Dr Craig Herbold
University of Vienna
Prokaryotes are everywhere. They reside throughout our bodies, in the food we eat, the water we drink, the ground we walk upon and even in the air we breathe. Many Prokaryotes have specific adaptations to survive desiccation and intense UV exposure, which allows them to be carried high in the atmosphere to far away lands. The travel is only part of the story though, once these tiny microorganims find a new location, they must have the necessary hardware to thrive in their new physicochemical environment and they must be capable of outcompeting others. Over time, their descendents must adapt to this new home and in turn outcompete any new “aliens” that likewise fall from the sky.
The process of colonization, adaptation and competition shape the taxonomic and functional makeup of microbial communities in ways that we don’t completely understand. Taxonomic selection occurs on an organismal level, in which an organism survives to produce a population in a new area or dies off completely. Functional selection, however, may be decoupled from taxonomic selection through the process of horizontal gene transfer (HGT). This allows organisms to assemble functional complexes that are not necessarily borne from vertical inheritance, but from a reticulate process of evolution.
My lab is interested in how dispersal affects the evolution of organisms and communities. We have several projects to examine dispersal of bacteria to and between ice-free areas of Antarctica. These locations are particularly valuable to study microbial dispersal because the influence of higher plants and animals is minimal. We combine marker surveys, metagenomics and database mining techniques to produce models of the flow of taxonomic and functional genes between locations and organisms.
Ultimately our aim is to develop unifying frameworks of microbial evolution in which the assemblage of genes in distinct genomes and metagenomes represent ephemeral points in space-time that are shaped by the past vertical and horizontal inheritance processes, and are destined to change.