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- Creator:
- Hernandez, Trang Manny
- Description:
- There is a possibility to eradicate infectious diseases with antibiotics. However, new infectious diseases are continually being identified and some known pathogens are again becoming a threat because of antibiotic resistance. Amphibians mostly live in a moist environment which is the best condition for the growth of bacteria and fungi as well. Antimicrobial peptides produced by serous glands in the amphibian skin play a key role in limiting microbial growth and preventing infections with pathogenic microorganisms. In addition to the antimicrobial peptides produced by serous glands, microbial symbionts on the bullfrog skin are also a source of antimicrobial peptides that can protect the amphibian against diseases. In this research, we investigated whether cutaneous bacterial species isolated from Rana catesbeiana (North American Bullfrog), an amphibian species that is resistant to chytridiomycosis, produce secondary metabolites that could be used to inhibit the growth of three species of dermatophytes (Microsporum gypseum, Epidermotphyton floccosum, Trichophyton mentagrophytes) which are known to cause skin infections in humans. The isolated bacterial species from R. catesbeiana may be useful as producers of antifungal metabolites that kill, or inhibit the growth of, dermatophytes known to cause topical or subdermal skin infections in humans.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Grimes, Adam John
- Description:
- The blunt-nosed leopard lizard (Gambelia sila) is a federally and state-listed endangered species, endemic to the San Joaquin Valley, Carrizo and Elkhorn Plains, and Cuyama Valley of central California. Habitat degradation has had a profound impact on the historic distribution and population size of G. sila. Although recognition of G. sila as a distinct species has been questioned by some authors (e.g., Cope 1900, Smith 1946), it is currently recognized as a full species separate from the wide-ranging long-nosed leopard lizard (G. wislizenii); however, genetic support for the specific status of G. sila is lacking. Furthermore, the genetic identity of leopard lizards in the purported hybrid zone between these two species in the Cuyama Valley in Santa Barbara and Ventura counties has not been evaluated using modern molecular techniques. Understanding the genetic identity of leopard lizards in the Cuyama Valley has practical as well as systematic implications. I investigated the sister taxon relationship of G. sila and G. wislizenii using 603 base pairs of sequence from the mitochondrial cytochrome oxidase III (CO3) gene from 37 individuals representing the two species sampled from various populations in western North America. Phylogenetic analysis revealed 17 haplotypes that are partitioned into two major clades that correspond to the range of G. sila and that of G. wislizenii haplotype groups, thus supporting the recognition of both lizards as distinct species. Additionally, I sequenced 682 base pairs of the mitochondrial cytochrome oxidase b (cyt b) gene from 34 individuals representing six populations of G. sila, including lizards from a remnant hybrid population. Phylogenetic analysis indicated that the cyt b sequences consisted of 18 haplotypes that are partitioned into three geographic clades: northern, central, and southern. All lizards from the Cuyama Valley exhibited the G. sila mitochondrial DNA signature and formed the "southern" clade that was joined as a sister group to the "central" clade. My morphological analysis placed some leopard lizards from the hybrid zone with true G. sila, whereas some aggregated with G. wislizenii, indicative of hybrid status. However, genetic signatures suggest that all lizards in the hybrid zone are true G. sila, and not hybrids.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Tennant, Erin Nicole
- Description:
- The Tipton kangaroo rat (Dipodomys nitratoides nitratoides), is an endangered subspecies of the San Joaquin Valley kangaroo rat, found in the Tulare basin of the San Joaquin Valley. Dipodomys n. nitratoides and the larger Heermann’s kangaroo rat (Dipodomys heermanni) are often found sympatrically throughout the San Joaquin Valley. However, potential competitive interactions and the nature of population fluctuations between these two species are largely unknown. Because I thought that D. heermanni could be negatively affecting a translocated population D. n. nitratoides on Allensworth Ecological Reserve, Tulare County, California, I initiated a study on potential competitive interactions between these two species. In this study my objectives were to (1) determine whether the presence of D. heermanni affects space use and foraging behavior of D. n. nitratoides and (2) compare D. n. nitratoides abundance and population trends between areas with and without D. heermanni. I found that in an exclusion area where D. heermanni were removed, D. n. nitratoides increased exponentially since the start the study, whereas on a control site with both species, D. n. nitratoides decreased significantly. My results suggest that D. heermanni are competitively depressing a population of translocated D. n. nitratoides on the study site. Furthermore, eliminating competitive effects of larger, coexisting species during reintroduction or translocation efforts for D. n. nitratoides may be an important factor in success. To further test optimal translocation and reintroduction methods for protected kangaroo rats in the San Joaquin Valley, possibly an important conservation strategy, I translocated the group of non-protected D. heermanni that was removed from the exclusion area during the competitive interactions part of my study. During this part of my research, my objective was to determine whether soft-release methods, which involve a 30-day acclimation period in a wire mesh cage, help to improve survivorship of translocated kangaroo rats. My results indicated that hard-released individuals had higher survivorship than soft and semi soft- released individuals. I believe that one of the factors that may have contributed to the success of hard-released individuals was the high number of available burrows on the translocation site, often not found at sites, which provided refugia for translocated individuals. ii
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Keldgord, Heather Elayne
- Description:
- Rhus ovata is an evergreen shrub species that is common to low elevations in southern California. This species is subdioecious, i.e. some individuals are functionally females and produce fruit while others are functionally male and produce flowers with pollen. I hypothesized that because female plants allocate greater resources to reproduction through the formation of both flowers and fruit, female plants have fewer resources available for vegetative growth, survival, and defense. Therefore, I predicted that female plants would be smaller and less competitive. I sampled Rhus ovata populations at six sites across a rainfall gradient (221mm/yr to 701 mm/yr) and predicted that populations would be male dominated at drier sites because of their greater stress tolerance. At each site I measured the ratio of male to female plants within the sampled population. For a subset of individuals at each site, I measured crown size, stem tissue density, specific leaf area, reproductive investment, and distance to the nearest neighbor. As expected, female plants had greater total reproductive investment although the amount of investment was highly variable and females exhibited more variability than males. However, this differential reproductive investment did not lead to sexual size dimorphism. Ratios of functional male plants to functionally female plants differed among sites, but these differences were not correlated with rainfall and across sites the ratio of males to females did not significantly differ from a one to one. Plasticity in allocation to reproduction among females in this long-lived woody species may mitigate reproductive costs and reduce sexual dimorphism.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Atwood, Robert Christopher
- Description:
- Opuntia basilaris Engelm. & Bigelow var. treleasei (J.M. Coult.) Toumey (OBT), commonly known as Bakersfield cactus, is endemic to parts of Kern County, California. O. b. var. treleasei is one of four varieties of Opuntia basilaris and is state and federally listed as endangered (USFWS 1990). The purpose of this study was to assess the genetic differentiation between OBT and Opuntia basilaris var. basilaris (OBB), and within and among populations of OBT throughout its range. Samples were collected from 200 individual plants representing 32 populations of OBT and one population of OBB and were analyzed using amplified fragment length polymorphisms (AFLP). The AFLP protocol was successfully used to differentiate between an outgroup population of OBB and the great majority of the sampled populations of OBT using 195 polymorphic fragments. Two dendrograms were created using unweighted pair group method with arithmetic mean (UPGMA); one for all individuals and the other where each population was treated as a discreet unit. In the dendrogram based on all individuals, most samples did not cluster as distinct geographic populations, suggesting little genetic differentiation, due to a partial or complete restriction of gene flow, among the majority of OBT populations. Extensive genetic variation was found within and among OBT populations based on an analysis of molecular variance (AMOVA). Twenty three percent of the genetic differentiation was found among fragmented populations and 77%from within individuals of OBT populations suggesting that genetic variation exists between individuals within the OBT populations analyzed. In the UPGMA diagram by population, all five of the Wheeler Ridge populations clustered together. Moreover, three of the Wheeler Ridge populations formed a distinct cluster in a principal coordinates analysis (PCoA) suggesting some level of genetic structure among OBT populations. The only population with a large sample size where virtually all representative samples grouped together was for ‘OEO2’, which is located in the eastern portion of the Southern San Joaquin Valley. The results of this population genetics study will likely be useful in the conservation management of this endangered taxon.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Castaneda, Alejandro Realivazquez
- Description:
- The purpose of this study is to investigate the level of genetic divergence among populations of Vaejovis confusus in the southern San Joaquin Valley and across the state of California. Although there has been considerable research to measure genetic variation among and within scorpion species, little work has been done to investigate the impact of anthropogenic factors on genetic variation within populations. Anthropogenic factors such as man-made barriers can fragment populations and may serve as mechanisms of reproductive isolation. Particularly in the southern San Joaquin Valley, vast arrays of canals and artificial channels have been constructed to divert water from the Kern River for agricultural purposes. In the southern San Joaquin study, the level of genetic divergence is examined in a fragmented population as a result of an anthropogenic barrier, the California Aqueduct, at Coles Levee Ecosystem Preserve. Sequencing of the mitochondrial 16S ribosomal RNA gene in 20 Vaejovis confusus individuals of each fragmented population was performed. Neighbor-joining and maximum parsimony analysis of DNA sequences elucidated the level of genetic divergence. For comparison, an identical analysis was performed across a natural barrier, the Kern River at the Panorama Vista Preserve, which has separated Vaejovis confusus populations for a much longer period of time. The results of this study showed the presence of five haplotypes at the Coles Levee Ecosystem Preserve, with three haplotypes common to both sides of the California Aqueduct. Similarly at Panorama Vista Preserve, five haplotypes were found, with two haplotypes shared at both field sites across the Kern River. These results indicate that scorpion populations across the California Aqueduct and Kern River are not genetically partitioned, despite the isolating effect of these barriers. The existence of the California Aqueduct for over 50 years is not enough time to cause genetic divergence among fragmented populations. The occasional drying of the Kern River may promote gene flow between the populations or amount of time after reproductive isolation may be insufficient to cause evolutionary divergence between the two populations. In the California analysis the mitochondrial 16S rRNA gene is examined in 22 individuals from 9 counties to determine the effects of isolation by distance on the geographic-genetic structure of Vaejovis confusus populations. Scorpions were obtained from a collection of samples from the California Academy of Sciences, San Francisco. Neighbor-joining and maximum parsimony analyses were used to resolve the level of evolutionary relatedness among the populations of Vaejovis confusus throughout California. Fourteen haplotypes were found in this analysis. Eleven haplotypes were unique to their field site, whereas three were common across the state across large geographic distances (approximately 350 miles). Mitochondrial markers found high genetic variation (9.6%) in this species. Nearly half (154/325) of pairwise distance comparisons showed a 2.0% or higher sequence divergence and supported an overall isolation by distance effect. The occurrence of three haplotypes across the state results in a weak association between geography and genetic structure of V. confusus. Notably however, there is some geographic partitioning between haplotype D common in western California and haplotypes A and C common in eastern California. However, the overall lack of genetic partitioning with respect to geography among the California populations is likely due to an insufficient amount of elapsed time to promote genetic differentiation.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Hayes, Christine C.
- Description:
- The phorid fly genus Apocephalus is the largest assemblage of ant-parasitizing Phoridae. Apocephalus is currently organized into two subgenera: A. (Apocephalus) and A. (Mesophora). The species of A. (Mesophora) attack a wide variety of non-ant hosts including stingless bees, spiders, wasps, bumble bees, and cantharoid beetles. The species of A. (Apocephalus) are the true “ant-decapitating flies” and are divided into six species groups: the A. attophilus group (parasitoids of attine leaf-cutting ants), “A. miricauda group” (parasitoids of ponerine ants), A. pergandei group (parasitoids of Camponotus carpenter ants), A. mucronatus group, A. feeneri group, and A. grandipalpus group. Here I report on a preliminary molecular phylogenetic study of Apocephalus, including representatives of both subgenera and exemplars of five currently recognized species groups. Maximum parsimony, maximum likelihood, and Bayesian phylogenies were inferred using four nuclear (AK, TPI, CAD, 28S) and four mitochondrial (12S, 16S, COI, ND1) gene fragments (4284 bp total). For all analyses Apocephalus was recovered as a monophyletic group relative to the outgroup taxa included in the study. In addition, subgenus A. (Mesophora) was recovered as a monophyletic group, but was not a sister group to the subgenus A. (Apocephalus).A phylogenetic hypothesis for exemplars of five Apocephalus species groups is presented and compared to hypotheses based on morphology.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Duquette, Marc Roland
- Description:
- With over 1,300 known species, the genus Megaselia Rondani is the largest phorid genus, largely the result of high cryptic diversity and a past tendency for researchers to lump species into the genus that defied convenient classification. For many of these species, little information is available beyond one or two morphological characters. The first molecular study of such a species, Megaselia sulphurizona Borgmeier, is presented here. New sequence data from two mitochondrial loci (cytochrome oxidase, COI; NADH 1 dehydrogenase, ND1) for a total of 792 bp were obtained from 22 M. sulphurizona specimens collected from four populations in California, plus 12 other phorid taxa using standard DNA extraction and PCR techniques. Neighbor-joining, maximum likelihood, and maximum parsimony analyses revealed M. sulphurizona to be a cryptic species complex, constituting three distinct species in the Riverside, Monrovia, and Bakersfield/Tehachapi areas. These findings suggest greater cryptic diversity within M. sulphurizona, and have broader implications for phorid biodiversity.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Blackhawk, Nicole Cherri
- Description:
- The Giant Kangaroo Rat (Dipodomys ingens) is a federally and state-listed endangered species, endemic to the San Joaquin Valley, Carrizo and Elkhorn Plains, and the Cuyama Valley. Populations of the endangered Giant Kangaroo Rat (Dipodomys ingens) have decreased over the past 100 years because of habitat fragmentation and isolation. Changes in the population structure that can occur due to habitat fragmentation can significantly affect the population size and the dispersal of these animals. Dr. David Germano and I collected small ear clippings from male and female Giant Kangaroo Rats from six sites along the southern San Joaquin Valley to determine the genetic population structure of this species in this part of their range. We predicted that geographic distance and isolation of populations would decrease genetic relatedness compared to populations closer together. Having a better understanding of the genetic structure in this species will help with conservation actions, such as translocating individuals within the range of the species. These data were compared to published estimates of genetic diversity of Giant Kangaroo Rats in the Carrizo Plain to the west and the Panoche area to the north, the other large population centers of this species.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- MacKinnon, Evan D.
- Description:
- Non-native grass invasion is a major concern for land management and native plant conservation. In the southern San Joaquin Valley of California, human-disturbed environments that are heavily invaded by non-native grasses often contain some native annual species. These “weedy” native species apparently have the functional traits and life history characteristics to compete and persist in disturbed and invaded landscapes. We categorized several native plants into either a weedy or non-weedy habit based on several criteria, and confirmed this habit designation using a field trial where we controlled for other factors likely to influence species abundance under field conditions. We then measured functional traits for a group of five non-weedy species that occur locally but are not abundant in invaded areas, to a group of four weedy plant species that included the invasive grass red brome. We hypothesized that a suite of functional traits would define the weedy plant habit. We examined this hypothesis in a specific community, where we compared functional traits between weedy and non-weedy plant habits, and between native species and red brome. A principal components analysis (PCA) identified three distinct ecological clusters among the analyzed species (weedy native forbs, non-weedy native forbs, and grasses), and suggested the presence of a weedy functional type. Weedy species were different from non-weedy species in several traits (larger leaf area investment, larger root biomass allocation, heavier diaspores, and dormant seeds requiring cold-stratification for germination). The PCA suggested complementarity as an explanation for the co-occurrence of weedy native species and red brome, but individual trait similarities and a competition experiment suggested that competition can occur for some resources. Further understanding of the traits shared among weedy native plant species may lead to cost-effective approaches to restoring invaded landscapes.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Turnbull II, John
- Description:
- Examination of fish skeletal remains from archaeological sites serves both archaeological and biological interests. For archaeologists, it can establish the role of fish consumption in a people’s diet, provide clues to their fishing technology and overall maritime capability, and even suggest movement patterns and settlement (Rick et al. 2001, Erlandson et al. 2008, Des Lauriers 2010). Analysis of fish bones from excavations on San Miguel Island, of the southern California coast, suggested use of boats and early evidence of hook-and-line fishing techniques, concurrent with an estimate that fish comprised over 50% of the edible meat for the early islanders (Rick et al. 2001). Fishbone identifications have contributed to determining where early Paleocoastal peoples settled, to indicating occupation in some areas earlier than previously thought, and to suggesting that at least some southward Pacific coastal migration in North American may have been by sea (Erlandson et al. 2008). For ichthyologists, identifications of fish remains provide a historical or prehistorical survey of fishes in an area, and with comparison to modern surveys of those same areas, provide bases for examining fish distribution, fish diversity, and marine habitats over time (Gobalet 2000, Salls 2000, Erlandson et al. 2008). In supporting Point Conception, California, as a landmark for a marine faunal break, Gobalet (2000) compared the distribution of fishes identified from the archaeological record to their current distributions. Salls (2000) used bone identifications from archaeological sites on Southern California’s San Clemente Island to describe probable offshore habitats for as early as 9,000 calendar years before the present (cal BP). For over a decade, archaeological excavations on Cedros Island, which lies off the Pacific coast of the Baja California peninsula, have unearthed evidence of early colonization in the Cedros area, with implications for Paleo-human migrations (Des Lauriers 2010). Unfortunately, no on-site scientific survey of the fishes or marine habitats at Cedros Island has been published against which to compare fishbone analysis, but modern surveys of the waters close to Cedros Island exist and can be useful. Regarding habitats, Quast (1968), Engle (1993), and Bond et al. (1999) represent influential earlier studies that established the use of fish species associated with specific habitats. More recent marine faunal surveys that included the Cedros marine environment (but not specifically Cedros Island) also describe fish assemblages associated with habitats. Stephens et al. (2006) examined such associations for the rocky reef/kelp bed habitats of the southern San Diego Province, as did Pondella II et al. (2005) for the San Benito islands that lie close to Cedros. Allen and Pondella II (2006) provided a comprehensive ecological review of the California coast south to central Baja and identified fish species associations with a wide range of habitats. In this thesis, I report the identifications of fish bones from archaeological excavation sites on Cedros Island. The archaeological investigation indicates the settlement of the area about 12,000 cal BP and the establishment of a society that existed into the 18th century of our current era (CE; Des Lauriers 2005, 2008, 2010). These identifications then are provided to assist this investigation on Cedros in its efforts to better understand the Cedros islanders and to lend some insight as to the types of fishes they harvested and the predominant habitats those fishes represented.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Madsen, Angela
- Description:
- Ecological interactions can vary in strength depending on environmental conditions. The outcomes of these interactions are often dependent on the abiotic environment, but can also depend on the presence of other biotic species, including mutualists, which can further alter these effects due to trade-offs in nutrient allocation for multiple interactions. For example, some plants produce extrafloral nectar, a specialized nectar used to attract ants that will defend the plant against herbivory. If plants with extrafloral nectaries also have a second mutualistic relationship with the soil bacteria rhizobia, this second mutualism has been shown to alter the attraction of ants to the extrafloral nectar of the plant. This change in ant attraction could be caused by changes in nectar production or nectar composition, although the exact reason is unknown. Plants do alter extrafloral nectar production and composition for other reasons, for example if a plant is experiencing herbivory the plant will increase the quantity of the extrafloral nectar which will attract more ants. What is not well understood is what specific changes to the nectar, if any, cause it to become more attractive or if the attraction is simply due to a higher quantity of the extrafloral nectar. In my thesis research I explored how the chemical composition of extrafloral nectar, specifically nectar quantity and sugar, is affected by rhizobia mutualists, soil nutrients, and herbivory. Moreover, I explored how these changes influence the ant community and herbivorous arthropod community, as well as plant traits and overall fitness of the Vicia faba plant and its associated mutualistic rhizobia. I tested the effects of these factors through a series of greenhouse and field experiments, running the extrafloral nectar through a total carbohydrate assay to quantify carbohydrate (i.e. sugar) content. I found that under most conditions, the composition of the extrafloral nectar remained constant. However, when plants associated with the soil bacteria rhizobia, the rhizobia mutualism caused a decrease in sugar content in extrafloral nectar but increased the overall quantity of extrafloral nectar produced when outside of herbivory pressure. The reason for this could be due to limited resources, as the plant has a finite amount of carbon and has to allocate this carbon to both the extrafloral nectar and to rhizobia. This need for resource allocation and the altered quantity and composition of extrafloral nectar had no effect on plant fitness traits nor on ant or arthropod visitation in my study, although so few ants were present that conclusions on ant visitation effects cannot be made. These results allow for other new and exciting questions in plant and insect ecology, such as what effect these resource allocations have on plant competition, growth, fitness, and how it impacts the broader ecological community.
- Resource Type:
- Masters Thesis
- Identifier:
- 10091
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Castro, Viridiana
- Description:
- Transporting water efficiently is one of the chief functions of plant vascular systems. Highly efficient transport is generally beneficial; however, tradeoffs arise because vascular systems have multiple functional roles that interact with one another. One example of a tradeoff may be related to how plants respond to water deficits. Some plants growing in arid and semi-arid environments form xylem networks that are able to tolerate water deficiencies and cope with embolism spread. Distinguishing patterns in embolism spread is important to understand how plants are vulnerable to water stress and what tradeoffs are involved in water stress resistance. Flowering plants found in mediterranean-type ecosystems differ in conduit (vessels and tracheids) presence and abundance. Little is known about how embolism spreads in plant vascular systems and the role tracheids play in the spread of emboli in vessel-bearing plants. I hypothesized that patterns in vessel embolism spread are linked to the type of conduit connections. I assumed that the propagation of embolism most commonly occurs through vessel-to-vessel connections. Therefore, I predicted that the presence of tracheids minimizes embolism spread compared to species with only vessels that have greater numbers of vessel-to-vessel connections. By contrast, greater vessel-to-vessel connections promote greater hydraulic transport efficiency. To test this hypothesis, I quantified embolism spread using computer assisted tomography (microCT) and hydraulic efficiency (hydraulic conductivity per unit xylem area; Ks) in six different species of woody plants that differ in tracheid presence, vessel structure, and hydraulic function. In Chapter 1, I briefly review how plants respond to water stress and what effects have been noticed to occur within their xylem conduits as a result. In Chapter 2, I present microCT, hydraulic efficiency, and percentage loss in conductivity (PLC) results from dehydration treatments for six species native to mediterranean-type climate regions in California, Cercoparpus betuloides, Malosma laurina, and Heteromeles arbutifolia; and the Mediterranean Basin, Laurus nobilis, Olea europaea, and Cistus ladanifer. In Chapter 3, I summarize my findings in the broader context of plant vascular function. My chief conclusion is that the connections between vessels are a key determinant of the tradeoff between hydraulic safety from cavitation and transport efficiency.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Parker, Jeffrey Thomas
- Description:
- The purpose of this study is to compare the genetic distances of Mimetus hesperus and Theridion neomexicanum within and between the San Joaquin Valley and Mojave Valley regions. To my best knowledge this is the first genetic study of M. hesperus. Mountains and distance are well known barriers to gene flow in species with lower vagility. For short lived spiders, the only non-synanthropic transport method over mountains is ballooning. Ballooning spiders rely on surface area for lift, and larger spiders have a difficult time sustaining flight as they have less surface area per unit weight. M. hesperus hunts other spiders and probably has large spiderlings which make it difficult to balloon from hatching. With insufficient ballooning the Sierra Nevada Mountains should act as a barrier to gene flow for M. hesperus. I predict that comparisons between populations of M. hesperus on the same side of the Sierra Nevada Mountains will show smaller genetic distances than comparisons between populations on opposite sides of the mountains. M. hesperus and T. neomexicanum were collected from sites around the Sierra Nevada Noubtains and either died of natural causes or were humanely euthanized in <0°C ethanol. DNA was extracted and PCR was run to amplify the cytochrome oxidase 1 sununit c gene. Amplified sequences were run in two percent agaorse gel to look for banding of appropriate length and gels showing target band were purified and sent to the University of Florida for sequencing. All other bands were heavily troubleshooted and re amplified Sequence chromatograms were analyzed to ensure only pure sequences were used in analysis. Insufficient numbers of T. neomexicanum were resolved so they were used as outgroups in analyzing M. hesperus. Sequences were aligned using clustalW and cut in MEGA to ensure accurate comparisons. Pairwise distances were calculated between all specimens. A neighbor joining tree was calculated, and overall percent divergence based on collection sites, and tree groupings was computed. Character based maximum parsimony and maximum likelihood trees were calculated to confirm results seen in neighbor joining analysis. Haplotype diversity was shown by grouping all single nucleotide polymorphisms for comparison of haplotypes and by collection site and tree groupings. Genetic distance and trees reveal three distinct groupings of M. hesperus, but a permutation test found distance within populatioins from both sides insignificant, so all specimens were grouped as either east or west of the mountains. Although anecdotal at best, haplotype diversity hints that M. hesperus may have brached from the west to the east. The Sierra Nevada Mountains appear to separate populations of M. hesperus in the Central Valley and in the Mojave more than distance alone. M. hesperus populations collected over 100 miles apart on the west side of the mountains showed no significant divergence, indicating some unknown mechanism of gene flow linking these populations, but a larger sample size is needed to confirm this.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Hult, Susan Marie
- Description:
- The Blainville's Horned Lizard (Phrynosoma blainvillii) is endemic to California and ranges from northern California (Butte County), to the northwestern tip of Baja California in the southern part of its range, west of the Sierra Nevada Mountains and the southern California deserts in the eastern part of its range, and along the Pacific coast from northern Baja California to Monterey, California in the western part of its range. Phrynosoma blainvillii is listed as a California Species of Special Concern and a Bureau of Land Management (BLM) Sensitive Species. Human activities have been primarily responsible for declines in populations. There has been few field research studies published on the general ecology of P. blainvillii, particularly in the San Joaquin Valley. I initiated a radio-telemetry study to collect data on home range size and habitat use at two sites (Atwell Island and Semitropic Ridge Preserve) in the southern San Joaquin Valley, California. I calculated home range size from 10 lizards, five at each site. Using the 100% Minimum Convex Polygon (MCP) estimator I found home range sizes were between 0.58 ha to 13.93 ha, with an average size of 4.98 ha (± 1.54). When above ground and active, P. blainvillii at either site used areas of bare ground more often than expected based on equal use. At the Semitropic site, the lizards used areas under shrubs almost as often as bare ground, while at the Atwell site the lizards used areas of sparse vegetation more often than expected, but not as much as bare ground. Lizards at both sites used medium-dense and dense areas of vegetation much less than expected based on equal use. In adult P. blainvillii, we recorded a moderately skewed sex ratio of more males than females, but in young P. blainvillii, there were more females than males. Average snout-vent length (SVL) of females was 72.31 mm and for males 68.81 mm. The adult horned lizards were most active in April and May while young horned lizards were most active in August and September. In the spring, the morning activity hours peaked at 0900–1100, in summer, it was 0900–1000, and in fall, it was 0900–1300. All age classes of P. blainvillii were most often above ground and active at surface temperatures of 28–34°C. The presence of alkali flats and sandy soil correlated with a high abundance of horned lizards, and within our two study locations, they revealed a distinct preference for Sandridge loamy fine sand over other available soil types. The lizards used kangaroo rat burrows rather than shrubs for heat refugia but used shrubs frequently as an escape from predators. Food items found in scats were predominantly ants, but beetles and other arthropods were also found in large numbers.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Westall, Tory Lynn
- Description:
- The San Joaquin kit fox (Vulpes macrotis mutica) is an endangered species endemic to the San Joaquin Desert in the Central Valley of California. Much of the habitat in the San Joaquin Desert has been converted for agricultural, industrial, and urban development. The remaining San Joaquin kit foxes exist as a meta-population in several satellite populations and three core areas, the Panoche Valley, the Carrizo Plain, and western Kern County. Another substantial population that could be considered a core area is the urban population that is living in the City of Bakersfield. This population is fairly large and critical in contributing to the conservation of the species as a whole. The urban population of San Joaquin kit foxes has higher survival rates, lower dispersal potential, and higher reproductive success as well as increased incidence of philopatric young and larger family groups when compared to populations living in natural areas. The San Joaquin kit fox is a socially monogamous species, but philopatric young have been classified as Helpers because they assist in rearing future litters. Understanding how the altered ecosystem in the urban environment can affect reproductive traits of an endangered species is important for conservation. In this study I investigated the relative contributions of adult group members to pup rearing in urban San Joaquin kit foxes. My objectives were to quantify the relative time contributions of each individual, the different tasks performed by each individual, and the changes in time contributions and tasks performed by each individual as the pups aged. To quantify den attendance and behavior, I used proximity logging collars and base stations at each natal den, performed direct observations of behaviors, and set up remote camera stations at dens. I also compared these methods for efficiency in detecting behaviors. To determine role, I used behaviors and genetic analyses to classify each individual to one of three categories: Mother, Father, or Helper. To monitor changes in behavior as pups aged, I split the breeding season into three periods: Preparturition, Nursing, and Weaned. I monitored six groups at four locations in Bakersfield, California and had four groups that successfully reproduced and were consistently monitored. I found that proximity logging collars were unreliable in measuring den attendance of kit foxes. Cameras were an effective method for documenting behaviors, but they significantly underestimated the amount of time that foxes spent at the den. Direct observations were the most accurate method of gathering behavioral data and were used for analyses of parental care. I found that Mothers play a critical role in pup rearing. Mothers spend significantly more time at the den than either Fathers or Helpers. While Fathers spend most of their time away from the den, they provision the same amount of food as Mothers, whereas Helpers provisioned significantly less than either Mothers or Fathers. Mothers primarily groomed young, provisioned, guarded while young played, and performed den defense. Fathers primarily provisioned and provided den defense. Helpers mostly interacted with the pups through play, which may teach the pups the social hierarchy and establish dominance. While Helpers do not provide direct care to young, they may provide a form of insurance of parental care of young should something happen to either of the parents. Helpers are likely tolerated within their natal range because there is an increased abundance of food within the urban environment and their presence is not detrimental to the success of the current litter. I also documented two incidences of social polygyny and genetic polyandry over the course of my study. This is likely tied to the super abundance of resources because more plentiful resources result in a decreased need for paternal care and so one male can split his time between multiple litters. My results indicate that there is a decreased need for assistance in pup rearing in the urban environment due to the increased resources available. Helpers do not actually help in rearing pups and Fathers are not as necessary to successful pup rearing. Mothers play an essential role in pup rearing and are necessary for successful reproduction in the urban environment.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
17. Maternal provisioning and the effect of stress on tetrodotoxin production in terrestrial vertebrates
- Creator:
- Susbilla, Calvin Bron
- Description:
- Chemicals are often sequestered by various organisms to defend against predators by making prey noxious, and in some cases, toxic. Sequestration has been observed in various taxa, however, there are few vertebrate examples available. Further, little is known about maternal provisioning of sequestered toxins. The Asian natricine snake, Rhabdophis tigrinus, sequesters bufadienolides from toxic toad prey and allocates toxins to offspring. Likewise, the common garter snake, Thamnophis sirtalis, sequesters the neurotoxin tetrodotoxin (TTX) in its liver from newt prey. However, maternal provisioning in this natricine snake has yet to be investigated. To investigate maternal investment of TTX in T. sirtalis, gravid snakes from Benton County, Oregon were offered toxic newts for consumption. The liver of female snakes and neonates were later dissected and TTX levels were quantified using a Competitive Inhibition Enzymatic Immunoassay. Dams were found to possess TTX in their livers, whereas, TTX was not detected in any neonate liver samples.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Kelly, Erica Crystal
- Description:
- My results suggest that Desert Kit Foxes in the Mojave Desert in California prefer to consume rodents and invertebrates, but will prey upon a variety of other items, especially when preferred prey has declined due to drought or seasonal conditions. Overall, my study supported the scientific consensus that kit foxes are specialists on heteromyid rodents. Invertebrate prey, though, does provide an important supplement when rodent prey is less available. For Coyotes, the most frequently occurring items consumed were rodents and lagomorphs. Thus, Desert Kit Foxes and Coyotes did eat many of the same prey items throughout the study which could promote exploitative competition, but they did so in varying frequencies depending on the year and season.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Kalouch, Mirva
- Description:
- In order to further investigate the presence of these antibiotic biosynthetic pathways, this study focused on ten genes and the identification of genes that code for enzymes in these antifungal and antibacterial pathways; Flagellin (hag), Mucosubtilin synthetase B (mycB), Translocationdependent antimicrobial spore component (tasA), 4’-phsophopantetheinyl transferase (surfactin) (sfp, sfpA, and sfpAA), Subtilin (spaS1 and Spas2), Iturin A (ituA), and Subtilosin A (sboA) (Yang et al. 2015, Velho et al. 2013, Hassan et al. 2010, and Mora et al. 2011). I hypothesize that our 16 Bacillus samples will contain genes that are known to be involved in known antibiotic biosynthetic pathways.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Kaur, Prabhjeet
- Description:
- Coccidioidomycosis, also known as Valley Fever, is a re-emerging infectious disease of the American continent. Coccidioidomycosis is a respiratory disease caused by the inhalation of arthroconidia produced by the dimorphic ascomycete fungi Coccidioides immitis or Coccidioides posadasii known to live in soil environments as a saprophyte. Coccidioides sp. are known to thrive in loamy and highly saline soils. These fungi have the ability to form spores known as arthoconidia, which can survive the dry, hot summers. When soil is disturbed, spores become airborne and can cause infection when inhaled by a host. Recently, the incidence of valley fever has increased significantly in endemic areas of the pathogen such as the Western Mojave Desert and among the general public and has also affected prisoners incarcerated in correctional facilities, such as the one east of California City, our study area. The objective of this research was to determine the soil properties that are essential for the growth of Coccidioides immitis in the Northwestern Mojave Desert near California City. Different physical and chemical properties of soils such as soil pH and soil type are known to determine the distribution of plants, which can therefore indicate certain soil conditions, but these parameters also affect the growth of microorganisms and fungal communities in diverse microhabitats. The hypothesis of this project was that the presence or absence of the pathogen in the soil can be linked to yet to be determined environmental parameters and/or depends on the presence or absence of certain soil microorganisms that could act as antagonists to the pathogen. The physical and chemical soil parameters, as well as plant diversity were determined for each sampling site. In this study, culture independent techniques, such as DNA extraction followed by PCR and DGGE were used to detect the presence of C. immitis, and to determine the diversity of the soil fungal communities in 43 soil samples collected long several transects in 2014 and 2015. Results of this study revealed that the study area is highly endemic for the pathogen, but its presence could not be linked to specific soil parameters. The fungal diversity in the soil was generally low and showed the dominance of members of the Pleosporales and Hypocreales. Members of the fungal genus Ascobolus were only found in soils that were negative of the pathogen and could potentially include antagonists to C.immitis.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Coleman, Mitchell Lewis
- Description:
- Invasive annual grasses of mediterranean origin dominate large areas in the arid and semi-arid regions of the San Joaquin Valley in California and create numerous management challenges. Much of the invaded habitat would be native saltbush shrub communities (Atriplex spp.); however, the presence of these grasses may inhibit saltbush recruitment. One way this could occur is due to competition for water between the grasses and saltbush seedlings. Another possibility is that when invasive annual grasses die after setting seed, they leave behind a dense cover of residual dry matter (RDM) as dead shoots, which alters the habitat by shading the soil. I tested the hypothesis that grasses limit saltbush seedling recruitment, leading to persistently invaded grasslands and thereby inhibiting saltbush succession. I predicted that competition from grasses during the rainy season reduces soil moisture available to saltbush seedlings at the critical seedling stage of their life cycle. Furthermore, I predicted that the presence of dense RDM blankets formed during the dry season shades the soil and inhibits the natural succession of saltbush shrublands in the San Joaquin Valley at old-field areas. Moreover, I predicted that grass competition and RDM affects saltbush recruitment due to alterations in soil temperature, soil moisture, and light penetration to the ground. To address these questions, I used a combination of manipulative and natural field experiments to assess the factors affecting recruitment of the saltbush Atriplex polycarpa (Torr.) S. Watson. I conducted experiments manipulating the effects of invasive grass competition and RDM on saltbush seedling germination, mortality, and survival. I also conducted a number of comparative studies between six mature saltbush stands at Tejon Ranch, wherein I assessed differences in seedling recruitment, demographic composition, water relations, and soil conditions. The goal of the study was to more precisely elucidate mechanisms governing saltbush germination in the San Joaquin Valley. Overall, I found than invasive grass RDM functions to inhibit saltbush seed germination to a degree that precludes long-term seedling recruitment in the San Joaquin Valley. Competition between saltbush seedlings and the grasses during the wet season also inhibits recruitment to a smaller degree. Saltbush recruitment is affected by alterations to soil moisture, temperature, and light levels created by invasive grasses. I also found that older seedling survival is greater in grassy areas compared to native saltbush habitat, ostensibly due to higher pressures of herbivory in the saltbush habitat. This creates a seed-seedling conflict wherein seed germination is inhibited in grassy areas, but seedling survival is higher in grassy areas. Thus, field conditions with a low amount of RDM over saltbush seeds and no seedling herbivory are ideal for saltbush recruitment in the San Joaquin Valley. My findings are relevant for the conservation and management of important remaining saltbush habitat and the continued expansion of invasive annual grasses in the San Joaquin Valley and throughout the mediterranean-type climate regions of California.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Baumgardner, Aaron W.
- Description:
- Global-change-type drought has resulted in large numbers of woody plants suffering mortality in California during the most recent droughts from 2012-2018. These droughts are ecological droughts that impact ecosystems and trigger responses. The factors that trigger ecological droughts are not well established. One limitation of studies considering drought is the lack of a clear set of criteria used to define aspects of drought that should be examined when assessing the effect of drought on an ecosystem. The most common way to evaluate drought is to use indices that are calculated from annual metrics such as annual precipitation. Other indices are calculated on an ongoing basis and integrate both temperature and precipitation such as the Palmer Drought Severity Index (PDSI). In this work, I examined other climate extreme indices that can be used to understand woody plant dieoffs. For example, the number of days without precipitation and the intensity of storms, relative to long-term averages, are some factors that may be important in evaluating drought effects on woody plants. I applied these criteria to understand which factors best correspond to recent woody shrub die-offs in southern California chaparral shrublands. I hypothesized that there are aspects of droughts that: 1) drive the response of vegetation and 2) create tipping points that trigger ecological droughts. To test this, I coupled existing remotely-sensed vegetation data from satellites with weather-derived climate indices over 17 rainfall years (2000-2016) from field sites located in the Santa Monica, Santa Rosa, and Tehachapi mountains of southern California. Vegetation indices (NDVI, EVI, LAI, and fPAR) were calculated using Moderate Resolution Imaging Spectroradiometer (MODIS) data, and climate indices, in addition to PDSI, were calculated using daily summaries from PRSIM (Parameter-elevation Relationships on Independent Slopes Model) weather data. I found that the climate in our coastal study region has become more drought prone in the 30-year data set, whereas the desert region has become neither drier nor wetter. PDSI was more predictive of vegetation health than a combined, multiple climate extremes index developed in this study. Vegetation indices were lowest during the most intense drought years, but during longer-term droughts of lower intensity did not show continued decline. Coastal chaparral sites contain high biodiversity and many localized endemic species, which may be threatened by a warming and drying climate. Monitoring these regions using remotely sensed data may help to identify affected areas to inform land management agencies and conservation priorities.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Baer, Alex Benjamin
- Description:
- Xylem is a complex vascular tissue that performs several functions related to the growth and survival of woody plants. These functions include the transport of water, biomechanical support, and the storage of water and nutrients. Trees are large organisms that have a highly branched growth form that is specialized to extract finite resources from the soil, move them to the shoot, and acquire limited carbon dioxide from the atmosphere. Because trees have large bodies that must transport water over long distances of changing environments, I hypothesized that their vascular system changes at different tree positions. I examined how xylem functional traits of water storage, strength, stiffness, and xylem density changed at different positions within the roots and shoots of the model tree species Populus trichocarpa (Torr. & Gray). I predicted the following: (1) xylem functional traits changed depending on tree position, most notably between root and shoot organs; (2) within organs, xylem traits differed depending upon organ diameter or position relative to the tree base. Because different parts of the vascular system may specialize in specific ways that balance the proficiency of one trait at the expense of another, I predicted (3) there would be functional trade-offs within the xylem, especially between biomechanical and storage functions. My hypotheses and predictions were tested by analyzing xylem samples from 6 juvenile P. trichocarpa trees grown in an irrigated plot at California State University, Bakersfield. For each tree, xylem was sampled at 1 m spaced positions from base to tip of the dominant root and leader shoot. My first prediction was supported; xylem density, xylem strength, and xylem stiffness were higher in shoots and lower in roots. Xylem water storage was higher in roots and lower in shoots. Support for the second prediction depended on organ and trait, where wider organ diameter and more basal positions positively associated with xylem density, xylem strength, and xylem stiffness in roots. In shoots, more apical positions and narrower organ diameters positively associated with xylem strength and stiffness, but shared no relationship with xylem density. Xylem water storage did not correlate with organ diameter or position within roots or shoots. I found that roots and shoots appear to be specialized, with roots having greater hydraulic storage with reduced biomechanical support, and shoots having biomechanically reinforced xylem with minimal water storage. These findings support the predicted trade-off of xylem traits across organs but not within them. My hypothesis was supported: the tree vascular system changes at different tree positions. Intra-organismal examinations can be used to find trade-offs and changes in vascular systems across plant bodies. Understanding how xylem functions differ throughout tree bodies is important in understanding how these terrestrial plants can maintain towering canopies and endure numerous environmental challenges over decades of growth.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Fickle, Jaycie
- Description:
- The vascular transport system of most flowering plants is composed of vessels that are responsible for bulk axial water transport. Transport through vessels may become blocked by gas emboli following freeze-thaw events because gasses come out of solution in the vessels while freezing and these small gas bubbles may coalesce into larger emboli when stems thaw. Emboli may also form in vessels during water stress when gasses are pulled into vessels through a process termed air-seeding. Xylem vessels are not all equally vulnerable to the formation of emboli and there are specific traits that are associated with having more embolism resistant vessels. In general, the traits that confer resistance to embolism are also associated with reduced ability to efficiently transport water through the xylem. I examined and compared xylem structural and hydraulic traits of five chaparral shrub species occurring at two sites representing the lower and upper elevation distribution limits for these species along a steep transect in the southern Sierra Nevada mountains, California, USA. These sites represented the lower and upper ecotones of the chaparral community. The higher elevation site experiences more frequent freeze-thaw stress, lower temperatures, and receives more precipitation compared to the lower elevation site. I hypothesized that the environmental differences between the two sites would correlate to differences in xylem traits. I also compared traits among different organs (roots and stems) within species, as roots are buffered from freezing and thawing. Xylem vessel traits differed between species and between roots and stems but did not generally differ between the sites. Rather, the ratio of stem area to leaf area of shoots differed between sites, with plants growing more xylem tissue per leaf area at the lower site. Studies examining how traits may vary within individuals and within species have been relatively limited to date and knowledge of the structure and function differences between roots and stems is likely important in understanding whole-plant response to environmental stressors.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Deatherage, Nicole Anne
- Description:
- Human population growth and rapid urbanization have created new, attractive environments for opportunistic animals including some species of wild canids. San Joaquin kit foxes (Vulpes macrotis mutica) are a federally listed endangered and California listed threatened canid that persists in the city of Bakersfield, California, where they form a unique ecological guild with three other canid competitors: coyotes (Canis latrans), red foxes (Vulpes vulpes), and gray foxes (Urocyon cinereoargenteus). These four canids typically exhibit avoidance and/or resource partitioning due to overlapping niches, with smaller fox species avoiding attacks from more dominant foxes and coyotes by selecting alternative resources, finding refuge, occupying different habitat types, or adjusting behavior. Recent carnivore sympatry in urban areas may be due to behavioral adjustments and adaptations to complex urban environments, including heterogeneous landscape matrices and new, abundant resources. I investigated carnivore sympatry in urban environments using 5 y of remote camera survey data collected throughout the city of Bakersfield to first determine how landscape attributes within heterogeneous urban landscapes influence San Joaquin kit fox occupancy patterns, and if canid competitors (i.e., coyotes, red foxes, and gray foxes) affect San Joaquin kit fox distributions with the use of occupancy modeling. Second, I investigated how the presence of canid competitors or domestic dogs (Canis familiaris) in the same 1-km2 area affects San Joaquin kit fox spatiotemporal activity with the use of Two-way Contingency Tables, One-way Analysis of Variance, and Kruskal-Wallis tests. I found the most supported occupancy model for San Joaquin kit foxes to be an additive effect of two urban landscape attributes, percentages of paved roads and campuses (e.g., schools, churches, and medical centers) in cells. The percentage of paved roads was a negative predictor of San Joaquin kit fox occupancy while the percentage of campuses was a positive predictor. The percentage of paved roads was ultimately the most supported covariate for predicting San Joaquin kit fox occupancy (or lack thereof) in my study system. Roads are the main source of mortality for urban San Joaquin kit foxes and have greater noise pollution, development, disturbance, and human activity, which may discourage San Joaquin kit foxes from incorporating roads into their urban home ranges. Conversely, campuses have landscaping, sports yards, quadrangles, and walkways that offer open space, which San Joaquin kit foxes select for in natural habitats. These sites also afford security from excess human disturbance and larger predators due to fences and other security measures employed by campuses, as well as anthropogenic food sources from cafeterias and people directly feeding San Joaquin kit foxes. I concluded that San Joaquin kit foxes were avoiding paved roads while selecting for campuses in the urban environment. The presence of coyotes, red foxes, and gray foxes was not a contributing factor of urban San Joaquin kit fox occupancy patterns, though this may have been a result of low sample sizes of other canids compared to San Joaquin kit foxes. Apart from one association between the number of days in which San Joaquin kit foxes occurred alone and the number of days in which they occur with other canids in 2018, I found no other associations between San Joaquin kit fox and other canid occurrences in cells or on given days. I also found differences between the number of days San Joaquin kit foxes occurred alone and the number of days they occurred with another canid for all years collectively and each year individually. I concluded that urban San Joaquin kit foxes rarely occur with coyotes, red foxes, gray foxes, and domestic dogs in the same 1-km2 area within the same day, same year, or 5-y span, suggesting spatiotemporal avoidance of canid competitors. In instances when San Joaquin kit foxes and other canids did occur on the same camera on the same survey night, I found San Joaquin kit foxes delay their time to appearance following sunset by about 3 h at camera stations where another canid species appeared. Furthermore, variances in mean consecutive min that San Joaquin kit foxes spent at stations showed that they had the least predictability in the potential window of time spent at the station if another canid visited the camera station on the same night but did not appear first. San Joaquin kit foxes had the most predictability in the potential window of time spent at the station if another canid appeared first. These results indicate that San Joaquin kit foxes may require a more immediate predator presence cue than scent to perceive imminent risk from nearby competitors. Finally, my results show that if multiple canid species did occur there were never more than three, though primarily only two canids occurred in any given cell or on any given day, with a majority of co-occurrences between kit foxes and domestic dogs. Because domestic dogs are abundant in urban areas, they may not be novel or threatening to kit foxes, allowing domestic dogs and kit foxes to co-occur at higher frequencies than kit foxes and other wild canids. Additionally, where coexistence does occur, canids may only be willing to exist with one other canid species at any given time. In both analyses, I confirm that San Joaquin kit foxes occur in higher abundances than any other wild canid species in Bakersfield. San Joaquin kit foxes may be more receptive and adaptive to highly developed urban areas than other canids and are frequently observed denning in inner city landscapes; whereas past studies show that coyotes require larger, connected ranges and natural habitat, that red foxes avoid coyotes in intermediate human-modified habitats (i.e., suburbs with house densities of < 20 houses/ha), and that gray foxes select for urban edges or more natural, tree covered areas. My results also demonstrated a sizeable decrease in kit fox abundance over the years, with a 69% decrease in San Joaquin kit fox abundance at camera stations and a 40% decrease in probability of San Joaquin kit fox occupancy from 2015 to 2019. This is explained by the recent outbreak of sarcoptic mange (Sarcoptes scabiei) skin disease in San Joaquin kit foxes in Bakersfield, which is highly infectious and 100% fatal in untreated kit foxes. Overall, I conclude that while San Joaquin kit foxes rarely occur with other canid species within a 1-km2 urban area, they may require immediate predator presence cues to perceive risk from competition, while avoidance of paved roads and selection for campuses as urban landscape characteristics may be of greater importance in explaining occupancy dynamics in urban San Joaquin kit foxes. Understanding how top predators adapt to developing landscapes provides insight towards species conservation and management in urban areas, which is particularly important for the San Joaquin kit fox. Conserving the unique urban population in Bakersfield may be significant for the overall health, survival, and recovery of this species as human development is projected to continue, and upcoming conservation efforts may be particularly critical considering the current mange epidemic within this population.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Yanez, Ivette
- Resource Type:
- Thesis
- Identifier:
- 10047
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Percolla, Marta I.
- Resource Type:
- Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology