Signaling peptides encompass a myriad of highly diversified sequences showing variation within and across species and without a common phylogenetic origin.
6 As with many eukaryotes, the trypanosome genome is effectively partitioned into the core, containing genes under purifying selection and where most mutation is repaired, and subtelomeres, where multigene families associated with organismal phenotypic variation diversify rapidly.
The fact that they are under diversifying selection suggests that variation in these genes may contribute to disease and life history variation in African trypanosomes.
The observed dichotomy between sets containing the MHC exon ('Outlier 1') and MHC intron ('Outlier 2') was however unexpected based on the premise that diversifying selection should fix variation in tightly linked sites around the adaptive mutation; here, we have assumed that the MHC exon may have a selective advantage, whereas the MHC intron is subjected to hitchhiking selection [ 33].
It is known that NBS-LRR genes are undergoing diversifying selection [28], e.g., variation in the sequence of the Arabidopsis gene RPS2 shows a signature consistent with pathogen-stimulated selection [29].
China's most important oilseed crop, grown on over 13 million ha, is therefore also a potentially rich source of genetic variation to diversify these narrow gene pools.
Bacterial species have mechanisms for gene exchange (transformation, conjugation and transduction), and genetic recombination is believed to play a prominent role in diversifying species by distributing variation and generating new allele combinations [ 11].
To capture this diversify, we characterized the variation in gene expression across human breast tumors using DNA microarrays and identified at least five distinct tumor subtypes that are statistically significant predictors of patient overall survival [ 1].
If the pattern of polymorphism is a reflection of variation in selection across the genome, we predict that purifying selection would be stronger in regions of low variation, while diversifying selection or relaxed purifying selection would allow for increased polymorphisms in other regions.
In addition, the variation in gene structure and the difference in motif compositions among different subfamilies indicate that GAox subfamilies are functionally diversified.
