Genetic drift at expanding frontiers promotes gene segregation

By O. Hallatschek, P. Hersen, S. Ramanathan, D. Nelson. Proceedings of the National Academy of Sciences of the United States of America, 2007

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Competition between random genetic drift and natural selection play a central role in evolution: Whereas nonbeneficial mutations often prevail in small populations by chance, mutations that sweep through large populations typically confer a selective advantage. Here, however, we observe chance effects during range expansions that dramatically alter the gene pool even in large microbial populations. Initially well mixed populations of two fluorescently labeled strains of Escherichia coli develop well defined, sector-like regions with fractal boundaries in expanding colonies. The formation of these regions is driven by random fluctuations that originate in a thin band of pioneers at the expanding frontier. A comparison of bacterial and yeast colonies (Saccharomyces cerevisiae) suggests that this large-scale genetic sectoring is a generic phenomenon that may provide a detectable footprint of past range expansions.

Subfields: Genetics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/20f8c7ed842478c254e8ab6d678bbab26fe07285

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Citations in the corpus

Detecting loci under selection in a hierarchically structured population (2009, background): “, 2006) can also lead to high levels of differentiation between populations in the periphery of the range at a random locus (Hallatschek et al., 2007; Excoffier and Ray, 2008).”
Evolutionary game theory: Theoretical concepts and applications to microbial communities (2010, result): “As an example, recent studies looked at growth patterns of two functionally equivalent strains of Escherichia coli and showed that, due to fluctuations alone, they segregate into well-defined, sector like regions [36,46].”
The Kardar-Parisi-Zhang equation and universality class (2011, methodology): “They were introduced in [85] to study the domain walls of Ising models with impurities [110] and have been applied to other problems like vortices in superconductors [22], roughness of crack interfaces [82], Burgers turbulence [71], interfaces in competing bacterial colonies [78] (see also the physi”
Emergence of Spatial Structure in Cell Groups and the Evolution of Cooperation (2010, background): “Experiments with bacterial colonies on agar have revealed that expanding cell groups can segregate into sectors that are each dominated by a single genetic lineage [26,27].”
Predicting evolution (2017, background): “1), detect low-frequency variants, and resolve the spatio-temporal evolutionary dynamics in extended populations 95–97 .”