2010 Annual Science Report

Massachusetts Institute of Technology Reporting  |  SEP 2009 – AUG 2010

Executive Summary

Oxygenation of Earth’s atmosphere and surface oceans over the interval c. 800 to c. 540 million years ago is widely considered to have been a critical environmental driver for the appearance and diversification of animal life. Further, understanding the interconnections between atmosphere-ocean oxygenation, anomalies in the biogeochemical carbon cycle, and planetary-scale glaciations remain one of the great puzzles in the history of life on Earth. Accordingly, in this reporting period members of the MIT Team of the NAI continued their study of the Neoproterozoic rock record for chemical evidence of ocean oxygenation and corresponding paleontological and paleoenvironmental data concerning the state of biological complexity. Collaborations between team members Tanja Bosak, Francis Macdonald, Phoebe Cohen, David Johnston and Samuel Bowring has explored the timescales, geochemical trends and microfossil diversity just prior to and during the early stages of the Cryogenian Period. The Cryogenian does not ... Continue reading.

Field Sites
24 Institutions
12 Project Reports
48 Publications
1 Field Site

Project Reports

  • Environmental Oxygen and the Rise (And Fall) of Metazoans

    The viability of complex animals is intimately linked to the availability of molecular oxygen. This project looks at the environmental signatures of oxygen production and availability on a range of timescales and the connection between the stages of Precambrian oxygenation and biological complexity. Increasingly, it is becoming clear that the major mass extinction events of the Phanerozoic are strongly correlated to episodes of deoxygenation.

  • Astrobiological Exploration of Mars

    Astrobiological research informs many NASA missions and especially those concerned with exploring our near neighbor Mars. MIT team members have been making notable contributions to the Mars Exploration Rovers and Mars Science Laboratory missions.

  • Biomechanics of the Rangeomorph Fauna

    Some of the oldest, multicellular organisms in the fossil record are enigmatic creatures called rangeomorphs. Although there is much debate as to whether the rangeomorphs are animals, fungi, or something completely unique, recent studies of the fossils suggest that the rangeomorphs used high surface areas to capture dissolved organic matter (DOM) as an energy source. In this project, we attempt to model how nutrients would have flowed over these deep-water organisms, to see how their large size might have helped them compete with bacteria for DOM. Our work suggests that competition with bacteria was a driving force in the evolution of the first complex organisms.

    ROADMAP OBJECTIVES: 4.2 5.2 6.1
  • Paleoecology of the Mistaken Point Biota

    The Ediacara biota represent an enigmatic group of soft-bodied organisms that flourished in the late Precambrian oceans some 578-542 million years ago. These exquisite fossils have a worldwide distribution, however some of the most remarkable specimens are found all along the southeastern coast of Newfoundland, Canada, known worldwide as the Mistaken Point Ecological Reserve. Here, Ediacaran fossils are preserved as complete census populations allowing scientists to investigate these ancestral organisms using modern ecological analyses. Our work used ecological and morphometric studies to investigate the likelihood that some of these enigmatic organisms actually represent some of the oldest examples of sponges. Furthermore, our work highlights the necessity of a non-uniformitarian mechanism to deliver bio-accessible (labile) dissolved organic carbon to the Mistaken Point seafloor, which formed the primary food source for these deep-water organisms.

  • Timscales of Events in the Evolution and Maintenance of Complex Life

    We are establishing geological histories for different parts of each history (namely 252 and 720 million years ago) using a combination of dating of volcanic ash beds and correlating rocks between continents using the variation in isotopic signatures.

  • Modelling Planetary Albedo & Biomarkers in Rocky Planets’/moons Spectra

    The recent discovery of several potentially habitable Super-Earths (planets up to about 10x the mass of our own Earth that could be rocky) and the first nearby super-Earth planets around the habitable Zone of Gl581, has proven that we can already detect potentially habitable planets and makes this research extremely relevant. We model atmospheric spectral signatures, including biosignatures, of known and hypothetical exoplanets that are potentially habitable.
    The atmospheric characterization of such Super-Earths and potentially habitable Moons, will allow us to explore the condition on the first detectable rocky exoplanets and potentially characterize the first detectable Habitable Exoplanet.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 6.2 7.2
  • Genomic Relationships Among Basal Metazoans

    Understanding the origins of animals (“Metazoa”) and the advent of metazoan complexity requires a proper understanding of the interrelationships among the living forms. To properly place animals like sponges and jellyfish into the tree of life, we have taken a multi-faceted approach using two different kinds of molecular data: traditional sequence-based molecular phylogenetics, and a new type of binary data, the presence or absence of specific microRNAs (short ~22 nucleotide non-coding RNA genes). Both data sets suggest that sponges are paraphyletic: some sponges are more closely related to jellyfish and humans than they are to other sponges (e.g., bath sponges). These results suggest that the last common ancestor of all living animals was organized like a true sponge, and thus our origins as complex animals lies within sponge biology.

  • Geochemical Signatures of Multicellular Life

    This project aims to identify geochemical fossils (biomarkers) in sediments that reflect the transition from microbial life forms to their multicellular animal descendants.

  • Paleontological Investigations of the Advent and Maintenance of Multicellular Life

    This years research has targeted several areas associated with the origin and early diversification of multicellular life. Team member Knoll and colleagues (Harvard) have investigated the molecular basis of complex multicellularity, which developed in a variety of different groups. They have also continued work on the evolution of biomineralization in early eukaryotes. Team member Erwin has continued work on the evolution of developmental gene regulatory networks in early metazoans and, with Jim Valentine (UC Berkeley) completed the manuscript on the Ediacaran-Cambrian diversification of animals.

  • Origins of Multicellularity

    By comparing animal genomes with genomes from their closest living relatives, the choanoflagellates, we can reconstruct the genome composition of the last common ancestor of animals.

  • Evolution and Development of Sensory and Nervous Systems in the Basal Branches of the Animal Tree

    Animals interact with the world through complex sensory structures (eyes, ears, antennas, etc.), which are coordinated by collections of neurons. While the nervous and sensory systems of animals are incredibly diverse, a growing body of evidence suggests that many of these systems are controlled by similar sets of genes. We are looking at early branching and understudied lineages of the animal family tree (using the jellyfish Aurelia and the worm Neanthes respectively) to see if these animals use similar genes during neurosensory development as the better-studied fruit fly and mouse. This research is critical for determining which structures are shared between animals because of common ancestry (known as homologous structures) and those that evolved independently in different lineages. Ultimately, such research informs how morphologically and behaviorally complex animals evolve.

  • Metabolic Networks From Single Cells to Ecosystems

    We use mathematical and computational approaches to study the dynamics and evolution of metabolism in individual microbes and in microbial ecosystems. In particular, we take advantage of sequenced genomes to study the complete network of biochemical reactions present in an organism. We have been extending these approaches from single genomes to multiple genomes, generating ecosystem-level models of metabolism, which can help us understand some of the key transitions in the history of life on our planet.

    ROADMAP OBJECTIVES: 4.1 4.2 5.1 5.2 6.1