“…This neglects the accumulating evidence from both comparative and experimental studies that synonymous mutations (i.e., mutations that change the codon but not the encoded amino-acid) can display non-negligible fitness effects (Singh et al, 2007;Drummond and Wilke, 2008;Kudla et al, 2009;Zhou et al, 2009;Lind et al, 2010;Plotkin and Kudla, 2011;Sauna and Kimchi-Sarfaty, 2011;Agashe et al, 2013;Bailey et al, 2014;Firnberg et al, 2014;Hunt et al, 2014;Bali and Bebok, 2015;Presnyak et al, 2015;Agashe et al, 2016;Choi and Aquadro, 2016;Knöppel et al, 2016). For example, recent studies have shown that synonymous mutations can affect the speed and accuracy of translation (Drummond and Wilke, 2008;Saunders and Deane, 2010;Plotkin and Kudla, 2011;Bali and Bebok, 2015), mRNA structure (Shabalina et al, 2013;O'Brien et al, 2014;Presnyak et al, 2015), expression in response to environmental changes (Shabalina et al, 2013), and that they are associated with several organismal malfunctions (Parmley and Hurst, 2007;Hunt et al, 2014).…”