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- Creator:
- Kalt, Jennifer L.
- Description:
- Five species of western gooseberries (Ribes: Grossulariaceae) hybridize to varying degrees in northwestern California and southwestern Oregon. Pollinator surveys and hand-pollination experiments were conducted to identify reproductive barriers between the species pairs. I found little evidence of isolation due to pollinator behavior, since the five species tended to attract the same pollinators. My attempts to assess the level of post-pollination isolation were hindered by high rates of fruit abortion. Nevertheless, it appears that R. roezlii and R. menziesii are fully interfertile, and that unilateral barriers operate when R. lobbii, which has the longest styles of the set, is the maternal parent in crosses with the other species. Since the level of post-pollination isolation is not correlated with the observed frequency of hybridization in the field, ecological and/or geographical differences may play the most important role in isolating the species.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Humboldt
- Department:
- Biology
- Creator:
- Sinnott, Aaron M.
- Description:
- Potential long term neurocognitive (NC) and psychological effects from exposure to concussive and subconcussive forces are of growing international concern. Athletes with a history of prior concussions exhibit lower objective performances and higher symptom reporting when compared to those with fewer injuries. Due to this observation, researchers have hypothesized a dose-response relationship between concussion history and decrements in NC function. For this study, we hypothesized an association between a history of multiple concussions and NC deficits in current soccer and football participants. Those with three or more concussions were predicted to perform worse than those with no prior injuries before an athletic season and experience NC decrements after a season. Athletes (n=101) from 5 high schools and one NCAA Division II university in Humboldt and Del Norte Counties were administered a computerized neurocognitive test with related demographics (ImPACT) and asked to self-report symptoms (PCSS) immediately before and after a competitive athletic season, and were administered an additional survey related to concussion history postseason. A FOUR (concussion history-0, 1, 2, 3 or more) X TWO (time- preseason, postseason) MANOVA was used to analyze ImPACT composite and PCSS scores between the concussion groups and between preseason vs. postseason. Athletes with three or more concussions (n=13) did not obtain lower preseason (baseline) scores than athletes without a history of concussion (n=53) and there were no significant changes from preseason to postseason composite scores across any concussion group. While findings from this study did not show significant changes in NC scores after a single competitive soccer or football season, there were observed trends that shed light on the importance of comprehensive large scale longitudinal studies.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Humboldt
- Department:
- Kinesiology
- Creator:
- Ryan, Desiree, Kiewel, Laura, Galioto-Marquez, Angela, and Axthelm, Kashia
- Description:
- Idealism is defined as believing that desirable consequences can, with the “right” action, always be obtained. This involves decreasing the amount of negative outcomes and increasing the amount of positive outcomes. Due to the lack of a reliable and valid existing measure of idealism, our goal was to create a psychometrically sound scale. Morality and justice are two important domains that were addressed during item creation. The HIQ was compared to the Global Belief in a Just World Scale in order to establish criterion validity; the short form of the Marlowe-Crowne Social Desirability Scale was used for discriminant validity.
- Resource Type:
- Poster
- Campus Tesim:
- Humboldt
- Department:
- Psychology
- Creator:
- Diamond, Nancy
- Description:
- Adult female Dungeness crabs (Cancer magister) can be inseminated only while in a soft-shell condition immediately after molting. Population modelers have therefore assumed that all adult female Dungeness crabs undergo an annual molt. Based on this assumption, a tag-recovery project was initiated in northern California to determine demographic statistics of the adult female stock. Of 12,037 adult female crabs tagged and released, recoveries of 492 crabs in the commercial fishery showed that a large proportion of adult female Dungeness crabs fail to molt annually and that extrusion of viable eggs does not require annual molting and mating. A size-specific annual molting probability estimator was developed which accounts for commercial gear selection biases. Estimates using this technique showed that annual molting probabilities decline with increasing adult female size and become zero above 155 mm. Therefore, size and age are weakly correlated. Size-related population statistics are probably more meaningful than age-related statistics because molt increments and molting probabilities appear to be more dependent on size than age. Width frequency distribution separation failed to allow year class strength extraction and size-specific survival rate estimation. However, comparisons of width frequency histograms across years show apparent variation in year class strength. Tag-recoveries provided an annual survival rate estimate of 0.2 for crabs fully vulnerable to the commercial gear (> 155 mm). Truncation of width frequency distributions over larger female sizes suggests that survival rates for smaller female crabs are greater. The extremely low survival rate and the cessation of molting for large adult females imply that adult female Dungeness crabs may become senescent after reaching a terminal size.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Humboldt
- Department:
- Fisheries
- Creator:
- Olivarria, Sarah, Shine, Zahra, and Kissinger, Megan
- Description:
- Although college students have access to many free or low-cost services, a majority do not take advantage of these resources. For decades, researchers have sought solutions to this misalignment of service availability, need, and utilization. Impeding this goal is the lack of a sufficiently broad psychometric instrument that can measure and predict help-seeking in an individual. At this time, no such measure currently exists. The purpose of this study was to develop the College Help-Seeking Behavior Scale (CHSB) to assess college students’ intention and past behavior regarding seeking help from social networks and on-campus services for various problems.
- Resource Type:
- Poster
- Campus Tesim:
- Humboldt
- Department:
- Psychology
- Creator:
- Torgerson, Ted J.
- Description:
- Scent-marking, the deposition of a scent-containing excretion as a means of intraspecific olfactory communication, is common among mammals. For the North American river otter (Lontra canadensis) the latrine serves as a primary area for scent-marking where they regularly deposit scat, urine, and anal sac secretions. Latrine sites provide an efficient means for the indirect study of river otter ecology. This study was conducted on the river otter population located in the Humboldt Bay region of northern California. There were two main areas of focus: the evaluation of otter latrine site selection and examining trends in scent mark deposition at latrines. Paired logistic regression was used to compare models of habitat characteristics present at latrine sites to those at nonlatrine sites, identifying features selected for by river otters in the establishment of latrines. River otters selected for the presence of fallen logs as well as greater water depths and shore heights for the establishment of latrines across the study area. In more forested habitats, greater canopy cover was also selected for latrine establishment. The number of otter scent marks occurring at latrines located in different habitat types was recorded biweekly over the course of a year. Latrine use was compared among habitats using Poisson regression in a mixed model approach, testing the hypothesis that seasonal patterns of habitat use by river otters existed within the study area. Overall trends in seasonal scent mark deposition by river otters at latrines were similar to those found in previous studies, with peaks occurring in the spring and fall. Results suggested that seasonal fluctuations of several prey species influenced the use of habitats by river otters. Information gained through this study may benefit future research efforts by speeding the process of locating river otter latrines, allowing search efforts to focus on areas containing habitat features selected by otters. Seasonal peaks in scent-mark deposition at latrines may also provide optimal times for locating latrine sites and collecting scent marks for use in diet or demography studies. Evidence of seasonal habitat use by river otters provides insight into otter ecology and may also aid future research and land management activities.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Humboldt
- Department:
- Wildlife
