An Australian study on genetic differences between Australian Working Kelpies (working lines) and Australian Kelpies (show lines):
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4579362/
In depth explanation of the biology behind resilience:
https://www.patriciamcconnell.com/theotherendoftheleash/resilience-can-we-increase-it-in-dogs