GREATER PLASTICITY IN YOUNGER GENES. “In all instances, the younger tandem duplicated genes showed higher intraspecific gene expression variation than the average Arabidopsis gene. Surprisingly, the older segmental duplicates also showed evidence of elevated intraspecific gene expression variation albeit typically lower than for the tandem duplicates.”
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0001838