Biology Commons^™

Dissolved Organic Matter Influences The Timing Of Embryonic Development Of The Purple Sea Urchin, Strongylocentrotus Purpuratus., Corbin J. Hodges

Master's Theses

Marine dissolved organic matter (DOM) comprises one of the largest carbon reservoirs on earth and has long been considered a potential energy source for marine invertebrates. The importance of DOM transport has been adequately demonstrated for unicellular organisms, where DOM can meet 100% of an organisms energy needs, but the effects of DOM uptake for marine metazoans are less well understood. In this study, three general areas involving the influence of DOM transport to marine invertebrates were explored. First, we assessed the effects of using seawater exposed to high intensity ultraviolet radiation (UVR) on the study organism; embryos of the …

Sex And Microhabitat Influence The Allocation Of Mycosporine-Like Amino Acids To Tissues In The Purple Sea Urchin, Strongylocentrotus Purpuratus, Sarah A. Gravem

Master's Theses

Field surveys of Strongylocentrotus purpuratus demonstrated that concentrations of natural sunscreens, mycosporine-like amino acids (MAAs), were higher in females than males for both gonadal and epidermal tissues, increased in ovaries as spawning season approached, and were influenced by the sea urchins’ microhabitat. Sea urchins occupying burrows, or “pits”, had lower concentrations of MAAs than those outside pits, suggesting a trade-off between physical and UV protection. Overall, UV irradiance did not influence MAA accumulation in gonadal tissues. However, males increased their allocation of MAAs to epidermal tissues in the microhabitat with the highest irradiance. Relative concentrations of individual MAAs were similar …

Mimicking Fire For Post-Mining Restoration Success, Katherine M. Wilkin

Master's Theses

This study is based at Rocky Canyon Quarry (RCQ), a 200-acre granite aggregate open-pit quarry with chaparral-dominated plant communities located in San Luis Obispo County, CA. At RCQ, the Surface Mining and Reclamation Act (SMARA) of 1975 was interpreted as restoring the landscape to native plant communities. Native plant community restoration projects have occurred there since 1993 through cooperation with California Polytechnic State University Biology Department in San Luis Obispo, CA. I evaluated past restoration at RCQ and researched new techniques to improve chaparral restoration based on the natural processes of fire.

Chaparral is an important fire-dominated plant community within …

Impact Of Weed Management Practices On Grapevine Growth, Yield Components, Plant And Arthropod Abundance, And Carabid Seed Predation In Paso Robles Vineyard, Paolo Sanguankeo

Master's Theses

In the Central Coast of California, USA, wine grape growers are making efforts to identify weed control practices that promote biodiversity in their vineyards while maintaining yields. A field study was conducted in Paso Robles, CA in 2006 and 2007 evaluating the effect on Zinfandel grape-vine growth and production, groundcover plant, and ground dwelling arthropod communities of five weed control practices: 1) flumioxazin, 2) simazine, 3) cultivation, 4) cover crop, and 5) untreated control.

The herbicide treatments had the lowest weed biomass followed by the cultivation, being approximately 10 and 2 times lower than the weed biomass of either the …

Exposure To Ultraviolet Radiation Causes Proteomic Changes In Embryos Of The Purple Sea Urchin, Strongylocentrotus Purpuratus, Joseph Paul Campanale

Master's Theses

The amount of solar ultraviolet radiation (UVR, 290-400 nm) reaching Earth’s surface is increasing due to ozone depletion and global climate change. Embryos of the purple sea urchin, Strongylocentrotus purpuratus, provide an ideal system for examining how UVR affects developing marine organisms and cells in general. To model the protein-mediated cell cycle response to UV-irradiation, six batches of S. purpuratus embryos were exposed to UVR, monitored for delays in the first mitotic division and examined for global proteomic changes. Embryos from each batch were exposed to or protected from artificial UVR for 25 or 60 min. Embryos treated with …

Spatial, Seasonal, And Size-Dependent Variation In The Diet Of Sacramento Pikeminnow In The Main Stem Of Chorro Creek, Central Coast California, Brian G. Dugas

Master's Theses

This study examined the diet composition of ninety-nine Sacramento pikeminnow (150-410 mm [5.9-16 in] fork length [FL]) collected from the upper and lower main stem of Chorro Creek, Morro Bay Watershed, California in 2006. The goal of this study was to characterize the spatial and seasonal variability in the diet of Sacramento pikeminnow within Chorro Creek and to determine what proportion of the diet is represented by rainbow trout (Oncorhynchus mykiss) and their anadromous form (steelhead). Prey was identified in 88% of the samples collected in the early season and 84% of the samples collected in the late season. Fish …

Investigating The Roles Of Ndj1 And Tid1 In Distributive Segregation Using Non-Exchange Chromosomes, Jonathan V. Henzel

Master's Theses

Meiosis is a specialized cell division that leads to a reduction of ploidy in sexually reproducing organisms through segregation of homologous chromosomes at the first meiotic division. Improper segregation of chromosomes during meiosis results in anueploidy, which is usually fatal during embryonic development. The meiotic process is therefore tightly regulated. Typically, proper segregation of homologs at meiosis I requires pairing of homologous chromosomes, followed by crossover recombination between homologs. Crossovers enable proper chromosomal segregation during the first meiotic division in part by establishing tension in the meiotic spindle. However, in the absence of crossovers, some cells maintain the ability to …

The Relationship Between Plasma Steroid Hormone Concentrations And The Reproductive Cycle Of The Northern Pacific Rattlesnake, Crotalus Oreganus, Craig Michael Lind

Master's Theses

To gain a better understanding of the role of steroid hormones in vertebrate reproduction, we quantified steroid hormone concentrations in a free ranging population of the Northern Pacific rattlesnake, Crotalus oreganus. Plasma steroid hormone concentrations were quantified for both male and female snakes throughout the active season (Mar-Oct). We measured testosterone (T), 5α-dihydrotestosterone (DHT), and corticosterone (B) concentrations in male and female snakes. 17β-estradiol (E2) and progesterone (P) were measured in females only. We also observed breeding behaviors (e.g. consortship, courtship, and copulation) in the field and measured testis and follicle size in male and female snakes from museum collections. …

Effects Of Experience On Maternal Behavior In Belding’S Ground Squirrels (Spermophilus Beldingi): Older And Wiser?, Mikael Langner

Master's Theses

Maternal behavior is an important behavior because it influences whether or not raising one’s offspring is successful. Maternal experience is positively correlated with successful maternal behavior. This association is evident when comparing first-time mothers with mothers who have prior experience raising young. Life experience not related to raising young can also positively influence maternal behavior. In this work, the hypothesis that is tested is whether or not maternal experience enhances the ability of a female to assess the threat level of a situation. The model species used to conduct the study is the Belding ground squirrel (Spermophilus beldingi), …