Circadian Rhythm in Feeding Behavior of Daphnia dentifera

Abstract

Circadian rhythms enable organisms to mediate their molecular and physiological processes with changes in their environment. Although feeding behavior directly affects within-organism processes, there are few examples of a circadian rhythm in this key behavior. Here, we show that Daphnia have a nocturnal circadian rhythm in feeding behavior that corresponds with their diel vertical migration (DVM), an important life history strategy for predator and UV avoidance. In addition, this feeding rhythm appears to be temperature compensated, which suggests that feeding behavior is robust to seasonal changes in water temperature. A circadian rhythm in feeding behavior can impact energetically demanding processes like metabolism and immunity, which may have drastic effects on susceptibility to disease, starvation risk, and ultimately, fitness.

Daily feeding rhythm linked to microbiome composition in two zooplankton species

“…In Daphnia species, diel vertical migration (DVM) is a host behavior intrinsically tied to feeding. Zooplankton consume more food at night when migrating up the water column in the relative safety of darkness from visual predators, then return to darker, deeper layers of the water column in daylight, where they consume less food [ 10 , 57 ]. Because Daphnia in this experiment were raised individually in 30 mL tubes, we demonstrate that changes in feeding behavior observed here are strongly associated with changes in microbial diversity in the absence of host migration through the water column.…”

“…dentifera show a robust DVM behavior in laboratory and natural systems regardless of genotype [ 20 ]. Daphnia dentifera also have a circadian rhythm in feeding behavior that is consistent with DVM [ 10 ]. Given these differences, we predicted that D .…”

“…Daphnia are dominant herbivores and serve as keystone species by linking primary producers with secondary consumers in freshwater systems [ 7 ]. Daphnia are an ideal system for addressing if and how feeding behavior and microbial composition are linked because (1) they have a relatively simple microbiome, which has been characterized in multiple species [ 8 , 9 ], (2) they have core clock genes and show circadian expression of feeding behavior, immune, and sensory genes [ 10 – 13 ], and (3) quantifying individual feeding behavior is straightforward [ 14 ].…”

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“…In D. magna DVM may be tightly linked to genotype [18,19]; whereas D. dentifera show a robust DVM behavior in laboratory and natural systems regardless of genotype [20]. Daphnia dentifera also have a circadian rhythm in feeding behavior that is consistent with DVM [10]. Given these differences, we predicted that D. dentifera's microbiome composition would be more diverse during their active phase (night).…”

“…Daphnia are dominant herbivores and serve as keystone species by linking primary producers with secondary consumers in freshwater systems [7]. Daphnia are an ideal system for addressing if and how feeding behavior and microbial composition are linked because (1) they have a relatively simple microbiome, which has been characterized in multiple species [8,9], (2) they have core clock genes and show circadian expression of feeding behavior, immune, and sensory genes [10][11][12][13], and (3) quantifying individual feeding behavior is straightforward [14].…”