Phenetic cladistics

The most commonly used techniques for estimating trees for sequences may be grouped into three categories (1) distance methods, (2) maximum parsimony, and (3) maximum likelihood based methods. There are other methods but they are not widely used. Further, each of these categories covers many variations and even distinct methods with different properties and assumptions. These methods have often been divided different ways (different from the three categories here) such as cladistic versus phenetic, character-based versus non-character-based, method-based versus criterion-based, and others. These divisions may merely reflect particular predjudices by the person making them and can be artificial. 

For evolutionary studies, the classification of species also allows the construction of phytogenies, which may shed light on the relationship between observed pattern of speciation and the nature of evolutionary forces. A distinction should be made between phenetic and cladistic data. The phe-netic relationships are similarities based on the degree of similarity, whereas cladistic relationships contain information about ancestry and can be used to study evolutionary pathways. Both of these relationships are best portrayed as phylogenetic trees or dendrograms, respectively (57). 

Apart from the underlying principles, there are the questions of how the data are obtained and their limitations. With the phenetic method, characters used are those for which it is possible to make the necessary quantitative measurements. With the cladistic method, it is rarely possible to determine each branch point, especially where convergent evolution has occurred. The phenetic method produces a practical classification but lacks the deeper philosophical justification of the cladistic method. However, both methods often give similar results, but differences arise, as in the example in Fig. 1.2. Although the crocodile and lizard show greater morphological similarity to one another than to the bird, birds and crocodiles have more recent common ancestors than crocodiles and lizards. 

Phenetic Cladistics Elegant Analyses with Many Sources of Errors... 

As character analyses are usually missing in phenetic cladistics, several sources of errors may exist (see also Wagele, 1994) ... 

FIGURE S.6 A major difference between phylogenetic cladistics and phenetic cladistics is that the quality of the empirical data Is evaluated before the cladistic step in the Hennigian approach. 

Paleontology of the past is revived in molecular systematics of the present, in its search for ancestors and centers of origin. The revival ignores, or retreats from, the cladistic reform of paleontology of the 1970s, with historical roots in the work of Louis Dollo (1857-1931) and fossil Inngfishes. The subsequent development of cladistics has been arrested, too, by compnter implementations of character optimization and the ideology of total evidence, which reflects a phenetic rather than cladistic objective the overall similarity of synapomorphy. 

Numerical taxonomy in its cladistic phase became animated through the real progress in systematic theory over the past two decades. .. the discoveries that phenetics is false that parsimony [or compatibility, or likelihood] is essential that exact solutions to parsimony problems [or compatibility problems, or likelihood problems] are possible (Farris and Platnick, 1989 308). Animation flowed from the belief that (Farris, 1968 9) perhaps the most impressive theoretical advantage of the parsimony criterion is that it is certain to give a correct tree, provided the data consist of a sufficient array of non-convergent characters, and from similar beliefs, with similar provisos, that compatibility, or maximum likelihood, might alternatively — even certainly — give a correct tree. 

Homologues and Homology, Phenetics and Cladistics ISO Years of Progress 193... 

Sneath, PH.A., The phenetic and cladistic approaches, in Prospects in Systematics, Hawksworth, D.L., Ed., Clarendon Press, Oxford, 1988, pp. 252-73. 

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