Necturus Electrophoresis 
45 
The only variants found in the N. lewisi sample were at the Got-1 
locus. Six individuals were heterozygous for the a and b alleles, one was 
homozygous for b. 
Two unspotted N. punctatus were each heterozygous at single loci 
(Pgi-1, Pgm-2). The only difference between the spotted and unspotted 
samples was in the frequency of the Pgi-1 alleles (Table 1). 
Table 1. Fixed genetic differences in three Necturus species. 
Locus 
Allele 
N. lewisi 
N. maculosus 
N. punctatus 
Mdh-1 
b 
a 
spotted 
b 
unspotted 
b 
Me-2 
a 
b 
b 
b 
Got-1 
a (0.80) 
c 
b 
b 
Got-2 
^(0.20) 
b 
c 
a 
a 
Ldh-2 
c 
b 
c 
c 
Pgi-1 
b 
a 
c(0.81) 
d 
Me-1 
a 
a 
J(0.19) 
b 
b 
The three species were unequivocally different at four {N. lewisi vs. 
N. punctatus) or six {N. maculosus vs. N. lewisi or N. punctatus) of the 
seventeen loci investigated; alleles were not shared at these loci (Table 1). 
Nei’s standard genetic distance estimates between each pair of species 
(Table 2) are indicative of a long history of isolation of the gene pools. 
Electrophoretic examination of one N. maculosus from the Mills River, 
Henderson County, North Carolina confirms the genetic distinction 
found between the larger samples of allopatric N. maculosus and N. 
lewisi. 
Table 2. Standard genetic distance (D) between species of Necturus examined. 
12 3 4 
N. lewisi 
0.0 
N. maculosus 
0.435 
0.0 
N. punctatus (unspotted) 
0.348 
0.435 
0.0 
N. punctatus (spotted) 
0.339 
0.426 
0.040 
0.0 
