Ma. Leibold et al., GENETIC, ACCLIMATIZATION, AND ONTOGENIC EFFECTS ON HABITAT SELECTION BEHAVIOR IN DAPHNIA-PULICARIA, Evolution, 48(4), 1994, pp. 1324-1332
Daphnia pulicaria from three different populations were observed to ex
press within-population variation in habitat-choice behavior in field
assays. Individuals from different habitats (i.e., lake depths) were i
solated and cultured as clonal lines under standard conditions. Habita
t choices by clonal descendants were then estimated in the held, using
replicate experimental columns. There was significant heritable and o
ntogenetic variation in habitat choice, but the heritable effect was s
mall relative to the phenotypic variation of the original isolates. In
a second set of experiments, D. pulicaria that were acclimatized to d
ifferent habitats showed a strong tendency to choose the habitat to wh
ich they had been acclimatized. These data suggest that a given genoty
pe can use a wide range of habitats, given appropriate acclimatization
. Although genetic variation is significant, we hypothesize that natur
al selection on correlated ecological traits is more likely to maintai
n patterns of genotypic segregation among habitats in Daphnia.