Genetic Variation 
123 
Table 1. 
Allele frequencies at polymorphic loci in Crangonyx antennatus popula- 
tions. (N) = number of individuals examined. Abbreviations as in Fig. 
1. 
Locus 
allele 
RD 
MW 
SP 
S 
C 
G 
PGM 
a 
0.536 
0.043 
b 
0.923 
0.155 
0.203 
0.250 
0.391 
0.281 
c 
0.077 
0.155 
0.250 
0.750 
0.196 
0.188 
d 
' — 
0.107 
0.391 
— 
0.369 
0.250 
e 
— 
0.036 
0.141 
— 
— 
0.156 
(N) 
(26) 
(42) 
(32) 
(36) 
(23) 
(16) 
PGI 
a 
0.200 
— 
— 
— 
— 
0.800 
b 
— 
0.400 
0.500 
0.500 
0.200 
— 
c 
— 
0.100 
— 
0.500 
0.800 
0.200 
d 
0.800 
0.400 
0.500 
— 
— 
— 
e 
— 
0.100 
— 
— 
— 
— 
(N) 
( 5) 
( 5) 
( 5) 
( 5) 
( 5) 
( 5) 
heterozygous per individual (heterozygosity) can be estimated in two 
ways: by direct count, and by expected heterozygote proportions in each 
population assuming Flardy-Weinberg equilibrium. Heterozygosity 
values per cave range from 0.021 (counted) and 0.058 (expected) to 0.276 
(counted) and 0.124 (expected) (Table 2), and overall mean 
heterozygosities (H), weighted by sample size, in C. antennatus equal 0.1 18 
and 0.136, respectively. The greater spread in values for the counted 
heterozygosities primarily results from assay in some populations of only 
small numbers of specimens at the apparently monomorphic loci. At the 
PGM locus there was a consistent tendency for pool populations to ex- 
hibit significant heterozygote deficiencies relative to Hardy-Weinberg 
Table 2. Heterozygosity (H) values in populations of Crangonyx antennatus. Ab- 
breviations' as in Fig. 1. 
Population 
Frequency of heterozygous loci in 
an average individual 
Counted 
Expected ±1 Standard Error 
RD 
0.021 
0.058 ± 0.042 
MW 
0.130 
0.161 ± 0.106 
SP 
0.102 
0.149 ± 0.099 
s 
0.183 
0.109 ± 0.073 
c 
0.276 
0.124 ± 0.087 
G 
0.216 
0.107 ± 0.073 
