“…Rhabditid sperm generally displays a conserved pattern during spermatogenesis known as the "rhabditid" pattern (Slos et al, 2015;Yushin et al, 2016;Yushin & Malakhov, 2014 A congruence test between specific traits shows a remarkable and strongly supported, correlated evolution between the presence of filopodia and the absence of MO (BF > 6). Both MOs and filopodia play a role in MSP assembly: filopodia appear to represent an intermediate stage in sperm activation, and agents that interfere with fibre growth likewise affect filopodia assembly (Miao, Yi, Mackey, & Roberts, 2007;Singaravelu & Singson, 2011); MOs meanwhile play an essential role in regulating MSP cytoskeleton assembly (Zhao et al, 2012). However, despite their similarities in function, a functional explanation for this correlated evolution remains elusive.…”