An allozyme variation of loci-encoding lactate dehydrogenase was compared i
n different vertebrate classes, A lower level of heterozygosity in warm-blo
oded as compared to cold-blooded vertebrates was shown, The highest heteroz
ygosity was revealed in anurous and caudate amphibians; the lowest, in bird
s and mammals, Fishes and reptiles exhibited an intermediate level of heter
ozygosity, In higher groups of vertebrates, differences in the electrophore
tic mobilities between alleles decreased. A key aspect of this is a hiatus
of these differences in fishes and mammals, On the basis of this analysis,
the following conclusions may be drawn: (1) the rate of amino-acid substitu
tions in homologous proteins is unequal in distant phylogenetic lineages; (
2) the level of heterozygosity is related to the average amount of electrop
horetic allelic differences at the class level; (3) significant differences
in variation pattern in the phylogenetic lineage of vertebrates is probabl
y associated with the evolutionary features of the genomic organization of
groups at different evolutionary levels.