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- 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:
- Stevens, Samantha K.
- Description:
- Purpose of the Study: The Russian River watershed stretches across a significant portion of Sonoma and Mendocino counties, covering 1,485 square miles, and is home to not only humans, but countless fish and wildlife species as well. The Russian River valley is famous for being an ideal place to grow wine grapes and other agriculture, in part for its fertile soil, as well as the region’s Mediterranean climate. In addition to this, the Russian River is a year-round recreational hotspot for both tourists and locals alike. Maintaining a high quality of water in any area is important, and this is especially true when the local economy relies so heavily upon surface water. According to the North Coast Regional Water Quality Control Board, the entire Russian River watershed is impaired for sediment and temperature, and recent data also show pathogen impairment throughout the watershed. The Laguna de Santa Rosa sub-watershed is also impaired for phosphorus and dissolved oxygen, in addition to the impairments throughout the watershed (Russian River Watershed Overview, 2019). Land uses and water quality are interconnected in the Russian River watershed, but causal patterns between the two are not well understood. Procedure: Water quality data was obtained via the United States Geological Survey (USGS) and input into Microsoft Excel to generate time series graphs of different water quality constituents. The three sites selected are Jimtown, Digger Bend, and Hacienda Bridge. A model from the USGS ScienceBase inventory was utilized for this project, which consists of future land use, land cover, and population projections for the state of California for the period of 2001-2101. This model was projected as a layer in ArcGIS Pro in order to estimate the land cover changes based on low, medium, and high population projections for the years 2050 and 2100. In order to estimate the nutrient input for these different scenarios, models were constructed using WikiWatershed’s Model My Watershed tool. Within Model My Watershed, the land cover was altered to emulate the six models by adding polygons of the desired land cover, running the model, and observing the resulting nutrient and total suspended sediment load output. An additional aspect of this project is to conduct an analysis of policies. Findings: As land is developed into managed cropland, nutrients are typically added in order to increase production and profit. As a result, the runoff from cropland is typically nutrient rich when infiltration rates are low. Records from the Sonoma County Crop Reports indicate that the acreage of vineyards nearly doubled between 1990 and 2000. The exploration of potential land use and land cover changes through the projection of the USGS ScienceBase layers in ArcGIS and the modeling of nutrient load in Model My Watershed showed both an increase in agricultural land use as well as an increase in nutrient load, which is expected. The data obtained from the USGS Water Quality monitoring site did not show many points of interest or concern and generally followed a seasonal pattern. The policies in place in Sonoma County regulate both point source and non point source pollution, which is an extremely effective way to minimize polluted runoff from entering the streams and river in the Russian River watershed. The federal, state, and county regulations seem to be adequately minimizing point source agricultural pollution, and could benefit from increased riparian vegetative buffer zones to help slow the flow of polluted runoff, increase infiltration, and minimize the amount of nutrients that reach the waterways throughout the watershed. Conclusion: While this project did not result in a definitive answer as to what is causing the most nutrient pollution in the Russian River watershed, based on the findings of project, it is safe to speculate that total loads of suspended sediment, nitrogen, and phosphorus were lower throughout Sonoma County when there was less agricultural land use since the modeling data predicts higher total loads as agricultural land use increases. In addition to an increase in vineyard, the Sonoma County Crop Reports recorded a two - fold increase in the number of cattle in the county between 1990 and 2018.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Sperou, Emily S.
- Description:
- Purpose of the Study: Long-lived iteroparous females may suppress reproduction during unfavorable conditions to maximize lifetime reproductive success. Capital breeders must accrue sufficient body reserves to support reproductive effort or they may exhibit reproductive failure. The basis of these reproductive decisions is not well understood. Northern elephant seals are seasonal, colonial breeders with a period of embryonic diapause and biannual foraging trips divided by a breeding and molting haul out. Being capital breeders, they use the post-breeding foraging trip to recover body mass lost during lactation and the gestational foraging trip to accumulate resources for lactation. Females exhibit high natality, roughly 15% of females skip breeding each year. A previous study suggested alteration in baseline cortisol concentrations may be the proximate mechanism linking foraging success and reproductive suppression, but evidence of an interaction between cortisol and reproductive hormones is currently lacking. Procedure: We investigated a suite of reproductive hormones (progesterone, 17β- estradiol, inhibin A, prolactin) and cortisol, to determine patterns across life-history stages. We analyzed 1,029 serum samples from 441 adult female NES during their biannual haul outs. Included in this dataset were 30 females known to have skipped breeding. Findings: The data confirmed a highly seasonal pattern to changes in sex hormones. Estradiol and inhibin were high during the late breeding haul out, suggesting the timing of ovulation. Progesterone was highest at the end of the molt, indicating implantation had occurred. Path analysis revealed strong influences of estradiol and prolactin on progesterone, indicating these three hormones are key for implantation. Individual variation suggests important regulatory roles for prolactin, inhibin, and cortisol in modulating implantation. The data suggest that some females suppress implantation under the modulation of cortisol and inhibin. Most females that skip breeding appear to implant but fail to maintain gestation. Conclusions: Failure to recover body reserves from the preceding reproductive event may inhibit implantation, but most non-breeding females fail to maintain pregnancy during the gestational foraging trip. This bet-hedging strategy is likely one component of a capital breeding life-history that buffers females against short-term changes in foraging success, but limits fitness costs to reproduction through multiple check-points for body reserves.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Hudson, Daniel
- Description:
- Purpose of the Study: To understand male and female mate choice patterns affecting species and gender recognition via long distance chemical cues, this study examined the rough skin newt, Taricha granulosa, in both pond and creek habitats. Response to chemical cues of males vs. females was examined for T. granulosa, whereas the California newt (Taricha torosa), and the red-bellied newt (Taricha rivularis) were used to examine how T. granulosa would respond to heterospecific chemical cues as compared to conspecific cues in a region of the species’ ranges where all three species occur in sympatry. Methods: To simulate mate choice decisions in nature as closely as possible, we conducted behavioral experiments in the field using a Y-maze apparatus (olfactometer). All trials were run in the field using unique individuals. Data were combined across multiple years. Mate choice was analyzed using a nominal logistic regression model accounting for variation among year, researcher, Y-maze apparatus, sex, and species. Findings: T. granulosa females chose chemical cues of conspecific males significantly more than heterospecific males, whereas males showed no preference between chemical cues of conspecific and heterospecific females. In addition, T. granulosa males chose chemical cues of conspecific males over conspcific females, whereas females showed no preference between chemical cues of conspecific males and females. Conclusions: The results of this study support long-standing theoretical paradigms that males, who have less parental investment in offspring will adopt a strategy of seeking matings with females regardless of quality, whereas females, with greater levels of parental investment, will engage in a more discriminating mate choice strategy. In this case, females use chemical cues to avoid heterospecific males during breeding season encounters and reduce wasting her singular mating event on an act of hybridization. A result of this mating strategy is that reinforcement of reproductive isolation is maintained in this region of sympatric range overlap. In contrast, will mate with any female across multiple mating events, and use chemical cues to either locate females or to avoid other males (or both).
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Tercero, Anthony D.
- Description:
- The perciform suborder Notothenioidae is comprised of Antarctic and sub-Antarctic fishes, several of which have lost their ability to rapidly upregulate major heat shock proteins (HSP’s) in response to thermal stress. In fact, some notothenioid species have instead adopted a pattern of expression resembling ancestrally constitutive genes. It is possible that evolution in the Southern Ocean has selected for increased expression of molecular chaperones given the denaturing effect extreme cold temperature has on proteins. The selective pressures of the sub-zero water may have also favored duplication events that bolster quantitative output of chaperones via gene dosage effects. Given that newly duplicated genes are under more relaxed selective pressures, it is plausible that gene duplication preceded alterations in the regulatory regions of the inducible HSP genes, enabling altered regulation of such highly conserved gene products. To test for evidence of these mechanisms, gene copy number of ancestrally inducible and constitutive isoforms within the major heat shock gene families were characterized via qPCR and compared for the Antarctic notothen Trematomus bernacchii, which has lost the inducible HSR, and the non-Antarctic notothen, Notothenia angustata, which has maintained an inducible HSR. Results indicate duplication of inducible isoforms within the Hsp70 and Hsp40 superfamily have occurred in the genome of T. bernacchii. The findings from this study suggest adaptive gene duplications may have played a role in maintaining increased protein folding efficiency in the sub-zero waters of the Southern Ocean and provided a mechanism for the evolution of alternative regulation of these conserved gene families.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Rzucidlo, Caroline L.
- Description:
- Purpose of the study: Adipose tissue is essential to endotherms for thermal regulation and energy storage as well as functioning as an endocrine organ. Adipose derived hormones, or adipokines, regulate metabolism, energy expenditure, reproduction, and immune function in model systems but are less well studied in wildlife. Female northern elephant seals (NES) achieve high adiposity during foraging and then undergo natural prolonged fasts while breeding, lactating, and molting, resulting in large changes in adipose reserves. Procedure: We measured circulating levels of four adipokines, leptin, resistin, adiponectin, and kisspeptin-54, in 196 serum samples from female NES at the beginning and end of their breeding and molting fasts. We examined the relationships between these adipokines and life history stage, adiposity, mass, cortisol, and the immune cytokine interleukin 6 (IL-6). Findings: All four adipokines varied with life history stage. Leptin concentrations were highest during the beginning of the breeding haul-out and resistin concentrations were higher throughout the breeding haul-out compared to the molt haul-out. Adiponectin was highest during the beginning of both haul-outs and kisspeptin-54 concentrations were highest during the end of the breeding haul-out. Leptin, resistin, and adiponectin were associated with measures of body condition, either adiposity, mass, or both. Resistin, adiponectin, and kisspeptin-54 were associated with circulating cortisol concentrations. Resistin was strongly associated with circulating IL-6, a multifunctional cytokine associated with the innate immune response. Adiponectin was associated with glucose concentrations and may be a driver of tissue-specific insulin sensitivity during life history stages categorized by high adiposity. Increased cortisol concentrations late in lactation were associated with increased kisspeptin-54 which may play a role in initiation ovulation in NES. Conclusions: This study suggests dramatic changes in circulating adipokines with life history and body condition that may exert important regulatory roles in NES. Differences from biomedical model systems suggest the potential for modifications of expression and function of adipose-derived hormones in species that undergo natural changes in adiposity as part of their life-history.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- O’Gorman, Cory James
- Description:
- Purpose of the Study: California black oak, Quercus kelloggii, plays an important role in the lifeways of many indigenous tribes throughout California. Native peoples tend black oaks using Traditional Ecological Knowledge (TEK) to encourage the development and proliferation of specimen oaks. These mature, large, full crowned trees provide a disproportionate amount of ecosystem services, including acorns and habitat, when compared to smaller black oaks. Altered approaches to land management and the cessation of frequent low intensity cultural burns places these specimen oaks at risk from encroachment, forest densification, and catastrophic fire. Procedure: This project is a collaboration between Sonoma State University and the Native Advisory Council of Pepperwood Preserve. Data were collected from 55 specimen black oaks at Pepperwood Preserve in north east Sonoma County. Ecological variables were measured to identify abiotic and biotic drivers of growth habit, scorch height and fire fuels. A certain crown shape is desired by many of today’s traditional gatherers including those represented on the Pepperwood Native Advisory Council. Findings: Encroachment was found to have a significant negative effect on both canopy area (p=0.0027) and live crown ratio (p=0.0378). Encroachment did not affect surface and ladder fuel load accumulation since the Tubbs Fire in October 2017 (p>0.05). Neither surface and ladder fuels nor encroachment variables significantly affected scorch height on the specimen oaks (p>0.05) following the Kincade Fire. Conclusions: This work will allow for the reimplementation of TEK to nurture specific specimen black oaks at Pepperwood Preserve at the discretion of the Native Advisory Council and increase access to land and culturally significant plants by local tribal communities. This has far reaching implications on tribal peoples’ well-being, their ability to engage in cultural practices, and ecosystem health.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Molinaro, Holly
- Description:
- Hamadryas baboons (Papio hamadryas) live in a complex multilevel social system with the one-male-unit (OMU) at the core. OMUs consist of an adult alpha male with one or several adult females, their dependent offspring and sometimes a few follower males. Previous research has documented that OMUs form in four distinct ways in wild populations. In December 2015, Oakland Zoo introduced two juvenile males into the hamadryas baboon exhibit. At the time of this study, these males were approaching sexual maturity. The complex social structure of this species and the changing social dynamics that might result as they reach sexual maturity provide a unique opportunity to utilize social network analysis (SNA) methods to examine OMU formation in a captive setting with an eye towards potential management strategies. SNA is a visualization method of looking at social data that allows researchers to understand sociality in terms of the importance of each individual, any subgroups, as well as the larger overall group dynamic. Behavioral and proximity data were collected over a six-month period (July- Dec 2019). These data were then transformed into networks to analyze the two now subadult males’ behavior over time and the presence of any subgroups. I found that one of the subadult males formed his first OMU following one of the four pathways found in wild studies. Despite changing group dynamics, overall group cohesion remained unchanged. This study reveals hamadryas OMU formation patterns in captivity as well as suggests potential welfare management issues that might arise.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Hernandez, Manuel
- Description:
- Purpose of the Study: Understanding impacts of invasive pathogens and wildfire on forests is a major challenge facing scientists, land managers, and policymakers. In this study, I used a long-term plot network in eastern Sonoma County to disentangle the interactions among an exotic pathogen (Phytophthora ramorum), fire fuels loads and climate in oak woodlands. I investigated the interactions among: 1) sudden oak death (SOD) inoculum loads, disease prevalence and pre-fire surface and ladder fuel loads, 2) surface and ladder fuel loads and canopy condition, and 3) canopy condition and post-fire surface and ladder fuel loads. Procedure: From 2004-2016, measurements of disease prevalence, tree growth, tree mortality and tree survival were collected for the three most abundant SOD host tree species: coast live oak (Quercus agrifolia), California black oak (Quercus kelloggii), and California bay laurel (Umbellularia californica). In 2014, surface fire fuel loads were quantified, and airborne Lidar data were collected. Elevation, slope, average potential solar insolation, and topographic moisture index, and climate water deficit were also calculated for these plots to determine the interactions of microclimate and topography on pre-fire fuel loads. In 2019, I recorded tree mortality and survival of these same species and quantified surface and ladder fuel loads across 33 plots (15 x 15 m) with a range of burn severity following the 2017 LNU Complex Fires. To analyze the interactions among abiotic and biotic factors over time I created a hypothesized pathway to describe potential direct and indirect effects of oak mortality, disease load, microclimate, topography, climatic water deficit, pre-fire fuel loads, and canopy condition on post-fire fuel loads. I tested this pathway using a path analysis. Findings: I found that P. ramorum disease load had no effects on pre-fire fuel loading. However, oak mortality in 2014, indirectly affected by P. ramorum disease load, significantly increased the amount of large surface fuels, and decreased ladder fuels. Plot elevation and maximum temperature also had a positive correlation with pre-fire ladder fuel amounts. Pre-fire ladder fuels, in concert with drought intensity and slope interacted to effect canopy condition post-fire (in particular, percent canopy damage). Percent canopy damage was greater in less sloped plots with greater amounts of ladder fuels and increased drought severity. Pre-fire ladder fuels also had a significant direct effect on post-fire ladder fuels, whereas increased amounts of post-fire ladder fuels were observed in less-sloped plots with greater amounts of pre-fire ladder fuels and more percent canopy damage. Surprisingly, plots with increased fire severity due to increased fuels had increased re-sprouts and re-growth of U. californica trees immediately following fire. Conclusions: Current management practices in oak-woodlands include the removal of U. californica in the presence of oaks to reduce the potential P. ramorum inoculum load. My results support this practice, as SOD indirectly increases fire fuel loads, which may in turn increase both the future susceptibility of the ecosystem to fire and the severity of these future wildfires.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Ghavamian, Yasmeen
- Description:
- All zoos grapple with challenges of keeping captive animals engaged in natural behaviors, especially for bears which prove to be among the more challenging species to keep stimulated. In captivity, a common indicator of poor welfare is the presence of stereotypic behaviors. In this study, we test whether providing increasingly complex feeding enrichment decreases the duration of stereotypic behavior and increases enrichment interaction for three adult female sun bears (Helarctos malayanus) at Oakland Zoo in California. We compared the effects of two different feeding enrichment devices- presented to the bears at three complexity levels- on sun bear stereotypic behavior. After three weeks of baseline data collection when no complex enrichment was present, we introduced the complex enrichment three times a week per level over six weeks. In addition, we measured each bear’s interaction with the enrichment devices to examine the effect of complexity on enrichment use. Providing increasingly complex enrichment decreased the duration of stereotypic behavior when compared to the baseline phase. Across the six weeks, the duration of stereotypic behavior was significantly less on the complex enrichment days compared to the days when complex enrichment was absent. Increasing enrichment complexity had variable effects on enrichment use. Our results indicate that providing complex enrichment decreased the duration of stereotypic behaviors, however, the effects of complex enrichment did not carry over on the days when the enrichment was no longer present. These results suggest that providing increasingly complex enrichment may have a positive influence on the behavior of captive bears.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology