Ck. Geedey et al., HABITAT HETEROGENEITY, ENVIRONMENTAL-CHANGE, AND THE CLONAL STRUCTUREOF DAPHNIA POPULATIONS, Functional ecology, 10(5), 1996, pp. 613-621
1. Organisms capable of asexual reproduction often maintain substantia
l clonal diversity within their populations. We ask whether such diver
sity in Daphnia pulicaria populations is maintained by temporal and sp
atial variation in selection. 2. We monitored temporal and spatial var
iation in the relative abundance of electrophoretically determined clo
nal groups in three lake populations of D. pulicaria from April to Oct
ober 1991. 3. Clonal composition differed among lakes, but within each
population we observed strong temporal changes in the relative abunda
nce of different clonal groups. The timing and rate of this clonal suc
cession was associated with the rate of loss of deep water habitat fro
m seasonal anoxia. 4. Within each lake, clonal groups also segregated
vertically into shallow and deep water assemblages. The magnitude of t
his habitat segregation varied temporally and was associated with the
abundance of a shallow water competitor species, D. galeata. 5. We sug
gest that strong associations of clonal succession and clonal habitat
segregation with environmental changes (habitat availability and compe
titor abundance) indicate selection operating on the clonal compositio
n of these populations.