Isozyme characters of the tuatara, Sphenodon punctatus, were examined by starch gel electrophoresis. The characters investigated included: (1) the number of presumptive structural gene loci encoding for each of 30 enzyme systems; (2) the formation of interlocus heteropolymers in polymeric, multi locus enzyme systems; and (3) the tissue-specific distribution of 51 presumptive structural gene loci among 15 tissues. The number of loci controlling the various enzyme systems in the tuatara was similar to that reported in other vertebrates. No unexpected duplicated loci were observed although some silencing may have occurred. All anticipated interlocus heteropolymers were observed, except for dihydrolipoamide dehydrogenase; most loci were widely distributed among the tissues examined. With respect to the first two characters, Sphenodon appears to exhibit the primitive condition. However, analysis of the tissue-specific distribution of loci suggests that, when compared to other members of the class Reptilia, the tuatara is not necessarily the most primitive taxon. For this character, the tuatara appeared more primitive than the prairie rattlesnake yet more derived than the American alligator. The results suggest that isozyme characters may be of value in examining both the intra-and interpopulation genic variability of the tuatara as well as the phylogenetic relationships of Sphenodon and other reptilian taxa.
ABSTR^CT.--This paper is a survey of applications of electrophoretic techniques in ornithology, with an emphasis on post-1970 publications. The majority of electrophoretic studies of birds have been limited in a variety of ways. Many have dealt with "domesticated" species or have been limited to the examination of blood and/or egg-white proteins. Problems in comparing results from different studies have arisen because of: (1) dissimilar electrophoretic techniques; (2) varying numbers of taxa; (3) nonstandardized enzyme and locus nomenclature; and, especially, (4) different methods of data analysis. These methodological problems must be addressed in order to broaden the utility of electrophoretic data in avian systematics. I suggest that the enzyme names recognized by the International Union of Biochemistry be used exclusively and that a standardized locus nomenclature, comparable with that used in other vertebrate classes, be developed. The predominating use of allozyme characters can be supplemented by "isozyme characters" (e.g. different numbers of genes, heteropolymer assembly, and regulation of expression sensu Buth in press), which possibly could be applied to a determination of systematic relationships of higher-level taxonomic ranks. Allozyme and/or isozyme data should be retained in particulate form (i.e. not summarized as genetic distances). The use of outgroups to assign evolutionary direction is encouraged.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.