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has been performed using molecular data (e.g., Sarich 1976; Arnason & Widegren 1986: 

 Shubin et al. 1990; Baram et al. 1991; Arnason et al. 1993, 1995; Mouchaty et al. 1995; 

 Perry et al. 1995), but only a few biomolecules have been analyzed, and typically only 

 for a very limited number of species. However, the analysis of molecular data seems to 

 hold more promise than does morphological data [but see Cummings et al. (1995) for 

 possible limitations of such data]. As mentioned above, molecular data appear to provide 

 better resolution at the lower taxonomic levels, and therefore might be able to resolve the 

 polytomy within the Phocini. As well, in contrast to their high morphological intraspecific 

 variability, particularly with respect to the skull (Mivart 1885; Doutt 1942; Davies 1958b; 

 Ray 1976b), pinnipeds, like most marine mammals, display an unusually low genetic 

 variability (Arnason 1972. 1982; Shubin et al. 1990; Arnason et al. 1993). Presumably, 

 this lower variability would allow for a clearer and stronger signal. Finally, the strong 

 possibility of a molecular clock for some biomolecules (see Thorpe 1982) may allow for 

 the dating of various divergence events, which, in turn, would allow for the examination 

 of such ancillary questions as rates of speciation or extinction (see Harvey & Nee 1993). 

 Yet, resolution at the lower taxonomic levels within the phocids may also be provided by 

 a morphometric analysis of morphological data. Such analyses are commonly used at the 

 specific or intraspecific level to assess differences within or between taxa (e.g., Jolicoeur 

 1975; Thorpe 1975a. 1975b; Youngman 1982). By themselves, morphometric analyses 

 only indicate degrees of similarity between taxa (Albrecht 1980); however, the results of 

 such analyses could easily be transformed into cladistic characters [but see Farris (1990) 

 for potential abuses of this]. This could make a vast suite of additional characters available 

 for cladistic analyses that were previously avoided as their complexity (e.g., shape 

 characters) makes them difficult to obtain and/or to code objectively, or because they were 

 held to be phylogenetically uninformative. However, the phenomenon whereby two 

 characters used in concert may show increased discriminatory power over when either is 

 used in isolation (Lubischew 1962). allows for even seemingly uninformative characters 

 to potentially play some phylogenetic role. As well, morphometric analyses may give us 

 a more objective (i.e., statistical) means to judge the degree of information content in a 

 character. Together, the cladistic analyses of both molecular data and morphological data 

 using morphometric characters should enable a fully-resolved species level solution of the 

 phocids. However, it should be realized that full resolution may not be possible, and that 

 the indicated polytomy within the Phocini (plus Erignathus here) does, in fact, describe 

 a real evolutionary event. 



The second problem concerns the unusual biogeography of the phocids. The combination 

 of a postulated North Atlantic origin for the phocids, plus the poor paleontological data 

 for the family, has led to much uncertainty in attempts to explain the far-flung pattern of 

 its extant members. These attempts are further hindered by being based largely on a rather 

 superficial view of the phylogenetic relationships of the extant species. Of primary concern 

 here is the tacit assumption of the monophyly of some higher level phocid taxa, the dangers 

 of which are presented in this study. The monophyletic status of some of these taxa has 

 also been called into question (Wyss 1988a; this study). However, with the lack of suffi- 

 cient fossil evidence, any biogeographic hypothesis must minimally accord with current 



