ON INFERRING HYBRIDITY FROM MORPHOLOGICAL INTERMEDIACY

The type of intermediacy that separates hybridity from divergence is not multivariate intermediacy; it is the coincidence of intermediate character states. For the purpose of showing hybridity, analyses should distinguish between the two types of intermediacy. (1) Hybrid indices fail to do so. (2) Principal components analysis does so only in an ambiguous way. (3) Pictorialized scatter diagrams properly present the evidence for an interpretation that is intuitive, (4) Counting characters as intermediate or not-intermediate is an explicit approach that allows for statistical evaluation given that certain assumptions are made. Simulated data representing hybridity and divergence are presented to illustrate each method and to provide a prototype of how to document hybridity using the favored methods.