Plasticity in filtering screens of Daphnia cucullata × galeata hybrids and parental species at two food concentrations

Abstract

The coexistence of Daphnia cucullata × galeata hybrids with the parental species D. galeata and D. cucullata was investigated by measuring areas and mesh sizes of filtering structures of these herbivorous zooplankton taxa cultivated at low and high food concentrations. The clearance rates and somatic growth rates were also determined. When reared at low food concentration, all taxa had larger filtering areas. Larger filtering areas also resulted in higher clearance rates. Differences between taxa in both filtering area and clearance rate were caused mainly by interspecific size differences. Hybrids had the largest absolute mesh sizes, and the parental species had smaller mesh sizes. Hybrids also showed heterosis in somatic growth rate at high food concentration. The observed taxon-specific differences in mesh size and somatic growth rate contribute to resource partitioning between the taxa and thus to their successful coexistence in lakes.

Maternal effects on offspring consumption can stabilize fluctuating predator–prey systems

“…Experiments could determine if the maternal foodinduced change in offspring feeding rate abates with time, or with changes in the food available to offspring. Indeed, many taxa, for example Daphnia [24][25][26][27][28][29][30], are known to alter their consumption rate within a generation in response to changes in food availability. Second, we assumed that the predators only differ in their feeding rates, but other traits, like longevity and fecundity, are likely to also differ as a consequence of feeding.…”

Nonrandom sexual reproduction and diapausing egg production in a Daphnia hybrid species complex

“…Another reason may be that the two lakes exhibit differences in environmental conditions that may favor different genealogical classes. Taxonomic differences can be influenced by the ability of different genealogical classes to cope with alterations in food composition (Repka et al 1999), fish predation (Spaak et al 2000), or parasites (Wolinska et al 2004).…”

Effect of Body Size on Toxicity of Zinc in Neonates of Four Differently Sized Daphnia Species

“…Each species was represented by one clone: D. galeata by clone TG100 (Repka et al 1999), D. pulex by clone PXCL4 , D. pulicaria by clone PU3 and D. magna by clone HK (clone a sensu Baird et al 1989;Vesela et al 2006a). To prevent differences caused by acclimation to zinc, the animals were kept at a temperature of 20 ± 1°C and cultured in the same medium (40-lm sieve filtered pond water) for at least 3 months before start of the experiments.…”