Gene duplication is an important mechanism that can lead to the emergence of new functions during evolution.
All the above allows to explore the emergence of new functions in the process of speciation as well as in response to demands of the environment.
It has been suggested that the pSymA megaplasmid is involved principally in structural fluidity and the emergence of new functions (Galardini et al., 2013).
Third, sequence divergence frequently observed between genes sharing the same tandem array suggests that selective pressures are applied to such areas, favoring the emergence of new functions.
In contrast, in the birth-and-death evolutionary model, sequence divergence within a TGA favors the emergence of new functions but also gene inactivation or disappearance.
Hence de novo evolution of genes appears to have occurred continuously throughout evolutionary time and should therefore be considered as a general mechanism for the emergence of new gene functions.
This makes it extremely valuable to support the analysis of the emergence of new biological function in mammals.
A paradigm in evolutionary biology is that gene duplication represents the major mechanism for emergence of new functions, as one of the two copies is potentially freed from selective pressure and will accumulate more mutations during evolution [ 28, 29].
The present analysis of the HEPN domain also supports the recent hypothesis that prokaryotic intra- and inter-genomic conflict systems provided raw material for the emergence of new core cellular functions in eukaryotes [ 1].
Positive selection is one of the major forces in the emergence of new motifs and functions in genes after duplication events.
This influence occurs namely through the demand for non-productive functions leading to the emergence of new modes of occupancy.
