HYPOTHESIZING HYBRIDS AND PARENTS USING CHARACTER INTERMEDIACY, PARENTAL DISTANCE, AND EQUALITY

A simple method for objectively screening morphological variation in s tudy sets suspected of containing hybrids is presented. The method app lies to a collection of specimens in which two or more species along w ith some or all of their hybrids are suspected to be represented. The purpose of the method is to hypothesize which specimens might be of hy brid origin, and for each of these specimens to indicate which other t wo specimens resemble those that might have been its parents. The meth od is employed in the computer program HYWIN by using two kinds of com putationally intense techniques: evaluation of a hybrid optimality sco re for each triplet generated from three quantitatively defined criter ia: hybrid intermediacy (IN), parental distance (PD), and equality (EQ ); and simulation of a probability hypothesis to generate measures of the level of statistical certainty. The method can be applied in direc t studies of hybrids and their parents, taxonomic treatments, pinpoint ing of specimens that merit study with other techniques, and screening of data sets for putative hybrids and hybrid species prior to phyloge netic reconstruction.