The induction of diapause in Moina by species-specific chemical cues

Abstract

The ability to change the reproduction mode and produce diapausing eggs, which is prevalent in many zooplankton species, significantly impacts on the evolution and ecology of aquatic communities. The production of diapausing eggs is controlled by multiple effects of biotic and abiotic factors, including infochemicals. We have investigated the effects of chemicals exuded by conspecifics and ecologically close competing congers, Moina brachiata and M. macrocopa, which coexist in the same water body, and by larger Cladocera species (Daphnia magna) on the change of reproduction mode, specific growth rate and fecundity of M. brachiata and M. macrocopa females. The production of gametogenetic eggs in both species was detected only in waters from crowded cultures of conspecifics. The water from crowded cultures of conspecifics reduced the specific growth rate of the juvenile females of both species that later switched to gametogenesis. While it either did not affect (in M. macrocopa) or even increase (in M. brachiata) the specific growth rate of the juvenile females that later reproduced by parthenogenesis. Females of M. macrocopa released significantly fewer neonates in the water from crowded cultures of conspecifics than in all other treatments, while the fecundity of M. brachiata females was the same in all treatments. To understand the phenomenon of diapause induction under the effect of chemical cues in zooplankton, a link between laboratory tests and ecological research should be established, and the chemical composition of the signals should be determined.

Predation cues do not affect the induction and termination of diapause in small‐bodied cladocerans

“…Although predation apparently does not induce a shift from parthenogenesis to sexual reproduction in M. micrura , other biotic factors may have an important role for particular Moina species. For example, high concentrations of conspecific chemical cues switch the reproductive mode of Moina macrocopa (Straus) and Moina brachiata Jurine (Zadereev & Lopatina, 2007). Male and female neonates in a single clutch, as we observed in this study, seem not so common but have been previously observed for M. micrura (Martínez‐Jerónimo, Rodriguez‐Estrada & Villasenor‐Cordova, 2007).…”

Current knowledge of South American cladoceran diapause: A brief review

“…Several studies have focused on understanding these signals in temperate aquatic ecosystems (reviewed in Radzikowski, 2013) and both light and temperature continue to be considered the most important proximate stimuli triggering both the induction and termination of diapause (Stross, 1966;Hairston et al, 1990Hairston et al, , 2000Vandekerkhove et al, 2005b). However, more recently, the relevance of other factors has been pointed out, including: food shortage (Alekseev and Lampert, 2001), predation cues (Pijanowska and Stolpe, 1996), and crowding (Zadereev and Lopatina, 2007).…”

Two hundred years of zooplankton vertical migration research

“…In species whose resting eggs are sexually produced, crowding increases the chances of female and male encounters and thus elevates the production of resting eggs (Wood, 1932). Crowding can also elevate the concentrations of conspecific or competitor exudates, metabolites and excretory substances in the water column (Hobaek & Larsson, 1990; Ban & Minoda, 1994), which promotes resting egg production through the suppression of parthenogenetic reproductive output (Zadereev & Lopatina, 2007) or inhibition of feeding (Lürling et al ., 2003). Strickler & Twombly (1975) forwarded a different perspective, in which they highlighted the possibility that freshwater cyclopoids enter diapause in response to elevated invertebrate predation.…”