Figure - available from: Functional & Integrative Genomics
This content is subject to copyright. Terms and conditions apply.
Structure of the complete mitogenome of Daphnia galeata. Yellow: protein-coding genes; red: rRNA genes; pink: tRNA genes; orange: control region
Source publication
Daphnia galeata is an important plankton in aquatic ecosystems. As a widely distributed species, D. galeata has been found throughout the Holarctic region. Understanding the genetic diversity and evolution of D. galeata requires the accumulation of genetic information from different locations. Even though the mitochondrial genome (mitogenome) seque...
Citations
... When Daphnia are exposed to fish kairomones, variations in life-history traits, morphological, physiological, and behavioral plasticity, as well as other effects, have been reported (Lampert, 1993;Carter et al., 2013). Among the Daphnia species, Daphnia galeata is a relatively large zooplankton found throughout the northern hemisphere and has been identified as a dominant plankton species in the Han River, Korea (Choi et al., 2023a). The freshwater crustacean D. galeata, which has a short life cycle, a rapid response to environmental stress, convenient clonal reproduction under laboratory conditions, and typical defense mechanisms induced by predators in life-history traits, is an appropriate organism for research in this field (Tams et al., 2018;Choi et al., 2023b). ...
The gut microbiota plays a crucial role in host physiology and the disruption of host–microbiota relationships caused by environmental stressors can impact host growth and survival. In this study, we used Daphnia galeata as a model organism to investigate the interactive effects of fish kairomones on the life-history traits and gut microbiota alterations of D. galeata, as well as the relationship between life-history traits and gut microbiota composition. The presence of fish kairomones enhanced fecundity, decreased growth, and altered gut microbiota, with significant changes in alpha diversity but not in beta diversity in the genotype KB5 of D. galeata. Statistical analysis revealed that the relative abundance of the Pseudomonadaceae family significantly increased upon exposure to fish kairomone, while the relative abundance of the Comamonadaceae family significantly decreased. The decreased growth in genotype KB5 may be associated with a significant increase in Pseudomonas, a member of the family Pseudomonadaceae, which is generally deficient in essential fatty acids, potentially negatively impacting growth. Meanwhile, it is speculated that the significant decrease in Limnohabitans belonging to the Comamonadaceae family is associated with the reduction of body size and increased fecundity of KB5 when exposed to fish kairomones. Furthermore, the genus Candidatus Protochlamydia was observed only under the fish kairomones-treated condition. These data suggest that variations in host life-history traits related to reproduction and growth are potentially associated with the relative abundance or presence of these microbial genera. Our research findings provide valuable insights into understanding the impact of biotic stress on the interaction between hosts and microbiota.
... D. galeata is a relatively large-sized zooplankton found throughout the northern hemisphere and identified as a dominant plankton species in the Han River, Korea [27,28]. It is also a member of the Daphnia longispina complex, which includes D. longispina, D. cucullata, D. hyalina, and D. galeata, and a widely distributed species, whose genetic diversity has been investigated in several countries in Asia, Europe, and North America [28][29][30]. ...
... D. galeata is a relatively large-sized zooplankton found throughout the northern hemisphere and identified as a dominant plankton species in the Han River, Korea [27,28]. It is also a member of the Daphnia longispina complex, which includes D. longispina, D. cucullata, D. hyalina, and D. galeata, and a widely distributed species, whose genetic diversity has been investigated in several countries in Asia, Europe, and North America [28][29][30]. Although this species does not exhibit substantial morphological changes or diel vertical migration in response to vertebrate predator cues, it exhibits marked phenotypic variation in life-history traits when facing predation risk [31]. ...
... D. galeata individuals were cultured under laboratory conditions (20℃, 16 h light/8 h dark cycle, ISO medium); 1.0 mg C L − 1 Chlorella vulgaris was used as food source once daily. The two genotypes examined were identified by mitochondrial cytochrome oxidase I (cox1) and NADH dehydrogenase subunit 2 (nd2) gene sequence analyses [28,30]. As a result, we identified only two different genotypes with sequence differences in the cox1 and nd2 genes. ...
Background
Phenotypic plasticity is a crucial adaptive mechanism that enables organisms to modify their traits in response to changes in their environment. Predator-induced defenses are an example of phenotypic plasticity observed across a wide range of organisms, from single-celled organisms to vertebrates. In addition to morphology and behavior, these responses also affect life-history traits. The crustacean Daphnia galeata is a suitable model organism for studying predator-induced defenses, as it exhibits life-history traits changes under predation risk. To get a better overview of their phenotypic plasticity under predation stress, we conducted RNA sequencing on the transcriptomes of two Korean Daphnia galeata genotypes, KE1, and KB11, collected in the same environment.
Results
When exposed to fish kairomones, the two genotypes exhibited phenotypic variations related to reproduction and growth, with opposite patterns in growth-related phenotypic variation. From both genotypes, a total of 135,611 unigenes were analyzed, of which 194 differentially expressed transcripts (DETs) were shared among the two genotypes under predation stress, which showed consistent, or inconsistent expression patterns in both genotypes. Prominent DETs were related to digestion and reproduction and consistently up-regulated in both genotypes, thus associated with changes in life-history traits. Among the inconsistent DETs, transcripts encode vinculin (VINC) and protein obstructor-E (OBST-E), which are associated with growth; these may explain the differences in life-history traits between the two genotypes. In addition, genotype-specific DETs could explain the variation in growth-related life-history traits between genotypes, and could be associated with the increased body length of genotype KE1.
Conclusions
The current study allows for a better understanding of the adaptation mechanisms related to reproduction and growth of two Korean D. galeata genotypes induced by predation stress. However, further research is necessary to better understand the specific mechanisms by which the uncovered DETs are related with the observed phenotypic variation in each genotype. In the future, we aim to unravel the precise adaptive mechanisms underlying predator-induced responses.
