BIOLOGY OF CLADOCERA
When and how can Daphnia prepare their offspring
for the threat of predation?
Andrzej Mikulski
•
Joanna Pijanowska
Published online: 7 March 2010
Ó Springer Science+Business Media B.V. 2010
Abstract The life history of Daphnia exposed to
fish kairomone at different developmental stages was
examined in a laboratory experiment. The strongest
life history response to the applied predation threat
was observed in females exposed during the 4th
instar. Compared to Daphnia experiencing the pres-
ence of fish at earlier or later instars, these individuals
reached maturity at a smaller size and released fewer
neonates. Moreover, their offspring also demon-
strated the strongest reaction to predation threat,
exhibiting the broadest phenotypic plasticity in the
life history response to predation. The breadth of their
reaction norm was, on average, two times larger
comparing with individuals from other treatments.
Broader phenotypic plasticity may offer clear selec-
tive advantages under the unpredictable predation
regime. This finding highlights the adaptive role of
maternal effect in shaping life history of cladocerans.
Keywords Daphnia Á Maternal effect Á
Fish kairomone Á Reaction norm Á Life history
Introduction
The anti-predator mechanisms of Daphnia represent
an excellent example of adaptive phenotypic plastic-
ity (Tollrian & Dodson, 1999; Lass & Spaak, 2003).
Under the threat of predation, Daphnia may change
their behavioral (Dawidowicz & Loose, 1992),
morphological (Dodson & Havel, 1988; Dodson,
1989), and life history performance (Riessen, 1999).
In the presence of fish, individuals may mature when
younger and smaller, and the neonates from their first
clutch are usually smaller at the time of release,
compared to non-threatened animals. These adapta-
tions either reduce the vulnerability of Daphnia to
predation or allow for survival and reproduction
under stress conditions.
Maternal effect is one of the most important
mechanisms regulating the expression of phenotypic
reaction to environmental factors (Rossiter, 1996;
Mosseau & Fox, 1998). The role of maternal effect in
the expression of adaptive phenotypic plasticity was
demonstrated in Daphnia in the context of resting egg
production induced by low food (LaMontagne &
McCauley, 2001) or low food combined with photo-
period (Alekseev & Lampert, 2001), as well as in
predator-induced changes in morphology (Agrawal
et al., 1999) or life history (Mikulski & Pijanowska,
2009). It is not known whether the strength of the
maternal influence on their offspring is affected by the
timing of when ‘mothers’ encounter environmental
stress. Two alternative hypotheses may be considered:
Guest editors: M. Silva-Briano & S. S. S. Sarma / Biology of
Cladocera (Crustacea): Proceedings of the VIII International
Cladocera Symposium
A. Mikulski (&) Á J. Pijanowska
Department of Hydrobiology, University of Warsaw,
Banacha 2, 02-097 Warsaw, Poland
e-mail: hans@hydro.biol.uw.edu.pl
123
Hydrobiologia (2010) 643:21–26
DOI 10.1007/s10750-010-0131-0