Habitat fragmentation can have negative effects throughout an ecosystem, but its impact is dependent on the spatial scale at which community members respond to the environment. Because solitary bees are central-place foragers, their access to floral r . . .

Oct4 is a POU class V transcription factor that functions to maintain the pluripotent state of embryonic stem cells by activating or repressing the transcription of hundreds of target genes (Boyer et al. 2005). Aberrant expression of Oct4 has been rep . . .

Determining the factors that shape arthropod communities has a long history in ecology. I examined the direct and indirect effects of nitrogen availability on plant productivity and plant community composition to assess their effects on arthropod comm . . .

Many turtle species require aquatic and terrestrial habitats during different times in their life history for foraging, mating, nesting, estivation and overwintering. The status of many turtle populations depends directly on the condition of both envi . . .

This study examined changes in Sequoia sempervirens foliage along gradients of height and light availability. In tall trees (108-113 m), shoot morphology and physiology were analyzed at the base of the live crown, the mid-crown, and treetop. Both ligh . . .

The South Fork Trinity River is an undammed river in Northern California that drains a watershed with a long history of varied anthropogenic uses including mining, logging, cattle grazing, and associated road construction. These activities modify ripa . . .

In this study, I examined the effects of FMRFamide on the isolated crop-gizzard of the earthworm, Lumbricus terrestris. The peptide induced contractions of both the longitudinal and circular muscles of the crop-gizzard at concentrations examined (10-9 . . .

The relationship between eelgrass bed characteristics and animal use is important in better understanding what the optimal habitat features are for specific taxa. The focus of this study was to look at structural and geographical aspects of eelgrass h . . .

Different loci within a multigene family often experience unique evolutionary pressures; this phenomenon is often observed in proteins involved in reproduction. Chemical communication using secreted proteinaceous pheromones is critical for reproductiv . . .

A total of 17 transgenic strains of Caenorhabditis elegans were evaluated for use as bioindicators for the presence of toxins in an environmental sample. Every strain used had Green Fluorescent Protein (GFP) production driven by the promoter region of . . .

The tallest tree species, coast redwood (Sequoia sempervirens), provides an ideal model for investigating both the adaptations allowing maximum height growth in plants and the factors that limit it. Within the crowns of tall redwoods there exists broa . . .

A number of isolated high temperature, low pH geothermal sites exist in Lassen Volcanic National Park (LVNP) and Hawai’i Volcanoes National Park (HVNP) that allow for the growth of thermoacidophilic microbial communities. Horizontal gene transfer (HGT . . .

This study examined how pollinator visitation and local neighborhood density may affect pollen limitation (PL) of reproductive success for Vancouveria chrysantha Greene (Berberidaceae), a rare plant, strictly endemic to serpentine substrates in northw . . .

A great effort has been made in the last few decades to restore and preserve coastal dunes in northwest California. The restoration effort has largely focused on removal of invasive plants, with little study on how invasive plant removal affects nativ . . .

Lithobates catesbeianus (American bullfrogs) are not native to states west of the Rocky Mountains. Since their introduction to California, they have been implicated in the decline of amphibian species. On California’s north coast, bullfrogs may be cau . . .

The following research addresses the question: does color vision occur in animals that can only see rudimentary images? Since the morphological and neurological requirements of color vision are minimal relative to those necessary for image formation, . . .

Boiling Springs Lake (BSL) is a 52˚C, pH 2, iron and sulfur-rich thermal feature in Lassen National Volcanic Park (California, USA). Previous community composition studies of small subunit rRNA and RuBisCo genes revealed an abundance of phylotypes clo . . .

Plecoptera (stoneflies) were collected during the spring emergence in the Willow Creek basin, Humboldt County, California. Both adults and nymphs were collected using qualitative methods. Water chemistry, substrate size, and riparian vegetation were u . . .

Nonpathogenic bacterial endosymbionts have been shown to contribute to their arthropod hosts’ fitness by supplying them with essential vitamins and amino acids. Little is known about the nutritional basis for the symbiotic relationship of endosymbiont . . .

Many conservation strategies for bats focus on supporting or enhancing their roosting and foraging needs. With increasing urbanization and loss of natural habitat, many species have adapted to roost in anthropogenic structures, resulting in increased . . .

Mytilus californianus beds along the wave-exposed coast of the eastern North Pacific Ocean serve as an important habitat, harboring a high diversity of species due to their colonizable hard surfaces as well as through the creation of microhabitats wit . . .

Habitat modeling techniques are widely used to determine where species occur on the landscape and what habitat or environmental factors influence their presence. These techniques are particularly useful for rattlesnakes, which have life history traits . . .

Humboldt Bay contains two populations of eelgrass; Zostera marina L., a sparse population in North Bay and a significantly denser population in South Bay. No study has attempted to determine the cause of this density difference despite the importance . . .

The vascular transport system of most flowering plants is composed of vessels that are responsible for bulk axial water transport. Transport through vessels may become blocked by gas emboli following freeze-thaw events because gasses come out of solut . . .

A population of Eumetopias jubatus and Zalophus californianus was studied during the summers of 1983 and 1984 on the coast of Humboldt County. The population of E. jubatus and Z. californianus peaked during June and August. Z. californianus numbers pe . . .

To obtain the most complete understanding of a species’ life history requirements, one must know what habitat characteristics and resources are critical to each life history stage. Rana boylii are known to associate with various stream habitats throug . . .

Coastal shrublands of Humboldt and Del Norte Counties, California were classified and described based on data from 140 plots sampled at 46 sites. Twinspan was used to separate plots into groups. Indicator species analysis was used to determine which s . . .

I describe the spatial and temporal distribution, abundance and habitat use of Steller sea lions (Eumetopias jubatus) in northern California between 2006 and 2011 obtained through shore and at-sea surveys and by tracking branded individuals. Understan . . .

The flowers of the California pitcher plant, Darlingtonia californica, are unusual and have been the subject of much speculation. Despite the efforts of several workers, the pollination ecology of this plant, including the identities of pollinators, r . . .

Coastal ecosystems are under intense pressure from anthropogenic and environmental factors in California. Human development, pollution and climate change continue to degrade coastal habitats. Marine predators such as marine mammals that depend on near . . .

Bioassessment utilizes biological assemblages to assess ecological condition in disturbed areas. The most popular quantitative evaluation of biological health in streams involves an Index of Biotic Integrity (IBI) for benthic macroinvertebrates (BMIs) . . .

Variation at mitochondrial D-loop sequences and microsatellite loci were studied in three sub-populations of recently introduced red foxes (Vulpes vulpes) in California. Red foxes were introduced separately in northern and southern California near the . . .

Bumble bees (Bombus: Apidae) can maximize foraging efficiency in a resource-patchy environment by visiting mainly rewarding flowers and avoiding those that are either empty or less rewarding. This study investigated how bumble bees avoid unrewarding f . . .

Analyzing DNA sequence data from multiple unlinked loci in a coalescent framework is a powerful means for assessing the genetic isolation of populations by estimating population divergence times and gene flow since divergence. This approach was used t . . .

The hoary bat is a migratory, foliage-roosting bat with a mostly solitary roosting habit. Little is known about the social interactions of this species, but as a solitary roosting bat, most interactions between conspecifics are thought to involve mati . . .

Populations of Rana aurora Baird and Girard (red-legged frog) and Rana catesbeiana Shaw (Bullfrog) were studied at Freshwater Lagoon from December 1990 through January 1991. Significant differences in habitat-use between species were confirmed using l . . .

A geographic information system allows for the ability to predict potential distributions of spreading non-native species by identifying suitable, unoccupied habitat. Zostera japonica (Asch. and Grabn.), a non-native seagrass from the subtropical west . . .

The Crescent City wastewater treatment facility services a small community on the northern coast of California, where treated wastewater is discharged into a rocky intertidal community. A biological assessment of the habitat was conducted to determine . . .

A growing body of literature supports the position that both natural habitat surrounding farms and high flowering crop diversity helps insure farms against pollination shortfalls and an overreliance on European honeybees. I assessed the importance of . . .

Various aspects of the ecology and natural history of Darlingtonia californica Torrey 1853, populations in northern California were studied as they relate to the species' reproductive biology. Experimental investigations of the breeding system to esti . . .

Floristic studies are especially timely since habitat loss is increasing dramatically. From the conservation perspective, it is imperative to document the distribution of plant species in areas that are floristically rich. For this study, I conducted . . .

Tetrapods began the water-to-land transition during the Devonian period, approximately 400 million years ago. To succeed in this new environment the sensory systems of the early terrestrial explorers underwent specific adaptations. A similar challenge . . .

My thesis is an inventory of invertebrate species found in the low region of a Humboldt Bay salt marsh during four seasons, from July 1999 to April 2000. Invertebrates are an integral part of the salt marsh, contributing to detritus breakdown and food . . .

The tropical monodominant tree Dicymbe corymbosa, vegetatively regenerates via epicormic shoots and roots, resulting in multi-stemmed trees with stabilizing pseudotrunks and root mounds. In two 1-ha forest plots on the Guiana Shield, we quantified the . . .

The Lassics lupine (Lupinus constancei T.W. Nelson & J.P. Nelson) is a rare herb of limited distribution, with fewer than 400 reproductive individuals restricted to a single square kilometer in the Lassics Geological and Botanical Area of the Six Rive . . .

Eight owl species of special concern occur in the Sierra Nevada: California Spotted Owl (Strix occidentalis occidentalis), Northern Spotted Owl (Strix occidentalis caurina), Long-eared Owl (Asio otus), Burrowing Owl (Athene cunicularia), Great Gray Ow . . .

Eleven vegetation types occurring within two communities have been described for the lakeshore habitat of the Sky Lakes area. The shrub-dominated community has two closely related heath shrub types. The herb-dominated community comprises a diversity o . . .

Tricostate mosses and associated bryophilous fungi from the early Two novel fossil mosses (Tricosta plicata gen. et sp. nov. and Krassiloviella limbelloides gen. et sp. nov.) and several fungal morphotypes associated with one of these mosses are descr . . .

This study explores nectar production in Scrophularia californica, a native California herbaceous perennial. I conducted a series of field experiments to determine whether S. californica can replenish nectar in response to extractions, whether the rat . . .

Hauling site fidelity, movement patterns, and the proportion of harbor seals hauling out were examined for one year by radiotagging 12 seals in the Klamath River, California. Hauling site fidelity was highest during the spring and summer months, with . . .

Salt marsh ecosystems are an extremely important part of estuarine ecosystems around the world. What might happen to these systems if predictions about climate change are realized is largely unknown. I studied the effects of warming on salt marsh plan . . .

Field observations of the nesting biology and foraging ecology of Osmia lanei (Megachilidae), a solitary native bee species were made in northern California (40˚ 47’ 30” N, 123˚ 41’ 00” W). O. lanei nests in dense aggregations within rocky clearings i . . .

Harbor seals have been listed as a species likely to benefit from new Marine Protected Areas (MPAs) in California as part of the Marine Life Protection Act. Whereas seals may experience direct and indirect effects from these MPAs as a whole, the impac . . .

Although much attention is currently focused on the dynamics of invasive species, we have only a limited understanding of the mechanisms that promote spread of non-natives. In coastal dune habitats of northern California, the non-native yellow bush lu . . .

Batrachochytrium dendrobatidis (Bd), is an emerging pathogenic fungus of amphibians that has caused species decline and extinction worldwide. A decade ago, Nieto (2004) found that Bd existed in larval Rana aurora at a low (6.4%) overall prevalence thr . . .

Dicamptodon tenebrosus (Pacific giant salamander) was evaluated for suitability as an indicator of aquatic habitat quality relative to increasing loads of fine sediment from timber harvest and road building. I compared three surrogates of D. tenebrosu . . .

There is concern and debate as to the effects and factors influencing species introduction and invasion. Experimental findings suggest that factors such as species richness and available free space may play crucial roles in determining the outcome of . . .

Previous vegetation studies on granitic soils in the Klamath Region of Northern California suggest the area is typically floristically rich and vegetationally complex. My initial reconnaissance suggested the Bear Lakes area is much simpler in both res . . .

The California Blackworm (Lumbriculus variegatus) has great ability to regenerate from small fragments into a new worm depending on two forms of regeneration: epimorphosis and morphallaxis. Both patterns of regeneration work in concert with each other . . .

Ixodes pacificus is a primary vector of Lyme borreliosis and human anaplasmosis to people and animals in the Pacific states of the United States. This tick is also a host for a number of other bacterial species including members of the genus Rickettsi . . .

Analyzing DNA sequence data from multiple unlinked nuclear loci in a coalescent Isolation-with-Migration (IM) model is a statistically powerful method for estimating population divergence times, effective population sizes, and gene flow. This approach . . .

I surveyed the flora of the San Joaquin Roadless Area, a 44km2 area on the east side of the central Sierra, and then analyzed its floristic affinities (origins) using Sorensen's similarity coefficient, cluster analysis, and Bray-Curtis ordination. The . . .

This study examined the effects of copper exposure on neurons and the excretory cell in the nematode, Caenorhabditis elegans, using transgenic strains with specific green fluorescent protein (GFP)-tagged cells. Exposure to CuSO₄ damaged particular neu . . .

In species where offspring are restricted to neonatal habitats, fitness is dependent upon oviposition site selection by females, a concept often referred to as the preference-performance hypothesis. Before determining if this hypothesis can be applied . . .

Coastal grasslands in Redwood National Park, known locally as the Bald Hills, are dominated by introduced species. The most dominant and invasive is tall oatgrass, Arrhenatherum elatius. Increasing in cover and distribution rapidly since 1985, it has . . .

The biogeographic area between Cape Mendocino, California and Cape Blanco, Oregon spans over 320 km and is characterized by prominent coastal headlands that act as genetic and species barriers for marine organisms. Because of a lack of a current macro . . .

A whole-plant concept was developed for the Early Devonian (Lochkovian – Pragian, ca. 410 Ma) drepanophycalean lycophyte Sengelia radicans gen. et sp. nov. from the Beartooth Butte Formation of Wyoming, based on 1131 fossil fragments. The concept, dev . . .

Recent research on sea urchins has shown that they possess unexpected visual capabilities. Behavioral tests have revealed that they are able to detect the spatial distribution and wavelength of light using the surface of their body. The well-studied p . . .

Oyster reefs serve an important role in estuarine ecosystems. Their shells create a complex habitat that serves as a home for future generations of oysters, other sessile invertebrates, and fishes. Native oysters, Ostrea lurida, are thought to have be . . .

I examined differences in native macroinvertebrates among four lake management categories (fish stocked, temporary stocking suspension, fish removal lakes, and historically fishless lakes) and among three habitats (rock, organic/silt substrate, and em . . .

Understanding the movements of anurans is important for developing successful conservation plans because breeding, foraging, and overwintering resources are often separated by time and space. I used radio-telemetry to study the movements and habitat u . . .

This study is a systematic assessment of eleven species of ectomycorrhizal fungi from the genus Clavulina (Clavulinaceae, Cantharellales, Basidiomycota) from the interior rainforests of the central Guiana Shield. Additionally, the presence of the resu . . .

Marine habitats are under increasing threat of invasion by exotic species, the successful establishment and spread of which are poorly understood. Cryptic yet genetically distinct bryozoans in the genus Watersipora have invaded bays throughout Califor . . .

Premise of research. Climate change may alter the timing of flowering and pollinator activity to differing degrees, resulting in phenological mismatches between mutualist partners. Assessing the potential for such mismatches requires an understanding . . .

The relationship between tidal elevation and the distribution of salt marsh vascular plants was investigated in Humboldt Bay, California. Plant species composition and cover were assessed and elevation surveyed in 148 one-square-meter plots in July-Au . . .

Crop pollination by wild bees is an ecosystem service of great value, particularly in heavily developed tropical settings. Self-fertile Coffea arabica is an important cash crop for many tropical countries. I used pollinator surveys and exclusion exper . . .

Whitebark pine (Pinus albicaulis) is vulnerable to a number of threats including an introduced pathogen (Cronartium ribicola), epidemic levels of native mountain pine beetle (Dendroctonus ponderosae), competition, and climate change. To elucidate fact . . .

Changing the fire regime of a plant community can result in significant alterations to its structure and composition. Seed banks have the potential to increase a population's ability to survive in areas where fire regimes have been altered by fire-sup . . .

Between October 2011 and September 2013, I designed and implemented an effort-based beach survey protocol for stranded marine mammals and seabirds in Humboldt County. This study was designed to create a baseline data set that is comparable to other pr . . .

Increased sophistication in methodology of echolocation monitoring has enabled the pursuit of a widened array of research and management objectives for bats. I developed and tested an automated program for detecting, measuring and classifying species . . .

Phytoplankton community descriptions are becoming an increasingly important component in studies of oceanographic and nearshore marine ecosystems. These primary producers play a major role in the global carbon cycle and are the foundation of nutrition . . .

The morphology and proportions of the limb skeletons of thirteen species of North American mustelids are examined. A series of forty-nine ratios is generated for each species. Ratios are analyzed using standard descriptive statistics; mean, standard d . . .

This study examined wrack-associated macrofaunal communities in northern California, providing base line data and documenting potential prey for federally threatened Western Snowy Plovers. I investigated three hypotheses regarding beach wrack macrofau . . .

Natural riparian habitats are among the most diverse, productive, and structurally complex of terrestrial habitats. Although litter-decomposing fungi are integral components of riparian habitats, they are often omitted in studies of riparian ecology a . . .

Baseline information is needed to protect pollinators in at-risk ecosystems. One such system, Tolowa Dunes (Crescent City, California), in northern California, is undergoing habitat fragmentation caused by an introduced, invasive plant, Ammophila aren . . .

Pinus balfouriana Grev. and Balf., foxtail pine, is endemic to California, occurring as two subspecies: P. balfouriana ssp. austrina in the southern High Sierra and P. balfouriana ssp. balfouriana 500 km to the north in the Klamath Mountains. Previous . . .

The science of immunology, for much of its history, has focused on the ability to induce the biological acquisition of specific immunity or on the ability to produce specific immune agents. Examples are, respectively, vaccinations that enable vertebra . . .

The identification of organisms present in an environment is a crucial prerequisite for understanding the role of organisms in the environment and the processes influencing the diversity of those organisms. In general, the basic ecology of acidic ther . . .

The Caenorhabditis elegans SPE-26 protein is involved in the formation of viable spermatids. Two-hybrid interaction analysis was performed in order to determine with which proteins SPE-26 physically interacts. Fusing the carboxy terminal 471 amino aci . . .

The abundance, distribution, prey availability, and prey consumed by gray whales (Eschrichtius robustus) in northern California were investigated during 1999 and 2000. Systematic shore-based observations from four sites occurred year-round but were co . . .

The utility of nocturnal flight calls as an indicator for monitoring bird migration has been demonstrated and its usage continues to grow. However few studies have addressed how and if nocturnal flight calls can be used as a measure of migrating bird . . .

Gray whales (Eschrichtius robustus) are ‘living islands’ to a diverse assemblage of crustacean ectoparasites that includes at least three species of highly specialized whale lice (Cyamus spp.). These lice are obligate parasites that undergo direct dev . . .

The marine copepod, Tigriopus californicus (Baker), is commonly found in high rocky splash-pools between Alaska and Lower California. In this habitat the animal has the ability of withstanding a great range of temperature and salinity. The body of thi . . .

Spartina densiflora, a non-indigenous, invasive, perennial cordgrass has colonized and modified roughly 90% of the remaining salt marsh habitat in Humboldt Bay, California. As part of a region wide effort to ameliorate the effects of this invasion, tw . . .

Bacterial endosymbionts often contribute to the nutritional fitness of their host, as seen with Buchnera endosymbionts in aphids and Wolbachia endosymbionts in Cimex lectularius. Conventionally, amino acids and vitamins provided by bacterial endosymbi . . .

In this study I tested the ability of the pollination syndrome model to predict the most effective pollinator of a tropical forest tree, Hibiscus elatus (Malvaceae), at three sites in Jamaica, West Indies. The floral characteristics of this species su . . .