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- Creator:
- Ha, Melissa K.
- Description:
- Indirect biotic interactions can change seasonally with changes in the abundance of other community members. In this way, pollinator sharing between plant species may range from competition to facilitation depending on the seasonal pollinator community. I examined this phenomenon with experimental arrays in which flowering time of Clarkia unguiculata plants was crossed factorially with four floral neighborhood treatments including a manipulation of C. unguiculata density, arrays with other Clarkia, and arrays with plants in other genera. I measured pollinator composition, number of pollinator visits, and pollen limitation of seed set. Clarkia unguiculata plants growing with other Clarkia species (congeners) were less pollen-limited, indicated by the difference in seed set between pollen-supplemented (S) and unsupplemented (U) plants, than those growing among conspecifics in only the late season, suggesting late-season facilitation (95% CI for seed set (S-U) conspecifics = (69.9, 88.9); 95% CI for seed set (S-U) congeners= (24.8, 44.6)). The outcome of pollinator-mediated interactions thus varied temporally, and this could be due to differences in pollinator effectiveness among pollinator species rather than pollinator visit frequencies. The identities of pollinators varied between flowering times (Pearson Χ2 = 114.8, d.f. = 4, P < 0.001), and early- and late-season pollinators may have responded differently to floral neighborhoods. Evidence, for temporal variation such as found here in the outcome of an indirect interaction mediated by mutualists, offers a partial mechanism for the success of a species within a community.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
- Creator:
- Ashe, Jeremey Brandon
- Description:
- I studied fall and winter habitat utilization of Eurasian Wigeon (Anas penelope), and American Wigeon (Anas americana) using time budgets in the Sacramento Valley, California. Habitat utilization by American and Eurasian Wigeon differed only in the proportion of time spent in locomotion and vigilance. Resting, feeding, and locomotion were the top three behaviors exhibited by wigeon (American and Eurasian Wigeon collectively) during each month and in each pond. Increased feeding by wigeon from November through February suggested an increase in their energetic demands. Seasonally flooded wetlands were determined to be an important habitat for wigeon, as feeding and resting were the most common behaviors each month in these habitats. Asymmetric aggressive behavior patterns of Eurasian Wigeon toward American Wigeon suggested these wigeon species may be competing for resources. I studied the migration patterns of Eurasian Wigeon and their associations with Highly Pathogenic Avian Influenza Virus H5N1. One Eurasian Wigeon was equipped with a North Star solar-powered 16g platform transmitter terminal (PTT). I followed this bird’s two-day migration to Central Washington and, subsequently, its daily movements for the final six months of its life. Using a data base of all banded Eurasian Wigeon from 1929 to 2010, a map was constructed showing migration routes, stopovers, and a pattern of winter philopatry. In addition, oral and cloacal swabs of eight Eurasian Wigeon were taken, with negative results for H5N1.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
43. Ecogeographical and intrinsic postzygotic isolation between MIMULUS GLAUCESCENS and MIMULUS GUTTATUS
- Creator:
- Habecker, Nicole M.
- Description:
- The mechanisms by which species are formed is a central question in evolutionary biology. The Biological Species Concept has provided a framework for quantifying, via reproductive isolation, the extent of divergence between populations. The relative strengths and importance of individual reproductive isolation barriers is unclear. This study estimated the strength of ecogeographic (prezygotic) isolation and intrinsic (postzygotic) isolation barriers (genetic incompatibilities between hybrids) between the closely related annual monkeyflowers, Mimulus glaucescens and M. guttatus. Georeferenced herbarium records and environmental data were used to model each species ecological niche and to measure their habitat overlap. Reciprocal crosses between species were performed to measure hybrid seed set, germination success of the resulting seeds, biomass of F1 adult plants, total number of days to first flower (developmental rate), total flower production, ovule numbers, and pollen viability, as intrinsic postzygotic isolation. The species exhibited both ecogeographical isolation and non-reciprocal intrinsic isolation (observed in seed set, developmental rate, and ovule production). These results suggest that isolation was a result of geologic history causing divergent ecological selection, where ecogeographical isolation acted before and limited a minimum of 45% gene flow compared to intrinsic postzygotic isolation factors, which acted later and limited a minimum of 21% of the gene flow on average between M. glaucescens and M. guttatus. The morphological differences between these species may reflect their genetic differences due to local adaptation.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
- Creator:
- Clark, Elizabeth
- Description:
- MicroRNAs are important regulators of eukaryotic cellular processes and their misregulation is associated with many human diseases. MicroRNA-375, a regulator of insulin secretion in pancreatic beta cells, is misregulated in human type 2 diabetes. The aim of this study is to elucidate the regulation of microRNA-375. My hypothesis is that microRNA-375 is regulated in pancreatic beta cells through protein kinase A. With this hypothesis, I aimed to uncover fundamental mechanisms which lead to type 2 diabetes. Using bioinformatics, I identified putative binding sites in the microRNA-375 promotor for transcription factors in the protein kinase A pathway. With microRNA target prediction algorithms, I found some of these transcription factors may in turn be targeted by microRNA-375. Luciferase reporter assays indicated that cyclic-AMP increases the transcriptional activity of discrete regions of the microRNA-375 promoter. Chromatin immunoprecipitation assays revealed RNA polymerase II associates with the microRNA-375 promoter in response to cyclic-AMP. Cell treatments and real time PCR indicate that microRNA-375 is regulated by glucose and cyclic-AMP in a protein kinase A dependent manner.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
- Creator:
- Bowen, Heather L.
- Description:
- Body shape of juvenile fall-run Chinook salmon (Oncorhynchus tshawytscha) reared in a perennial stream environment were compared to juveniles reared in an ephemeral stream environment. In the Central Valley of California, habitat characteristics differ substantially between these two stream types and therefore present different challenges with respect to water discharge, water temperature, food availability, and habitat complexity. Using multivariate analyses conducted via geometric morphometrics, this study presents morphological differences observed within and between two stream types. As predicted, juvenile Chinook salmon exhibit rearing habitat-specific body shapes. Differences in juvenile Chinook salmon morphology between stream types were primarily associated with expansion of the mid-body region relative to, differences in body length. Specifically, juvenile Chinook salmon that reared in the ephemeral stream expressed increased body depth dominated by dorsal-ventral elongation of the dorsal fin-body insertion points, increased adipose fin-body dorsa-posterior angle, and increased anal fin-body ventral posterior angle. Additionally, eye position and gill opercula-body insertion points were anteriorly shifted in the juvenile body shape of the ephemeral stream. Differences between ephemeral and perennial stream environments likely influence the body shapes observed in this study, and suggest that juvenile Chinook salmon are morphologically flexible and readily adapt to rearing habitat conditions
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
- Creator:
- Reeder, William Henry Harrison IV
- Description:
- ABSTRACT DIVERSITY AND ACTIVITIES OF PHAGOTROPHIC MICRO-EUKARYOTES IN BOILING SPRINGS LAKE, LASSEN VOLCANIC NATIONAL PARK by William Henry Harrison Reeder IV Master of Science in Biological Science California State University, Chico Fall 2011 The biology of extreme environments has focused on diversity and adaptations, largely concentrating on the prokaryotic community. Only recently have investigations targeted eukaryotic diversity in extreme environments, and few studies have examined food web interactions. In this thesis, I studied the protist grazing component of the Boiling Springs Lake (BSL) food web. Boiling Springs Lake is a flooded fumarole that contains a 1.8 ha pool of pH 2.2, 52°C water in California’s Lassen Volcanic National Park. It is an NSF-funded Microbial Observatory focused on understanding the diversity and interactions of the entire microbial community. Using a combination of culture and genetic approaches, I found the major predator in BSL to be a unique vahlkampfiid amoeba capable of surviving the physical extremes of BSL. It is closely related via rRNA sequence to Tetramitus thermacidophilus, a heterolobose amoeboflagellate recently isolated from volcanic geothermal acidic sites in Europe and Russia, and an uncultured heterolobosean amoebae from the nearby Iron Mountain Mine acid mine drainage site. Transects studies showed the organism is endemic to the lake, and cysts were present at an average of ~500 viable cells mg-1 on the shoreline. The amoeba form is active up to 52 C, is a strict acidophile, and was observed grazing on native ascomycete Phialophora sp., as well as bacteria such as Micrococcus sp. Other grazing protists were identified in lakeshore environments, but were unable to grow in the extreme conditions of the lake. These include the lobose amoebae Hartmannella sp. and Acanthamoeba sp., and the kinetoplastid flagellate Bodo sp. Acanthamoeba and Bodo were acid tolerant, but could not grow at temperatures above 30C, while Hartmentalla was thermotolerant but could not grow at low pH. Microscopic analysis showed the presence of a variety of other morphotypes that I tentatively identified as ciliates, euglenids, cercozoans, and various flagellates from colder areas around the lake. However, I was not able to culture these, and no genetic identification was obtained. Additionally, I observed apparent large DNA viruses in Acanthamoeba sp. cultures, which resembled Mimivirus. While still tentative, this is possibly the first observation of a eukaryotic virus from an acidothermal environment.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
- Creator:
- Sall, Bennett R.
- Description:
- Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of this research allowed for the utilization of Landsat 5 imagery, analysis software, and ground based methods to study two northern California wild-land fires: Butte Humboldt Complex (BHC) and Butte Lightning Complex (BLC) of 2008. Multi-temporal and NDVI satellite imagery were used to visually assess levels of landscape change, under two temporal scales. Visual interpretation indicated noticeable levels of landscape change and relevant insight into the magnitude and impact of both wild-land fires. Satellite NDVI, local temperature, and precipitation time-based (1998-2010) data were incorporated to contrast pre- and post-wild-land fire vegetation response and recovery. NDVI trends may have been influenced by low precipitation, substrate flammability, and vegetation accumulation. Statistical analysis using Coefficient of Determination R2 comparison of satellite to ground based NDVI, resulted in weak linear correlations for BHC (R2 = 0.0859) and Richardson Springs (R2 = 0.3555), in contrast to a slightly negative correlation for BLC (R2 = 0.001). Normalized Burn Ratio (NBR) and delta NBR data allowed for quantitative analysis of burn severity levels. Delta NBR results indicated unburned, low severity, and low re-growth for BHC “burned center” subplots. In contrast, delta NBR values for BLC “burned center” subplots indicated low and mid to high burn severity levels. Examination pre- and post-wild-land fire vegetation demonstrated potential for wildland fires and associated influences to be detected by way of remote sensing technology.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
- Creator:
- Gilbart, Meghan
- Description:
- ABSTRACT THE HEALTH OF BLUE ELDERBERRY (Sambucus mexicana) AND COLONIZATION BY THE VALLEY ELDERBERRY LONGHORN BEETLE (Desmocerus californicus dimorphus) IN RESTORED RIPARIAN HABITAT by Meghan Gilbart Master of Science in Biological Sciences California State University, Chico Summer 2009 Horticultural restoration of floodplains recreates riparian habitat that is critical to a diversity of wildlife, including many endemic, threatened and endangered species. This type of restoration frequently occurs on highly regulated rivers, where the natural processes that shape riparian plant communities have been modified and truncated. The truncation of river processes places importance on restoration planting designs, which must consider the heterogeneous nature of the environment, complex natural vegetation structure as well as the succession of plants adapted to fluvial systems. One of the largest riparian restoration efforts in the country is along the regulated Sacramento River in the Central Valley of California, where restoration targets imperiled xii wildlife such as the federally threatened Valley elderberry longhorn beetle (Desmocerus californicus dimorphus, VELB). The VELB is endemic to the Central Valley and specializes on facultative riparian blue elderberry shrubs. As a target species of the restoration, over 96,000 elderberry shrubs have been planted in the last 16 years in a range of planting designs to create VELB habitat. The planting designs that include elderberry range from open to closed canopy communities, yet there has been no monitoring of elderberry among the different planting designs beyond the initial three-year monitoring period. Using a factorial design, I sampled elderberry shrubs across both open and closed planting designs, and in old and young sites in 23 restoration fields of the Sacramento River National Wildlife Refuge to evaluate the current health of planted elderberry and the corresponding occupation by VELB. My results indicate that open, low cover planting designs can allow elderberry to develop into larger, more robust shrubs that will reach maturity, whereas closed canopy designs likely stress elderberry shrubs and reduce living material over time. Recent VELB occupation was observed in 78% of all fields but only 21% of all shrubs searched. Beetle occupation increased with restoration age but showed a weaker and inconsistent relationship with cover. Closed canopy planting designs may attract beetles initially through chemicals released by stressed elderberry shrubs, but in light of successional changes that will take place in the planted fields over time, open canopy planting designs provide more consistent habitat. A diversity of planting designs is therefore recommended for restoration of VELB habitat, but both elderberry health and VELB occupation should be monitored over time in these sites as plants continue to age.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
- Creator:
- Layhee, Megan
- Description:
- ABSTRACT EMPLOYING STABLE ISOTOPES TO INVESTIGATE THE IMPACTS OF INVASIVE SPECIES ON HAWAIIAN STREAM FOOD WEBS by Megan Layhee Master of Science in Biological Sciences California State University, Chico Spring 2011 Anthropogenic disturbance around the world is restructuring ecosystems and changing interactions within ecological communities. In the Hawaiian Islands, one of the most significant forces of disturbance is the widespread presence of invasive species. In this study stable isotopes of carbon and nitrogen were used to examine trophic and energy flow changes occurring in Hawaiian stream communities due to biotic disturbances including invasive species. On the island of Kaua’i, we extensively sampled all members of the stream community, including primary producers and consumers, from four streams with varying levels of disturbance. The streams chosen in this study included Limahuli, Kapa’a, Hulē’ia and ‘Opaeka’a. δ13C, δ15N signatures, and trophic positions of stream members were calculated to determine differences in overall food web structure, changes to native consumer isotopic signatures, and differences in food web diversity and trophic redundancy. Comparison of streams with varying levels of disturbance showed that 1) overall food web structure varied dramatically among locations, 2) natives were nearly absent in heavily disturbed and highly invaded streams while at the same time a suite of non-native consumers are replacing the trophic roles left by the natives, 3) isotopic signatures and trophic position of native consumers were not significantly different across streams, and 4) heavily disturbed and highly invaded streams had more trophic diversity and generally lower trophic redundancy. Our study was able to quantitatively depict and compare differences in both the structure and trophic interactions of Hawaiian freshwater ecosystems webs due to varying levels of disturbance and species invasion.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences
- Creator:
- Walther, Rebecca C.
- Description:
- ABSTRACT SPATIAL AND TEMPORAL ECOLOGY OF FISH LARVAE IN SEASONAL AND PERENNIAL TRIBUTARIES OF THE SACRAMENTO RIVER, CALIFORNIA by Rebecca C. Walther Master of Science in Biological Sciences California State University, Chico Spring 2009 Many studies have shown the benefits of off-channel habitats, such as floodplains, for the early life stages of fishes, but little work has examined the differences in the abundance and distribution of fish larvae between seasonal and perennial stream habitats. To examine this, drift nets were used to compare the spatial and temporal distribution of fish larvae among two seasonal and two perennial tributaries of the Sacramento River, California, during the winter and spring of 2004. Additionally, a detailed examination of the distribution of fish larvae in Mud Creek, a seasonal stream, was conducted in 2006 and 2007. Higher temperatures and an earlier date of first occurrence of fish larvae in the seasonal streams were observed. In addition, Mud Creek produced extremely high numbers of fish larvae and had the greatest diversity and species richness xii among the four sample streams. Taken together, the findings suggest that seasonal streams in the Central Valley are used as spawning and rearing habitat, and the associated warmer water temperatures may elicit earlier adult spawning. These same factors may also contribute to increased fitness and survival of fish larvae, which in turn can enhance recruitment success and year class strength for native fishes, many of which are in decline.
- Resource Type:
- Thesis
- Campus Tesim:
- Chico
- Department:
- Biological Sciences