Biology Commons^™

A Post-Fire Comparison Of Resprouts To Unburned Malosma Laurina Shrubs In The Santa Monica Mountains Of Southern California, Anthony Joseph Adducci Ii, Sierra Jo Smith, Dylan Jesse Waddill

Featured Research

Fire is a cornerstone to Mediterranean ecosystems but increased droughts, climate change and human interference has caused a shift in fire frequency and severity. This experiment accessed the physiological performance of Malosma laurina resprouts in burned areas compared to mature Malosma laurina in unburned areas. Specifically, we hypothesized that the stomatal conductance, photosynthesis rate, and electron transport rate of the burned resprouts would all be higher than the unburned shrubs as there are more nutrients available in the soil post-fire and the resprouts have a larger root to stem ratio. Using the LI-6400 Portable Photosynthesis System, we measured the physiological …

A Survey Of Post-Fire Chaparral Species’ Densities Using Point Quarter Sampling, Emma C. Stenz, Brandon R. Grinovich, Catherine H. William, Michael E. Gayed, Stephen D. Davis, Grace Palmer

Featured Research

The purpose of this observational study was twofold: to add to the existing data regarding the plant species composition of the Pepperdine hillsides and to set in place a foundation for post-fire chaparral recovery studies that will ensue over the coming years through various programs and classes. The 2018 Woolsey Fire burned nearly all of the natural environment surrounding Pepperdine University and the greater Malibu region, so it is a matter of urgency to take this opportunity to learn more about how this natural environment of the chaparral responds to a catastrophic event like fire. We focused primarily on facultative …

Soil Respiration In Burned And Unburned Sites Of The Santa Monica Mountains, Sydney C. Jones, Micah S. Kim, Sierra H. Ball, Stephen D. Davis

Featured Research

Soil respiration (the flux of CO₂ released by the soil due to microbial and root respiration and organic matter decomposition) can be affected by fire (Qu et al., 2009, Richards et al., 2012, Ryu et al., 2009). After the 2018 Woolsey Fire in the Santa Monica Mountains, we hypothesized that soil respiration would be greater in unburned soil than in burned soil. This is because fire can decrease soil nutrient concentration, which could decrease soil microbial concentration and also because fire could burn and kill soil microbes and roots. To test this relationship, we recorded soil respiration on three …

The Presence Of Fungal Pathogen, Botryosphaeria Dothidea, In Post-Fire Malosma Laurina Resprouts, Georgiana Gibson, Sarah Parker, Lauren Van Tress

Featured Research

Botryosphaeria dothidea is an opportunistic fungal pathogen that infects plants, causing cankers to form on branches and stems, ultimately causing cell cavitation and embolism in the plant. Botyrosphaeria dothidea was found in much of the chaparral vegetation present in the Santa Monica Mountains prior to the November 2018 fire. In this study, we focused on the presence of Botryosphaeria dothidea in the chaparral plant Malosma laurina on Pepperdine University’s campus in 2 different populations: unburned and resprouts. We looked at whether the November 2018 fires had eliminated the pathogen from post-fire Malosma laurina resprouts, using the unburned Malosma laurina population …

Comparative Fitness Of Post-Fire Transplant Stipa Pulchra And Wild Stipa Pulchra In Competition With Avena Fatua, Ashley Bonin, Madison Cook, Sara Head

Featured Research

In the Spring Semesters of 2016 and 2017, research was conducted on the relative fitness of Stipa pulchra in the transplant garden on the Drescher campus at Pepperdine University. The first study in 2016 examined the fitness of Stipa pulchra and Avena fatua in the transplant and wild gardens after a five year drought in California. In the results of this experiment, the hypothesis was supported when observing that the wild S. pulchra depicted higher fitness that the transplant S. pulchra in areas of stomatal conductance, height, water potential, percent sun and dark-adapted fluorescence. The second study in 2017 investigated …

Post Fire Seedling And Resprout Survival Of Melasma Laurina, Matthew Sturtevant, Gil So

Featured Research

For this research project we set out to see how seedling and resprout survival rate of melasma laurina would fare in the post fire environment found around pepperdine. The expected seedling survival was set to be 1% and the resprout survival was at 100%. From our field research we found that the the seedling survival was 41% and the resprout 57.3%. By using a T-test we had a p value < 0.001 for both data sets, this means that our data deviated greatly from our expected data and meant that we had to reject our hypothesis.

Carbon Dioxide Flux Rate For Cold Burn And Hot Burn Sites, Sophia Cheong, Alexander G. Grissom, Grace K. Lank

Featured Research

This experiment seeks to further expand modern understanding of post-fire ecology via systematic measurement of soil respiration within areas burned by cool, mild flames and hot, intense flames caused by the recent Woolsey Fire. We theorized that within hot burned areas, soil respiration would be less than that of the cool burned areas because the microbe population in the hot burned areas would be affected far more than those subjected to a cool burn. By measuring soil respiration with our Li-6800 CO₂ soil flux chamber at each of the according disc sites within hot and cold burned areas we …

Comparison Of Postfire Seedling Recruitment Of 2019 In Three Key Chaparral Species, Karagan Smith, Reid Furukawa, Brett Muramoto, Stephen D. Davis

Featured Research

Fire is a common natural disaster that sweeps through Southern California. Combined with periods of acute, and most recent, chronic drought, we have seen an increase in the damage and frequency of these fires in recent years. Three chaparral species are common to the Pepperdine campus: Malosma laurina, Ceanothus spinosus, and Ceanothus megacarpus. The survival of these three native species is essential because they serve as biomarkers for the changes that are occurring in our local ecosystem and provide further implications for how our ecosystem is responding to natural disaster. Seedling recruitment is a mechanism that is used by …

Heteromeles Arbutifolia Associated Post-Fire Soil Microbiome Recovery And Respiration In A Chaparral Ecosystem, Gabrielle Boeger, Lauren Dedmon, Emma Thomsen, Alexander Soloniuk

Featured Research

The purpose of this post-Woolsey Fire project is to examine the relationship between soil respiration in areas of cool burns and hot burns relative to individuals of Heteromeles Arbutifolia. It was hypothesized that the soil subjected to a cooler burn would have greater respiration rates due to increased survival of microorganisms compared to a hotter burn. An Li-6800 CO2 Flux Chamber was used to collect measurements for several replicates. Significance was detected in the “Day 3” data, with the soil respiration higher at the cool burn site. Temperature and soil flux also varied directly. In the future experiments including increasingly …

Combating Drug Resistance - Comparison Of The Antibiotic Effect Of Hydrastis Canadensis Extract And Pure Berberine Via Minimum Inhibitory Concentration Assay, William Luke Scott, Timothy D. Trott

Research in Biology

Herbal medicines are a melee of complex organic chemicals, making it difficult to ascertain their direct mechanism of action. In contrast to mainstream pharmaceuticals, it is argued that herbal medicines are effective because of multiple constituents working synergistically. The complexity of herbal medicines may give them advantages over simpler pharmaceuticals in combating antibiotic resistant microbes, but these advantages can be difficult to quantitate. Popular literature frequently espouses the healing properties of herbal medicines, but many of these claims are not scientifically supported. Many gains could be realized in public health and medicine if more research was aimed at validating / …

Diversity Of Nitrogen Fixing Bacteria In A Sample Aquaponics Ecosystem, Joshua Trombley, Haley Depner

Thinking Matters Symposium Archive

In natural ecosystems, nitrogen-fixing bacteria act as the primary source of useable nitrogen for many plants by converting atmospheric N2 into ammonia. In an aquaponics system, however, the primary source of ammonia is provided by fish waste. We are investigating the effect of this ammonia saturation on the diversity of nitrogen-fixing bacteria in a sample aquaponics system. We seek to answer two fundamental questions: First, what nitrogen fixing microbes are present in these systems? Second, does the character of these microbial communities have any effect on plant growth? In order to answer these questions, we first determine whether nitrogen-fixing bacteria …

Influence Of Indirect Cues And Vegetation Density On Foraging Behavior In Snowshoe Hares (Lepus Americanus), Zachary Lankist

Thinking Matters Symposium Archive

Prey avoid chemical cues from predators at feeding sites because the risk of death outweighs the benefit of food. However, we lack information regarding avoidance of chemical cues from competitors as well as how foraging behavior changes alongside vegetative cover. To test if chemical cues and vegetative cover alter prey vigilance, number of visits, and time spent at feeding sites, I observed snowshoe hares (Lepus americanus) in plots containing coyote (Canis latrans; predator) and moose (Alces alces; competitor) urine across a spectrum of vegetation densities. Snowshoe hares significantly reduced the number of visits to feeding plots when coyote or moose …

Effects Of Increased Precipitation On The Life History Of Spring- And Autumn-Germinated Plants Of The Cold Desert Annual Erodium Oxyrhynchum (Geraniaceae), Yanfeng Chen, Xiang Shi, Lingwei Zhang, Jerry M. Baskin, Carol C. Baskin, Huiliang Liu, Daoyuan Zhang

Biology Faculty Publications

Future increased precipitation in cold desert ecosystems may impact annual/ephemeral plant species that germinate in both spring and autumn. Our primary aim was to compare the life history characteristics of plants from spring-germinating (SG) and autumn-germinating (AG) seeds of Erodium oxyrhynchum. Plants in field plots with simulated increases in precipitation of 0, 30 and 50 % in spring and summer were monitored to determine seedling survival, phenology, plant size, seed production and biomass accumulation and allocation. Germination characteristics were determined in the laboratory for seeds produced by plants in all increased precipitation treatments. Increased precipitation in spring significantly improved survival …

Individual-Based Modeling Of Amazon Forests Suggests That Climate Controls Productivity While Traits Control Demography, Sophie Fauset, Manuel Gloor, Nikolaos M. Fyllas, Oliver L. Phillips, Gregory P. Asner, Timothy R. Baker, Lisa Patrick Bentley, Roel J. W. Brienen, Bradley O. Christoffersen, John Del Aguila-Pasquel

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

Climate, species composition, and soils are thought to control carbon cycling and forest structure in Amazonian forests. Here, we add a demographics scheme (tree recruitment, growth, and mortality) to a recently developed non-demographic model—the Trait-based Forest Simulator (TFS)—to explore the roles of climate and plant traits in controlling forest productivity and structure. We compared two sites with differing climates (seasonal vs. aseasonal precipitation) and plant traits. Through an initial validation simulation, we assessed whether the model converges on observed forest properties (productivity, demographic and structural variables) using datasets of functional traits, structure, and climate to model the carbon cycle at …

Cytotoxic And Antimicrobial Activities Of The Constituents Of Ten Plant Species From Tanzania, Joan J. E. Munissi

Tanzania Journal of Science

This paper reports on the antimicrobial and cytotoxicity activities of crude extracts from the plant species Clemaptosis scabiosifolia (Ranunculaceae), Diospyros mafiensis (Ebenaceae), Dolichos kilimandscharicus (Leguminosae), Gnidia kraussiana (Thymelaeaceae), Hugonia castaneifolia (Linaceae), Neorautanenia mitis (Pappilionaceae), Tagetes minuta (Asteraceae), Uvaria acuminata (Annonaceae), Vernonia amygdalina (Asteraceae) and Zanha africana (Sapindaceae). All crude extracts were screened for their cytotoxicities in the brine shrimp lethality test (BST). Fractions and pure compounds from Hugonia castaneifolia, Diospyros mafiensis and Uvaria acuminata were tested for their cytotoxicity and antimicrobial activities against ten microorganisms, namely Candida albicans, Bacillus anthracis, Escherichia coli, Klebsiela pneumoniae, Proteus sp., Pseudomonas aeruginosa, Salmonella typhimurium, …

Where Has All The Ceanothus Megacarpu S Gone?, Alden Kruse, Hudson Kruse, Naomi Kruse

Biology

Background: Wildfire is a large part of the chaparral biome, where seedlings from sclerophyllous plants need fire to crack the seed coat. When shrubs reach maturity they produce seeds, allowing for greater genetic diversity and variation. We visually, noticed that the coastal chaparral appeared to be in distress and suspected climate extremes of drought and frequent fire were the cause.

Method: Following the Woolsey Fire (2018) we quadrat sampled three chaparral sites on the Pepperdine Campus in Malibu, CA. All three experienced fire and drought. One site had been subjected to five fires in less than 35 years. Another experienced …

A Stimulatory Role For Cytokinin In The Arbuscular Mycorrhizal Symbiosis Of Pea, Dane M. Goh, Marco Cosme, Anna B. Kislala, Samantha Mulholland, Zakaria M.F. Said, Lukáš Spíchal, R.J. Neil Emery, Stéphane Declerck, Frédérique C. Guinel

Biology Faculty Publications

The arbuscular mycorrhizal (AM) symbiosis between terrestrial plants and AM fungi is regulated by plant hormones. For most of these, a role has been clearly assigned in this mutualistic interaction; however, there are still contradictory reports for cytokinin (CK). Here, pea plants, the wild type (WT) cv. Sparkle and its mutant E151 (Pssym15), were inoculated with the AM fungus Rhizophagus irregularis. E151 has previously been characterized as possessing high CK levels in non-mycorrhizal (myc^-) roots and exhibiting high number of fungal structures in mycorrhizal (myc⁺) roots. Myc^- and myc⁺ plants were …

Seasonal Origins Of Soil Water Used By Trees, Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, Gregory R. Goldsmith

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Rain recharges soil water storages and either percolates downward into aquifers and streams or is returned to the atmosphere through evapotranspiration. Although it is commonly assumed that summer rainfall recharges plant-available water during the growing season, the seasonal origins of water used by plants have not been systematically explored. We characterize the seasonal origins of waters in soils and trees by comparing their midsummer isotopic signatures (δ2H) to seasonal isotopic cycles in precipitation, using a new seasonal origin index. Across 182 Swiss forest sites, xylem water isotopic signatures show that summer rain was not the predominant water source …

Extending The Osmometer Method For Assessing Drought Tolerance In Herbaceous Species, Robert J. Griffin-Nolan, Troy W. Ocheltree, Kevin E. Mueller, Dana M. Blumenthal, Julie A. Kray, Alan K. Knapp

Biological, Geological, and Environmental Faculty Publications

Community-scale surveys of plant drought tolerance are essential for understanding semi-arid ecosystems and community responses to climate change. Thus, there is a need for an accurate and rapid methodology for assessing drought tolerance strategies across plant functional types. The osmometer method for predicting leaf osmotic potential at full turgor ((o)), a key metric of leaf-level drought tolerance, has resulted in a 50-fold increase in the measurement speed of this trait; however, the applicability of this method has only been tested in woody species and crops. Here, we assess the osmometer method for use in herbaceous grassland species and test whether …

Seed Germination Responses To Seasonal Temperature And Drought Stress Are Species‐Specific But Not Related To Seed Size In A Desert Steppe: Implications For Effect Of Climate Change On Community Structure, Fengyan Yi, Zhaoren Wang, Carol C. Baskin, Jerry M. Baskin, Ruhan Ye, Hailian Sun, Yuanyuan Zhang, Xuehua Ye, Guofang Liu, Xuejun Yang, Zhenying Huang

Biology Faculty Publications

Investigating how seed germination of multiple species in an ecosystem responds to environmental conditions is crucial for understanding the mechanisms for community structure and biodiversity maintenance. However, knowledge of seed germination response of species to environmental conditions is still scarce at the community level. We hypothesized that responses of seed germination to environmental conditions differ among species at the community level, and that germination response is not correlated with seed size. To test this hypothesis, we determined the response of seed germination of 20 common species in the Siziwang Desert Steppe, China, to seasonal temperature regimes (representing April, May, June, …

Life Line - February 2019, Otterbein Biology And Earth Science Department

Life Line - The Biology Department Newsletter

Curricular Changes, Dr. Young's Sabbatical, Coal, Gas & Oil - Geology trip to eastern Ohio, Rebekah Perry is engaging the community in natural history, Student Research, Fem in STEM, Zoo students on Belize Trip, Scientific Art

Distribution And Population Structure Of The Invasive Nitellopsis Obtusa (Desv. In Loisel.) J. Groves And Native Species Of Characeae In The Northeast U.S.A., Robin Sleith

Dissertations, Theses, and Capstone Projects

Freshwater ecosystems are some of the most biologically diverse environments on Earth. Billions of humans rely on functioning freshwater ecosystems for drinking water and many other services. These ecosystems are increasingly threatened by human impacts including nutrient pollution, invasive species, and climate change. Here I contribute four research chapters that investigate freshwater diversity and ecosystem threats using the Characeae, a family of freshwater green macroalgae, as a study system. Characeae are a diverse and ancient group with more than 500 extant species and a fossil history spanning at least 250 million years. These algae are macrophytes in freshwater ecosystems, and …

Refernment: An R Package For Annotating Rna Editing In Plastid Genomes, Tanner A. Robison, Paul G. Wolf

Biology Faculty Publications

PREMISE OF THE STUDY: In the absence of cDNA, the annotation of RNA editing in plastomes must be done manually, representing a significant time cost to those studying the organellar genomes of ferns and hornworts.

METHODS AND RESULTS: We developed an R package to automatically annotate apparent nonsense mutations in plastid genomes. The software successfully annotates such sites and results in no false positives for data with no sequencing or assembly errors.

CONCLUSIONS: Compared to manual annotation, ReFernment offers greater speed and accuracy for annotating RNA editing sites. This software should be especially useful for researchers generating large numbers of …

Arachidin-1 And Arachidin-3 Modulation Of Rotavirus-Infected Ma104 Cells, Caleb M. Witcher, Rebekah Napier-Jameson, Hannah N. Lockwood, Macie N. Mattila, Stormey B. Wisdom, Luanna L. Saade Ferreira, Josephine Taylor, Beatrice Clack, Fabricio Medina-Bolivar, Judith M. Ball, Rebecca D. Parr

Faculty Publications

Rotavirus (RV) causes severe life-threatening diarrhea in young children and immunocompromised individuals. There are several licensed attenuated vaccines for young children, but there are no vaccines or antiviral therapeutics for immunocompromised patients of any age. Previously, our laboratory demonstrated that arachidin 1 (A1) and arachidin 3 (A3) decreases the number of infectious simian RV particles and RV non-structural protein 4 (NSP4) in a human intestinal cell line which suggests effects on RV replication. This study examined the effects of the arachidins on the human RV (Wa)-infected African green monkey kidney cell line, MA104. The addition of either A1 or A3 …

Embl2checklists: A Python Package To Facilitate The User-Friendly Submission Of Plant And Fungal Dna Barcoding Sequences To Ena, Michael Gruenstaeudl, Yannick Hartmaring

Biological Sciences Faculty Publications

Background The submission of DNA sequences to public sequence databases is an essential, but insufficiently automated step in the process of generating and disseminating novel DNA sequence data. Despite the centrality of database submissions to biological research, the range of available software tools that facilitate the preparation of sequence data for database submissions is low, especially for sequences generated via plant and fungal DNA barcoding. Current submission procedures can be complex and prohibitively time expensive for any but a small number of input sequences. A user-friendly software tool is needed that streamlines the file preparation for database submissions of DNA …

Global Temporal Patterns In Plant Nutrient Resorption Plasticity, Rebecca E. Drenovsky, Nicole Pietrasiak, Thomas Short

2019 Faculty Bibliography

Aim Leaf nutrient resorption is a key nutrient conservation trait, which also influences nutrient cycling rates and pools. Most global biogeochemical models assume that resorption is non‐varying at a temporal scale. However, this trait can differ substantially within populations among years. We assessed the commonality of attaining proficient resorption, the factors associated with proficient resorption, as well as the variability of this trait and the factors controlling trait variability.

Functional Traits Explain Variation In Chaparral Shrub Sensitivity To Altered Water And Nutrient Availability, Reina L. Nielsen, Jeremy J. James, Rebecca E. Drenovsky

2019 Faculty Bibliography

Worldwide drylands are threatened by changes in resource availability associated with global environmental change. Functional traits may help predict which species will be most responsive to these alterations in nutrient and water availability. Current functional trait work focuses on tissue construction and nutrient concentrations, but plant performance in low resource environments also may be strongly influenced by traits related to nutrient budgets and allocation. Our overall objective was to compare trait responses in a suite of serpentine and nonserpentine congener pairs from the California chaparral, a biodiverse region facing nutrient deposition and future changes in precipitation. In a common garden …

Interactive Effects Of Salinity And Inundation On Native Spartina Foliosa, Invasive S. Densiflora And Their Hybrid From San Francisco Estuary, California, Blanca Gallego-Trevar, Brenda J. Grewell, Caryn J. Futrell, Rebecca E. Drenovsky, Jesus M. Castillo

2019 Faculty Bibliography

Sea level rise (SLR) associated with climate change is intensifying permanent submersion and salinity in salt marshes. In this scenario, hybridization between native and invasive species may result in hybrids having greater tolerance of abiotic stress factors than their parents. Thus, understanding the responses of native and invasive halophytes and their hybrids to interacting physiological stresses imposed by SLR is key to native species conservation. We analysed how salinity, inundation depth and their interaction impact the functional traits of native and invasive cordgrass species and their hybrid (genus Spartina; Poaceae).

Resprouting Potential Of Rhizome Fragments From Invasive Macrophyte Reveals Superior Colonization Ability Of The Diploid Congener, Brenda J. Grewell, Caryn J. Futrell, Maria Iannucci, Rebecca E. Drenovsky

2019 Faculty Bibliography

Non-native aquatic Ludwigia species from a polyploid complex are among the world’s most problematic invasive plants. These emergent, floating-leaved species respond to disturbance through fragmentation of shoots and/or rhizomes, spreading rapidly by hydrochorous dispersal and posing challenges for invasive plant management. While recruitment of clonal aquatic plant species from shoot fragmentation is well documented, regeneration from rhizome bud banks, although common, often is overlooked. It is further unclear how interactions among ploidy and resource availability influence regeneration success of rhizome fragments. We conducted a full factorial experiment in aquatic mesocosms to compare trait responses of Ludwigia congeners differing in ploidy …

Functional Traits Explain Variation In Chaparral Shrub Sensitivity To Altered Water And Nutrient Availability, Reina Lee Nielsen, Jeremy James, Rebecca E. Drenovsky

2019 Faculty Bibliography

Worldwide drylands are threatened by changes in resource availability associated with global environmental change. Functional traits may help predict which species will be most responsive to these alterations in nutrient and water availability. Current functional trait work focuses on tissue construction and nutrient concentrations, but plant performance in low resource environments also may be strongly influenced by traits related to nutrient budgets and allocation. Our overall objective was to compare trait responses in a suite of serpentine and nonserpentine congener pairs from the California chaparral, a biodiverse region facing nutrient deposition and future changes in precipitation. In a common garden …