Mountain Scholar :: Browsing by Author "Bailey, Larissa L., committee member"

Browsing by Author "Bailey, Larissa L., committee member"

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Open Access
Ecological consequences of warming climes for cold-adapted species – evidence from mountain goats
(Colorado State University. Libraries, 2023) Hayes, Forest Parker, author; Berger, Joel, advisor; Bailey, Larissa L., committee member; Wilson, Kenneth R., committee member; McGrath, Daniel, committee member
Global climate change from human activity is changing ecological communities at unprecedented rates. Coupled with recent and extraordinary loss of biodiversity, assessing the consequences for vulnerable species – and effecting proactive conservation – will be fundamental to stymieing these losses. Among the areas most strongly impacted by these changes are montane regions, which are warming at rates 2–5x the global average. Within those, cold-adapted organisms are among the most strongly impacted as they may experience thermal stress at moderate temperatures. Past species- and taxa-level responses to warming environs includes numerous concentrated extirpations at the southern peripheries of distributional ranges during the late Pleistocene. Less clear are localized capacities of cold-adapted species to mitigate thermal challenges against warming temperatures, especially through proximate behavioral and physiological adjustments. In this dissertation, I address three key tendrils of the ecological consequences of warming climes for cold-adapted species. First, I evaluate the role of snow patches in mediating the physiological impacts of warming temperatures. Despite strong associations between many taxa and cold environs, great uncertainty remains about the biological benefits, if any, of using persistent snow during summer months. Contrary to the prevalent hypothesis that persistent snow provides thermal relief for cold-adapted species, I demonstrate that use of snow patches facilitates insect avoidance and not thermoregulatory gains. While the duration and spatial extent of snow declines globally as the climate warms, its diminishing availability is likely to have substantive impacts to populations given a general pattern of associations between insects and temperatures at high elevations and latitudes. Next, I evaluate changes in spatial use relative to high temperatures and the influence of snow on resource selection. While thermal challenges to persistence are well evidenced through historical extirpations, attention to near-term shifts in resource use and snow as a driver of summer resource selection remains under-investigated. I found strong shifts in resource selection during periods of high temperature, with increased selection for cooler habitats, little effect from snow, and evidence of ecological tradeoffs in avoidance of heat. These results point to possible demographic consequences of changing behavior and illustrate the importance of proactive consideration of changing patterns of use in management policies. Finally, I evaluate the importance of climate refugia and human translocation for the applied conservation of biodiversity. Despite a long history of relocating wildlife, translocations outside native ranges have rarely been conducted for conservation and populations introduced beyond their native ranges have seldom contributed to in situ species conservation within native ranges. Herein, I identify three cases of introductions to climate refugia and highlight the untapped conservation value of existing populations outside of native ranges. I report species in these refugia offer not only a reservoir for reintroductions but also a buffer against temperature-driven distributional change and may prove invaluable in stymieing current and future loss of biodiversity under continued climate challenges. In concert, this dissertation addresses physiological and geographical consequences of warming climes for cold-adapted species, identifies the need for proactive conservation, and highlights one avenue through which meaningful conservation benefits may be achieved.
Open Access
Effects of outdoor recreation on wildlife in protected areas
(Colorado State University. Libraries, 2019) Larson, Courtney Louise, author; Crooks, Kevin R., advisor; Reed, Sarah E., advisor; Bailey, Larissa L., committee member; Knight, Richard L., committee member
Biodiversity is undergoing dramatic declines worldwide. Protected areas are the primary strategy used to conserve biodiversity, but they are rarely completely free from threats that imperil ecological communities. The vast majority of protected areas are open to recreation and have a dual mission to conserve natural resources while providing access for outdoor recreation. Many protected areas receive high levels of recreational use, particularly those near large human populations. An increasing body of evidence shows that recreation can have negative effects on animals, but questions remain about the frequency, consistency, and magnitude of the effects of recreation. To address these knowledge gaps, I conducted a global meta-analysis of the effects of recreation on vertebrate richness and abundance. I reviewed and extracted data from 34 articles that compared vertebrate richness and abundance at sites with low and high levels of recreational use, and estimated that vertebrate richness and abundance are lower in association with higher levels of recreation in over two-thirds (70%) of cases. I observed a moderate negative group-level effect of recreation on bird and mammal abundance, but the group-level effect on fish and reptiles was not significant. Effects were stronger for carnivores and herbivores than for omnivores, and stronger for small-bodied birds and ground-nesting birds than larger and tree- and shrub-nesting birds. Terrestrial and non-motorized activities were associated with reduced vertebrate abundance, whereas aquatic and motorized activities were not. While categorical comparisons between low and high levels of use can help establish whether recreation effects exist, managers who must plan and regulate recreational use of protected areas need to understand the levels of human activity that trigger animal responses. I assessed shifts in mammal habitat use and relative activity over a broad gradient of human activity levels at 92 sampling points located in 14 nature reserves in San Diego County, California, USA. I used camera traps to measure both human and mammal use of reserves, and I modeled mammal habitat use (occupancy and detection probability) and relative activity rates (hours per day with detections) in association with daily counts of total human activity, pedestrians, and cyclists. Human activity was associated with declines in habitat use of several mammal species, particularly bobcats and mule deer, though the strength of these effects was less than the effects of covariates characterizing habitat, topography, and development. Although human activity may not often extirpate mammal species from urban habitat fragments, it can reduce habitat suitability. In particular, bobcat, gray fox, mule deer, and raccoon were less active in areas with higher levels of human activity. Recreation has negative consequences for many animal species, but its effects on reptiles are largely unknown. I evaluated the effects of non-motorized, non-consumptive recreation on reptiles within urban protected areas in a fragmented landscape in coastal southern California, USA. I surveyed for lizards and snakes, quantified human activity, and modeled species richness, community composition, and occupancy as a factor of human activity along with other variables known to affect reptile distributions. I observed a decline in species richness in association with human activity, which was driven primarily by a decrease in lizard richness. The proportion of specialist species was not affected by human activity. Human activity was associated with a decline in occupancy of the common side-blotched lizard (Uta stansburiana), a slight but uncertain decline in occupancy of the orange-throated whiptail (Aspidoscelis hyperythra) and no relationship with western fence lizard (Sceloporus occidentalis) occupancy. Our study demonstrates that human activity can reduce the ability of urban protected areas to conserve diverse reptile communities. My study demonstrates the importance of examining the effects of recreation across a wide gradient of human activity and across a broad suite of species to understand which species are sensitive to recreation, to what thresholds of disturbance they respond, and whether their response results in reduced activity, local extirpation, lower species richness, or a change in community composition. These results pose a challenge to natural resource management agencies who must balance recreation access with natural resource protection, and to conservation organizations that rely on outdoor recreation for public support and funding. I recommend that managers plan recreational access at a regional scale and include some areas that are closed to recreation to minimize trade-offs between recreation and species conservation.
Open Access
Evaluating the success of Arkansas darter translocations in Colorado: an occupancy sampling approach
(Colorado State University. Libraries, 2011) Groce, Matthew Christopher, author; Fausch, Kurt D., advisor; Bailey, Larissa L., committee member; Poff, N. LeRoy, committee member
Like many fishes native to western Great Plains streams, the Arkansas darter Etheostoma cragini has declined, apparently in response to changes in flow regimes and habitat fragmentation. I investigated the effectiveness of translocation as a management strategy to conserve this threatened species in the Arkansas River basin of southeastern Colorado. I used a multiscale design to sample darters and several attributes of their habitat at the local 10-m site scale, the 3.25-km translocation segment scale, and the 10-km riverscape scale, in 19 streams where darters were previously translocated. I used multistate occupancy estimation, based on two consecutive dipnetting surveys, to determine habitat characteristics correlated with site occupancy and detectability of Arkansas darters. Darters were present in 11 of 19 streams, although 5 were completely dry when visited. Darters had reproduced in 10 of the 11 streams (one criterion in the state recovery plan), and 6 streams also met a second criterion for abundance (>500 individuals). However, populations in only two streams unequivocally met the third criterion of being self-sustaining, because the other four streams had been stocked annually with hatchery-reared darters. Detectability of darters at sites where water was present was high for both age groups, 91% for age-0 darters and 76% for age-1 darters, and was a function of Julian date (age-0) and habitat depth (age-1). Residual stream temperature (a site-scale variable) and the total length of available habitat (a riverscape-scale variable) were the strongest predictors of site occupancy for both age groups. The models were useful in identifying fragmentation by a road culvert as a potential impediment to success in another stream where conservation biologists have proposed translocating darters. These models can be used to guide habitat conservation and land management practices that seek to conserve, protect, and restore current and future critical habitat for Arkansas darters.
Open Access
Social and ecological aspects of conservation development as a strategy for biodiversity conservation on private lands
(Colorado State University. Libraries, 2015) Farr, Cooper Marie, author; Pejchar, Liba, advisor; Reed, Sarah E., advisor; Bailey, Larissa L., committee member; Seidl, Andrew F., committee member
Private lands harbor a large proportion of the world’s biodiversity, and they are also facing widespread threats from extractive land uses, anthropogenic disturbances, and land conversion for residential and commercial development. With decreased funding and support for public land acquisition and management, developing effective and economically viable tools for conservation on private lands is increasingly important. One method is conservation development (CD), an alternative to residential sprawl designed to decrease negative environmental impacts by clustering houses in a small portion of a property while preserving the remaining land as protected open space. Although CD makes up approximately one-fourth of all of the private lands conserved in the U.S., little research has assessed where and why this tool is implemented, long-term management of CD open space, or specific positive or negative effects on wildlife communities. I conducted a thorough investigation of CD as a private land conservation strategy using a variety of methods. In chapter one, I investigated CD’s ability to successfully protect animal populations by examining bird and mammal occurrence in 14 CD subdivisions (range: 14-432 ha) in Northern Colorado, USA. Using point count and camera trap data in an occupancy modeling framework, I evaluated the relative importance of 9 subdivision design factors (e.g. housing density, proportion of CD preserved, total area of the protected space) and 14 stewardship factors (e.g. mowing, livestock, native vegetation cover) in influencing the richness of human-sensitive and human-adapted species and probability of use by 16 birds and 6 mammals. I found that bird and mammal species richness and habitat use were associated predominantly with design characteristics that maximize the natural or undisturbed land area both within and surrounding the development (e.g., proportion of CD preserved, total area of the protected space, proportion of natural land cover types at large scales). Habitat use by birds was frequently influenced by local habitat composition and quality, and several bird and mammal species had decreased habitat use in areas with increased localized disturbances such as the presence of humans and mowing in the open space. In chapter two, I used Social Network Analysis (SNA) to examine participation of individuals and companies (actors) in CD implementation. Using data gathered from public county records, I quantified actor participation in CD subdivisions in six counties in Colorado, USA. I examined and compared the patterns of actor participation in CDs among counties and identified the individuals and organizations that were most consistently associated with the implementation of CDs within each county. I found that social networks of actor participation in CD differed among counties, and network characteristics varied depending on the population of the county, the total number of CDs in the county, and the total number of actors in the network. My results also showed that the most highly connected actors that were consistently involved in the implementation of many CDs were biological and geological consultants, surveyors, engineers, and planners. In chapter three, I formally assessed the content of management plans and conservation easements for existing CD subdivisions in six Colorado counties. I quantified the proportion of CDs with management documents. I also examined the land uses and stewardship activities that were prohibited, permitted, encouraged or required in the protected open space of existing CDs. I determined which activities and practices were most and least frequently addressed in these documents in order to prioritize strategies to improve CD as an effective private land conservation tool. More than two-thirds (69%) of 302 CDs had documents on file that included guidelines and regulations for the long-term stewardship of the protected land. However, CD management documents rarely mentioned issues relating to wildlife habitat improvement, species-specific monitoring and management, homeowner education, and access to the open space by domestic pets. This research identifies several key design and stewardship factors that influence the conservation value of CD open space for birds and mammals, and the key actors and actor types in CD implementation. These findings can inform the strategies used to communicate recommendations to improve CD effectiveness at achieving conservation objectives. This research also examines the current strengths and weaknesses in the documents that guide stewardship of CD subdivisions. Using these findings, I made recommendations for critical guidelines and regulation that should be included in management documents to attain conservation benefits. By incorporating characteristics that promote the persistence of sensitive animal species on private lands, CDs have strong potential to balance the housing needs of growing human populations with the preservation of diverse and abundant animal communities. With direct application to improving the way that CDs are designed, developed and managed, my findings could enhance the potential of CD to sustain native biodiversity on private lands.
Embargo
Songbird trend estimation and density-habitat relationships to inform and prioritize conifer management in the sagebrush and pinyon-juniper ecotone
(Colorado State University. Libraries, 2022) Van Lanen, Nicholas J., author; Aldridge, Cameron L., advisor; Pejchar, Liba, committee member; Koons, David N., committee member; Bailey, Larissa L., committee member
To view the abstract, please see the full text of the document.
Open Access
Testing the effects of gene flow on adaptation, fitness, and demography in wild populations
(Colorado State University. Libraries, 2015) Fitzpatrick, Sarah Warner, author; Funk, W. Chris, advisor; Angeloni, Lisa M., committee member; Angert, Amy L., committee member; Bailey, Larissa L., committee member; Ghalambor, Cameron K., committee member
Gene flow should reduce differences among populations, potentially limiting adaptation and population growth. But small populations stand to benefit from gene flow through genetic and demographic factors such as heterosis, added genetic variation, and the contribution of immigrants. Understanding the consequences of gene flow is a longstanding and unresolved challenge in evolutionary biology with important implications for conservation of biodiversity. My dissertation research addresses the importance of gene flow from evolutionary and conservation perspectives. In the first study of my dissertation I characterized natural patterns of gene flow and genetic diversity among remaining populations of Arkansas darters (Etheostoma cragini) in Colorado, an endemic to drying streams of the Great Plains, and a candidate for listing under the US Endangered Species Act. I found low diversity and high isolation, especially among sites with low water availability, highlighting this as a species that might eventually benefit from a well-managed manipulation of gene flow. I then turned to the Trinidadian guppy system to test the effects of gene flow using a model species for studying evolution in natural populations. My work capitalized on a series of introduction experiments that led to gene flow from an originally divergent population into native recipient populations. I was able to characterize neutral genetic variation, phenotypic variation, and population size in two native populations before the onset of gene flow. The goal of my first study using this system was to evaluate the level of gene flow and phenotypic divergence at multiple sites downstream from six introduction sites. I found that traits generally matched expectations for local adaptation despite extensive homogenization by gene flow at neutral loci, suggesting that high gene flow does not necessarily overwhelm selection. I followed up on this study by measuring many of the same traits in a common garden environment before and after gene flow to test whether gene flow caused genetically based changes in traits, and to evaluate the commonly held 'gene flow constrains divergence' hypothesis versus the 'divergence in the face of gene flow' hypothesis. I found that gene flow caused most traits to evolve, but whether those changes constrained adaptation depended on initial conditions of the recipient population. Finally, to link gene flow to changes in fitness and demography I conducted a large-scale capture-mark-recapture survey of two native populations beginning three months prior and following 26 months after upstream introductions took place. I genotyped all individuals from the first 17 months of this study to compare the relative fitness (survival and population growth rate) of native, immigrant, and hybrid guppies. In total this survey spanned 8-10 guppy generations and documented substantial increases in genetic variation and population size that could be attributed to gene flow from the introduction site. As a whole, the results from my research suggest that gene flow, even from a divergent population, can provide major demographic benefits to small populations, without necessarily diminishing locally important traits.

Browsing by Author "Bailey, Larissa L., committee member"

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