BIOVERMICULATION BIOPATTERNS AS UNIVERSAL SIGNATURES OF EXTANT AND EXTINCT LIFE (Invited Presentation)

Although individually miniscule, microorganisms frequently produce distinctive macroscopically visible communities that often trap sediment or precipitate minerals in situ. We have discovered and characterized instances of complex, unique maze-like 2 and 3 dimensional patterns that we have observed in caves, lavatubes, mines, Mayan ruins, cryptogamic soils, under hypolithic desert clasts, and at the bottom of saline streams. Other studies have reported similar patterns in desert higher vegetation. We have developed mathematical approaches to characterize and reproduce these striking patterns. The pattern features represent the influence of various properties of both the environment (e.g. fluid flow regime and velocity, access to nutrients, etc.), and features of the biology (e.g. degrees of filamentousness, “gluiness”, intrinsic growth geometries, etc.). The mathematical similarity of the biopatterns at widely differing spatial scales, and involving very different organisms and environments, have led us to seek unifying principles behind the production of these patterns. Such unity of ecological principles is applicable to a broad range of systems and could represent a type of biosignature that could be found in any system, specifically because we believe we are seeing morphological expressions of behavior in response to ecological drivers. Such broad potential application may qualify as “universal” and be decoupled from the fundamental biochemistry of whatever type of life may be involved.

Because of the unusual structure of biovermiculations and the their propensity to trap sediment and provide circumstances in which minerals typically precipitate, they are very likely to essentially “auto-fossilize” as a result of accumulation of geological material that adheres to and eventually can entomb or replace the microbial communities that produce them. The visually identifiable nature of such patterns can provide strong indicators that biology was involved in their production even though they may be long departed in the living state. We suggest that not only are such patterns useful in interpreting living and ancient indicators of microbial communities on Earth, but that they must be added to the still small list of visual biosignatures for application to the search for life on Mars and elsewhere.