Evolution of microbial populations with spatial and environmental structure

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Title: Evolution of microbial populations with spatial and environmental structure
Author: Miller, Eric Louis
Abstract: Rarely are natural conditions constant , but generally biologists study microbes in artificially constant environments in the laboratory . I relaxed these assumptions of constant environments through time and space as I investigated how microbial populations evolve . First , I examined how bacteriophage evolved in the presence of permissive and nonpermissive hosts . I found that bacteriophage evolved discrimina - tion in mixed environments as well as in one of two environments with homogeneous , permissive hosts . This showed the asymmetry of host -shifting in viruses as well as the possibility of large , and somewhat unpredictable , pleiotropic effects . Secondly , I reconstructed ancestral environmental conditions for soil bacteria groups using phy - logenetics and environmental variables of extant species’ habitats . These generaliza - tions suggested characteristic phenotypes for several phylogenetic groups , including uncultured Acidobacteria . Lastly , I collected genetic sequences and global collection information for 65 bacteria genera across the domain . In examining the relation - ship between genetic distance , environmental conditions , and geography , I observed positive relationships specifically between genetic distance and geography or genetic distance and environmental conditions for bacteria from land sites but not from wa - ter sites . Phylogenic classifications or phenotypes of the genera could not predict these correlations . In all of these projects , variations in the environment created evolutionary signals that hinted at past environments of microbial populations .
URI: http : / /hdl .handle .net /2152 /ETD -UT -2010 -05 -1018
Date: 2011-01-07


Evolution of microbial populations with spatial and environmental structure. Doctoral dissertation, University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /ETD -UT -2010 -05 -1018 .

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