| Daphnia pulicaria | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Branchiopoda |
| Order: | Anomopoda |
| Family: | Daphniidae |
| Genus: | Daphnia |
| Subgenus: | Daphnia |
| Species: | D. pulicaria |
| Binomial name | |
| Daphnia pulicaria Forbes, 1893 | |
Daphnia pulicaria is a species of freshwater crustaceans found within the genus ofDaphnia, which are often called "water fleas," and they are commonly used as model organisms for scientific research.[1] Like other species ofDaphnia, they reproduce via cyclic parthenogenesis.[2]D. pulicaria are filter-feeders with a diet primarily consisting of algae, includingAnkistrodesmus falcatus, and they can be found in deep lakes located in temperate climates.[3] Furthermore,D. pulicaria are ecologically important herbivorous zooplankton, which help control algal populations and are a source of food for some fish.[4]D. pulicaria are closely related toDaphnia pulex, and numerous studies have investigated the nature and strength of this relationship because these species can produceDaphnia pulex-pulicaria hybrids.[5] In recent years,D. pulicaria along with otherDaphnia species have been negatively affected by invasive predators, such asBythotrephes longimanus.[6]
Daphnia pulicaria generally live in deep, permanent lakes.[7] These lakes provide a more stable environment than temporary ponds, which eventually dry up, so populations ofD. pulicaria tend to have lower mortality rates thanD. pulex populations living in ponds.[7] Furthermore,D. pulicaria have a relatively long lifespan of 60–65 days.[8] The populations ofD. pulicaria in the Great Lakes in the United States have been negatively affected by the invasive speciesBythotrephes longimanus.[6] This invasive predator ofD. pulicaria has also contributed to a decline of other zooplankton species in the Great Lakes.[6]
Cyclic parthenogenesis is the primary mode of reproduction inD. pulicaria and other species within the genusDaphnia.[2] Therefore,D. pulicaria are capable of switching between sexual and asexual reproduction based on environmental conditions.[9] Typically,Daphnia undergo asexual reproduction when living in favorable conditions, such as in environments with abundant food or with negligible crowding.[9] In contrast, they produceephippia, which are dormant eggs, and reproduce sexually if environmental conditions worsen.[9] Some studies suggest that populations ofD. pulicaria in lakes in North America reproduce using the expected pattern of cyclic parthenogenesis while other populations in smaller ponds have shifted toward obligate parthenogenesis.[2] The number of offspring produced through asexual reproduction is heavily influenced by the environmental conditions experienced by an individual.[10] For instance, females in a high-food environment with a longer photoperiod tend to have more offspring.[10] Environmental cues, such as food level, photoperiod, and temperature, significantly influence the reproduction ofD. pulicaria.[10]
Daphnia pulicaria have a translucent carapace and two prominent second antennae, which they use to move.[11] The carapace, composed primarily of chitin, helps protect the feeding apparatus, and it is periodically shed during an individual's life.[11]Daphnia have a compound eye, and they are known to have an optomotor response.[12]D. pulicaria generally have a body length less than 3mm.[3] Because of the clear carapace ofDaphnia, it is possible to see the heart and digestive tract, which often appears to be green due to the consumption of algae.[11] The abdominal claw is also visible toward the end of the abdomen, and it can be used to dislodge any algae from the feeding apparatus if some begins to stick.[11]
D. pulicaria are considered to be part of theDaphnia pulex species complex and can produce hybrids withD. pulex.[3] While it is difficult to distinguish between these two species using morphological traits,D. pulicaria andD. pulex have significant genomic differences.[13] Phylogenetic studies, using mitochondrial DNA analysis, have identified genetic divergence betweenD. pulicaria andD. pulex.[5] For instance, variations in theLactate dehydrogenase gene can help identifyD. pulicaria from others in theD. pulex species complex.[13]
Species ofDaphnia, includingD. pulicaria, are commonly used as model organisms for studying life-history traits and phenotypic plasticity.[4] For example,D. pulicaria can detect and respond to kairomones produced by predatory fish.[4] Their sensitivity to environmental cues contributes to the observed seasonal trends in population sizes ofD. pulicaria.[4] Moreover, becauseD. pulicaria reproduce using cyclic parthenogenesis, they are ideal models for genetic studies, including ones concerning spontaneous mutations.[14]
{{cite book}}:|website= ignored (help)