Fig. 1. Tokogeny versus phylogeny. (a)   Processes occurring among sexual species (phylogenetic processes) are   hierarchical. That is, an ancestral species gives rise to two descendant   species. (b) Processes occurring within sexual species (tokogenetic processes)   are nonhierarchical. That is, two parentals combine their genes to give rise   to the offspring. (c)The split of two species defines a phylogenetic   relationship among species (thick lines) but, at the same time, relationships   among individuals within the ancestral species (species 1) and within the   descendant species (species 2 and 3) are tokogenetic (arrows).

图1。家系发育（tokogeny）与系统发育。（a）行有性生殖的物种的演化过程（系统发育过程）是级联式的，即一个祖先物种产生两个后代物种。（b）有性生殖物种内的传承过程（家系发育过程）是非级联式的。即父母合并他们的基因传给共同的后代。（c）两个物种的分开定义了物种间的关系（粗线），但同时，无论是祖先种内（物种1），还是在继代物种内（物种2和3）个体间的关系都是家系发育式关系（箭头所示）。