Abstract
Understanding evolutionary mechanisms is fundamental to a balanced biological education, yet practical demonstrations
are rarely considered. In this paper we describe a bacterial liquid microcosm which can be used to demonstrate
aspects of evolution, namely adaptive radiation, niche colonisation and competitive fitness. In microcosms
inoculated with Pseudomonas fluorescens SBW25, evolved mutants such as the Wrinkly Spreader (WS) rapidly arise to
form biofilms covering the air–liquid (A–L) interface. WS are readily isolated due to a distinctive colony morphology
and reach ∼30% of the population within five days. When re-inoculated into static microcosms, WS preferentially
colonises the A–L interface by producing a biofilm, demonstrating a niche preference distinct from the
ancestral SBW25 which grows throughout the liquid column. This ability provides the WS with a ∼2.5× competitive
fitness advantage over the non-biofilm forming ancestral SBW25. However, WS and SBW25 have similar
fitness in shaken microcosms where biofilms cannot form. These practical demonstrations of WS evolution, suitable
for secondary or tertiary-level classes, can be linked with a literature-based review of the underlying molecular biology
of the WS phenotype to provide a true exemplar of the modern evolutionary synthesis, the current paradigm in
evolutionary biology.
Original language | English |
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Pages (from-to) | 54-59 |
Number of pages | 6 |
Journal | Journal of Biological Education |
Volume | 45 |
Issue number | ` |
DOIs | |
Publication status | Published - Mar 2011 |
Keywords
- Mutation
- Niche
- Bacteria
- Evolution
- Fitness
- Microcosms
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Dive into the research topics of 'Evolution in a test tube: rise of the Wrinkly Spreaders'. Together they form a unique fingerprint.Student Theses
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Adaptation and niche construction by Pseudomonas fluorescens SBW25
Author: Koza, A., Feb 2011Supervisor: Spiers, A. J. (Supervisor) & Otten, W. (Supervisor)
Student thesis: Doctoral Thesis
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