However, the emergence of heterogeneous populations following infection in small inocula may serve as an important diversifying factor for microbes, perhaps providing microbes with an adaptive edge in the co-evolutionary "tug-of-war" between pathogens and their hosts.
Thus, the rapid expansion in the lakes surveyed [ 76] corroborates the independent simulations, pointing to genetic drift as an initial diversifying factor for observed population differentiation.
That hummingbird pollination per se is not a diversifying factor is also implied by our tabulation of 33 sister clades with and without hummingbird pollination (Additional file 5: Table S7).
Although drought is seen as a diversifying factor in population dynamics [ 30] we show that in contrast to previous studies [ 41] and in accordance to others [ 42, 43], a substantial variation exist within diverged populations in drought response, supported by both phenotypic and transcriptome analysis.
Delmont et al. (2011) recently showed that up to 80% increase in genetic diversity is achievable by diversifying the extraction factors (meaning, adding extra extraction modules) in comparison to the most effective single extraction strategy.
The authors incorporated several features, such as gaps and polyadic sequence elements, to handle diversified transcription factor binding sites.
Therefore it might be that parasites represent a stronger diversifying force than the factors underlying chromatic differentiation.
These four core factors have diversified during evolution by gene duplication, horizontal gene transfer (HGT) and subfunctionalisation to result in a variety of factors with different taxonomic ranges.
Finally, we performed a codon-based evolutionary analysis indicating a general high level of purifying selection in the three Cucurbitaceae MLO gene families, and the occurrence of regions under diversifying selection in candidate susceptibility factors.
