Oral Annual Conference of the Genetics Society of Australasia with the NZ Society for Biochemistry & Molecular Biology

Commemorating 60 years of bidirectional selection: Applying genomics to the Virginia body weight chicken lines (541)

Mette Lillie , Christa F Honaker 1 , Paul B Siegel 1 , Örjan Carlborg
  1. Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA

This year marks the 60th anniversary of the founding of the Virginia body weight chicken lines. With each year representing one generation of bidirectional selection on 8-week body weight, this White Plymouth Rock population represents a valuable resource for studying long-term selection for a complex trait. Response to selection has resulted in over 16-fold difference in the body weight between the high and low line, but also in drastic physiological, metabolic, and behavioural changes. We apply pooled genome sequencing to the Virginia lines to characterise the genomic consequences of this long-term selection. We characterised over 50 regions with extreme differentiation between the two lines, revealing the wide genomic impacts of this selection regime. Overlap between differentiated regions and growth QTL previously mapped in this population lend support to these candidate selective sweeps. We observed a general trend across the candidate sweep regions where one line was fixed, creating long homozyogous blocks, whereas the other line would still maintain high heterozygosity, with many haplotypes continue to segregate. Therein lies an indication of the haplotypic complexity that would have been present in the founder population. By investigating the significant growth1 QTL on chromosome 1 of the pooled genomes, we are able to show this haplotypic complexity in more details and identify a strong candidate variant present from standing genetic variation. Overall, we have gained better insights into the genomics of this experimental model system, where standing variation at many loci have contributed to the strong response to bidirectional selection.