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- Creator:
- Yoder, Sean C.
- Description:
- The genus Mycobacterium is commonly associated with diseases such as leprosy, tuberculosis and other pulmonary infections. Mycobacterium avium is increasingly identified as a cause of disseminated disease in AIDS patients. A need for a better understanding of possible sources and routes of transmission of this organism is necessary. This study firc
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Traugh, Courtney
- Description:
- California chaparral shrubs have developed different life history types that are categorized by response to fire disturbance and that include sprouting (S) and non-sprouting (NS) species. Plants that resprout after fire (S) use carbon stored in roots and a specialized root structure termed a lignotuber to produce shoots. In contrast, non-sprouting plants (NS) are killed by fire and establish in the post-fire environment through the recruitment of seedlings from a fire-cued seed bank. Previous studies have found that NS have greater cavitation resistance than S, presumably because they must survive the hot dry summers characteristic of the Mediterranean-type climate of California at the seedling stage of development in an open-canopy environment when rooting depth is limited. The focus of this study was to examine tradeoffs between root and stem water stress resistance, carbohydrate storage capacity, and biomechanics of six evergreen NS and S species of shrubs. I predicted that S would have increased storage at the cost of reduced biomechanics and stress tolerance and that NS would have traits associated with increased water stress resistance and biomechanics at the cost of decreased storage. Carbohydrate storage was estimated by the percentage of starch during the fall and the percentages of total non-structural carbohydrates which includes starch, sucrose and glucose. Mechanical strength was estimated using xylem density and water stress resistance was estimated using cavitation resistance. Tradeoffs between traits were analyzed as correlations between traits. There were no differences in storage, xylem density, or cavitation resistance between NS and S. Among all species, there were no trade-offs between water stress resistance and biomechanics or between carbohydrate storage and biomechanics; however, there was a trade-off between carbohydrate storage and resistance to cavitation. The results suggest that allocation differences between NS and S are not strong determinants of stem and root xylem function. Other tradeoffs may be more important such as differences in growth or reproductive investment.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Metz, Mark A.
- Description:
- Two syrphine flies (Diptera: Syrphidae) were studied to measure the possible difference in the abdominal color pattern variation of sternites 2-5. Toxomerus marginatus, a non-mimetic syrphine, shows much more variation in its abdominal color pattern than Ch,ysotoxum derivatum, a high fidelity syrphine mimic of vespid wasps. Chrysotoxum derimtum also showed stability of its abdominal color pattern with little heterogeneity of abdominal color pattern types. It is assumed that organisms under strong selection pressure for a phenotypic character will show a narrow range of phenotypes for that character in a population. This study demonstrates that the homogeneity of the mimetic abdominal color pattern of Chrysotoxum derivatum is probably due to discriminatory visual predation.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- McFaddin, Joe
- Description:
- The position of the United States as a global leader in science and technology is being undermined, not by out-competing nations, but by the waning development of domestic science talent (NSB 2002; NSB 2003). Even though demand for professionals in science fields will outpace many other career fields (Dohm and Schniper 2007; NSB 2010), there is a projected shortfall of educated professionals resulting from low enrollment in science-based college programs (NSB 2002) and the problem is further compounded by large numbers of science and engineering retirees in the coming decade (NSB 2002). Also, United States students have not exhibited the best performance in core science subjects when compared internationally (Gonzales et al. 2008; Baldi et al. 2007) and domestic programs have not produced consistent improvements in science proficiency (Rampey et al. 2009). Science Technology Engineering and Math (STEM) initiatives are increasingly becoming perceived as a remedy for promoting early development in STEM-fields and increasing student preparation for entrance into STEM-related degree programs. Upon receiving a large amount of federal and corporate sponsorship, the Taft College STEM Program was initiated in 2009 and began outreach and associated program development within the Taft College campus as well as at K12 schools in the College’s service area. The Mobile Science Center (MSC) was conceived as an innovative tool that would house a Mobile Mission Command Center for the Goldstone Apple Valley Radio Telescope (GAVRT). While physics-based curriculum was prepared for engaging students in the use of the GAVRT, additional curriculum was developed for promoting learning in other STEM-subjects. Two modules, Forensic Science and Alternative Energy, were developed for implementation in local K-12 programs. This paper highlights the development and implementation of STEM curriculum for the MSC and includes an assessment of the effectiveness of STEM curriculum implementation in two test groups from Lincoln Junior High School and Taft College. In general, initial results do not support an improvement in student performance as determined by pre-post test analysis (Taft College p=0.19; Lincoln Junior High School p=0.053); however, there were indicators that future implementation has a high potential to yield positive measurable outcomes. 1
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- 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:
- Lewis, Ryan D.
- Description:
- Purpose of the Study: The endangered Sonoma County population of the California tiger salamander, Ambystoma californiense, undergoes migrations between breeding pools and upland dry-season refugia. Orientation in this species during breeding migrations has been addressed minimally in previous studies, and literature is particularly sparse concerning newly metamorphosed juveniles. Previous works have not addressed the ability of metamorphs to orient or the way in which they search for upland refugia. The purpose of this study is to evaluate if California tiger salamander metamorphs can re-orient during initial migration and if search movements constitute a Correlated Random Walk. Procedure: We evaluated fine scale movements of newly metamorphosed California tiger salamanders as they moved away from breeding pools, by capturing salamanders with a drift fence. Metamorphs received different orientation treatments, and subsequent movement was tracked with fluorescent powder. We measured turning angles and step lengths at each segment of the tracks, and compared the effect of different treatments. Findings: Here we show that newly metamorphosed juveniles can re-orient to their upland migration path after being interrupted and disoriented. Further, we demonstrate that while searching for burrow refugia, metamorph movement is a correlated random walk. Conclusions: The initial migration from natal pools to uplands following metamorphosis has been identified as a crucial life history juncture for the persistence of this species. Our findings show that these migrations are directed by some orientation, and that these movements are not random. The presence of a Correlated Random Walk is consistent with search patterns in many vertebrates.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- 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