FIGURE 1 (b) Some time after X. anonymosa forms byanagenetic speciation (multiple changes represented by the thick bar), it is divided into two reproductively isolated populations that follow different evolutionary paths. One isolated population does not change much and continues to be recognized as Xylosa anonymosa, while the other undergoes many rapid changes to evolve into X. synonyma; this is cladogenetic speciation. X. synonyma, in turn, almost immediately speciates to form two new species, X. asymmetrica and X. symmetrica, again by cladogenetic speciation.