Other Ecology and Evolutionary Biology Commons^™

How Semiflightless Birds Adapt: A Survey From Barú, Costa Rica, Eli P. Laloudakis

Scripps Senior Theses

When we think of birds, we think of flight. Because of this, scientific research often focuses on how birds evolved flight and how their wings function during flight. However, not all birds can fly or fly well, as wings wax and wane on developmental, seasonal, and evolutionary time scales (Dial and Heers 2021). Consequently, rudimentary wings can be found in developing birds, secondarily flightless or semiflightless birds, birds that undergo simultaneous molts, and extinct theropods with “protowings” (structures that preceded fully functional wings). Secondarily flightless and semiflightless birds often evolve where there is no/low predation, abundant year-round food supply, and …

We Found Love In A Wetter Climate: The Impact Of Varying Climatic Conditions On The Prevalence Of A Fungal Endophyte In Elymus Virginicus Populations, Audrey Yung

Scripps Senior Theses

Epichloë is a genus of endophytes– symbiotic fungi residing within a plant’s tissue– that can provide mutualistic benefits to its host. The stress gradient hypothesis predicts that mutualism between species becomes stronger in conditions of high abiotic stress. We tested this idea by assessing how Epichloë prevalence in Elymus virginicus populations is affected by varying climatic conditions. We established plots of E. virginicus with known endophyte frequencies in the spring of 2023 at five sites across a precipitation gradient in Texas and Louisiana. We collected E. virginicus recruits in June and July 2024 at all field sites. To determine recruits’ …

Assessing The Effects Of Wildfire Season Pm2.5 Exposure And Environmental Variables On Breeding Season Avian Body Condition, Cira Seyer-Ochi

Scripps Senior Theses

The increasing frequency and intensity of wildfires pose growing threats to wildlife, yet the indirect effects of wildfire smoke on avian populations remain largely unstudied. This exploratory study provides an initial assessment of how particulate matter 2.5 (PM2.5) associated with smoke pollution from the 2017 California wildfire season, in conjunction with precipitation and habitat type, influences the body condition of four resident bird species during the 2018 breeding season. Using bird banding data from 29 Monitoring Avian Productivity and Survivorship (MAPS) stations, I assessed the potential interactions between PM2.5 concentrations, precipitation, and habitat type with body condition for Song Sparrows …

Biogeography Of Special Metabolites Produced By Ant-Associated Bacteria, Katherine Hansen

Scripps Senior Theses

There is an urgent and growing need for novel antibiotics with the growing prevalence of antibiotic-resistant pathogens. Ecologically-guided discovery is a strategy that focuses on how and where specially evolved metabolites such as antibiotics are used in nature. This strategy reveals unique active molecules with potential for human use. An unexplored niche with great potential for antibiotic discovery exists with Southwestern fungus-farming Trachymyrmex ants and their Actinobacteria symbionts. In exchange for nutrients from the ant, the ants’ bacterial symbiont produces antifungal molecules that protect the ants’ fungal cultivar from invasion by pathogenic microorganisms. They also produce antibacterial molecules to protect …

Understanding The Environmental Implications Of The Microbiome Of Canals In Bangkok, Thailand, Emma Tao

Scripps Senior Theses

The canals of Bangkok, Thailand hold significant economic and social value, yet the increasing urbanization of the city has resulted in increased water pollution. Agricultural runoff and urban waste contribute to the degradation of the water quality, which has impaired its safe usage by the people of the city. This study focused on analyzing the microbiome of the water in the canals in correlation with the surrounding environment, both in and out of the water. Ten sites along the Bangkok canals were analyzed. DNA was isolated for the sequencing of the 16s rRNA gene to determine the microbial diversity of …

Cost Of Co-Infection In Peromyscus Leucopus Mice, Ananya Sagar

Scripps Senior Theses

Abstract

Co-infections occur frequently across humans & wildlife, and can have effects on host health. Despite the prevalence of microparasite-helminth co-infections, majority of the research focuses either on singular infections or on concurrent infections in a laboratory setting. This fails to take into account the interspecific interactions between the multiple parasites and the host in natural settings. The interactions could be direct by resource competition, or indirect via the host immune system. In our research, we studied the relationship between nematodes and coccidia in their host, Peromyscus leucopus mice, at the Mountain Lake Biological Station, Virginia. We further evaluated the …

The Chumash Heritage National Marine Sanctuary: An Exploration Of Changing The Discourse On Conservation, Arielle Ben-Hur

Pitzer Senior Theses

In 2015, the Northern Chumash Tribal Council submitted a National Marine Sanctuary Nomination to establish the Chumash Heritage National Marine Sanctuary– a means by which to ensure the protection of one of the most culturally and biologically diverse coastlines in the world. On October 5, 2015, John Armor of the National Oceanic and Atmospheric Administration (NOAA) responded to the nomination, adding it to the inventory of areas NOAA may consider in the future for national marine sanctuary designation.

In my thesis, I explore how the nomination of the Chumash Heritage National Marine Sanctuary acts as a platform from which Traditional …

Antifungal Defense Molecules From Bacterial Symbionts Of North American Trachymyrmex Ants, Georgia Scherer

CMC Senior Theses

Defensive symbioses, in which microbes provide molecular defenses for an animal host, hold great potential as untapped sources of therapeutically useful antibiotics. Fungus-growing ants use antifungal defenses from bacterial symbionts to suppress pathogenic fungi in their nests. Preliminary chemical investigations of symbiotic bacteria from this large family of ants have uncovered novel antifungal molecules with therapeutic potential, such as dentigerumycin and selvamicin.

In this study, the bacterial symbionts of North American Trachymyrmex fungus-growing ants are investigated for antifungal molecules. Plate-based bioassays using ecologically-relevant fungal pathogens confirmed that these bacteria have antifungal activity. In order to purify and identify the antifungal …

Potential For Climate Induced Methane Hydrate Dissociation, Graham Macwilliams

Pomona Senior Theses

Methane hydrates are frozen deposits of methane and water found in high pressure or low temperature sediments. When these deposits destabilize, large quantities of methane can be emitted into the atmosphere. This is significant to climate change because methane has 25 times more greenhouse gas potential than Carbon Dioxide. Worldwide, it is estimated there are between 2500 and 10000 gigatons of methane stored in hydrate deposits. This represents more carbon than all fossil fuels on Earth. It is estimated that between 200 and 2000 gigatons of methane are stored in hydrates in Arctic waters acutely vulnerable to greenhouse warming. Over …

Slowing The Evolution And Outbreak Of Antibiotic Resistance, Connie Okasaki

HMC Senior Theses

Antibiotic resistance is a problem of significant and growing international concern, in part due to the rapid evolution of new resistances. One potentially important factor in the emergence of resistance is concentrated antibiotic use in environments such as hospitals. Such high use creates a strong selective pressure for pathogens to evolve resistance. We analyze some strategies hospitals can use to slow the evolution of resistance, and estimate the length of the delay between evolution and outbreak of resistance.

A Distributed Intelligence Approach To Multidisciplinarity: Encouraging Divergent Thinking In Complex Science Issues In Society., Jarod Kawasaki, Dai Toyofuku

The Transdisciplinary STEAM+ Journal

The scientific issues that face society today are increasingly complex, open-ended and tentative (Sadler, 2004). Finding solutions to these issues, not only requires an understanding of the science, but also, concurrently dealing with political, social, and economic dimensions that exist (Hodson, 2003). For example, 40 years after the first congressional hearing on climate change held by Al Gore in 1976, the 2012 Intergovernmental Panel on Climate Change (IPCC) report states that climate change is still getting worse, despite efforts by governments, businesses, social actors such as Non-Government Organizations, and scientists. With the top minds in the world, across all disciplines, …

Implications Of Land Development On Nomadic Pastoralism: Ecological Relaxation And Biosocial Diversity In Human Populations, Hannah R. Bradley

Scripps Senior Theses

Nomadic pastoralism is an ancient subsistence strategy, historically balanced and in continuity with sedentary societies. Sedentarization of nomads occurs normally because of ecological disasters, economic opportunities, urbanization, and government policy. In this paper, I examine the effect of changing land use patterns on nomadic pastoral populations in Asia, Africa, and the Middle East, using biogeographic methodology to further explore the contemporary relationship between humans and their environments. Nomadic population information gleaned from diverse ethnographic studies, and GIS data on anthropogenic biome distributions, were used to calculate changes in nomadic population, area of developed land, and nomadic/sedentary population density over the …

The Vascular Flora Of Greater San Quintín, Baja California, Mexico, Sula E. Vanderplank

CGU Theses & Dissertations

The plants of San Quintín (Baja California, Mexico) were documented through intensive fieldwork and the collection of herbarium specimens to create a checklist of species. This region is home to a diverse flora with high levels of local endemism and many rare plants. The flora documented in this study was compared to historical records from the region and shows the impact of agriculture and urbanization on the plants, including several extirpated species. A study of the perennial vegetation using a 1 km grid provides species distribution data for 140 native species, which were assessed to highlight areas of significant species …