Persistent maternal identity effects on life history traits in Daphnia.

The aim of the present study was to examine the magnitude and persistence of maternal effects in Daphnia, in particular maternal identity effects. I studied life history traits of a single clone of Daphnia galeata born to 40 different mothers belonging to three age groups. Maternal identity had large effects on offspring traits, that is, identically treated clonal females differed substantially in respect to the traits of their offspring, including size at birth, age at maturity, and number of second generation offspring. The effects of maternal identity on these traits were largely independent of maternally induced differences in offspring size, indicating that maternal effects were mediated through offspring quality. Maternal age also affected offspring traits: older mothers gave birth to larger offspring which matured earlier, were larger and more fecund, and survived better until maturity. Individuals which were larger at birth also had a better chance of survival. Contrary to expectation, I found little evidence that maternal identity or maternal age had any influence on their offsprings' response to fish kairomones.