Appalachian Trechus of the vandykei Group 
145 
P/SGANENS/S 
r-H 
TUSQU/TEE 
BOWLING! 
VANDYKE! 
HAOE 
BG 
BP 
DG 
WH 
*MP 
■SM 
■CH 
TU 
CG 
•RC 
HE 
WP 
BA 
UN 
MM 
•SN 
• CC 
* BB 
HA 
— i 
0.00 
0.15 
0.10 
0.05 
ROGERS DISTANCE 
Fig. 2. UPGMA dendrogram of 19 populations of the Trechus vankydei species 
group, generated from Rogers’ Distance values for eight biochemical loci. 
and the single haoe population has its closest affinities with this 
subgroup. 
Genetic differentiation can also be described using Nei’s (1977) gene 
diversity. In this analysis the total gene diversity observed (Ht) can be 
apportioned among the various levels of a specified hierarchy (Table 6). 
We recognize four hierarchical levels of gene diversity: (1) within 
colonies (populations), He; (2) among populations within subgroups, 
Dcs; (3) between subgroups within regions, Dsr; and (4) between 
regions, Drt, where the two regions are the areas northeast and southwest 
of the Asheville basin, respectively. Approximately 4-5% of total gene 
diversity is attributable to differences between infrasubgroup populations 
(Dcs). More than 50% of gene diversity is a result of differentiation 
between subgroups (Dsr and Drt). Differentiation between subgroups 
within regions (Dsr) appears to be as great as (PGI) or greater than 
(CAH) differentiation between regions (Drt) (Table 6). 
Affinities between various subgroups can also be seen in the 
geographic patterns of certain diagnostic electromorphs at the two 
variable loci (Table 2). Electromorph “C” at the PGI locus is restricted 
to populations in the northeast region, where it occurs in all but the CC 
(westernmost) population of the vandykei subgroup. Conversely, 
electromorph “D” at the PGI locus is present in only two vandykei 
