These include molecular evolution of transcription factors or changes in transcriptional regulation (Enard et al., 2002; Konopka et al., 2009), accelerated evolution of small non-coding RNAs (Pollard et al., 2006), changes in the tissue - specificity of enhancer elements (McLean et al., 2011; Prabhakar et al., 2008), or changes in
patterns of alternative splicing of specific genes (Calarco et al., 2007).