In the presented work the bacterial family Vibrionaceae was used as a model to investigate bacterial diversity on a gene level and to analyze the underlying concepts of bacterial niche adaptation and evolution. For this, the genomes of a diverse dataset of 64 Vibrionaceae isolates from various environments and temperature zones were analyzed using existing as well as newly developed bioinformatics tools. By building the pan-genome of the investigated isolates, i.e., determining the sets of shared and unique genes of each included isolate, the genetic diversity of members of this bacterial family was analyzed. Also, the distribution of the determined pan-genome on the chromosomes of all completely assembled genomes included in this study was analyzed with focus on speciation and evolution of Vibrionaceae. In a subsequent study general adaptation strategies of cold-adapted Vibrionaceae were investigated using membrane proteins that are conserved among all investigated isolates. In summary, the results presented in this thesis highlight the variety of different evolutionary processes that contribute to the adaptation and speciation of bacteria in general and Vibrionaceae in particular.

Paper 2 of this thesis is not available in Munin: 2. Tim Kahlke, Alexander Goesmann and Peik Haugen: 'The Vibrionaceae pan-genome hints at gene expression as the major driving force for unequal gene distributions on Vibrionaceae chromosomes' (manuscript)