Thirdly, we compare the purifying selection in obligate intracellular symbionts (gamma-proteobacteria) and obligate intracellular parasites (alpha-proteobacteria).
We observed increased effectiveness of purifying selection in obligate intracellular alpha-proteobacterial parasites as compared to obligate intracellular gamma-proteobacterial symbionts.
In an ancillary analysis, we found that model selection of obligate species occurrence using the Bayesian Information Criterion produced qualitatively similar results, emphasizing the same important independent variables as AICc.
These results provide an initial analysis of these genes and might be interpreted to suggest that genes associated with amino acid metabolism and biochemical utilization might have undergone different evolutionary selection among obligate carnivores compared to omnivores and herbivores.
Overall this study suggests that, while we are obligated to maintain the selection for the spread of the drug resistances, the 'fight evolution with evolution' approach could help us even out the outcome to our favour.
In fact, even marginal increases in mutation rate are capable of overwhelming purging in obligate selfing populations under strong selection against mutation accumulation [14].
The factors promoting the richness of orchid species may include specific interactions between orchid flowers and pollinators [ 2], sequential and rapid interplay between drift and natural selection [ 3], obligate orchid-mycorrhizal interactions [ 4], and epiphytism.
Factors promoting orchid species richness include specific interaction between the orchid flower and pollinator [ 2], sequential and rapid interplay between drift and natural selection [ 3], obligate interaction with mycorrhiza [ 4], and epiphytism which is true for most of all orchids and probably two-thirds of the epiphytic flora of the world.
They [ 4] provide a pathway for the transition from facultative sex to obligate asexuality that operates through selection.
This finding was somewhat surprising, as all of these clones grew well without tryptophan, indicating the obligate presence of the trpA selection marker.
The purifying selection in parasitic obligate intracellular bacteria is more effective as compared to symbiotic ones, possibly due to the higher recombination level in the former.
