Remarkably, some cladists
have understood the union of numerical
Continual improvement of phylogenetic hypotheses and associated improvements in nomenclature to reflect that increased knowledge is advocated by Practicing Cladists
Because DNA-DNA hybridization produces obligate distance data, many systematists, particularly cladists
, deny the utility of the method as a means of estimating phylogenetic relationships (e.
, on the other hand, distinguish between two types of similarity - those that are derived through descent from a common ancestor (synapomorphies), and those representing retained ancestral characters (symplesiomorphies) - and argue that only the former count as evidence when assessing degrees of relatedness.
Polyphyletic species are abhorrent to cladists
- this was set up as a rule to eliminate polyphyly caused by improper classification and taxonomy, but polyphyly is also caused by hybridization and introgression of traits from one species to others, including sister clades.
, by contrast, in opting for phylogenetic criteria, assume that any adequate response to the species problem must make patterns of descent explicit.