Maternal control of resting-egg production in Daphnia

Abstract

Many planktonic organisms produce 'resting' stages when the environmental conditions deteriorate. Like seeds, resting stages can survive unfavourable conditions. The crustacean Daphnia normally reproduces by means of parthenogenetically produced normal, not resting, eggs-but occasionally switches to bisexual reproduction, which results in two resting eggs encased in a robust structure carried on the back of the female. This 'ephippium' is shed with the next moult, and can survive dormant for many years. The induction of resting-egg production requires multiple environmental stimuli, one of them being photoperiod. The switch from production of parthenogenetic eggs to resting eggs in Daphnia has recently been shown to be influenced by a maternal food effect. Here we present evidence that female Daphnia transmit information not only about food but also on photoperiod to their offspring, and influence the production of resting eggs in the next generation. The combined maternal effects can be relevant for the correct timing of resting-egg production-for example, in discriminating between spring and autumn conditions.

An experimental test of the ability of Daphnia galeata resting egg production in Lake Biwa

“…However, both strains produced resting eggs at a frequency of >50% in lake water. These frequencies are comparable to the resting egg production rates reported for other experimental studies on Daphnia species (Alekseev and Lampert, 2001;LaMontagne and McCauley, 2001). Thus, we conclude that even D. galeata individuals collected in March maintained the ability to produce resting eggs comparable to those of Daphnia in other studies.…”

“…Daphnia populations are known to produce resting eggs during late spring and/or fall (Cáceres, 1998;Alekseev and Lampert, 2001). Thus, individuals collected in November and March are at stages after or before the resting-egg-producing seasons.…”

“…The experiments were designed to stimulate resting egg production, such as reducing the food supply to a level lower than that available during the maternal generation (Alekseev and Lampert, 2001;LaMontagne and McCauley, 2001). To initiate the experiment, 10 neonates (1 st generation) from maternal individuals grown with a non-limiting supply of nutrient-sufficient green algae (Scenedesmus actus), a suitable food for Daphnia, were placed in 300 mL of each treatment water with algae at 1.0 mg C L −1 (one individual/30 mL).…”

“…For Daphnia, which are typical planktonic cladocerans in lakes, sexual reproduction is induced by various natural environmental stimuli including decreased food levels (Alekseev and Lampert, 2001;LaMontagne and McCauley, 2001), degree of crowding (Cáceres, 1997;Ban et al, 2009), intensity of predation pressure (Mellors, 1975;Ślusarczyk, 2001), and length of photoperiod (Alekseev and Lampert, 2001). Jankowski and Straile (2003) suggested that eutrophication may cause a decreased sexual reproduction in Daphnia species through, for example, changes in the genetic structure of the populations (Brede et al, 2009).…”

Interaction of changes in food quality and temperature reveals maternal effects on fitness parameters of a keystone aquatic herbivore

“…For example, in Daphnia, maternal food concentration has been found to affect juvenile survival, growth, reproduction, and longevity (Lynch and Ennis 1983). Maternal exposure to predator kairomones increased offspring defenses (Agrawal et al 1999), and an interaction between maternal and offspring food concentration and photoperiod affected offspring resting-egg production (Alekseev and Lampert 2001). Further, the lipid content and fatty acid composition of the maternal diet has been shown to affect reproductive strategies (Abrusan et al 2007), the biochemical composition of the eggs (Wacker and Martin-Creuzburg 2007), and the performance of offspring in Daphnia (Brett 1993).…”