Project Summary:
Species are fundamental units in plant and animal communities, but is this
true in the microbial world? There is considerable debate as to
whether bacteria evolve in fundamentally different ways than
eukaryotes due to their rapid reproduction, rare (and promiscuous)
sexuality, and evolutionarily significant gene exchange. Modern
genetic and genomic analyses make “named” bacterial species
(traditionally demarcated by phenotypic properties) appear to be
diverse, chaotic assemblages of rapidly exchanged genes. However,
modern population genetics analysis challenges the concept that
these named species are really biologically meaningful entities.
Furthermore, natural patterning of genetic diversity and
evolutionary theory suggest a more orderly concept of species as
discrete ecologically adapted populations (ecotypes). Our conceptual
framework is that ecotypes are the fundamental units of microbial
communities that play a central role in linking genetic diversity to
microbial community composition, structure and function. We will
investigate a well-studied hot spring microbial mat community in
Yellowstone National Park with ideal properties for employing sophisticated molecular methods. To
understand how genetic diversity is organized in the mat community,
we will compare (i) direct genomic sequencing of predominant mat
populations (to objectively assay genomic diversity and determine
how it is organized according to genetic criteria) with (ii)
theory-driven population genetics analysis and evolutionary
simulation designed to test for putative ecotypes. Genomic
sequencing will enable development of microarray technology and
high-throughput analysis of variant alleles that will be used to
evaluate whether, as expected, putative ecotypes occupy unique
niches and order gene distribution and expression within the mat
community. The discovery of genetically separable ecotypes will
broadly impact thinking in microbial evolution, systematics, ecology
and physiology and will unify evolutionary principles across the
breadth of size and complexity among organisms.
Broader
Impacts:
Our team is a
balance of young and established,
male and female investigators from geographically and demographically
diverse institutions. The research integrates principles from general
biology with microbiology and molecular biology, providing a
cross-training opportunity that will help fill the chasm separating these
fields. Participants will share their disciplinary perspectives
(microbial ecology, evolutionary biology, genomics and microbial
physiology) with each other and the scientific community through a
workshop series that will lead to web-based learning modules. The
microbial community is in Yellowstone Park, providing numerous
opportunities for interaction with the park’s trained informal educators.
Preparation of new educational resources (e.g., resource manual for
educating seasonal rangers and park managers, signage, trail guides,
websites and exhibits for a new
Visitor Education Center) will help
millions of annual visitors, young and old, change the way they think
about microorganisms. Five linked websites will broadly disseminate our
databases and interpret the interdisciplinary importance of our work for
nonscientists. Genomic websites will present sequences from direct mat
analysis as well as two closely related, ecologically distinct
pure-cultured thermophilic cyanobacteria (Synechococcus). Another
website will describe the microarray in detail and report comparisons of
gene expression in situ and in relevant Synechococcus
isolates grown in laboratory culture. A project website will collect all
data, report tests of our main hypotheses, and serve as a conduit for
dissemination of educational products.