE) was measured in tadpoles collected at 28 days and in juvenile frogs collected upon metamorphosis. In 2001, ChE activity was significantly higher in animals raised at Lassen (reference site), than at the other two parks, indicating less exposure to cholinesterase-inhibiting pesticides. This trend was not observed in 2002, although Sequoia ChE values were consistently lower than the other two parks. Temperatures were significantly different among the three parks for both years (p<0.0001) and lower temperatures may correlate with lower ChE levels. Survivorship to metamorphosis, days to metamorphosis, snout-vent lengths (SVL), and malformations were evaluated. Animals raised in Sequoia had shorter SVLs, took longer to metamorphose, and had lower survivorship to metamorphosis than in the other two parks (p<0.0001). Effects noted in P. regilla may be magnified in long lived ranid species. These findings may be important in evaluating the overall impact of aerially transported pesticides on declining frog populations in the Sierra Nevada Mountains.

University of Central Florida College of Education Thesis
During the 1960s and 1970s, major innovative science curricula were introduced into public schools in the United States, and federal funds were used to improve the quality of science teachers. Nevertheless, student achievement in science has generally declined since 1963. This research focused on changes in four of the key variables related to science achievement--teachers, students, curricula, and school goals. The research examined (a) meta-analyses of the effectiveness of the innovative science curricula on student achievement, (b) research on changes in teacher and student characteristics during the last 30 years, (c) educational literature on changes in the goals of public education during this same period, and (d) changes in student achievement. The results of this research suggest that the recent declines in science achievement are related to changes in student motivation, school goals, and school autonomy. The data indicate that contrary to the claims of some recent education commission reports, teachers and curricula have improved steadily over the last three decades. The conclusions developed from this research suggest that a number of the current educational reforms such as teacher competency testing, merit pay, curricular reform, student competency testing, and year-round schools should have little positive effect on student achievement. The research also suggests that parental involvement in education could have a negative influence on science achievement. The findings do suggest that schools of choice, corporate educational partnerships, and teacher empowerment could significantly improve student science achievement.
Ed.D.
Education
Education
Curriculum and Instruction (Science)
194 p.
x, 194 leaves, bound : ill. ; 28 cm.

Thesis: S.M. in Science Writing, Massachusetts Institute of Technology, Department of Comparative Media Studies/Writing, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 25-26).
In November of 2017, a group of researchers published a paper showing that since the 1980s, insect populations in protected areas in Germany have decreased by over 75 percent. The decline, dubbed by one reporter the "insect armageddon," was widespread, affecting sites on nature reserves across the country. It was also indiscriminate, affecting not just certain species, but overall biomass. In the following years, similar studies from Greenland, Puerto Rico, and locations in North America have also shown declines in number of insect species, abundance, and habitat. These declines have serious implications for ecosystems and for humans, some of which we can already see in effect, and some that scientists can't even predict to their full extent. This thesis will profile a research team in Costa Rica who are using caterpillar-parasitoid interactions to make estimates about insect population health, and explore the reasons for and extent of insect declines and their consequences for humans.
by Eva Charles Anna Frederick.
S.M. in Science Writing
S.M.inScienceWriting Massachusetts Institute of Technology, Department of Comparative Media Studies/Writing

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2006.
Title from PDF t.p. (viewed Nov. 18, 2008). Source: Dissertation Abstracts International, Volume: 67-12, Section: B, page: 6837. Advisers: Greg E. Demas; Craig Nelson.

Humans are modifying the global landscape at an unprecedented scale and pace. As a result, species are declining and going extinct at an alarming rate. Here, I investigate two main aspects of species’ declines: what factors are contributing to their declines and how effective our conservation efforts have been. I assessed one of the main mechanisms for protecting species by looking at the Endangered Species Act (ESA) in the United States. I examined three separate indicators of species declines for different groups of species: range contractions in Canadian imperilled species, declines in abundance in global amphibian populations and increases in temporal variability in abundance in North American breeding birds. I found that change in recovery status of ESA listed species was only very weakly related to the number of years listed, number of years with a recovery plan, and funding. These tools combined explained very little of the variation in recovery status among species. Either these tools are not very effective in promoting species’ recovery, or species recovery data are so poor that it is impossible to tell whether the tools are effective or not. I examined patterns of species’ declines in three different groups in relation to a number of anthropogenic variables. I found high losses of Canadian imperiled bird, mammal, amphibian and reptile species in regions with high proportions of agricultural land cover. However, losses of imperiled species are significantly more strongly related to the proportion of the region treated with agricultural pesticides. This is consistent with the hypothesis that agricultural pesticide use, or something strongly collinear with it (perhaps intensive agriculture more generally), has contributed significantly to the decline of imperiled species in Canada. Global increases in UV radiation do not appear to be a major cause of amphibian population declines. At individual sites, temporal changes in amphibian abundance are not predictably related to changes in UV intensity. Variability in species’ abundance of North American breeding birds, after accounting for mean abundance, is not systematically higher in areas of high human-dominated land cover or climate change. Rather, it appears that areas with a high proportion of human-dominated cover come to have a higher proportion of highly abundant, and thus more variable, species.

UA Open Access Publishing Fund
Background: Medical residency can be a time of increased psychological stress and sleep disturbance. We examine the prospective associations between self-reported sleep quality and resident wellness across a single training year. Methods: Sixty-nine (N69) resident physicians completed the Brief Resident Wellness Profile (M17.66, standard deviation [SD] 3.45, range: 017) and the Pittsburgh Sleep Quality Index (M6.22, SD 2.86, range: 1225) at multiple occasions in a single training year. We examined the 1-month lagged effect of sleep disturbances on residents’ self-reported wellness. Results: Accounting for residents’ overall level of sleep disturbance across the entire study period, both the concurrent (within-person) within-occasion effect of sleep disturbance (B 0.20, standard error [SE]0.06, p0.003, 95% confidence interval [CI]: 0.33, 0.07) and the lagged within-person effect of resident sleep disturbance (B 0.15, SE0.07, p0.037, 95% CI: 0.29, 0.009) were significant predictors of decreased resident wellness. Increases in sleep disturbances are a leading indicatorof resident wellness, predicting decreased well-being 1 month later. Conclusions: Sleep quality exerts a significant effect on self-reported resident wellness. Periodic evaluation of sleep quality may alert program leadership and the residents themselves to impending decreases in psychological well-being.

Relatively little research has been conducted on how economic recessions impact fertility intentions. In particular, uncertainty in reproductive intentions has not been examined in relation to economic shocks. The purpose of this paper is to estimate the impact of individuals' perception of negative changes in both their own and their country's economic performance on reproductive intentions in Europe during the time of the 'Great Recession' (2006-2011). Crucially, we examine both intentions and stated certainty of meeting these intentions. Using the 2011 Eurobarometer survey for 27 European countries, fertility intentions and reproductive uncertainty are regressed on individuals' perceptions of past trends in country's economic situation, household's financial situation, and personal job situation. Multilevel ordinal regressions models are run separately for people at parities zero and one as well as controlling for a set of socio-demographic variables. A worsening in the households' financial situation, as perceived in the years of the economic crisis, does not affect people's fertility intentions but rather the certainty of meeting these intentions. This relationship holds true at the individual-level for childless people. The more negative the individual's assessment of the household's financial situation, the higher the reproductive uncertainty. While this works exclusively at the country-level for people at parity one, the higher the share of people's pessimism on households' financial situation in the country the more insecure individuals of such a country are about having additional children. The empirical evidence suggests that individuals' uncertainty about realising their fertility intentions has risen in Europe and is positively linked to people's perceived household financial difficulties. If European economies continue to fare poorly, fertility intentions could eventually start to decline in response to such difficulties. (authors' abstract)

Lough Neagh Special Protection Area (SPA) was one of the most important non-estuarine sites for overwintering wildfowl in Britain and Ireland. Up to 100 000 diving ducks overwintered at the site during the early 1990s, however, by the winter of 2003/04, populations of pochard (Aythya ferina), tufted duck (A. fuligula), scaup (A. marila) and goldeneye (Bucephala clangula) had declined to 23 500 individuals. The changepoint in the temporal trend was the winter of 2000101 with the declines occurring rapidly within 2 winters. Comparable declines were observed in some resident and partially resident species. The density and biomass of benthic macro invertebrates, the main food source of diving ducks, declined by 66-67% between 1997/98 and 2010. This reduction was correlated with a major decline in chlorophyll a concentrations, suggesting a shift in the Lough Neagh ecosystem coincident with the changes observed in the bird community. However, there was no substantial shift in the diving duck diet comparable to the shift observed in the availability of their prey. Stable isotope analysis of duck tissue collected throughout 2010-2012 suggested that 57% of birds, mostly 1 st winter birds, had fed recently on other waterbodies, indicating high levels of dynamic within-winter movements and population redistribution. Analysis of ringing and recovery data provided support for the phenomenon of migratory short-stopping in goldeneye; however, this was not the case for the other species Neve11heless, a meta-analysis of count data suggested rapid climate-driven shifts in the wintering distributions of tufted duck and goldeneye in response to increasingly mild winter temperatures. It is concluded that intrinsic and extrinsic factors coincidentally conspired to make Lough Neagh a less attractive overwintering site, leading to a marked decline in diving duck numbers after the winter of 2000/01.

By the early decades of the eighteenth century alchemy and astrology had ceased to be considered respectable or credible by elite society. Astrology had been removed from university curricula, while alchemy largely ceased to be publicly practised by the educated and respected and became regarded by those of elite status to be little more than a tool for charlatans or quacks. This thesis draws out these twin declines and considers them in parallel, focusing on trying to analyse what changed intellectually and socially within England to so dramatically alter the fates of these arts. There is a scholarly tradition which has discussed the declines of alchemy and astrology as part of a broader notion of a decline in ‘occult practices’ or ‘magic’, an idea which is often twinned with the wider notion of a ‘rise of science’. This thesis will therefore consider alchemy and astrology as connected arts, which nevertheless possessed separate identities, and then analyse these arts’ declines alongside each other. Through this process it will explore to what degree and in what ways one can describe the declines of these arts as part of one unified trend, or if one needs to interpret these declines as purely grounded in their own unique circumstances. By utilising the works of alchemical and astrological practitioners and placing the decline of these arts in a longer historical context this thesis studies what those who practised the arts considered to be their core conceptual components and will therefore analyse how these elements were changed or challenged by intellectual developments that occurred in the second half of the seventeenth century. This is coupled with a wider analysis of academic and literary works which discussed these arts, which will be used to consider their social positions and how the events across the period in question affected and shaped perceptions of alchemy and astrology and their acceptability to early modern people.

Populations of many species are decreasing, but the underlying causes are often poorly understood, impeding effective conservation action. One useful approach is to determine which demographic rates drive variation in population growth rate () and identify ecological and environmental causes. I identified key demographic rates driving the decrease in Ring Ouzel (Turdus torquatus) population size, a species of high conservation concern in the UK, and explored underlying ecological and environmental causes. The number of breeding pairs decreased by 44-100% during 1979-2009 across 13 study areas throughout the UK. The population in my study area in Glen Clunie, Aberdeenshire, Scotland, decreased by 67%, from 39 to 13 breeding pairs, during 1998-2009. Mean  calculated from annual censuses was 0.91. I recorded reproductive success, and used re-sightings of marked individuals to estimate survival rates in each year, thus measuring the mean, variance and covariance among key demographic rates. Prospective elasticity analysis indicated that  was most sensitive to adult survival. However, integrated elasticity analysis, accounting for estimated demographic covariance, indicated that  was most sensitive to first-year survival. Retrospective decomposition of variance indicated that first-year survival contributed most to observed variation in . However, adult survival was low compared with species with similar life histories. Juveniles fledged from early-season broods had higher survival probability during each four-day period post fledging (0.952 ± 0.011) than juveniles fledged from late-season broods (0.837 ± 0.021). Predation was the main apparent cause of mortality. Juveniles foraged on invertebrates in grass-rich areas during June to mid-July, but then switched to feed mainly on moorland berries in higher-altitude, heather-rich, areas during mid-July to early-September. Thus, a variety of habitats providing different food types is required during the late summer. This thesis illustrates the value of integrating demographic and ecological studies to understand population change in species of conservation concern.

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2009.
Submitted in partial fulfillment of the requirements of the degree Master of Science in Natural Resources (Forestry), College of Natural Resources. Includes bibliographical references (p. 43-50).

Amphibian populations around the world have been declining rapidly over the past two decades, particularly in upland regions of the neotropics, where a fungal pathogen that causes chytridiomycosis has decimated many regions. Despite increasing concern over these and other dramatic losses of biodiversity, little information is available on the overall ecological effects of amphibian declines. As part of the Tropical Amphibian Declines in Streams (TADS) project, I quantified major energy fluxes, secondary production, and macroinvertebrate community structure for two consecutive years in four stream reaches in the Panamanian uplands, two with healthy amphibian populations and two that had experienced amphibian declines in 1996-1997. Despite relatively high year-round inputs of allochthonous organic materials, storage of detritus in the stream channels was low compared to streams in temperate regions. Organic matter inputs and standing stocks were similar between pre- and post-decline streams, and did not differ appreciably with season. Seston export was a major energetic flux in these systems, and differences in the nutritional quality (C:N) of seston in pre- and post-decline streams suggested that the loss of tadpoles may decrease the quality of materials exported from these headwaters. At coarse scales (e.g., total abundance) macroinvertebrate assemblages were similar between pre- and post-decline sites, but there were noticeable differences in production and functional and taxonomic structure. Pre-decline reaches had higher shredder production and post-decline streams had higher scraper production. In addition, taxonomic differences between pre- and post-decline streams were also evident, with a shift from dominance of smaller scraper taxa in pre-decline sites (i.e. Psephenus) to larger-bodied scrapers such as Petrophila in post-decline reaches. Filterer production was dominated by hydropsychid caddisflies in pre-decline reaches, whereas black flies dominated filterer production in post-decline reaches. Overall, detritus and detritivores dominated energy flow in all study reaches. However, scrapers were well represented in these systems and appeared to be food-limited, particularly in pre-decline reaches where grazing tadpoles were still abundant. During the second year of my study, predicted amphibian declines began at the pre-decline site. The loss of amphibians through this year resulted in subtle shifts in macroinvertebrate functional and taxonomic structure, which correlated with changes in available food resources. Some grazing mayflies responded positively to declining tadpole populations and subsequent increased periphyton resources, suggesting a potential for some degree of functional redundancy in these systems. However, other grazers, such as the water penny beetle Psephenus, showed no response during the period of study. My results indicate that responses of remaining consumers to tadpole declines in streams may not be evident at some coarse scales (e.g., total abundance, biomass). However, differences in secondary production at the community and the functional level, along with assemblage structure changes were evident, with some individual taxa responding relatively quickly. Long-term studies in these same stream reaches will further illuminate the ultimate ecological consequences of these dramatic and sudden losses of consumer diversity.

Rapid amphibian population declines and extinctions have occurred worldwide in recent decades, often in protected areas where no obvious human disturbance can be identified. Chytridiomycocis is an emerging infectious disease caused by Batrachochutrium dendrobatidis, a chytrid fungus that parasitizes the keratinized epidermis of post-metamorphic amphibians and the mouthparts of tadploes. Batrachochutrium dendrobatidis has been detected in over 200 amphibian species from five continents, and has been diagnosed in dead and dying frogs concurrent with population declines, extirpations and extinctions. Chytriiomycocis is thus considered a primary explanation for the global loss of amphibian biodiversity in recent decades.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environmental and Applied Sciences
Science, Environment, Engineering and Technology
Full Text

Thesis (M.S. in Management) Naval Postgraduate School, March 1999.
Thesis advisor(s): Ira A. Lewis, Theodore A. Hleba. "March 1999". Includes bibliographical references (p. 49-50). Also available online.

This thesis reports three experiments investigating how age-related declines in visual motion processing affect older drivers’ ability to drive safely. In particular, these experiments assess the efficacy of: 1) A test of motion sensitivity, the Peripheral Motion Contrast Threshold (PMCT) test, which evaluates ones’ contrast threshold for detecting motion in the periphery, and 2) the 3D multiple-object tracking test (3D MOT), which evaluates the maximum stimulus speed at which one can maintain visual attention on several objects moving in three dimensions. Two versions of the PMCT test—the PMCT-10 and the shorter PMCT-2—were employed. Driving safety was measured via a high fidelity driving simulator, in addition to several self-report measures and archival data. Study 1 showed that PMCT-2 and PMCT-10 thresholds were associated with number of crashes in the simulator and other indices of unsafe driving. Study 2 examined whether the PMCT-2 could predict older driver performance during a different set of simulated driving scenarios, and whether it was associated retrospectively with real world crash rates. PMCT-2 results were significantly correlated with simulated crash risk. Moreover, Study 2 provided the first evidence that PMCT scores are associated with real-world crash, albeit in a small retrospective sample. Study 3 examined the relationship between results from both the PMCT-2 and 3D MOT tests and simulated driving. Multiple object tracking has previously been associated with older drivers' performance. Results showed a strong relationship in our sample between crash rates and 3D MOT results. However, we failed to replicate the results showing a relationship between PMCT and crash occurrence. This may have been due to high rates of subject attrition due to simulator sickness, which resulted in a small final sample. Overall, findings from the three studies demonstrate that results from PMCT and 3D MOT are associated with older drivers’ performance measures, such as crash rates, dangerous lane deviations, and speeding. These findings support visual motion processing measures as viable candidates for inclusion in a multi-domain assessment of older drivers’ fitness to drive.

The purpose of this study was to describe the relationships among common signs/symptoms (depression, fatigue, declines in cognitive function) in women with multiple sclerosis (MS) using a modified version of Braden's Self Help Theoretical Model and evaluate whether depression, fatigue, declines in cognitive function and uncertainty, enabling skills (self-control in this study) and self-management (coping in this study) influence quality of life outcomes in women with MS. MS is one of the most common causes of disability among young adults and is the most prevalent neurological disease among young and middle-aged adults in certain parts of the world. Although research had previously been undertaken with regards to the common symptoms of MS, uncertainty, enabling skills, self-management and quality of life, there had been no studies undertaken that involved all of them. This descriptive study was the first to explore relationships among common symptoms of MS, uncertainty, enabling skills, self-management and quality of life in an MS population using Braden's Learned Response Chronic Illness Self Help Model. A cross-sectional descriptive study was conducted with 106 participants. Measurement tools utilized in the study included: 1) Demographic and Illness Characteristics, 2) The Modified Fatigue Impact Scale, 3) Perceived Deficits Questionnaire, 4) Patient Health Questionnaire-9, 5) Mishel's Uncertainty in Illness Scale- Adult, 6) Rosenbaum's Self-Control Scale- Modified, 7) COPE Inventory-Brief, and 8) SF-36 Health Status Questionnaire. Data analysis involved descriptive statistics, correlations and linear regression to answer the specific aims. The study findings indicate that relationships exist among depression, fatigue, declines in cognitive function, uncertainty, enabling skills and self-management in women with MS. The study findings also indicate that depression, fatigue, declines in cognitive function, uncertainty, enabling skills and self-management influence quality of life outcomes in women with MS. Finally, while only a first study, the research findings indicate using a modified version of Braden's Learned Response Chronic Illness Self Help Model (LRCISHM) is appropriate in a population of women with MS. Future research involving women with MS who meet the inclusion criteria across the contiguous United States as well as male military veterans with MS is recommended. Research involving this modified version of Braden's LRCISHM as well as research incorporating disability levels is recommended. Research to develop interventions to improve quality of life outcomes and minimize distress is also recommended.

Urbanisation is thought to be the leading cause of habitat loss and ecosystem fragmentation world-wide. Australian urban bird communities are constantly under threat from landscape modification and the associated disturbances. The Perth metropolitan region, Western Australia provides a unique case study to observe the impact of a developing city that is also located in a biodiversity hotspot. The long-term reporting rate of 66 small passerine birds was analysed on a time and spatial scale, utilising 20 years of citizen science from Birdata collected by birdwatchers. The study compared the overall change in reporting rate to changes in the urban environment, focusing on human population density and the canopy cover of native trees. Life history traits were also used to determine if certain groups/guilds of birds responded differently to changes in the urban landscape. This study revealed that a concerning number of urban sensitive native species are in decline and are being replaced by native and exotic ‘urban-exploiters’. Species that were found to be most at risk in this study were foraging specialists, particularly insectivores, small understorey-dependent birds, and species reliant on large bushland remnants. The study also found generalist species and large nectarivorous birds are increasingly dominating the urban community. Australian urban gardens and streets are lined with nectar-rich, seed-producing vegetation both native and exotic; therefore, favouring species that have the ability to exploit novel foraging resources. Significant loss of habitat in lower strata levels, as a result of land clearing, has reduced the connectivity between large bushland remnants. This has led to urban bird communities becoming overrun by species that frequently utilise the upper canopy and/or thrive in open green areas. Many endemic and native species are locally threatened, and by identifying ‘at risk’ species we can better understand the association between environmental and ecological factors and the impact they have on an individual’s urban tolerance.

As we have become increasingly aware of the rapidity of climate change in high elevation and high latitude environments, conservation concern has grown for arctic-alpine species. This thesis capitalises on the rare availability of detailed data from intensive site monitoring and Scotland-wide surveys conducted over five decades and supplements this with new data to investigate the potential factors driving declines of Dotterel (Charadrius morinellus), an enigmatic arctic-alpine specialist bird species in decline. In accordance with expectations of predictions of climate warming, Dotterel shifted uphill in their distribution and contracted their breeding range within Scotland to their historic core. Dotterel were less likely to be retained at survey sites at low elevations, with a narrow elevational range, where nitrogen deposition was high, where vegetation was tall and dominated by graminoids, and where Ravens were present. Data also suggested that snow lie patterns affected Dotterel distribution between sites, with abundance being substantially greater at generally snow rich sites when these were relatively snow-free (possibly due to the physical restrictions to breeding that snow lie imposes). Despite an increased presence of Ravens in the alpine zone, dramatic declines in the abundance of Tipula montana (a previously important prey resource) at many lower elevation sites and shifts to breeding earlier, we detected little substantial change in breeding success between 1987 and 2011. Despite identifying numerous mechanisms through which environmental change may have acted on Dotterel we found little quantitative evidence for climatic changes to have driven Dotterel abundance declines, suggesting factors elsewhere in the species distribution are worthy of investigation as driving changes within Scotland. This thesis contributes valuable knowledge that can be used to help increase the resilience of arctic-alpine species to environmental change and highlights the pressing need for an integrated, international approach to monitoring and research to contextualise regional changes in abundance.

The underlying mechanisms regulating the ability of skeletal muscle to regenerate after acute “damaging” eccentric or “non-damaging” concentric exercise in young human skeletal muscle is poorly defined. Age-related impairments in the regenerative mechanisms may contribute to the age-related loss of muscle mass and function, which has negative consequences for overall health and disease. Thus, the first aim of this thesis was to initially investigate multiple targeted mechanisms previously implicated in the regeneration process, over a comprehensive time-course following eccentric versus concentric exercise in young adults. Within this study it was found that post-exercise, in general, increased anabolic and repressed catabolic signalling preceded functional decline, whereas inflammation and ubiquitin proteasome system-related breakdown increased once functional recovery was initiated/achieved. Eccentric exercise led to greater anabolic signalling and inflammatory signalling response. As such, this study has provided a benchmark of muscle regeneration in young skeletal muscle, which implicates early anabolic and catabolic regulation in the rapid adaptation of muscle, whereas inflammation and ubiquitin proteasome system-related breakdown likely mediate longer term remodelling/adaptations, which may be greater following eccentric exercise. Using this benchmark, the aim of the second study was to identify age-related changes in targeted regenerative mechanisms. Concentric exercise did not cause a molecular regenerative response, whilst eccentric exercise induced anabolic signalling and satellite cell activation, prior to and at the nadir of force, respectively. Compared to the younger adults, ageing per se was associated with increased inflammation, whilst anabolic and catabolic signalling post-eccentric and concentric exercise was blunted. Interestingly, satellite cell activity was induced in the old only following eccentric exercise. These data suggest that eccentric exercise is potentially more advantageous for promoting muscle growth versus concentric exercise in older adults. Whilst, compared to the young, the old displayed blunted molecular responses which might underlie blunted muscle growth during ageing. Furthermore, the activation of satellite cells in the old might be the result of the impaired molecular mechanisms being suboptimal for repair thus, requiring additional regenerative means. In order to further characterise ageing muscle and the mechanisms of muscle regeneration, RNA sequencing was performed at the time of peak anabolic signalling to highlight more global and novel molecular networks. Ageing per se revealed genes involved in blood vessel development, plasma membrane and cell-cell junction expression were down-regulated, thus implicating these processes in age-related muscle loss. Following concentric exercise in older adults, there was an up-regulation of structural transcripts whilst there was a general down-regulation of genes related to metabolism, which might suggest impaired metabolism post-concentric exercise. Perhaps the blunted transcript responses contribute to the often observed age-related blunting of muscle mass adaptations in response to exercise training. Collectively, the data from this thesis has important implications for developing interventions for maximising hypertrophic responses and for counteracting the suboptimal regenerative responses observed in older adults.

Most organisms experience progressive declines in physiological function as they age. A number of studies in a variety of species support a strong link between oxidative damage, age-related functional declines and life span determination. Here, manipulating the expression levels of superoxide dismutase (SOD) isoenzymes SOD1 and SOD2, resulted in altered functional senescence and survival characteristics in Drosophila. Overexpression of cytosolic Sod1 using the yeast GAL4/UAS system conferred a 30-34% increase in mean life span and resulted in an attenuated senescence of odor avoidance behavior in aging flies. Tissue-specific Sod1 overexpression selectively in the nervous system or muscle failed to reproduce these delayed aging phenotypes suggesting that Sod1 overexpression in these tissues alone was not primarily responsible for the aging effects observed. Graded reduction of mitochondrially localized Sod2 expression in a series of Sod2 mutants led to progressive reductions in life span, accelerated age-related functional declines, mitochondrial oxidative damage and neuronal cell death. Tissue-specific Sod2 knock-down using RNA interference revealed that muscle is a key tissue underlying the accelerated age-related functional decline and mortality observed upon loss of SOD2. Sod2 knock-down in the musculature caused a degenerative phenotype consisting of a dramatic reduction in muscle mitochondrial content and ATP levels, elevated cell death and progressive locomotor dysfunction which culminated in early-onset mortality. Collectively, these studies highlight the important role of SOD enzymes in protecting against the impact of oxidative damage on senescence and survival. These findings also lend further support to the oxidative damage hypothesis of aging.

Thesis (Ph. D.)--Southern Illinois University Carbondale, 2008.
"Department of Zoology." Keywords: Amphibians, Biodiversity, Declines, Macroinvertebrates, Production, Streams. Includes bibliographical references (p. 100-114). Also available online.

Understanding relationships between biodiversity and ecosystem function is a critical challenge, particularly in freshwater ecosystems where species losses are occurring at unprecedented rates. There is a particular need to examine these relationships in natural settings at large spatial scales. Ongoing, disease-driven amphibian declines may influence the structure and function of stream ecosystems, but little is known of the potential roles of stream-dwelling tadpoles in consumer-resource dynamics, ecosystem functions such as decomposition, and ecosystem-level biogeochemical cycling. Tadpoles in tropical streams likely regulate flows and ratios of nitrogen (N), phosphorus (P), and carbon (C), influencing ecosystems by altering nutrient supplies to other animals and their food resources. I used ecological stoichiometry as a framework to assess how the sudden loss of consumer biodiversity in neotropical headwater streams affected ecosystem function. I quantified N and P excretion and C:N:P ratios of tadpoles, macroinvertebrates, and food resources in healthy sites (pre-decline) and sites where disease-driven amphibian declines had occurred (post-decline). I tested the hypothesis of consumer homeostasis (i.e., that organisms maintain consistent body nutrient ratios by altering excretion chemistry) over a range of taxa and size classes. I also used mesocosms in a natural stream setting to quantify the effects of grazing tadpoles, shredding macroinvertebrates and a combination of the two on leaf decomposition and associated microbial activity. Finally, I examined macroinvertebrate community structure and quantified biomass and nutrient storage in tadpoles, macroinvertebrates, and basal resources in pre-decline and post-decline sites. I also measured excretion rates, volumetric excretion, and nutrient turnover for both tadpoles and macroinvertebrates. Patterns of consumer-resource stoichiometry varied with the presence or absence of tadpoles. There were higher concentrations of C, N, and P in basal resources in pre-decline sites compared to post-decline sites, but little variation in elemental ratios among sites. Elemental composition and molar ratios in grazers and shredders varied, with pronounced differences in %N for gatherers and filterers across sites. Macroinvertebrate grazer elemental composition was higher for all elements and had lower C:N, N:P, and C:P molar ratios in pre-decline sites compare to grazers in post-decline sites, while shredders showed the opposite pattern. There were differences in both taxon-specific allometric and stoichiometric relationships in tadpoles and macroinvertebrates between pre- and post-decline sites. Body P content was a good predictor of tadpole P excretion and tadpoles in pre-decline sites excreted more P per unit body P than those in post decline sites. Individuals deviated from strict homeostasis, and the degree of deviation varied among taxa. Tadpoles also affected leaf decomposition by influencing microbial communities and altering shredding macroinvertebrate feeding. Higher respiration rates of leaf discs in chambers with tadpoles suggested that tadpoles enhanced microbial activity by excreting nutrients through feeding and excretion. Shredders alone had little effect on respiration rates, indicating that tadpoles play an important and unique role in enhancing microbial activity and litter decomposition. Leaf area loss was greatest when tadpoles and macroinvertebrates were together, indicating facilitation. Macroinvertebrates are important nutrient recyclers in neotropical headwater streams, but their role is greatly decreased in the absence of larval amphibians. I measured ~80% lower standing stocks and storage of C, N, and P in basal resources in post-decline compared to pre-decline sites. Storage of C, N, and P in both tadpoles and macroinvertebrates also decreased in post-decline sites. I also observed 98% decreases in tadpole nutrient excretion and egestion rates, and an additional decrease in macroinvertebrate excretion rates (~80%) for both N and P in post-decline versus pre-decline sites. These decreases led to >8,000% increase in the distance that it took tadpoles to turn over the ambient N pools in post-decline sites, and a 130% increase for macroinvertebrates. Similar patterns were evident for P turnover, with turnover distance increasing by 6,000% and 400% in post-decline sites for tadpoles and macroinvertebrates, respectively. My results indicate that N and P excretion by both tadpoles and macroinvertebrates constitute significant nutrient fluxes in these headwater streams. Both tadpole and macroinvertebrate communities were excreting nutrients at similar rates in pre-decline sites, suggesting that they were playing equally significant roles in their contribution to ecosystem demand. My results demonstrate that tadpoles are important consumers in Neotropical headwater streams and their loss significantly alters stream food webs and ecosystem functions.

I replicated a nesting study carried out 40 years ago in southern Utah to assess reasons for long-term population declines of mourning doves (Zenaida macroura) in the western United States. I compared current nesting patterns to similar data collected in 1952. I saw little difference in nest success and nest predation, but reproductive output and nest density decreased dramatically. The number of young fledged per pair of adults was only 64% of that estimated in 1952. A 1-2 week delay in the nesting season contributed to this decrease, but cannot explain it entirely. Nest density was about 20% of that in 1952 and total reproductive output for the study area about 12-19%. Underlying causes for these changes are uncertain, but patterns of delayed nesting, high nest abandonments, and low reproductive output are similar to those seen in stressed bird populations (e.g., food/nutrient limitation or increased toxicant levels). Finally, highest nest density occurred in a habitat type (i.e., Chalk Creek) considered unimportant for doves in 1952. Nests in Chalk Creek suffered higher predation and abandonment rates than those in irrigation ditches. I also examined the effect of perch sites on nest density and distribution in two ways. First, I demonstrated a significant correlation between nest density and perch s:te density in riparian plots. Second, I erected artificial perch sites in the second year of the study and recorded changes in nest densities. For the year of the study only, nest density was higher in the experimental plots, but the difference was not statistically significant. From the levels recorded the previous year, however, nest densities increased in the experimental plots and decreased in the control plots. This difference was statistically significant, suggesting that mourning doves use the presence of perch sites as cues for habitat selection. Finally, in comparing the presence of other avian species, I found significantly more blackbirds (Aqelaius phoenicus and Euphaqus cyanocephalus) and western meadowlarks (Sturnella neglecta) in experimental plots than in control plots.

Cell Biology
Ph.D.
Key clinical features of cumulative trauma disorders include pain, muscle weakness, and tissue fibrosis, although the etiology is still under investigation. Therefore, we first sought to characterize the temporal pattern of altered sensorimotor behaviors and inflammatory and fibrogenic processes occurring in forearm muscles and serum of young adult, female rats performing an operant, high repetition high force (HRHF) reaching and grasping task for 6, 12, or 18 weeks. Palmar mechanical sensitivity, cold temperature avoidance and spontaneous behavioral changes increased, while grip strength declined, in 18-week HRHF rats, compared to controls. Flexor digitorum muscles had increased MCP-1 levels after training and increased TNFα in 6-week HRHF rats. Serum had increased IL-1β, IL-10 and IP-10 after training. Yet both muscle and serum inflammation resolved by week 18. In contrast, IFNg increased at week 18 in both muscle and serum. Given the anti-fibrotic role of IFNg, and to identify a mechanism for the continued grip strength losses and behavioral sensitivities, we evaluated the fibrogenic proteins CCN2, collagen type I and TGFß-1, as well as the nociceptive/fibrogenic peptide substance P. Each increased in and around flexor digitorum muscles and extracellular matrix in the mid-forearm, and in nerves of the forepaw at 18 weeks. CCN2 was also increased in serum at week 18. At a time when inflammation had subsided, increases in fibrogenic proteins correlated with sensorimotor declines. Thus, muscle and nerve fibrosis may be critical components of chronic work-related musculoskeletal disorders. CCN2 and substance P may serve as potential targets for therapeutic intervention, and CCN2 as a serum biomarker of fibrosis progression. TGFß-1 and CCN2 are important mediators of tissue fibrosis by their stimulatory effect on extracellular matrix deposition, with CCN2 functions as a downstream mediator of TGFß-1. Substance P (SubP), a nociceptor-related neuropeptide, has also been linked to tissue fibrosis, although little work has been done to understand whether SubP directly causes fibrotic responses in tenocytes. Therefore, we sought to determine if SubP induces fibroblast proliferation and collagen production via CCN2 signaling directly or through the TGFß-1/CCN2 signaling pathway. We hypothesized that SubP may act directly through CCN2, independently from the TGFß-1/CCN2 signaling pathway, to increase fibroblast proliferation and fibrogenic and extracellular matrix protein production in vitro. To examine this question, we assayed cell proliferation and production of CCN2, TGFB1 and collagen type 1 in vitro using primary tendon fibroblasts (tenocytes) isolated from flexor digitorum tendons, and using rat dermal fibroblasts (RDF). We observed that cells isolated from flexor digitorum tendons that express proteins characteristic of tenocytes (vimentin and tenomodulin) underwent increased proliferation in a dose dependent manner after TGFß-1 treatment, but not SubP treatment, as did RDF cells. TGFß-1 treatment increased CCN2 production in both tenocytes and RDF cells, while SubP induced CCN2 production only in rat tenocytes. Expectedly, TGFß-1 treatment increased collagen expression in each cell type, as did SubP treatment alone using In-cell Western analysis. Interestingly, preliminary data that needs to be repeated showed that SubP treatment of each cell type enhanced TGFß-1 expression, assayed using In-cell Western and traditional western blot analyses. Our findings suggest that both SubP and TGFß-1 have distinct fibrogenic actions on tenocytes and dermal fibroblast and that both may be involved in tendinosis observed in animal models and patients with fibrosis. Inflammatory pain, muscle weakness, and tissue fibrosis are key clinical features of work-related musculoskeletal disorders. So, lastly, we evaluated the effects of therapeutic interventions on behavioral and cytokine changes in muscle, tendon and serum of HRHF rats that performed the reaching and grasping task for 11 weeks. We compared sensorimotor behavioral changes, and flexor digitorum tissue inflammation and fibrosis in rats receiving anti-TNFα therapy prophylactically during the initial training, or anti-TNFα therapy with or without rest as secondary interventions during the HRHF work task. Untreated or saline only treated animals at the end of the initial training period had decreased grip strength, increased mechanical sensitivity, and increased serum and tissue inflammatory cytokines (TNFα, IL-1ß, IL-6 and VEGF), changes prevented by prophylactic anti-TNFα treatment. Regarding the secondary interventions, four weeks of anti-TNFα therapy with or without rest, provided in HRHF task weeks 4-7, was more effective than rest alone for restoring grip strength; no treatments rescued forepaw mechanical sensitivity. Effectiveness of the 4-week anti-TNFα therapy extended to week 11, despite no further drug treatment after week 7, for maintenance of grip strength. Tissue cytokine analysis in week 11 showed that HRHF rats treated with saline had increased IL-18 in serum, muscle and tendon, and trends for increased muscle CCN2. Each treatment, particularly anti-TNF with or without rest, decreased serum and tendon IL-18 and IL-1alpha. Rats receiving combined rest and anti-TNFα therapy also had increased serum IL-10. Thus, similar short-term anti-TNFα therapy may be a potential intervention in WMSDs. These results demonstrate that both Substance P and CCN2 play important roles in the development of fibrosis in muscle and tendon in WMSDs based on our model of repetition reaching and grasping. Using in vitro methods, it was demonstrated that substance P is capable of inducing CCN2 in isolated tenocytes and rat dermal fibroblasts, independent of TGFß-1 signaling, a novel discovery that make suggest new treatments for fibrotic disorders. Finally, anti-TNFalpha treatment successfully prevented behavioral declines and increases in IL-18 in serum and tissues in our rat model when provided during the course of HRHF task performance. Key clinical features of cumulative trauma disorders include pain, muscle weakness, and tissue fibrosis, although the etiology is still under investigation. Therefore, we first sought to characterize the temporal pattern of altered sensorimotor behaviors and inflammatory and fibrogenic processes occurring in forearm muscles and serum of young adult, female rats performing an operant, high repetition high force (HRHF) reaching and grasping task for 6, 12, or 18 weeks. Palmar mechanical sensitivity, cold temperature avoidance and spontaneous behavioral changes increased, while grip strength declined, in 18-week HRHF rats, compared to controls. Flexor digitorum muscles had increased MCP-1 levels after training and increased TNFα in 6-week HRHF rats. Serum had increased IL-1β, IL-10 and IP-10 after training. Yet both muscle and serum inflammation resolved by week 18. In contrast, IFNg increased at week 18 in both muscle and serum. Given the anti-fibrotic role of IFNg, and to identify a mechanism for the continued grip strength losses and behavioral sensitivities, we evaluated the fibrogenic proteins CCN2, collagen type I and TGFß-1, as well as the nociceptive/fibrogenic peptide substance P. Each increased in and around flexor digitorum muscles and extracellular matrix in the mid-forearm, and in nerves of the forepaw at 18 weeks. CCN2 was also increased in serum at week 18. At a time when inflammation had subsided, increases in fibrogenic proteins correlated with sensorimotor declines. Thus, muscle and nerve fibrosis may be critical components of chronic work-related musculoskeletal disorders. CCN2 and substance P may serve as potential targets for therapeutic intervention, and CCN2 as a serum biomarker of fibrosis progression. TGFß-1 and CCN2 are important mediators of tissue fibrosis by their stimulatory effect on extracellular matrix deposition, with CCN2 functions as a downstream mediator of TGFß-1. Substance P (SubP), a nociceptor-related neuropeptide, has also been linked to tissue fibrosis, although little work has been done to understand whether SubP directly causes fibrotic responses in tenocytes. Therefore, we sought to determine if SubP induces fibroblast proliferation and collagen production via CCN2 signaling directly or through the TGFß-1/CCN2 signaling pathway. We hypothesized that SubP may act directly through CCN2, independently from the TGFß-1/CCN2 signaling pathway, to increase fibroblast proliferation and fibrogenic and extracellular matrix protein production in vitro. To examine this question, we assayed cell proliferation and production of CCN2, TGFB1 and collagen type 1 in vitro using primary tendon fibroblasts (tenocytes) isolated from flexor digitorum tendons, and using rat dermal fibroblasts (RDF). We observed that cells isolated from flexor digitorum tendons that express proteins characteristic of tenocytes (vimentin and tenomodulin) underwent increased proliferation in a dose dependent manner after TGFß-1 treatment, but not SubP treatment, as did RDF cells. TGFß-1 treatment increased CCN2 production in both tenocytes and RDF cells, while SubP induced CCN2 production only in rat tenocytes. Expectedly, TGFß-1 treatment increased collagen expression in each cell type, as did SubP treatment alone using In-cell Western analysis. Interestingly, preliminary data that needs to be repeated showed that SubP treatment of each cell type enhanced TGFß-1 expression, assayed using In-cell Western and traditional western blot analyses. Our findings suggest that both SubP and TGFß-1 have distinct fibrogenic actions on tenocytes and dermal fibroblast and that both may be involved in tendinosis observed in animal models and patients with fibrosis. Inflammatory pain, muscle weakness, and tissue fibrosis are key clinical features of work-related musculoskeletal disorders. So, lastly, we evaluated the effects of therapeutic interventions on behavioral and cytokine changes in muscle, tendon and serum of HRHF rats that performed the reaching and grasping task for 11 weeks. We compared sensorimotor behavioral changes, and flexor digitorum tissue inflammation and fibrosis in rats receiving anti-TNFα therapy prophylactically during the initial training, or anti-TNFα therapy with or without rest as secondary interventions during the HRHF work task. Untreated or saline only treated animals at the end of the initial training period had decreased grip strength, increased mechanical sensitivity, and increased serum and tissue inflammatory cytokines (TNFα, IL-1ß, IL-6 and VEGF), changes prevented by prophylactic anti-TNFα treatment. Regarding the secondary interventions, four weeks of anti-TNFα therapy with or without rest, provided in HRHF task weeks 4-7, was more effective than rest alone for restoring grip strength; no treatments rescued forepaw mechanical sensitivity. Effectiveness of the 4-week anti-TNFα therapy extended to week 11, despite no further drug treatment after week 7, for maintenance of grip strength. Tissue cytokine analysis in week 11 showed that HRHF rats treated with saline had increased IL-18 in serum, muscle and tendon, and trends for increased muscle CCN2. Each treatment, particularly anti-TNF with or without rest, decreased serum and tendon IL-18 and IL-1alpha. Rats receiving combined rest and anti-TNFα therapy also had increased serum IL-10. Thus, similar short-term anti-TNFα therapy may be a potential intervention in WMSDs. These results demonstrate that both Substance P and CCN2 play important roles in the development of fibrosis in muscle and tendon in WMSDs based on our model of repetition reaching and grasping. Using in vitro methods, it was demonstrated that substance P is capable of inducing CCN2 in isolated tenocytes and rat dermal fibroblasts, independent of TGFß-1 signaling, a novel discovery that make suggest new treatments for fibrotic disorders. Finally, anti-TNFalpha treatment successfully prevented behavioral declines and increases in IL-18 in serum and tissues in our rat model when provided during the course of HRHF task performance.
Temple University--Theses

Amphibian populations are declining even in pristine areas in many parts of the world, and in the Neotropics most such enigmatic amphibian declines have occurred in mid- to high-elevation sites. However, amphibian populations have also declined at La Selva Biological Station in the lowlands of Costa Rica, and similar declines in populations of lizards have occurred at the site as well. To set the stage for describing amphibian declines at La Selva, I thoroughly review knowledge of amphibian decline and amphibian conservation in Central America: I describe general patterns in biodiversity, evaluate major patterns in and ecological correlates of threat status, review trends in basic and applied conservation literature, and recommend directions for future research. I then synthesize data on population densities of amphibians, as well as ecologically similar reptiles, over a 35-year periods using quantitative datasets from a range of studies. This synthesis identifies assemblage-wide declines of approximately 75% for both amphibians and reptiles between 1970 and 2005. Because these declines defy patterns most commonly reported in the Neotropics, it is difficult to assess causality evoking known processes associated with enigmatic decline events. I conduct a 12-month pathogen surveillance program to evaluate infection of frogs by the amphibian chytrid fungus, an emerging pathogen linked to decline events worldwide Although lowland forests are generally believed to be too warm for presence or adverse population effects of chytridiomycosis, I present evidence for seasonal patterns in infection prevalence with highest prevalence in the coolest parts of the year. Finally, I conducted a 16-month field experiment to explore the role of changes to dynamics of leaf litter, a critical resource for both frogs and lizards. Population responses by frogs and lizards indicate that litter regulates population densities of frogs and lizards, particularly those species with the highest decline rate. My work illustrates that sites that are assumed to be pristine are likely impacted by a variety of novel stressors, and that even fauna within protected areas may be suffering unexpected declines.

Recent observed changes in bird distributions provide an unprecedented opportunity to gain a deeper understanding of the processes that influence species' persistence. By modelling presence-absence data from the North American Breeding Bird Survey, we found evidence that the breeding range of the western burrowing owl has contracted at its northern, western, and eastern boundaries since 1967. We suggest that the species' breeding distribution is also expanding southwards to former wintering grounds into northern Mexico, facilitated by the appearance of new breeding habitat created by irrigated agriculture in the arid areas of southwestern United States and northwestern Mexico. This dissertation explores the hypothesis that burrowing owls from northern migratory populations have become resident breeders in areas of northwestern Mexico that were formerly used only by migratory owls during winter, contributing to both population declines near the northern extent of the species' breeding range and population increases in the southern half of the species' range. We used novel DNA microsatellite markers to test patterns of gene flow predicted by this migration-mediated range-shift hypothesis. We genotyped 1,560 owls from 36 study locations in Canada, Mexico, and the United States. Analyses of molecular variance provided evidence that burrowing owl populations in both northwestern Mexico and Canada are genetically different from the rest of the populations in the breeding range, lending some support to the migration-mediated range-shift hypothesis. We found evidence of subtle genetic differentiation associated with subtropical irrigated agricultural areas in southern Sonora and Sinaloa, demonstrating that land use can produce location-specific population dynamics leading to genetic structure even in the absence of dispersal barriers. We also used stable isotopes 2/H, 13/C, and 15/N in feathers to test philopatry and breeding dispersal patterns predicted by this migration-mediated range-shift hypothesis. Burrowing owl populations near the northern edge of the species' breeding range had a high proportion of immigrants compared to interior populations, while other populations had high levels of philopatry. Stable isotopes also provided evidence of breeding dispersal events from Canadian populations to northwestern Mexico in support of the migration-mediated range-shift hypothesis, but similar isotope signatures in nestling feathers between these two regions prevent stronger inferences.

In Egypt, female genital cutting (FGC) is illegal and declining in prevalence; however, the majority of women continue to support the practice. Using data from the 2005 and 2014 Egypt Demographic and Health Surveys, I examine changes in attitude toward FGC to explain social change through the framework of developmental idealism (Thornton 2015). Models are estimated using logistic regression to test if support for discontinuation of FGC is greater among women who have adopted progressive values or among women who are more traditional. Findings indicate that women who were Christian, rural, married younger, and that underwent FGC became supportive of discontinuation at greater rates than women who were Muslim, urban, married older, and did not undergo FGC. Women at various levels of education, wealth, and other indicators of development changed support at equal rates. Findings indicate that women in all social strata are receptive to messages against FGC.

The expansion of agriculture throughout the world has precipitated serious biodiversity losses. Countries with relatively extensive natural habitats, such as Canada, continue to intensify agricultural land uses, threatening to expand the scope of the present mass extinction. This thesis tests likely mechanisms of butterfly species decline in agricultural landscapes of varying intensities in the most biologically diverse region of Canada. I measured site variables such as the richness of plants suitable for larval development, patch area and shape index, and landscape variables such as heterogeneity and land-cover within buffers that varied in size from 100m to 1000m. Several rare species were not present in the agricultural sites, whereas a few species typically associated with disturbed habitat were present and abundant among most study sites. I found that agricultural intensification acts across landscapes to reduce butterfly species richness by reducing the proportion of natural habitat available. This effect was especially pronounced at 100m to 200m distances, suggesting a threshold effect beyond which the proportion of natural land is less critical to butterfly biodiversity. Within-site factors, such as plant species richness and habitat area were not affected by agricultural intensity, nor did they affect butterfly species richness and abundance. These results suggest that the mechanism linking butterfly species decline to agriculture, at least for butterflies in this region, is the loss of small habitat remnants.

Anurans are declining worldwide because of the spread of Batachochytrium dendrobatidis (Bd), the fungus that causes chytridiomycosis. However, some frogs are resistant to this disease, and understanding why may be critical to saving those that are susceptible. In Peru, Gastrotheca excubitor is resistant to chytridiomycosis while Gastrotheca nebulanastes is susceptible. Two anuran skin defenses, symbiotic bacteria and antimicrobial peptides (AMPs), have demonstrated the ability to inhibit Bd in vitro when isolated from certain frogs. We tested if these defenses can explain the difference in susceptibility between the two Gastrotheca species. The cutaneous bacteria and AMPs of both species were collected, tested for their abilities to inhibit the growth of Bd, and analyzed for their compositions. Results indicate that 34%of the strains of skin bacteria from G. excubitor were able to inhibit the growth of Bd whereas only 10% isolated from G. nebulanastes were effective. Gastrotheca excubitor also has stronger anti-Bd skin bacteria. Neither frog species has peptide mixtures capable of completely inhibiting Bd, and overall species did not differ in the anti-Bd abilities of their peptides. These results suggest that the chytridiomycosis resistance experienced by G. excubitor may be attributed to its skin bacteria.

Tuart (Eucalyptus gomphocephala DC.) is an ecologically and culturally important tree species that grows across a narrow 400 km long coastal belt, from the Sabrina River south of Perth, to Jurien Bay in the north. Unfortunately, Tuart is also a species under considerable threat due to clearing, lack of recruitment and canopy decline. Canopy decline is of particular concern, being increasingly reported throughout the Tuart distribution. Despite this, previous studies of Tuart have generally been limited to localised canopy decline events. This two-phased study firstly involved an assessment of Tuart canopy condition at 46 sites across the species distribution. At each study site the canopy condition of no Jess than 20 Tuart trees was assessed using estimations of canopy completeness, measures of canopy size reduction, and through the scoring of canopy condition indices. The second phase of the study involved collecting data on a wide selection of environmental factors considered to be important to canopy condition. These included factors of stand structure, understorey composition,landform (soil type, geology, topography, and geography), climate (gradients and change), hydrology (depth, depth change, and chemistry), fire regimes, pollution and anthropogenic disturbance (fragmentation and site disturbance). Assessment of canopy condition indicates that most the Tuart distribution has slight to moderate canopy decline, and is characterised by a mean canopy completeness of 70 percent. Most of this canopy decline is considered to be background (stand level) decline and likely to be a characteristic of the species. However, the lack of comparative studies using similar methodology makes the determination of the current state of Tuart canopy condition difficult. Long-term monitoring of Tuart canopy condition is therefore recommended to determine temporal trends in canopy condition. The main area of concern for Tuart conservation was found to be the Yalgorup region, where trees had typically less than 30 percent canopy completeness. Severe canopy decline in this region is similar to dieback reported in other eucalypt species from across Australia, that is, gradually receding canopy foliage leaving stag-headed trees and abundant epicormic foliage. Localised cases of canopy decline, similar in structure to that of the Yalgorup region, were found at Yellagonga, Neerabup and Ludlow National Park. Investigations into environmental factors found severe canopy decline in the Yalgorup region is associated with higher rainfall, finer and shallower soil, higher groundwater alkalinity and salinity, and greater rates of groundwater salinity increase. Elsewhere Tuart canopy decline was found to be associated with nutrient enrichment (high topsoil ammonium nitrogen) and high levels of fragmentation. Environmental factors other than those mentioned do not appear to be causing Tuart canopy decline across the distribution, for example understorey competition, altered fire regimes and climate change. Future management of Tuart canopy decline needs to focus on the severe canopy decline in the Yalgorup region, and build upon the hypotheses proposed in this study to explain canopy decline. Low recruitment should also not be forgotten as a major cause of the species decline.

The Clinch River (CR) and North Fork Holston River (NFHR) contain some of the most diverse freshwater mussel assemblages in the United States; however, both rivers are experiencing declines in mussel populations. The first component of this study used histological evaluations and water quality data to determine whether mussels were negatively impacted in the CR zone of decline (ZD) and to inform future management of freshwater mussels in the river. In the 91 kilometer (km) section from Carbo, Virginia (CRKM 431) downstream to Speers Ferry, Virginia (CRKM 340), referred to as the ZD, mussel density decreased >90% from 1979 to 2014 at key sites such as Semones Island (CRKM 378.3) and Pendleton Island (CRKM 364.2). Laboratory propagated mussels were placed in cages in the river for one year from June 2012 to May 2013 at four sites within the ZD and four sites in reaches where mussel populations remain stable or are increasing, a zone of stability (ZS). The survival, growth and histological results indicated that there are continuing impacts to mussels in the ZD. Research investigating impacts to the ZD and methods to improve water quality in this zone are needed. The laboratory component of this study examined sublethal effects of potassium (K+), chloride (Cl-), and un-ionized ammonia (NH3-N) on mussel tissues at concentrations relevant to those found in the NFHR. Historical industrial activities at Saltville, Virginia, as well as continued pollution of the NFHR from chemical waste ponds at this location, are believed to be significant contributors to mussel declines. Contaminant seepages from the waste ponds that include Cl-, K+, and NH3-N have been shown to be toxic to adult and juvenile mussels. A three-month laboratory study was conducted to assess impacts to organ tissues (gills, digestive glands, kidneys, and gonads) of adult Villosa iris exposed to environmentally relevant concentrations of K+ (4 and 8 mg/L), Cl- (230 and 705 mg/L), and NH3-N (0.014 and 0.15 mg/L) using histological evaluations. No detectable differences were observed among the histological endpoints from mussels held in treatments and control (p>0.05). The study design was modified and repeated using increased concentrations of K+ (8, 16, and 32 mg/L) and Cl- (705, 1410, and 2820 mg/L) for a two-month exposure period. Due to issues with maintaining NH3-N in mussel holding chambers, the second study did not the second study did not include NH3-N exposures. Control mussels in both studies had a higher abundance of lipofuscin in kidneys and degraded cytoplasm in the digestive gland diverticula compared to baseline mussels, indicating that captivity influenced mussel tissues. Future studies are needed to more thoroughly address these captivity effects. Both survival and histological data in the second test showed a significant negative effect of the increased concentrations of Cl- and K+, which were representative of those found at some sites in the NFHR downstream of Saltville, Virginia.
Master of Science

Response inhibition, the ability to suppress or cancel a pre-potent motor action, is instrumental in the flexible adaptation of behaviour to an ever-changing external environment. Unfortunately, inhibitory performance deteriorates with ageing, which is detrimental to the functional independence of older adults. The main objective of this thesis was two-fold. Firstly, to ascertain if age-related declines in response inhibition can be ameliorated by transcranial alternating current stimulation (tACS), a form of non-invasive brain stimulation. Secondly, to gain mechanistic insight into the neurophysiological underpinnings of response inhibition in healthy older individuals. A narrative review (Chapter 1) was conducted to examine the available research evidence on the neural correlates of inhibitory performance. It was found that effective response inhibition performance is subserved by the functional connectivity between the right inferior frontal gyrus (rIFG) and the presupplementary motor area (preSMA), especially for neural activity at beta frequencies. The extant literature also indicates that dual-site tACS can exert facilitatory effects on the functional connectivity between brain regions. Specifically, in-phase tACS, which entails the delivery of currents at the same oscillatory phase to two target sites, was found to promote inter-regional connectivity. Conversely, anti-phase tACS, whereby the currents to the target sites are delivered at opposite phases, was found to weaken interregional connectivity. Therefore, it was deduced that the application of beta frequency inphase tACS over the rIFG and the preSMA could potentially mitigate age-related deficits in inhibitory performance. To test this hypothesis, a double-blind crossover study involving 18 healthy older adults and 15 younger older adults was carried out to elucidate the effects of in- and anti-phase beta tACS (1 mA; 20 min; applied at rest) on stop-signal task performance (Study 1: Chapters 2 to 5). In-phase tACS led to significant improvements in the action cancellation speeds of younger, but not older, individuals. Moreover, in-phase stimulation resulted in a significant brain-behaviour relationship between cancellation speed and resting-state rIFG-preSMA connectivity for younger participants only. The effects of tACS on inhibitory performance appeared to be contingent upon the endogenous beta-band phase angle difference between rIFG and preSMA during resting-state. Anti-phase tACS was also found to exert differential effects on cortico-cortical gamma-band coupling for older and younger individuals. However, these age-related differences in network connectivity were not reflected in inhibitory performance. tACS-induced changes in response inhibition performance also appeared to be independent of task-related rIFG-preSMA phase connectivity on the scalp- and cortical-level for both older and younger adults. A substantial inter-individual variability in tACS-induced neurophysiological outcomes was also detected, particularly for older participants. This suggests that there may be greater heterogeneity in the dose-response relationship of older adults, in comparison to their younger counterparts. Subsequently, electric field simulation modelling was conducted to explore how the current dosage of the dual-site tACS protocol could be modified to improve the intensity and focality of tACS-induced currents in the brain (Study 2: Chapter 6). It was found that higher field strengths are accompanied by poorer field focality to target sites, and that this strengthfocality trade-off must be considered when deciding on tACS current intensities. The current dosages of the tACS protocol utilised in Study 1 were revised in consideration of the findings of Study 2. A sham-controlled, double-blind, crossover study was conducted to test the efficacy of this modified tACS protocol (1.0 mA for rIFG, 1.6 mA for preSMA; 20 min) on improving the inhibitory performance of seven healthy older adults (Study 3: Chapter 7). The study also investigated if an ‘online’ approach, where tACS was administered during task performance, would be more efficacious than if tACS was applied ‘offline’, i.e., when participants were at rest and in a task-free state. Due to the small sample size, group-level and single-subject analyses were employed. The findings of Study 3 indicated that neither online nor offline tACS significantly improved stop-signal task performance. Furthermore, not only was cancellation speed not associated with beta-band phase-coupling between rIFG and preSMA during resting-state and task performance, their inter-regional phase connectivity was not a significant predictor of stop outcome, i.e., the success or failure of stop attempts. Instead, task-related gamma-band rIFG-preSMA phase-coupling was found to be a significant predictor of stop outcome. Changes in source-reconstructed cortio-cortical networks from pre- to post-sham stimulation were also indicative of potential fatigue-related changes in network connections – this is an important factor that future research will need to account for when studying tACS-induced changes in phase-coupling during task performance. Overall, the findings of this thesis suggest that rIFG-preSMA beta tACS was potentially efficacious in facilitating the inhibitory performance of healthy younger adults. However, its effects in healthy older individuals were subject to considerable heterogeneity. Despite the lack of clear evidence supporting the efficacy of this tACS protocol in alleviating age-related declines in response inhibition, the findings of this thesis have provided important insights into the neural underpinnings of inhibitory performance and contributed to a broader mechanistic understanding of the effects of dual-site tACS on functional connectivity.

For migrant birds, the non-breeding season can greatly influence survival and future reproductive success. Knowledge of annual and overwinter survival, the degree of site fidelity and habitat use in the non-breeding season, migration ecology, routes and stopovers, and whether these differ with age or sex is fundamental to understanding population dynamics, vulnerability to anthropogenic habitat degradation, and consequently for understanding the severe widespread declines of migrant bird species. The degree to which a migrant is a winter specialist or generalist is likely to be central to understanding population dynamics. I studied survival rates and the wintering and migration ecology of a declining Palearctic migrant, the whinchat Saxicola rubetra, wintering in West Africa, to establish how the non-breeding season may influence migrant population dynamics. Whinchats were extremely site faithful to both within and between years, holding distinct winter territories and returning to those territories in subsequent winters, despite the opportunity to relocate. Overwinter survival was very high and annual survival was comparable to or higher than that reported on the breeding grounds. Because our power to detect resident and dispersing birds was high, survival rates likely estimated true survival well. Habitat characteristics varied widely across territories and territories were smaller if more perching shrubs and maize were present. Most individuals showed a tolerance or even preference for human modified habitats. Some individuals may have multiple wintering sites. There was no evidence of dominance-based habitat occupancy or any differences in winter ecology, site fidelity, survival and most aspects of migratory behaviour between age and sex classes. Migratory connectivity occurred only on a large-scale and individual migratory behaviour was also varied. Fundamentally, the results suggest a generalist strategy in the non-breeding season within their wintering habitat of open savannah, most likely as an adaption to stochastic site selection within the wintering range for juveniles undertaking their first migration plus changing and unpredictable conditions both within and between years. Consequently, wintering conditions may not significantly limit whinchat populations and mortality is probably highest during active migration. Notably, non-specialist migrants such as whinchats may have some resilience at the population-level to the increasing anthropogenic habitat modification occurring in Africa, suggesting that conditions during migration and in Europe may be driving declines; yet establishing the currently unknown thresholds of any resilience is likely to be fundamental for the future conservation migrants.