Biology Commons^™

Effects Of High Light Exposure On Photosynthetic Rate And Fluorescence Of Eucrypta Chrysanthemifolia, Alec Flores, Gina Gilderman, Hannah Dario

Featured Research

In this experiment, we examined how a partial shade plant, Eucrypta chrysanthemifolia, found in the Santa Monica Mountains, responded to predictive models of higher light intensities created bydrought. We hypothesized that, with higher levels of light, Eucrypta chrysanthemifolia would respond with a decreased photosynthetic rate, light-adapted, and dark-adapted fluorescence. This was performed by comparing control plants grown in an artificial shade environment to plants exposed to a series of high light intensity treatments. These partial shade plants were found on Piuma Trail in the Santa Monica Mountains. Our data supported our null hypothesis, indicating the photosynthetic rates and light-adapted …

Seedling Resprouts Of Adenostoma Fasciculatum Between Wildfire Cycles Are Promoted By Environmental Conditions That Mimic Fire-Like Environments, Lexe Evans, Teal Speece, Stephen D. Davis

Featured Research

The Santa Monica Mountains represent one of the largest Mediterranean-type environments in the world. With sustained summer droughts, this ecosystem has become prone to frequent wildfires, a phenomenon that has affected the area with regularity (approximately 21 years apart). Naturally, this cycle of wildfires has had a great effect upon the mortality and survival of the diverse chaparral varieties that inhabit the Santa Monica Mountain region. This includes the Adenostoma fasciculatum (chamise), which is the most commonly-found form of chaparral shrub in California. (Redfeldt & Davis, 1996) This species of chaparral is particularly well-adapted to survival in a climate that …

Difference In Chaparral Species Population On The North And South Aspect On Pepperdine University Campus, Alexandra N. Lozano, Drew N. Rasmussen, Ashlyn L. Rawls

Featured Research

In this experiment, we analyzed the difference in population frequencies of chaparral plants along the north and south aspect of a slope on Pepperdine University campus in the Santa Monica Mountains in Malibu, CA. We began the experiment by hypothesizing the south aspect would receive the most sunlight, and thus would hold the most amount of plants. By using the Point Quarter Sampling Method, we were able to determine if our hypothesis was correct. After analyzing our data, we found no significant difference between the north and south aspect in terms on frequency. During our experiment we also measured the …

Possible Fungal Infection Leading To Malosma Laurina Dieback, Gabriella N. Palmeri, Braden S. Olsen, Kaitlyn E. Sauer, Stephen D. Davis

Featured Research

There is a significant and apparent dieback of Malosma laurina in the Santa Monica Mountains, some which is found near Pepperdine University. Other areas near Pepperdine show a flourishing growth of M. laurina and our objective was to determine why this difference in M. laurina health exists. We initially hypothesized that in addition to water stress, the unhealthy M. laurina was effected by a pathogen. Under further inspection, the unhealthy plants contained hyphae in some of their xylem vessels, while the healthy ones did not. We sought to determine whether the existence of hyphae in the unhealthy plant’s xylem affected …

Morphological Changes In Malosma Laurina Due To Prolonged Drought In The Santa Monica Mountains, Grace S. M. Bae, Majie C. Foster, Maryelizabeth S. Stein, Mariah K. Taylor

Featured Research

Observations of Malosma laurina seedlings in Sycamore Canyon, Malibu, CA, exhibit abnormally small and wrinkled leaves. We propose that the prolonged drought in California’s Santa Monica Mountains has lead to physical malformations indicative of water strain in the leaves of M. laurina plants. In this experiment, we tested water relations of six M. laurina plants found on Pepperdine University’s Malibu campus showing similar leaf patterns to those found in Sycamore Canyon. Six M. laurina plants devoid of the abnormal leaf growth patterns functioned as our control group. Stomatal conductance, water potential, and leaf mass to area data was gathered using …

The Effects Of Salinity On The Photosynthetic Rate Of Limonium Californicum, Adriana J. Borges, Elizabeth S. Chau, Justine M. Mckitrick

Featured Research

Halophytic plants, unlike most plants, are able to survive in stressful saline environments. Halophytes possess adaptations to osmoregulate, which gives them a competitive edge in saline environments such as coastal salt marshes. Our group analyzed the responses to salinity of the halophytic plant, Limonium californicum, which is present in California’s coastal salt marshes. We hypothesized that the photosynthetic rate of the Limonium californicum plants would decrease with increasing saline water treatments. In order to test this hypothesis, we watered L. californicum plants with solutions of varying salinity over the course of four days. We measured the photosynthetic rates using …

Correlation Between Hydration And Reflectance Of Yellow Petals On Encelia Californica, Jayci M. Givens, Kaylee A. Nussbaum, Caitin R. Kawata

Featured Research

It is known that the NDVI can be used as a measure of hydration in plants because of the variation in pigments due to xanthophyll cycling (Schmitz et al., 2013). Flower petals can also exhibit variations in petal reflectance invisible to the naked eye (Fam & Espinoza, 2013). It was hypothesized that overall hydration levels of a plant would correlate to a difference in the pigments produced for petal color, and thus differences in hydration levels would correlate to differences in petal reflectance. To test this hypothesis, three flowers and two stems were collected from ten different E. californica plants, …

The Effect Of Red Maple Leaf Toxicosis On Reduced Glutathione Levels In Equine Erythrocytes In Vitro, Madeline A. Rohl

Undergraduate Honors Thesis Projects

Red maple leaf toxicosis is an equine blood disorder resulting from the consumption of wilted red maple (Acer rubrum L.) leaves by horses. Compounds within the leaves of red maple have oxidative effects on equine erythrocytes and can cause hemolysis of erythrocytes, the conversion of hemoglobin to methemoglobin, and the production of Heinz bodies. Reduced glutathione is important in the protection of equine erythrocytes from these oxidative events; however, in the presence of red maple toxin, glutathione is rapidly oxidized and is unavailable. The objective of this study is to determine whether the presence of vitamin C alters levels …

The Ongoing Search For The Molecular Basis Of Plant Osmosensing, Elizabeth S. Haswell, Paul E. Verslues

Biology Faculty Research

Introduction: Cell viability and metabolism depend on cytoplasmic water and solute content, and organisms have evolved mechanisms to sense changes in cell water content, solute concentrations, cell volume, and/or turgor. This Perspective addresses the response to osmotic challenge in land plants and describes their special dependence on cellular water status for growth and development. Understanding how plants cope with water limitation may allow us to mitigate the agricultural effects of drought, a critical limitation on global crop productivity that is likely to increase in severity as the climate changes (Long and Ort, 2010). The signaling pathways by which plants respond …

Traversing Swanton Road, 19th Ed., James A. West

Academic, Government & Associated Organizational Research Resources

Situated at the northwest end of Santa Cruz County and occupying circa 30 square miles of sharply contrasted terrain, the Scott Creek Watershed concentrates within its geomorphological boundaries, at least 10-12% of California's flora, both native and introduced. Paradoxically, the use/abuse that the watershed has sustained over the past 140+ years, has not necessarily diminished the biodiversity and perhaps parallels the naturally disruptive but biologically energizing processes (fire, flooding, landslides and erosion), which have also been historically documented for the area for +60 years. This is an early edition of an extensive document by James A. West. Please visit the …

Differential Survival Of Chaparral Shrub Species In Response To Severe Drought, Hannah Dario, Stephen D. Davis

Biology

In this experiment, we examined how the plants in the Santa Monica Mountains are responding to the driest period in recorded history for California. Our hypothesis was that plant species with the deepest roots would have highest survivorship. We thought this because deep-rooted shrubs will have greater access to soil moisture. This hypothesis was tested by collecting data on plant survival, in a mixed chaparral stand, containing eleven species, growing in the Green Valley Preserve off of Stunt road, in the Santa Monica Mountains. The chaparral stand was 21 years old, having last burned in 1993 (Old Topanga Canyon Fire). …

Maria Sibylla Merian (1647-1717): Pioneering Naturalist, Artist, And Inspiration For Catesby, Kay Etheridge, Florence F.J.M. Pieters

Biology Faculty Publications

Book Summary: While accessible to the interested general reader, it is a technical standard that is usable academically. Containing significant new information, this work is the most comprehensive and accurate book written about Catesby and is the legacy of the Catesby Commemorative Trust’s Mark Catesby Tercentennial symposium held in 2012.

Chapter Summary: Merian's books on European and Surinamese insects and plants provided new models for representing nature that were echoed in the work of artists and naturalists working in the eighteenth century and beyond. This chapter discusses how Mark Catesby, the subject of the book, was particularly influenced by Merian.

Clonal Integration In Ludwigia Hexapetala Under Different Light Regimes, Rebecca E. Drenovsky, R. E. Glover, C. J. Futrell, Brenda J. Grewell

Biology

Physiological integration among ramets of invasive plant species may support their colonization and spread in novel aquatic environments where growth-limiting resources are spatially heterogeneous. Under contrasting light conditions, we investigated how clonal integration influences growth, biomass allocation and morphology of Ludwigia hexapetala, an emergent floating-leaved macrophyte that is highly invasive in a range of wetland habitat types. In aquatic mesocosms, stolons of offspring ramets were either connected or severed from parent plants, with the pairs exposed to homogenous or heterogeneous combinations of sun or 85% shade. Morphological traits of all ramets were strongly influenced by light environment, and low …

Traversing Swanton Road, 18th Ed., James A. West

Academic, Government & Associated Organizational Research Resources

Situated at the northwest end of Santa Cruz County and occupying circa 30 square miles of sharply contrasted terrain, the Scott Creek Watershed concentrates within its geomorphological boundaries, at least 10-12% of California's flora, both native and introduced. Paradoxically, the use/abuse that the watershed has sustained over the past 140+ years, has not necessarily diminished the biodiversity and perhaps parallels the naturally disruptive but biologically energizing processes (fire, flooding, landslides and erosion), which have also been historically documented for the area for +60 years. This is an early edition of an extensive document by James A. West. Please visit the …

Elevational Gradients In Β-Diversity Reflect Variation In The Strength Of Local Community Assembly Mechanisms Across Spatial Scales, J Sebastián Tello, Jonathan A. Myers, Manuel J. Macia, Alfredo F. Fuentes, Leslie Cayola, Gabriel Arellano, M Isabel Loza, Vania Torrez, Maritza Cornejo, Tatiana B. Miranda, Peter M. Jørgensen

Biology Faculty Research

Despite long-standing interest in elevational-diversity gradients, little is known about the processes that cause changes in the compositional variation of communities (β-diversity) across elevations. Recent studies have suggested that β-diversity gradients are driven by variation in species pools, rather than by variation in the strength of local community assembly mechanisms such as dispersal limitation, environmental filtering, or local biotic interactions. However, tests of this hypothesis have been limited to very small spatial scales that limit inferences about how the relative importance of assembly mechanisms may change across spatial scales. Here, we test the hypothesis that scale-dependent community assembly mechanisms shape …

Allelic Polymorphism Of Gigantea Is Responsible For Naturally Occurring Variation In Circadian Period In Brassica Rapa, Qiguang Xie, Ping Lou, Victor Hermand, Rashid Aman

Dartmouth Scholarship

GIGANTEA (GI) was originally identified by a late-flowering mutant in Arabidopsis, but subsequently has been shown to act in circadian period determination, light inhibition of hypocotyl elongation, and responses to multiple abiotic stresses, including tolerance to high salt and cold (freezing) temperature. Genetic mapping and analysis of families of heterogeneous inbred lines showed that natural variation in GI is responsible for a major quantitative trait locus in circadian period in Brassica rapa. We confirmed this conclusion by transgenic rescue of an Arabidopsis gi-201 loss of function mutant. The two B. rapa GI alleles each fully rescued the …

Increasing Expression Of Hepatitis B Surface Antigen In Maize Through Breeding, Erin Suzanne Miller

Master's Theses

The hepatitis B virus (HBV) is a common virus, with two billion people infected worldwide. It causes approximately 600,000 deaths each year, despite the availability of an effective vaccine since 1982. Maize as a platform for oral vaccination can supply a heat stable vaccine, which does not require syringes or trained personnel to administer. The Hepatitis B Surface antigen was transformed into maize and this seed was used to evaluate expression levels through the breeding process. The transgene was transferred into two elite maize inbreds by backcrossing. Highest expressing ears were selected each generation until approximately 99% commercial parent was …

Attraction, Repellence, And Predation: Role Of Companion Plants In Regulating Myzus Persicae (Sulzer) (Hemiptera: Aphidae) In Organic Kale Systems Of South Texas, Carlos R. Moreno, Alexis Racelis

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Annual outbreaks of green peach aphid, Myzus persicae (Sulzer), limit commercial production of brassica crops, especially in organic systems in subtropical areas such as South Texas. We assessed the influence of companion plants that emit attractant, repellent, and natural enemy-attractant stimuli (i.e., insectary plants) on abundance of green peach aphid in organic kale (Brassica oleracaea L. var. acephala) fields in South Texas. We also monitored the assemblage of arthropod predators and parasitoids on kale and evaluated the response of numerically dominant species to companion plants. Indian mustard (Brassica juncea (L.) Vassiliĭ Matveievitch Czernajew; attractant), dill (Anethum graveolens L.; repellent), fennel …

The Fragile Fiber1 Kinesin Contributes To Cortical Microtubule-Mediated Trafficking Of Cell Wall Components, Chuanmei Zhu, Anindya Ganguly, Tobias I. Baskin, Daniel D. Mcclosky, Charles T. Anderson, Cliff Foster, Kristoffer A. Meunier, Ruth Okamoto, Howard Berg, Ram Dixit

Biology Faculty Research

The cell wall consists of cellulose microfibrils embedded within a matrix of hemicellulose and pectin. Cellulose microfibrils are synthesized at the plasma membrane, whereas matrix polysaccharides are synthesized in the Golgi apparatus and secreted. The trafficking of vesicles containing cell wall components is thought to depend on actin-myosin. Here, we implicate microtubules in this process through studies of the kinesin-4 family member, Fragile Fiber1 (FRA1). In an fra1-5 knockout mutant, the expansion rate of the inflorescence stem is halved compared with the wild type along with the thickness of both primary and secondary cell walls. Nevertheless, cell walls in fra1-5 …

Sister Remberta Westkaemper: A Fine Lady And Excellent Field Botanist, Stephen G. Saupe

Forum Lectures

Sister Remberta, the first full-time president of Saint Ben's and founding member of the CSB Biology Department, was the preeminent authority on the flora of Stearns County. This presentation will focus on Sister Remberta's botanical activities with an introduction to the CSB|SJU Bailey Herbarium. This work was supported by a Centennial Year Fellowship.

Machine Learning For Predicting Soil Classes In Three Semi-Arid Landscapes, Colby W. Brungard, Janis L. Boettinger, Michael C. Duniway, Skye A. Wills, Thomas C. Edwards Jr.

Plants, Soils, and Climate Faculty Publications

Mapping the spatial distribution of soil taxonomic classes is important for informing soil use and management decisions. Digital soil mapping (DSM) can quantitatively predict the spatial distribution of soil taxonomic classes. Key components of DSM are the method and the set of environmental covariates used to predict soil classes. Machine learning is a general term for a broad set of statistical modeling techniques. Many different machine learning models have been applied in the literature and there are different approaches for selecting covariates for DSM. However, there is little guidance as to which, if any, machine learning model and covariate set …

Systematics And Biogeography Of Orthaea Kloztsch (Ericaceae: Vaccinieae), Nelson Salinas

Dissertations, Theses, and Capstone Projects

In the first chapter a study of the distribution patterns of the neotropical Vaccinieae (Ericaceae) is presented. Five areas of endemism were recovered: Central America, northern Chocó, southern Chocó, eastern Ecuador, and Yungas. Divergence times estimations indicate that the Andean clade of Vaccinieae migrated to South America during the Late Oligocene or Early Miocene (28.9-17.84 MA), and most of the subsequent diversification took place during the Tertiary. The Yungas was the first Andean area to be colonized, and several dispersals towards the north expanded their distribution range. Both areas of endemism and dispersal events were influenced by geological processes, such …

A Structure-Function Approach To Understanding The Dual Functions Of The Plant Mechanosensitive Ion Channel Msl10, Grigory Maksaev, Kira M. Veley, Elizabeth S. Haswell

Biology Faculty Research

MscS‐Like (MSL) 10 is a member of the MscS superfamily of mechanosensitive ion channels and one of 10 MSL proteins in the model flowering plant Arabidopsis thaliana. Unlike Escherichia coli MscS, MSL10 contains 6 transmembrane helices, and only its C‐terminal TM helix shows homology with EcMscS's pore‐lining domain. MSL10 has been shown to provide a mechanosensitive activity in plant cells and Xenopus oocytes. However, its structural organization and function in plants are just beginning to be elucidated.

Lineage Sorting In Multihost Parasites: Eidmanniella Albescens And Fregatiella Aurifasciata On Seabirds From The Galapagos Islands, Jose Rivera-Parra, Iris Levin, Kevin Johnson, Patricia Parker

Biology Department Faculty Works

Parasites comprise a significant percentage of the biodiversity of the planet and are useful systems to test evolutionary and ecological hypotheses. In this study, we analyze the effect of host species identity and the immediate local species assemblage within mixed species colonies of nesting seabirds on patterns of genetic clustering within two species of multihost ectoparasitic lice. We use three genetic markers (one mitochondrial, COI, and two nuclear, EF1‐α and wingless) and maximum likelihood phylogenetic trees to test whether (1) parasites show lineage sorting based on their host species; and (2) switching of lineages to the alternate host species depends …

Understory Diversity And Composition Drives Carabid Assemblages, Tierney Brosius, Michael Reisner

Biology: Faculty Scholarship & Creative Works

Fire suppression has nearly eliminated fire as a disturbance in temperate deciduous forests. Lack of fire is transforming these ecosystems through a positive feedback loop termed mesophication: cool, damp, shady conditions become continually more favorable for a few mesophytic species, while deteriorating for diverse array of heliophytic ones. Disturbances caused by urbanization fragment and degrade remnant forests. In urban settings, human management (or lack thereof) is often a dominate driver of succession. Carabid diversity, understory vegetation, patch size, patch connectivity, and permeable surface area were all examined in multiple forest plots in Rock Island and Moline. The result of this …

Using The Past To Restore The Future: Quantifying Historical Vegetation To Assist In Tidal Freshwater Wetland Restoration, Christopher D. Gatens

UROP Posters

Wetlands have been providing humans with critical natural ecosystem services throughout our time on Earth. Nevertheless, these invaluable ecosystems have been habitually altered as a cost of human progression. Two of the most common alterations to wetlands are damming and filling. Both occurred along Kimages Creek in Charles City County, VA during the 19^th and 20^th centuries. In 2010 the Lake Charles dam was partially removed, restoring the creek’s tidal communication with the James River. Upon the recession of the body of water, numerous woody stumps were revealed. We studied these stump remnants in an attempt to assess …

First Record On Secondary Pollen Presentation In The Cucurbitaceae Family, Shivani Jadeja

School of Biological Sciences: Faculty Publications

Aim – Secondary pollen presentation in flowers has been described only in a few species across about 25 plant families. The first report of secondary pollen presentation in the Cucurbitaceae family is given here.

Key result – Sechium talamancensis, endemic to high elevations in Costa Rica, presents nearly 39% of its pollen secondarily on the distal ends of its petals. The remaining pollen is presented on the anthers, the primary pollen presenters.

Significance – Closely related and commercially important congeners of S. talamancensis do not show secondary pollen presentation. Potential selective advantages of the phenomenon that differentiates S. talamancensis …

European Frogbit (Hydrocharis Morsus-Ranae) In The Champlain/Adirondack Region: Recent Inferences, Chris Martine, Stephen Langdon, Timothy Shearman, Casey Binggeli, Timothy B. Mihuc

Faculty Journal Articles

As part of its north-south movement following introduction to Canada, Hydrocharis morsus-ranae L. (Hydrocharitaceae) has recently become established in slow-moving waters of the Champlain/Adirondack region of the northeastern US. The species is present on both the New York and Vermont shores of Lake Champlain and, so far, at a single location in the interior of the Adirondack Park. The southernmost Champlain/Adirondack occurrence is in the Champlain Canal south of Whitehall, NY (L. Eichler, Darrin Freshwater Institute, pers. comm.), within 25 miles of the Hudson River watershed—a population first recorded around 2006. Entry into the Hudson watershed, whether from the canal …

A Novel Mechanism To Explain Success Of Invasive Herbaceous Species At The Expense Of Natives In Eastern Hardwood Forests, Frank S. Gilliam

Biological Sciences Faculty Research

Among the more intriguing topics in general ecology courses are the symbiotic relationships (the ‘-isms’ as I sometimes present them – mutualism, commensalism, and parasitism). Of these, mutualism is typically the most appealing to students. The scenario that different species can not only co-exist, but can also provide essential resources/services for one another, resonates well with all but the least interested in the course. Ultimately, however, there is also the palpable degree of dismay when they discover that these relationships arise from mutual exploitation, rather than from some benign force of nature. A flip-side of this, in many ways a …

Toxicity Of Leaf Extract Of Acer Spp. On Equine Erythrocytes, Bailey Katherine Dye

Undergraduate Honors Thesis Projects

Red maple toxicosis is a phenomenon that occurs in equines after the consumption of dried or wilted red maple (Acer rubrum L.) leaves. Within the erythrocytes, it causes hemolysis, methemoglobinemia, and Heinz body development. The toxic agent of red maple leaves has not yet been identified; however, the development of hemolytic anemia and methemoglobinemia in equines after ingestion of the leaves, suggests that the toxin is acting as a strong oxidant. Some studies have noted that not only are wilted red maples leaves toxic to equines, but that wilted leaves of other maple species may also be toxic. Therefore, …