INTRODUCTION TO BIOCHEMICAL SYSTEMATICS 



55 



mutants, while reaction rates for six different wild strains were 

 similar. These results suggest that the reverted mutants are not 

 qualitatively identical and represent further evidence for enzyme 

 heterogeneity, although simultaneously they emphasize the com- 

 plexity of the problem of establishing the phylogenetic meaning of 

 those differences which are disclosed. 



Another important question which is more apropos now than 

 ever before in the hght of advances in biochemical techniques is 

 raised by Anfinsen: 



One of the major questions to be answered in arriving at a clear 

 understanding of the phylogenetic relationships between different 

 forms of life is whether there exist identical, or closely homologous, 

 genes in widely separated species, or whether similarities in pheno- 

 types are due to analogous genes which determine equivalent appear- 

 ance or function by different pathways. 



Fig. 4-3. Esterase zymograms of serum from different species. 

 From Paul and Fottrell, 1961, "Molecular Variation in Similar 

 Enzymes from Different Species." Ann. N. Y. Acad. Sci. 94:671 



