Hypothetical model for the evolution of map-1 genes in root-knot nematodes.

The actual distribution of map-1 genes in Meloidogyne species is indicated at the bottom of the figure. Putative individual evolutionary events leading to such a distibution are indicated in circles according to the following code: D, L  =  gene duplication or loss, respectively; d, l, t  =  domain duplication, loss or truncation, respectively. Orange and blue boxes represent the 58-aa and 13-aa domains in MAP-1 encoded proteins, respectively.