Conclusion
This study demonstrates that feralisation is at least partly repeatable
at the genetic and phenotypic level in chickens, and involves
significant enrichment of shared sweeps between independently feral
populations. These sweeps also show little overlap to those produced by
recent improvement/ domestication in modern domestic birds, with a
single exception that shows how artificially-selected genome regions can
either retain signals of selection, or be continuously selected, during
the recolonization of wild habitats. As mentioned earlier, it is
important to note that most known improvement selective sweeps may not
be representative of the earliest domestication-related genes (i.e.
those polymorphisms/ mutations selected during the initial domestication
process), as pointed out by Flink et al (2014). Unfortunately, unless
(or until) all domestication genes are known, we cannot fully exclude
the possibility of their involvement in feralisation. Nonetheless, our
collective findings suggest that further studies of feralisation
genomics will continue to produce novel and complex discoveries. For
example, the two populations we compared herein exhibit both parallels
and differences in their recent evolutionary trajectories, and have
recruited haplotypes to high frequency that stem from both domesticated
and wild sources. This complexity is perhaps unsurprising, given that
feral populations consist of novel and uniquely human-impacted
organisms, and that these organisms exhibit, to remarkable and often
vexing degrees, a capacity to thrive in an increasingly human impacted
world.