Tag: Poster 58

The Cellular Basis of Dermal Bone Evolution and Development in Threespine Stickleback Fish

Presenter: Sophie Sichel

Mentor: William Cresko and Kristin Alligood, Biology

Poster: 58

Major: Biology 

In vertebrates the development of the cranial skeleton is imperative because it provides structure and support for a number of critical organs. Cranial structures vary immensely across vertebrates, but how did these different mechanisms of morphogenesis evolve at the developmental and cellular level? To elucidate the molecular mechanisms controlling variation in morphogenesis, I used the opercle bone of threespine stickleback fish as a model. Threespine stickleback are used as a model to investigate vertebrate evolution because of rapid changes between ancestral oceanic and derived freshwater forms of this fish. The opercle bone is a neural crest-derived dermal bone that is critical for respiration, foraging and communication in stickleback, undergoes morphogenesis during development, and varies among populations. Neural crest cells form the facial skeleton of vertebrates through intramembranous ossification. After the initial condensation, bone shaping is hypothesized to be dependent on the recruitment of new osteoblasts in a space and time dependent manner, and variation in bone morphogenesis would therefore be linked to differences in osteoblast recruitment. To test this hypothesis, I conducted in situ hybridizations using a probe to col10a1, which is a gene present in the cartilaginous precursor of mature dermal bone, on stickleback embryos at various times during embryonic development. This probe allowed me to visualize the developing opercle and a proliferation assay to visualize proliferating cells thought to be contributing to the developing bone. I quantified the number of proliferating cells and determined their distribution near the developing edge of the opercle in two different populations of stickleback: a population that exhibits an ancestral phenotype and a population representing the derived phenotype. I will present results describing how the number of cells recruited varies among populations. Determining the molecular and genetic factors that underlie opercle development and how they differ between ancestral and derived populations could provide evidence for how development and evolution interact on a larger scale.

The Ecology and Distribution of the Invasive Violet Tunicate (Botrylloides violaceus) in the Coos Estuary (OR)

Presenter: Sandra Dorning

Faculty Mentor: Craig Young

Presentation Type: Poster 58

Primary Research Area: Science

Major: Marine Biology

Funding Source: Undergraduate Research Opportunity Program Mini-Grant, University of Oregon Undergraduate Research Opportunity Program, $1000

Marine fouling communities on docks and other manmade structures are frequently susceptible to invasions of non-native ascidians—sessile, sac-like marine invertebrates. Botrylloides violaceus, the violet tunicate, has invaded such communities in harbors around the world, including Oregon’s Coos Estuary. In this study, I aim to explain the mechanisms behind the invasion and establishment of B. violaceus in this bay. I propose three potential factors influencing the distribution of this species in the Coos Estuary: 1) abiotic conditions (water temperature, salinity, and water current speed), 2) biotic conditions (competitive relationships with other fouling organisms), and 3)
limited transportation between fouling sites. I conducted quarterly photo quadrat surveys to determine the seasonal distribution of B. violaceus, in addition to short-term permanent quadrat and settlement plate monitoring to document B. violaceus growth patterns and interactions with other fouling species. In addition, I conducted laboratory experiments to determine the temperature and salinity tolerance of B. violaceus. Future experiments in this study will include transplantation of B. violaceus colonies for evaluating survival at currently uninvaded sites. The results of this project will document the extent of and mechanisms behind the Coos Estuary B. violaceus invasion. Understanding the interactions between B. violaceus and native fouling organisms and the potential for this species to expand its distribution is important for conserving native biodiversity and improving invasive species management in the Coos Estuary.

Bacterial and Fungal Community Composition Within Corn Seed

Presenter(s): Roxanne Fieldhouse − Biology

Faculty Mentor(s): Lucas Nebert, Brendan Bohannan

Poster 58

Research Area: Natural Science

Funding: UnderGrEBES Research Award

All plants contain within them an associated microbial community, functioning similar to the human gut community. These plant associated bacteria and fungi have recently come into focus as an important factor in fitness, helping to aid plants by increasing drought resistance, increasing limiting macronutrients available, and providing pathogen resistance. Importantly, many of these beneficial microbes can be inherited in the seed. Because some species can become pathogenic when the plant comes under stress, agricultural communities look to sterilize their seed of these complex communities. Little is known about the ecology of seedborne bacteria and fungi. The objective was to evaluate the microbial community of corn seeds, determine significant environmental factors, such as seed type, climate, and farm, affecting the microbial community composition. Additionally, we attempt to separate these environment-microbe interactions from the microbe-microbe interactions happening within the seed. We hoped to find microorganisms that negatively affect the presence of pathogenic microbes, specifically Fusarium, a genus of fungi that contains multiple species of corn pathogens. These fungi are relevant to human health because they produce a mycotoxin, fumonosin, which negatively impacts neurological development and liver function. Preliminary results have shown type of corn is a significant environmental factor in determining the composition of the microbial community and that significant microbe-microbe associations occur within a subset of the data. This research could allow future investigators to more clearly understand how host microbe interactions operate and reinforces the importance of

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a diverse microbiota.

The Effect of Geography on Genome-Wide Patterns in Mimulus Aurantiacus

Presenter(s): Conner Lane

Faculty Mentor(s): Matt Streisfeld

Poster 58

Session: Sciences

Characterizing patterns of the genome for species spanning a large geographic space may influence the way we understand evolutionary differences between populations. For example, areas of the genome that are highly differentiated and are presumed to result from natural selection may instead arise from genome properties such as low diversity that exaggerate the differences between populations. As a first step towards making conclusions about natural selection in Mimulus aurantiacus, a phenotypically diverse plant occurring continuously across Southern California, we tested for correlations between genome statistics to characterize ways in which properties of the genome may be contributing to differences between populations. As an example, we expect high within-population diversity (π) to mask “real” differences between populations, leading to a lower differentiation score (FST), which we did observe. We also expected this negative relationship between π and FST to grow stronger with higher distance corresponding to more “real” differences to be masked by the within-population variation, which we only observed weak patterns of. This trend of correlations existing but only being weakly associated with geographic distance held true for all statistical comparisons. We conclude that M. aurantiacus does display specific genome properties that may act as confounding variables for processes we wish to examine such as natural selection. However, these patterns do not strongly correlate with greater isolation due to distance, indicating that genome properties may have less of an effect on distantly related populations than we might have otherwise assumed.