Ahearn_23_October_2017

Ahearn_Olivia_23October_2017

Graduate School of Oceanography - OCG 695
23 October, 3:30 PM, Coastal Institute Auditorium

Evidence of Selection Between a Cosmopolitan Marine Diatom and Bacteria

Olivia Ahern

Diatom-bacteria interactions can influence diatom physiology, morphology, and lead to local changes in nutrient bioavailability and carbon cycling. These interactions are species-specific, with individual diatom species associated with particular bacterial assemblages. Furthermore, we recently showed that these interactions extend to the subspecies level, where genetically distinct populations are associated with taxonomically distinct bacterial assemblages that are curated over many generations and across ocean basins. It is unknown whether these taxonomically distinct bacterial assemblages are functionally redundant. In order to tease apart taxonomy from function, we compared the metabolic potential of bacterial assemblages from 40 single cell T. rotula isolates from two genetically distinct diatom populations. On the one hand, bacterial assemblages from the two populations shared many genes involved in primary metabolism, as expected. On the other hand, the two bacterial assemblages showed significantly different abundances of genes involved in the metabolism of diatom host-derived products, including genes related to methanotrophy and catabolism of dimethylsulfoniopropionate (DMSP). Differential abundances in genes key to diatom bacteria interactions suggest that bacterial assemblages may respond to different host-mediated phycosphere microenvironments. Physiological, genetic and, potentially, metabolic differences between diatom populations may influence the functional composition of the phycosphere microbiome through release of different metabolites and exudates. Intra-specific differences in diatom-bacteria associations may enable genetically divergent populations of T. rotula to persist in a wide range of habitats.

Olivia received a B.S. in Marine Biology from the College of Charleston in 2013. She entered GSO in Fall 2014. Her major professor is Tatiana Rynearson. Other core committee members include David Smith and David Rowley.

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* 1. EVALUATOR FIRST NAME

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* 2. EVALUATOR LAST NAME

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* 3. EVALUATOR ROLE

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* 4. What aspects of the presentation were successful? Why?

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* 5. What do you suggest to improve?

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* 6. ABSTRACT METHODS/RESULTS: Methods succinctly identified the methods used. Results are succinct and provide a specific explanation of what was discovered, accomplished, collected or produced.

EXCELLENT: Describes methodology in an organized, specific and concise manner. Describes what they have learned. Relates results to the research question. Results include quantitative data.

VERY GOOD: Discusses the methods or resources. States results only qualitatively.

GOOD: Discusses the methods or resources, but is lacking in specifics. Provides superficial explanation of results.

FAIR: Provides little or no discussion of the methods or resources used.
Provides no results or does not explain why results were not possible.

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* 7. ABSTRACT MOTIVATION/IMPACT: Succinctly describes and appropriately connects the subject and background to the purpose of the research . Provides a succinct interpretation of the results and evaluates what the results mean to the investigation and the field of study.

EXCELLENT: Describes how the investigation, whether completed or not, fits within a larger field or continuing investigation in a clear and concise manner.

VERY GOOD: Indicates main subject and purpose of the research. Provides an interpretation of results

GOOD: Indicates main subject and purpose of the research and indicates why research is important but is somewhat lacking in specifics. Provides an interpretation of results but fails to place results in the larger context of the field.

FAIR: Indicates main subject and purpose of the research but lacks organization, or lacks specific details or fails to make connections, or contains no introduction. Provides a conclusion that specificity or provides no conclusion.

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* 8. PRESENTATION ORGANIZATIONAL PATTERN: Specific introduction and conclusion, sequenced material within the body and transitions.

EXCELLENT: Organizational pattern is clearly and consistently observable and is skillful and makes the content of the presentation cohesive. Listener can follow the line of reasoning.

VERY GOOD: Organizational pattern is clearly and consistently observable

GOOD: Organizational pattern is intermittently observable. A few minor points may be confusing.

FAIR: Organizational pattern is not observable. Organization seems haphazard.

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* 9. PRESENTATION STYLE: Posture, gestures, eye contact and use of the voice. Speaker stands and moves with authority, looks more often at the audience than notes, uses the voice expressively, and uses few vocal fillers (‘um” “uh,” “like,” “you know,” etc.).

EXCELLENT: Delivery techniques (posture, gesture, eye contact, and vocal expressiveness) make the presentation compelling and the speaker appears polished and confident.

VERY GOOD: Delivery techniques (posture, gesture, eye contact, and vocal expressiveness) make the presentation interesting and speaker appears comfortable. Speaker uses pointer appropriately.

GOOD: Delivery techniques (posture, gesture, eye contact, and vocal expressiveness) make the presentation understandable and speaker appears tentative. Speaker reads from text rather than too the audience. Speaker does not use pointer to clarify material.

FAIR: Delivery techniques (posture, gesture, eye contact, and vocal expressiveness) detract from the understandability of the presentation and speaker appears uncomfortable

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* 10. PRESENTATION SUPPORTING MATERIAL: Slide contents, figures, table, supporting material support the presentation and facility the central message.

EXCELLENT: Font is large enough to be seen by all. Information is organized to maximize audience understanding. Details are minimized so that main points stand out. All figures/table clearly labeled.

VERY GOOD: Font size is appropriate. Appropriate information is included.

GOOD: Font size is appropriate. Appropriate information is included. Some material is not supported by visual aids. Colors may be used inappropriately. Layout is confusing.

FAIR: Font size is too small to be easily seen. Too much information is included, layout is crowded, not enough time is spent on each graphic to allow audience to follow along. Listeners become confused.

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* 11. PRESENTATION CENTRAL MESSAGE AND CONTENT: The main point/thesis/bottom line/take away of the presentation. A clear central message is easy to identify and compelling (broader impacts.)

EXCELLENT: Central message is precisely stated, appropriately repeated, memorable and strongly supported. Speaker provides accurate and complete explanation of key concepts and theories. Listeners gain insights. Information included is consistently accurate. Study is placed in large context.

VERY GOOD: Central message is clear and consistent and supported. For the most part, explanations of concepts and theories are accurate and complete. No significant errors.

GOOD: Central message is basically understandable but is not often repeated and is not memorable. Any significant errors are attributable to nervousness.

FAIR: Central message can be deduced but is not explicitly stated in the presentation. Explanations of concepts are inaccurate or incomplete. Listeners gain little from the presentation.

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* 12. PRESENTATION - ANSWER QUESTIONS: Speaker demonstrates understanding of material and answers the questions asked and is respectful.

EXCELLENT: Demonstrates deep understanding of topic.

VERY GOOD: Answers most questions with knowledge.

GOOD: Has some difficulty answering challenging questions.

FAIR: Does not understand the question or has difficulty answering questions.

Other (please specify)