62 research outputs found
Recommended from our members
Landscape-Level Approaches to Desert Bighorn Sheep (Ovis canadensis nelsoni) Conservation in a Changing Environment
No full textLandscape characteristics can strongly influence demographic and genetic processes in wildlife populations. Climate change and human land use are causing many landscapes to change rapidly, and the effects on wildlife populations must be understood to properly manage these threats and design effective conservation strategies. In this dissertation, I explored the implications of landscape heterogeneity for desert bighorn sheep (Ovis canadensis nelsoni), an ecologically and culturally important ungulate species in the southwestern United States, and demonstrated new approaches that can be applied to landscape-level conservation of many wildlife species in changing landscapes. This research focused on populations within and surrounding U.S. national parks, comprising a large portion of the desert bighorn sheep's geographic range, and utilized a genetic dataset including > 1,600 individuals that was developed during this and previous projects.
Landscape resistance models have been used extensively to predict potential linkages among fragmented wildlife populations, including desert bighorn sheep, but have rarely been used to guide systematic decision-making such as prioritizing conservation actions to maximize regional connectivity. In Chapter 1, I combined network theory and landscape resistance modeling to prioritize management for connectivity, including protection and restoration of dispersal corridors and habitat patches, in a desert bighorn sheep metapopulation in the Mojave Desert. I constructed network models of genetic connectivity (potential for gene flow) and demographicconnectivity (potential for colonization of empty habitat patches). I found that the type of connectivity and the network metric used to quantify had substantial effects on prioritization results; however, I was able to identify high-priority habitat patches and corridors that were highly ranked across all combinations of the above factors.
Potential diet quality varies across landscapes and through time for desert bighorn sheep and other ungulates, but is difficult to measure at fine spatial and temporal resolution using traditional field-based methods. The remotely sensed vegetation index NDVI can potentially overcome these limitations, but its relationship to diet quality has never been empirically validated for desert herbivores. In Chapter 2, I examined how strongly NDVI was associated with diet quality of desert bighorn sheep in the Mojave Desert using fecal nitrogen data from multiple years and populations, and considered the effects of temporal resolution, geographic variability, and NDVI spatial summary statistic. I found that NDVI was more reliably associated with diet quality over the entire growing season than with instantaneous diet quality for a population, and was positively associated with population genetic diversity (a proxy for long-term diet quality). Although NDVI was a useful diet quality indicator for Mojave Desert bighorn sheep, my analysis suggested that it may be unreliable if satellite data are too spatially coarse to detect microhabitats providing high-quality forage, or if diet is strongly influenced by forage items that are weakly correlated with landscape greenness.
Landscape genetic studies typically rely on neutral genetic markers to explore gene flow and genetic variation, but the potential for species to adapt to changing landscapes depends on how natural selection influences adaptive genetic variation. In Chapter 3, I optimized landscape resistance models for desert bighorn sheep in three regions with different landscape characteristics, and then used genetic simulations incorporating natural selection to determine how the spread of adaptive variation is influenced by differences among landscapes. Optimized landscape resistance models differed between regions but slope, presence of water barriers, and major roads had the greatest impacts on gene flow. Differences among landscapes strongly influenced the spread of adaptive genetic variation, with faster spread in landscapes with more continuously distributed habitat and when a pre-existing allele (i.e., standing genetic variation) rather than a novel allele (i.e., mutation) served as the source of adaptive genetic variation.
Climate change presents a substantial threat to desert bighorn sheep and wildlife worldwide, and adaptation may be required to persist in novel environmental conditions. Knowledge of how adaptive capacity - the potential to cope with climate change by persisting in situ or moving to more suitable ranges or microhabitats - varies across populations is needed to establish conservation priorities for minimizing climate change impacts to individual species. In Chapter 4, I explored variation in the evolutionary component of adaptive capacity for 62 desert bighorn sheep populations on and near U.S. national parks. I measured adaptive capacity of populations as a function of two factors that are strongly associated with the potential for evolutionary adaptation, genetic diversity and connectivity (estimated using a landscape resistance model from Chapter 3). Genetic diversity and connectivity were highly variable across regions and populations. I identified populations with high adaptive capacity that could serve as genetic refugia from climate change impacts (e.g., those in Death Valley and Grand Canyon National Parks), but also populations with low adaptive capacity that may require conservation actions to improve their potential for adaptation (e.g., those in eastern Utah and the southern Mojave Desert). Genetic structure analyses suggested that populations in eastern Utah were genetically distinct from the rest of the study area, likely resulting from restricted gene flow following regional population extinctions.
This dissertation highlighted the effects of landscape heterogeneity on genetic and demographic processes in desert bighorn sheep populations. Collectively, the information in these chapters should help guide management of desert bighorn sheep in the face of climate change and human land use. The landscape-level approaches demonstrated here may be useful for managing many other wildlife species
Using simulations to evaluate Mantel‐based methods for assessing landscape resistance to gene flow
No full textMantel-based tests have been the primary analytical methods for understanding how landscape features influence observed spatial genetic structure. Simulation studies examining Mantel-based approaches have highlighted major challenges associated with the use of such tests and fueled debate on when the Mantel test is appropriate for landscape genetics studies. We aim to provide some clarity in this debate using spatially explicit, individual-based, genetic simulations to examine the effects of the following on the performance of Mantel-based methods: (1) landscape configuration, (2) spatial genetic nonequilibrium, (3) nonlinear relationships between genetic and cost distances, and (4) correlation among cost distances derived from competing resistance models. Under most conditions, Mantel-based methods performed poorly. Causal modeling identified the true model only 22% of the time. Using relative support and simple Mantel r values boosted performance to approximately 50%. Across all methods, performance increased when landscapes were more fragmented, spatial genetic equilibrium was reached, and the relationship between cost distance and genetic distance was linearized. Performance depended on cost distance correlations among resistance models rather than cell-wise resistance correlations. Given these results, we suggest that the use of Mantel tests with linearized relationships is appropriate for discriminating among resistance models that have cost distance correlations <0.85 with each other for causal modeling, or <0.95 for relative support or simple Mantel r. Because most alternative parameterizations of resistance for the same landscape variable will result in highly correlated cost distances, the use of Mantel test-based methods to fine-tune resistance values will often not be effective
Ecological and sociopolitical assessment of congressional and presidential designation of federal protected areas
No full textPreserving Linked Data Integrity on the Semantic Web by application of techniques from Hypermedia
No full textThis report presents a Literature Review of past work in Hypertext link integrity and current work in the emerging area of Semantic Web link integrity. A design and prototype for a system which applies some ideas from Hypertext link integrity to the Semantic Web is presented alongside plans for future enhancements of this system. In addition other possible avenues of research regarding ideas from traditional Hypertext link integrity are briefly discussed
An analysis of a broad selection of the poetry and philosophical prose of James Beattie within its eighteenth-century context.
No full textThis study explores the significance and relevant contexts of the collected poems of James Beattie, within a detailed study of his own prose works and wider eighteenth-century intellectual debates. His position on the periphery of the literary canon means that this thesis deals largely with primary material, which permits a more thorough and objective analysis than has been conducted before. The first half of this study deals with Beattie’s poetic output. Chapter 1 focuses on Beattie’s first volume of poetry, Original Poems and Translations. In this chapter I analyse the poems within the context of other eighteenth-century poets, and explore Beattie’s engagement with patronage, the eighteenth-century conventions for success as a new poet, and poetic genius. Chapter 2 deals with Beattie's second volume, Poems on Several Subjects, to illustrate the evolution in his ideas concerning the usefti๒ess of poetry as a vehicle for philosophical investigation, and his engagement with eighteenth-century social and political issues. Chapter 3 explores his best known poem, The Minstrel: Or, the Progress of Genius. This chapter discusses the poem in its entirety and within the context of Beattie’s career as a poet and philosopher. Chapter 5 focuses on Beattie's final volumes of poetry, which represent his desire to control his poetic legacy. The second half of the study deals with selected critical and philosophical works, which provide insight into the development of Beattie’s poetry and express in prose many of the subjects in lus poetry. The most detailed attention in this section is given to the Essay on Truth, although there are also chapters examining other relevant critical works including Dissertations Moral and Critical. On Poetry and Music and On Laughter and Ludicrous Composition, and Beattie's collection of "Scoticisms." There are few modem critical studies of Beattie, and many of them are limited to The Minstrel and to specific areas of interest within this work. This study's comparative and interdisciplinary approach to Beattie’s poetry and selected prose aims to justify Beattie’s inclusion in our study of the eighteenth century. It is also intended to raise awareness of Beattie’s importance in the eighteenth-century and to illustrate his influence on three first- generation Romantic poets of generally recognised importance, namely Scott, Coleridge, and Wordsworth
Incorporating Wildlife Connectivity into Forest Plan Revision Under the United States Forest Service\u27s 2012 Planning Rule
No full textThe United States Forest Service promulgated new planning regulations under the National Forest Management Act in 2012 (i.e., the Planning Rule). These new regulations include the first requirements in U.S. public land management history for National Forests to evaluate, protect, and/or restore ecological connectivity as they revise their land management plans. Data and resource limitations make single-species, functional connectivity analyses for the myriad species that occur within the 78 million ha the Forest Service manages implausible. We describe an approach that relies on freely available data and generic species, virtual species whose profile consists of ecological requirements designed to reflect the needs of a group of real species, to address the new Planning Rule requirements. We present high-resolution connectivity estimates for 10 different generic species across a 379,000 ha study area centered on the Custer Gallatin National Forest (CGNF) in Montana and South Dakota under two different movement models. We identify locations important for connectivity for multiple species and characterize the role of the CGNF for regional connectivity. Our results informed the Plan Revision process on the CGNF and could be readily exported to other National Forests currently or planning to revise their land management plans under the new Planning Rule
Molyneux’s question and the phenomenology of shape
No full textWilliam Molyneux raised the following question: if a congenital blind person is
made to see, and is visually presented with a cube and a globe, would he be able to
call the shapes before him a cube and a globe before touching them? Locke,
Berkeley, Leibniz, and Reid presented their phenomenological view of shape
perception, i.e. their view as to what it is like to perceive shape by sight and touch, in
responding to Molyneux’s Question. The four philosophers shared the view that
visual perception delivers no solid shape. This view would provide a premise for an
argument for immaterial objects. The purpose of my thesis is to reject that argument.
Kant’s view and John Campbell’s externalist account offer a way to reject the
premise of the argument in question. However, my strategy is not to adopt their view.
I pursue Reichenbach’s view that the there is no congruence or incongruence
involved in the visual phenomenology. I develop his view, and propose the view that
visual perception delivers no flat or solid shape. Although my view endorses the
premise in question, I can offer a way to reject the argument. This is because my
view is compatible with a form of externalism about perception (which differs from
Campbell’s). My view can also do full justice to the phenomenological views
presented by the four philosophers
Recommended from our members
CreechPredictingDietQualityAppendixA.pdf
No full textDiet quality influences ungulate population dynamics but is difficult to measure at fine temporal or spatial resolution using field-intensive methods such as fecal nitrogen (FN). Increasingly, the remotely sensed vegetation index NDVI is used to represent potential ungulate diet quality, but NDVI's relationship with diet quality has yet to be examined for herbivores in desert environments. We evaluated how strongly NDVI was associated with diet quality of desert bighorn sheep (Ovis canadensis nelsoni) in the Mojave Desert using FN data from multiple years and populations. We considered effects of temporal resolution, geographic variability, and NDVI spatial summary statistic on the NDVI-diet quality relationship. NDVI was more reliably associated with diet quality over the entire growing season than with instantaneous diet quality for a population. NDVI was also positively associated with population genetic diversity, a proxy for long-term, population-level effects of diet quality. We conclude that NDVI is a useful diet quality indicator for Mojave Desert bighorn sheep and potentially other desert ungulates. However, it may not reliably track diet quality if NDVI data are too spatially coarse to detect microhabitats providing high-quality forage, or if diet is strongly influenced by forage items that are weakly correlated with landscape greenness.Keywords: Bighorn sheep, Mojave Desert, Fecal nitrogen, ForageKeywords: Bighorn sheep, Mojave Desert, Fecal nitrogen, Forag
Recommended from our members
Using network theory to prioritize management in a desert bighorn sheep metapopulation
No full textConnectivity models using empirically-derived landscape resistance maps can predict potential linkages among fragmented animal and plant populations. However, such models have rarely been used to guide systematic decision-making, such as identifying the most important habitat patches and dispersal corridors to protect or restore in order to maximize regional connectivity. Combining resistance models with network theory offers one means of prioritizing management for connectivity, and we applied this approach to a metapopulation of desert bighorn sheep (Ovis canadensis nelsoni) in the Mojave Desert of the southwestern United States. We used a genetic-based landscape resistance model to construct network models of genetic connectivity (potential for gene flow) and demographic connectivity (potential for colonization of empty habitat patches), which may differ because of sex-biased dispersal in bighorn sheep. We identified high-priority habitat patches and corridors and found that the type of connectivity and the network metric used to quantify connectivity had substantial effects on prioritization results, although some features ranked highly across all combinations. Rankings were also sensitive to our empirically-derived estimates of maximum effective dispersal distance, highlighting the importance of this often-ignored parameter. Patch-based analogs of our network metrics predicted both neutral and mitochondrial genetic diversity of 25 populations within the study area. This study demonstrates that network theory can enhance the utility of landscape resistance models as tools for conservation, but it is critical to consider the implications of sex-biased dispersal, the biological relevance of network metrics, and the uncertainty associated with dispersal range and behavior when using this approach.Keywords: Gene flow, Colonization, Connectivity, Dispersal, Graph theory, Extinction, Habitat patch, Fragmented population, Landscape resistanc
Recommended from our members
CreechTylerFisheriesWildlifeUsingNetworkTheory_SupplementaryMaterial.pdf
No full textConnectivity models using empirically-derived
landscape resistance maps can predict potential
linkages among fragmented animal and plant populations.
However, such models have rarely been used to
guide systematic decision-making, such as identifying
the most important habitat patches and dispersal corridors
to protect or restore in order to maximize regional
connectivity. Combining resistance models with network
theory offers one means of prioritizing management
for connectivity, and we applied this approach to a
metapopulation of desert bighorn sheep (Ovis canadensis
nelsoni) in the Mojave Desert of the southwestern
United States. We used a genetic-based landscape
resistance model to construct network models of genetic
connectivity (potential for gene flow) and demographic connectivity (potential for colonization of empty habitat
patches), which may differ because of sex-biased
dispersal in bighorn sheep. We identified high-priority
habitat patches and corridors and found that the type of
connectivity and the network metric used to quantify
connectivity had substantial effects on prioritization
results, although some features ranked highly across all
combinations. Rankings were also sensitive to our
empirically-derived estimates of maximum effective
dispersal distance, highlighting the importance of this
often-ignored parameter. Patch-based analogs of our
network metrics predicted both neutral and mitochondrial
genetic diversity of 25 populations within the study
area. This study demonstrates that network theory can
enhance the utility of landscape resistance models as
tools for conservation, but it is critical to consider the
implications of sex-biased dispersal, the biological
relevance of network metrics, and the uncertainty
associated with dispersal range and behavior when
using this approach.Keywords: Landscape resistance, Dispersal, Habitat patch, Graph theory, Fragmented population, Connectivity, Gene flow, Extinction, Colonizatio
- …
