456 Works

Indirect defenses show carrion are predictors of predator abundances on glandular manzanitas (Arctostaphylos glandulosa)

Sarah Layer, Ruth Alcantara & Jerry Addison
Plant systems commonly use interactions known as indirect defenses to protect themselves against herbivory. One such defense is two-staged, beginning with plants utilizing sticky hairs known as glandular trichomes as an indirect defense to attract and trap carrion and provision predators. However, no known studies have specifically tested the efficacy of this defense across a stickiness gradient. We tested if increasing levels of stickiness on glandular manzanitas (Arctostaphylos glandulosa) increase the effectiveness of their herbivory...

Anthropogenic effects on abiotic factors affecting the success of the threatened Rana boylii

Alma Meckler-Pacheco, Laura Navarro Ron, Sophia Puliatti & Zach Webster
Freshwater ecosystems disproportionately support a large number of species given the limited availability of suitable habitat. Anthropogenic disturbance in freshwater systems have caused a decline in over 5,700 species globally. Amphibians are especially sensitive to levels of disturbance due to their physiological requirements for homeostasis. Our study set out to investigate how differing levels of human disturbance affect abiotic variables on Foothill yellow-legged frog (Rana boylii) in the South Fork Eel River. We studied the...

Habitat partitioning of bat communities in Northern California

Paige Klotz, Vanessa Lundsten, Nic Morat & Kenna Sherman
The theory of niche partitioning states that species coexisting at equilibrium within a stable community must share limited resources (Hutchinson 1957). This theory has been widely studied in diverse community assemblages, but few studies have applied niche partitioning to bat communities. Specifically, little is known about how bat species occupy different microhabitats in order to coexist. Our study aims to understand the effect of habitat on bat diversity and abundance within the scope of niche...

Revisiting invasion on tussocks: Relating environmental variables to invasion

Martin Genova, Conall Gaffney & Anson Pang
Classic invasion theory predicts that higher species diversity increases the resistance of a community to invasion by non-native species. However, studies that challenge this theory propose that environmental variables that covary with native diversity play an important role in determining invasibility in communities. One way that environmental variables can act to determine community invasibility is by facilitating propagule pressure of non-native species. Here, we investigate how environmental variables, through the mechanism of propagule pressure, directly...

Characterizing tick microhabitat preferences in relation to lizard hosts at Angelo Coast Range Reserve, California

Haley Hurst, Cassidy Coker, Tim Torno & Trent McColl
Climate change negatively impacts biodiversity rates among species worldwide. Maintaining biodiversity is crucial to maintaining healthy ecological relationships including those between lizards and ticks. Lizard tick interactions are vital to understanding how disease affects a landscape because lizards act as an incidental host for Lyme Disease. Researching these changes are vital to better understand how disease ecology will affect natural environments in our future. Our study examined the relationship between lizards and ticks inhabiting the...

Patterns of nectar robbing on two manzanita species

Breana Dyste, , Kenny Ruiz & Benjamin Vargas
Pollinators provide ecosystem services and facilitate plant reproduction. Plant-pollinator interactions often benefit both partners and are considered mutualisms. However, cheating can occur in these interactions when floral visitors take resources from plants without providing any benefit (Smithson 2013). One example of this kind of cheating is nectar robbing, which occurs when a pollinator collects nectar from a hole in the flower’s corolla and bypasses pollination. We compared the variation of floral nectar robbing between two...

Phenotypic variation of the hemiparasite Pedicularis densiflora

Erick Amezcua, Stacy Lammers, Mary Polhemus & Lucia Soto-Hall
Phenotypic variation allows plants to survive in a wide variety of environments and has been a topic of study for many decades. However, relatively little is known about the effect of biotic and abiotic factors on the phenotypic variation of parasitic plants. In this study we examined how biotic factors related to host-parasite interactions affect the phenotype of Pedicularis densiflora. We surveyed four sites of serpentine chaparral habitat at McLaughlin Natural Reserve in Lower Lake,...

Effect of patch size on species richness and distribution of sub-alpine saxicolous lichens

Abraham Adida, Melody Griffith, Margot Kirby & Amanda Lin
Understanding how communities respond to environmental pressures is important for conservation planning and management. In this observational study, we examined the SLOSS debate and the ecological concept of nestedness in respect to how saxicolous lichen communities in sub-alpine habitats are structured. We analyzed the effects of patch size on the species richness and distribution of saxicolous lichen. We surveyed 242 granitic rocks in the White Mountains, California, and collected data on the different taxa found....

Dietary preference of Formica obscuripes depends on role not time

, Francisca C. Fazzio, Cal J. Huesby & Zaira B. Sepulveda Ochoa
Resource management is necessary for the success of a species. Optimal foraging theory states that a species will attempt to minimize the energy spent obtaining resources, whilst maximizing the resources collected. Optimal foraging theory can be examined through the lens of ant colony behavior. Formica obscuripes utilizes role specialization and resource partitioning in each colony to minimize its energy use while maximizing its nutrient reserve. However, nutrient preferences within roles have been largely unstudied. In...

Factors affecting acorn predation and infestation in three California oaks

Nicolette Balmaceda, Jovana Durovic, Sierra Montes & Kyler Plouffe
Oak woodlands are in decline due to failed oak recruitment in California. Oak recruitment is heavily impacted by vertebrate herbivory and insect infestation of acorns. Oaks have developed chemical defenses such as tannins to protect acorns from attack. Studies have explored infestation differences in red oaks but have not compared infestation between red oaks and white oaks. We explored how Cydia latiferreana (filbertworm) infestation, Curculio occidentalis (filbert weevil) infestation, and Sciurus griseus nigripes (western gray...

Effect of honey mesquite size and distribution on desert mistletoe parasitism

Angelique Leonard, Monica Rivas, Thomas Savoie & Olivia Zanzonico
Parasitic plants must rely on their hosts to survive. However, the distribution and survival of parasitic plants often depends on other organisms in addition to the host. Desert mistletoe (Phoradendron californicum) has a unique interdependent relationship with its preferred host, honey mesquite (Prosopis glandulosa), and its primary disperser, Phainopepla (Phainopepla nitens). We sought to study this relationship by testing the effects of honey mesquite size and distribution on the likelihood of infection by mistletoe. At...

Odonate communities across a desert development gradient

Ezra Garfield, Taylor Kang, Isak Kolding & Joshua Mayo
Deserts are changing rapidly due to urbanization and climate change. Although human development can destroy habitat, it can also create novel environments that organisms may use or adapt to. In this study we compared artificial ponds to natural oases to determine whether artificial water sources differ in the odonate communities they support, as odonate species are indicators of aquatic habitat quality. We found that odonate community composition differed markedly based on water source characteristics such...

Black-tailed deer and what they fear: vigilance responses to predator vocalizations as a window into current and historical predation pressure

Bryce Ahn, Marisol Morales, Ian Perrett, Mika Post, Francis Ulep & Yunqing Sara Ye
Predation is a potent ecological and evolutionary force, shaping the behavior of animals to minimize risk. Behavior itself can therefore provide clues into the predation pressure experienced by a population. We investigated anti-predator vigilance behavior in a California coastal population of black-tailed deer in response to vocal cues from three predator species of varying current and historical risk: grey wolf, coyote, and red-tail hawk. Vigilance was measured as the proportion of a herd alerting to...

Cattle grazing decreases ant abundance but not foraging success in Great Basin desert steppe

Ines Anuncibay-Childs, , Sanam Noorani & Brandon Mukogawa
Grazing has been documented to have widespread effects on flora and fauna in a variety of ecosystems. However, research has yielded conflicting results on determining the impact of grazing on ants; some have found that grazing increases ant abundance and alters composition while others have found the opposite pattern. It is critical to accurately survey the consequences of grazing in order to understand the implications of this widespread land management practices on ecosystems especially on...

The effect of resource limitation on floral visitors of Monardella odoratissima

Isabelle Everhart, Ashish Kothari, Chris McCarron & Tricia Nguyen
Fluctuating flowering patterns affect an environments floral abundance, impacting the spatial structure of nectar and pollen resources, ultimately influencing floral visitor foraging behavior. We examined the effect of reducing floral resources on floral visitors of Monardella odoratissima, commonly known as the mountain coyote mint. Isolated patches of M. odoratissima were created by removing all surrounding resources, in order to test its effect on floral visitor communities. Exploring how the resource-richness of a habitat affects this...

Effects of disturbance on biological soil crusts

Alexandra Reep, Christian Morgan & Lilianne De La Espriella
Drylands are prone to desertification as human disturbances degrade desert ecosystems and limit their capacity to bio-produce. Biological soil crusts, a specialized community of lichen and cyanobacteria, are particularly vulnerable to these disturbances. To gauge the effects of anthropogenic disturbance on soil particle size and soil crust growth, Collema, a widely-distributed genus of soil lichen, was used as an indicator of overall ecosystem health. We used the visual percent cover method in four “low disturbance”...

Paving the way for habitat disturbance: Different road types have distinct ecological impacts on annual plant communities and gall-forming insects in the Mojave Desert

Maria Carias, Emily Hascall, Kelsey Pennington & Jasmine Summers-Evans
Road disturbance can facilitate the establishment and growth of invasive plant species and herbivorous insects in adjacent ecosystems. The hydrological and atmospheric impacts of roads are especially important to understand in arid desert environments that are highly sensitive to water stress and dust pollution. In this study, we looked at how impacts of road disturbance change among different road types within the Mojave Desert. Specifically, we observed how three types of roads (paved road, dirt...

Benthic macroinvertebrates in Marin County streams: species richness is lower near human infrastructure

Alice Beittel, Madeline Hale, Caitlin Loeffler, Tanvi Mamtora & Natalia Mushegian
Streams and rivers represent less than 0.0001% of the planet's water, but are support up to 10% of its biological diversity and are fundamental to human life. As sources of drinking water, transportation, recreation, and energy, streams are both highly valuable and highly vulnerable to us. Humans have obvious imperative to protect stream ecosystems, but many effects are likely to be unintentional and unseen, incidental to our existing in a place. We sampled stream macroinvertebrate...

Rancho Seco vernal pool community data

Julia Michaels
Disturbance often increases local-scale (α) diversity by suppressing dominant competitors. However, widespread disturbances may also reduce biotic heterogeneity (β diversity) by making the identities and abundances of species more similar among patches. Landscape-scale (γ) diversity may also decline if disturbance-sensitive species are lost. California’s vernal pool plant communities are species-rich due in part to two scales of β diversity: (1) within pools, as species composition changes with depth (referred to here as vertical β diversity),...

The atomic-level physiochemical determinants of T cell receptor dissociation kinetics

Zachary Rollins, Roland Faller, Ilias Tagkopolous, Jun Huang & Steven George
The force-dependent bond lifetime of a T Cell Receptors (TCR) to 17 peptide-Major Histocompatibility Complexes (pMHCs) was simulated using Steered Molecular Dynamics. Physiochemical descriptors of the TCR-pMHC interaction during simulation were then filtered and selected to understand the best feature sets that predict bond lifetime. This methodology sets precedence on the rational design of TCRs via force-dependent bond lifetime enhancement.

Physiology trait and growing region climate data compiled from the literature for 34 wine grape cultivars

Megan Bartlett & Gabriela Sinclair
Selection for crop cultivars has largely focused on reproductive traits, while the impacts of global change on crop productivity are expected to depend strongly on the vegetative physiology traits that drive plant resource use and stress tolerance. We evaluated relationships between physiology traits and growing season climate across winegrape cultivars to characterize trait variation across growing regions and elucidate the mechanisms that adapted grapevines to hot, dry conditions. We compiled values from the literature for...

Dock‐based and dockless bikesharing systems: analysis of equitable access for disadvantaged communities

Xiaodong Qian, Miguel Jaller, Debbie Niemeier & Miao Hu
Dockless bikeshare systems show potential for replacing traditional dock-based systems, primarily by offering greater flexibility for bike returns. However, many cities in the US currently regulate the maximum number of bikes a dockless system can deploy due to bicycle management issues. Despite inventory management challenges, dockless systems offer two main advantages over dock-based systems: a lower (sometimes zero) membership fee, and being free-range (or, at least free-range within designated service areas). Moreover, these two advantages...

Coast live oak (Quercus agrifolia) legacy: Lasting influences on plant and soil compositions

, Keeley Lanigan, & Angel Ramnani
Around 90 percent of natural oak habitats have been cleared due to the development of agriculture, cattle ranching, and urbanization. This study focuses on the legacy of coast live oaks (Quercus agrifolia) and how they influence their surrounding environment through testing soil moisture, plant biomass, and plant percent cover. We located areas containing dead and living coast live oaks trees along two valleys at Sedgwick Reserve, examining trees that were living, recently dead (<15 years),...

Divergent processes drive parallel evolution in marine and freshwater fishes

Sarah Friedman, Mike Collyer, Samantha Price & Peter Wainwright
Evolutionary comparisons between major environmental divides, such as between marine and freshwater systems, can reveal the fundamental processes governing diversification dynamics. Although processes may differ due to the different scales of their biogeographic barriers, freshwater and marine environments nevertheless offer similar opportunities for diversification in benthic, demersal, and pelagic habitats. Here, we compare the evolutionary patterns and processes shaping teleost diversity in each of these three habitats and between marine and freshwater systems. Using specimens...

Wolbachia frequency data from: Why did the Wolbachia transinfection cross the road? Drift, deterministic dynamics and disease control

Michael Turelli & Nicholas Barton
Maternally inherited Wolbachia transinfections are being introduced into natural mosquito populations to reduce the transmission of dengue, Zika and other arboviruses. Wolbachia-induced cytoplasmic incompatibility provides a frequency-dependent reproductive advantage to infected females that can spread transinfections within and among populations. However, because transinfections generally reduce host fitness, they tend to spread within populations only after their frequency exceeds a critical threshold. This produces bistability with stable equilibrium frequencies at both 0 and 1, analogous to...

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