Astrobiology Colloquium

UWAB hosts a biannual colloquium series every spring and fall, featuring speakers from both UW and other institutions presenting on a wide range of astrobiology related topics. Here, you can find the schedule for upcoming colloquia and seminars, as well as an archive of abstracts and live recordings of past events.
 
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You can also watch a live broadcast of our events by logging in remotely during the scheduled colloquium time!
 
 
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Welcome to the 2017 Fall Astrobiology Colloquium Series!

 

Date Speaker Title of Talk
10/03/2017 NO COLLOQUIUM N/A
10/10/2017

Chris Reinhard

Georgia Institute of Technology

Title: Nutrients, ecosystems, and the evolving detectability of Earth's biosphere

Abstract: The chemistry of Earth’s atmosphere has changed dramatically over time, and this evolution has been inextricably linked with innovations in biological metabolism and ecosystem complexity. A prominent example is the evolution of Earth’s oxygen cycle – the accumulation of significant quantities of O2 in the ocean-atmosphere system has completely reshaped electron flow through Earth’s surface environments, and provides a conspicuous remotely detectable signal of a pervasive biosphere. The oxygen cycle is in turn governed by feedbacks linking it with the carbon and sulfur cycles, the cycling of major and trace nutrients, and the exchange of volatiles with Earth’s interior. This talk will explore the apparently protracted oxygenation of Earth’s ocean-atmosphere system subsequent to the emergence of oxygenic photosynthesis, with an eye toward the roles of nutrient cycling and ecosystem structure in regulating atmospheric chemistry. The implications of these results will then be discussed in the broader context of evolving climate stability and the emergence and maintenance of atmospheric biosignatures on Earth-like planets.

10/17/2017

Shintaro Kadoya 

&

Rodrigo Luger

University of Washington

Title: Conditions and lifetime of warm planets based on carbon cycle

&

Title: Probing the TRAPPIST-1 system with planet-planet occultations

10/24/2017

James Staley

University of Washington

Title: Evolution of the Bacteria, Eukarya and Archaea and Domain Cell Theory
 
Abstract: Current hypotheses on the origin of Carl Woese's three
Domains of Life will be discussed.  Most scientists believe that the first
organisms were Bacteria and Archaea that produced two of the domains of
life and that the Eukarya arose by a fusion event between a member of the
Bacteria and Archaea. The Nuclear Compartment Commonality (NuCom) hypothesis regards each of life's domains as separate cellular lineages that evolved independently according to Domain Cell Theory: Bacteria --> Bacteria, Eukarya --> Eukarya and Archaea --> Archaea.  In addition it regards the first members of the Bacteria as coming from the PVC Superphylum of nucleated Bacteria.  Further it states that the Eukarya have always been nucleated and the Archaea never became nucleated.
 
10/31/2017

Erik Sperling

Stanford University

Title: The Environmental Context of Early Animal Evolution

Abstract: Animals originated and evolved during one of the most unique times in Earth history—the Neoproterozoic Era. A large dataset of >10,000 Neoproterozoic-Paleozoic shale samples compiled by the Sedimentary Geochemistry and Paleoenvironments Project is interrogated here to better understand the landscape early animals inhabited. Using a space-for-time translation, animal ecosystems along modern natural gradients of oxygen and primary productivity are then used to conceptualize Neoproterozoic ecosystems. Analyses of redox-sensitive trace metals demonstrate that animals evolved in a relatively low-oxygen ocean, although perhaps not considerably less oxygenated than the Paleozoic. Anoxic water columns were generally ferruginous (iron-rich) rather than euxinic (sulfide-rich, as in the modern ocean), and sulfide stress was likely limited. Habitats suitable for chemosymbiotic lifestyles based on sulfide oxidation were also likely rare. Analyses of sedimentary total organic carbon suggest that early animals lived in an ocean with lower primary productivity compared to the preceding Mesoproterozoic or following Paleozoic. Combined with an inability to inhabit productive regions in this low-O2 ocean—where aerobic respiration would quickly draw down oxygen to lethal levels— Neoproterozoic animal communities would have likely been more food limited than generally appreciated, leading to important impacts on ecosystem structure and organismal behavior. 

11/07/2017

Alexis Templeton

University of Colorado, Boulder

Title: Seeking pathways of H2 and CH4 production and consumption within low-temperature serpentinites 

Abstract: Rocky bodies that have experienced extensive water rock interaction and hydration of ultramafic rocks are predicted to generate significant quantities of hydrogen and small molecular weight organics that could serve as metabolic energy sources.   However, there is significant uncertainty in the amount of hydrogen and methane that will be produced in systems that reside at low temperatures and do not experience hydrothermal activity.  In this talk, I will discuss why we are investigating peridotite aquifers in Oman as an excellent terrestrial example of active low-temperature serpentinization processes.  I will show how we are using experiments and field-studies to define the operative reaction pathways during low-temperature peridotite hydration.  I will also explore subsurface regimes where the in-situ microbial communities and the cycling of H2, CH4, S and N strongly contrast. 

11/14/2017 Lucas Mix

Title: Astrobiology and Human Significance

Abstract: Astrobiology reshapes the way we look at the cosmos and our place within it. By asking questions about the history, extent, and future of life in the universe, astrobiologists apply scientific reasoning to broader questions of human meaning, purpose, and significance. This talk looks at the relationship between data and philosophy in astrobiology. How our models of life in the universe impact us practically and ethically. Specifically, I will look at questions of human significance arising from location – are we central? – and biology – are we unique? Answers to these questions have always been at the crossroads between observation, philosophy, and religion. The ways we speak about them, and our history of answering them, can encourage us to think critically about the role of data and science in societal questions.

11/21/2017 THANKSGIVING N/A
11/28/2017

Steve Vance

Jet Propulsion Laboratory

Title: Geophysical investigations of habitability in ice-covered ocean worlds

Abstract: Geophysical measurements can reveal the structure of icy ocean worlds, including the trans- port of volatiles. The inferred interior density, temper ature, sound speed, and electrical con- ductivity thus characterize their habitability. We explore the variability and correlation of these parameters using 1D internal structure models and available constraints on the ther- modynamics of aqueous MgSO4, NaCl (as seawater), and NH3; pure water ice phases I, II, III, V, VI; silicates; and any metallic core that may be present. We identify limits in the ther- modynamic data that narrow the parameter space that can be explored: insufficient coverage in pressure, temperature, and composition for end-member salinities of MgSO4 and NaCl, and for relevant water ices; and a dearth of suitable data for aqueous mixtures of Na-Mg-Cl- SO4-NH3. For Europa, ocean compositions that are oxidized and dominated by MgSO4, vs reduced (NaCl), illustrate these gaps, but also show the potential for diagnostic and measur- able combinations of geophysical parameters. The low-density rocky core of Enceladus may comprise hydrated minerals or anhydrous minerals with high porosity. Titan’s ocean must be dense; thin ice and high salinity imply high heat flux. Titan may have little or no high- pressure ice. Ganymede’s silicious interior is deepest among all known ocean worlds, and may contain multiple phases of high-pressure ice, which will become buoyant if the ocean is sufficiently salty. Eutectic oceans cannot be adequately modeled using available thermo- dynamic data. Callisto may also lack high-pressure ices, but this cannot be confirmed due to uncertainty in its moment of inertia. 

12/05/2017

Betul Kacar

Harvard University

Title: Reconstructive biology as a window into historic biochemical optima

Abstract: Two datasets, the geologic record and the genetic content of extant organisms, provide complementary insights into the history of how key molecular components have shaped or driven global environmental and macroevolutionary trends. Changes in global physicochemical modes over time are thought to be a consistent feature of this relationship between Earth and life, as life is thought to have been optimizing protein functions for the entirety of its ~3.8 billion years of history on Earth. Organismal survival depends on how well critical genetic and metabolic components can adapt to their environments, reflecting an ability to optimize efficiently to changing conditions. The geologic record provides an array of biologically-independent indicators of macroscale atmospheric and oceanic composition, but provides little in the way of the exact behavior of the molecular components that influenced the compositions of these reservoirs. By reconstructing sequences of proteins that might have been present in ancient organisms, we can downselect to a subset of possible sequences that may have been optimized to these ancient environmental conditions. How can one use modern life to reconstruct ancestral behaviors? Configurations of ancient sequences can be inferred from the diversity of extant sequences, and then resurrected in the lab or in modern host organisms to ascertain their biochemical attributes. Here I present a novel approach, where the focus of the study is not just the sequence diversity of past proteins but the diversity and evolution of protein functionality. This functionality is evaluated in the context of geology's convoluted record of a multiplicity of enzyme functions acting upon environmental reservoirs over time. Studying the interface of past molecular behavior and environmental conditions may yield new insights into the interpretation of deep time biosignatures, as expressed by the impact of organismal optima on metabolites and fossil remains.

 


 

Archived Presentations:

 

Missed the last seminar series? See our archive for abstracts and video recordings of all past talks from 2003 - Present.