Taken together, human-mediated events in the mid-Holocene provide plausible explanations for both the dramatic events in B. anthracis evolution observed during this time period and the diversity among and within clonal lineages on the African and Eurasian landmasses.
Our genome structure analyses show total synteny among the five TPEs despite millions of years of divergence, and that this lineage follows the common path of genome evolution observed in other endosymbionts of diverse ancestries.
For example, comparative genomic and phylogenetic studies, for example, phylogenetic profiling (Pellegrini et al. 1999), have indicated that correlated evolution is commonly observed among different proteins that function in a pathway (Pazos and Valencia 2008).
This heterogeneity might be a logical consequence of the different clinical expressions and the evolution of the disease observed among these patients.
Host-symbiont co-speciation and reductive genome evolution have been commonly observed among obligate endocellular insect symbionts, while such examples have rarely been identified among extracellular ones, the only case reported being from gut symbiotic bacteria of stinkbugs of the family Plataspidae.
Not just the presence or absence of a gene but also when, how, and where certain genes are expressed are also important in the evolution of phenotypic diversity observed among and within orders (Zhang and Peterson 2006; Takahashi and Saitou 2012; Wittkopp and Kalay 2012).
On the other hand, in nature, larval adaptation to crowded conditions could not be the only driving force involved in the evolution of body size observed among natural populations of Drosophila, where size differences are mainly associated to the number of cells.
Moreover, understanding the common mechanisms of reproductive development also provides the basis from which to dissect the differences observed among species and the evolution of fruit form [ 77].
The distant relationship observed between LOS-associated C. coli and C. jejuni sialyltransferases could indicate evolution of different substrate specificity, which has been previously observed among Helicobacter sialyltransferases [ 52].
Based on data from several organisms, including fish, rRNA gene families seem to evolve according to a combination of the evolutionary processes of birth-and-death and concerted evolution [ 6, 61], which could explain the variability observed among related taxa.
