|
Best Selling Books by Laura JonesLaura Jones is the author of BEST Dad Ever Challenging Sudoku (2019), Grandma Challenging Sudoku (2019), Grandma Easy Sudoku & Coloring (2019), Medium Sudoku (2019), Easy Peasy Sudoku for Gardeners (2019).
41 - 80 of 1,000,000 results | << >> |
BEST Dad Ever Challenging Sudoku
release date: May 22, 2019
Grandma Challenging Sudoku
release date: May 22, 2019
Grandma Easy Sudoku & Coloring
release date: Jun 21, 2019
release date: May 15, 2019
Easy Peasy Sudoku for Gardeners
release date: May 12, 2019
release date: Oct 31, 2015
Cyber Ky and Tekkie Guy Manage the Risk of Being Online
release date: Feb 14, 2019
2020-2024 Five Year Planner
release date: Jul 12, 2019
The Berenstain Bears Coloring Book
release date: Oct 28, 2018
release date: Jan 01, 1995
A National Survey of Collegiate Sexual Health Services
release date: Jan 01, 1986
release date: Jan 01, 2003
Climate Variation and Pathogen Pressure Impact the Ecology and Evolution of Bees in Agroecosystems
release date: Jan 01, 2023
Fluctuations in temperature greatly influence species'' distributions and ecological interactions. Climate change does not only challenge the physiological limits of species via changes in temperature regimes, but can also increase exposure to novel infectious diseases by restructuring community composition. These risks are amplified in agroecosystems, where many aspects of the landscape are heavily modified. Humans rely on the services provided by species in these agricultural landscapes, including insect pollinators, who may be vulnerable to the risks posed by climate change. The overarching goal of my dissertation is to assess the roles of climate and landscape composition on the thermal tolerance and pathogen transmission dynamics of bees in agroecosystems. I explore these relationships among pollinators that visit Cucurbita (e.g., squash and pumpkin) crops. In chapter 1, I hypothesized that species have greater cold tolerance at higher latitudes and elevations due to adaptation or phenotypic plasticity in response to temperature, and have higher heat tolerance at sites with local extreme temperatures and high relative humidity. I investigated the impacts of climate on the thermal tolerance of one species, the squash bee Eucera (Peponapis) pruinosa. Additionally, I assessed a suite of mitochondrial genes for polymorphisms given the known association between mitochondrial sequence variation and differences in cold acclimation. This species recently expanded its geographic range northward from Mexico and the southwestern United States to the province of Québec over the past ~2-3 kya, tracking the human cultivation of its host plants in the genus Cucurbita. I compared the thermal limits between populations in the xeric region of their ancestral range and in two temperate regions within their recently expanded range. I did not find evidence of adaptation in mitochondrial genes, but I found that the lower thermal limit (ranging from -6.4 °C to 10.4 °C) of E. pruinosa correlated with latitude and was strongly predicted by annual mean temperature. Thus, adaptation or plasticity in cold tolerance may have enabled the rapid northward range expansion of E. pruinosa across North America. In contrast, E. pruinosa heat tolerance was variable across populations, and the effects of temperature and relative humidity were sex-specific. Overall, the average upper thermal limit of E. pruinosa in this study (53.1°C ± 3.7 °C) provides an ample thermal safety margin compared to the highest temperatures recorded within the sampled range. In chapter 2, I hypothesized that populations persisting in warmer environments would have higher heat tolerance, however smaller body size or pathogen infection may reduce heat tolerance. I investigated the roles of body mass, microclimate, and pathogen infection on heat tolerance and its population-level variance among E. pruinosa in Pennsylvania (USA). I assessed how these relationships differed between sexes given the larger size and ground-nesting behavior of female E. pruinosa. I predicted that populations of E. pruinosa are more heat tolerant at warmer sites, but that female heat tolerance is better predicted by soil texture than air temperature given their ground nesting behavior. Additionally, I predicted that parasite infection would reduce heat tolerance. I compared the upper thermal limit of male and female squash bees between 14 populations, characterized microclimate, and assessed pathogen infection by three common groups--trypanosomes, microsporidians, and bacteria. I found that heat tolerance increased with body mass, and males show twice the increase in heat tolerance per milligram body mass compared to females. I did not find evidence that microclimate predicted heat tolerance, but found that the population-level standard deviation in the upper thermal limit decreases by 0.72 °C with every 1 °C increase in maximum temperature. One parasite group that is associated with sublethal symptoms in bees, trypanosomes, was negatively associated with heat tolerance in females. This work demonstrates that heat tolerance is highly variable, and exemplifies the need to evaluate trade-offs between infection and thermal tolerance. In chapters 3 and 4, I investigated the roles of host diet breadth and pathogen host-use efficiency in pathogen transmission dynamics. To test the hypothesis that host diet specialization increases pathogen prevalence and intensity, I investigated pathogen sharing dynamics in a simple multi-host community composed of a diet specialist--the squash bee E. pruinosa--and two diet generalists--the western honey bee (Apis mellifera) and the common eastern bumble bee (Bombus impatiens). I quantified infection levels of viruses, bacteria, and eukaryotic pathogens to determine if they are able to replicate within the host they are found in or are instead passively picked up. I found that most pathogens are detected in bee hosts but do not show high titer levels, particularly viruses, suggesting low susceptibility. In contrast with previous work in pollinator communities, my investigations have revealed that landscape has a small effect on pathogen dynamics in multi-host communities. I found that the most abundant host species in this system is the diet specialist, E. pruinosa, and that this species drives the prevalence and intensity of pathogens detected across communities. This work provides critical insight into the roles of landscape and the ecology of hosts and pathogens on the pathogen transmission dynamics among bees in agroecosystems. In summary, my work has revealed that host-pathogen dynamics and the impacts of climate on bee thermal limits are highly context-dependent. I found that bee heat tolerance is highly variable and poorly explained by climate data, which suggests that heat stress may be hard to detect or predict for solitary bees. In addition, pathogen sharing dynamics were largely driven by the diet specialists who held the highest pathogen titers, which may indicate that these native bees are more vulnerable to frequent and intense infections. This work exemplifies the need to evaluate climate impacts on both bee and pathogen fitness to predict pathogen pressure in bee communities under future climate scenarios.
release date: Jun 08, 2013
Cultural Resources and the Stanford University Medical Center Facilities Renewal and Replacement Project
release date: Jan 01, 2007
From Data Physicalization to Data Experiences
release date: Jan 01, 2020
release date: Nov 12, 2015
release date: Oct 01, 2019
Effects of Statement on Auditing Standards No. 53 on the Privity of Auditors
release date: Jan 01, 1990
Influencing Factors in Film Costume Design
release date: Jan 01, 2003
Index of Leading Environmental Indicators
release date: Jan 01, 1998
Public School Personnel Administrators in North Carolina
release date: Jan 01, 1994
release date: Jan 01, 1986
Intraflow Chemical Variations in Servilleta Basalts
Cyber Ky & Tekkie Guy Talk about Cyber Bullying
release date: Apr 20, 2020
Structural Materials with In-situ Sensing Capability for Military Applications
release date: Jan 01, 2013
release date: Jan 01, 1991
release date: Jan 01, 1989
The Oregon Trail is Still Alive
release date: Jan 01, 1997
Social Network and Life Satisfaction of Elderly Albertans
The Significance of Caddy Compson in William Faulkner's The Sound and the Fury
Music Listening Habits and Psychological Well-being in Young Adults
release date: Jan 01, 2021
Equilibrium Limitations in Distillate Hydrotreating
release date: Jan 01, 2005
41 - 80 of 1,000,000 results | << >> |
|
|