Fig. 2.

Major transitions in TE content along are plotted along the mammalian phylogeny. The mammal phylogeny is modified from Meredith et al. (Meredith et al. 2011). Events were inferred to specific nodes using information from (Alföldi et al. 2011; Churakov et al. 2010; Gogolevsky et al. 2008; Gogolevsky et al. 2009; Green et al. 2014; Hillier et al. 2004; Kriegs et al. 2007; Lupan et al. 2015; Nikaido et al. 2003; Novick et al. 2010; Pace et al. 2008; Pagan et al. 2010; Pritham and Feschotte 2007; Ray et al. 2015; Ray et al. 2006; Rinehart et al. 2005; Shimamura et al. 1999; Smit et al. 1995; Suh et al. 2014; Vassetzky and Kramerov 2002; Walsh et al. 2013; Wang et al. 2005; Warren et al. 2008) and are generally classified into four categories. “Origination Events” (red) refer to the de novo or composite origin of new TEs. “Horizontal Transfer Events” (blue) refer to the horizontal transmission of TEs from non-mammalian lineages. “Reduction or Expansion Events” (green) refer to dramatic shifts in accumulation patterns. “Ancestral Elements” (pink) refer to elements that were present in the ancestral mammalian genome