Resident-intruder aggression in Avpr1b KO mice was decreased without co-occurring deficits in predatory aggression or anxiety and remained deficient in a KO on a more outbred strain of mice (Wersinger et al., 2007, 2008; Caldwell and Young, 2009; Caldwell et al., 2010). This evidence concerns the gene AVPR1B and Anxiety.