Signals of selection and ancestry in independently feral G. gallus  populations
Authors: Gering, E#1., Johnsson, M.#2,3, Theunissen, D.# 2, Martin Cerezo, M.L.#2, Steep, A.4 Getty, T.5, Henriksen, R.2, and Wright, D.*2
Affiliations:
1 Department of Biological Sciences, Halmos College of Arts and Sciences, Nova Southeastern University, Florida 33314-7796. USA
2 AVIAN Behavioural Genomics and Physiology group, IFM Biology, Linköping University, Linköping 58183, Sweden
3 Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
4 Genetics and Genome Sciences Program, Michigan State University, East Lansing, MI 48824, USA
5 Kellogg Biological Station, Michigan State University, 3700 East Gull Lake Road, Hickory Corners, MI 49060, USA
# These authors contributed equally
*Corresponding author, email dominic.wright@liu.se/ domwright@gmail.com
Keywords: Feralisation, Population genomics, Invasion Biology, Adaptive evolution
Abstract
Recent work indicates that feralisation is not a simple reversal of domestication, and therefore raises questions about the predictability of evolution across replicated feral populations. In the present study we compare genes and traits of two independently established feral populations of chickens (G. gallus ) that inhabit archipelagos within the Pacific and Atlantic regions to test for evolutionary parallelism and/or divergence. We find that feral populations from each region are genetically similar despite their geographical isolation and divergent colonization histories.
Next, we used genome scans to identify genomic regions selected during feralisation (selective sweeps) in two independently feral populations from Bermuda and Hawaii. Three selective sweep regions (each identified by multiple detection methods) were shared between feral populations, and this overlap is inconsistent with a null model in which selection targets are randomly distributed throughout the genome. In the case of the Bermudian population, many of the genes present within the selective sweeps were either not annotated or of unknown function. Of the nine genes that were identifiable, five were related to behaviour, with the remaining genes involved in bone metabolism, eye development, and the immune system.
Our findings suggest that a subset of feralisation loci (i.e. genomic targets of recent selection in feral populations) are shared across independently-established populations, raising the possibility that feralisation involves some degree of parallelism or convergence and the potential for a shared feralisation ‘syndrome’.