Dataset Information

Phenotypic plasticity of senescence in Daphnia under predation impact: no ageing acceleration when the perceived risk decreases with age.

ABSTRACT: Recognising the nature of the predation risk, and responding to it accurately, is crucial to fitness. Yet, even the most accurate adaptive responses to predation risk usually entail costs, both immediate and lifelong. Rooting in life-history theory, we hypothesize that an animal can perceive the nuances of prey size and age selectivity by the predator and modulate its life history accordingly. We test the prediction that-contrary to the faster or earlier senescence under predation risk that increases with prey size and age-under predation risk that decreases with prey size and age either no senescence acceleration or even its deceleration is to be observed. We use two species of indeterminate growers, small crustaceans of the genus Daphnia, Daphnia Pulex and Daphnia magna, as the model prey, and their respective gape-limited invertebrate predators, a dipteran, midge larva Chaoborus flavicans, and a notostracan, tadpole shrimp Triops cancriformis. We analyse age-specific survival, mortality and fertility rates, and find no senescence acceleration, as predicted. With this study, we complete the picture of the expected non-consumptive phenotypic effects of perceived predation pressure of different age-dependence patterns.

SUBMITTER: Pietrzak B

PROVIDER: S-EPMC7062089 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Phenotypic plasticity of senescence in <i>Daphnia</i> under predation impact: no ageing acceleration when the perceived risk decreases with age.

Pietrzak Barbara B Rabus Max M Religa Maciej M Laforsch Christian C Dańko Maciej J MJ

Royal Society open science 20200205 2

Recognising the nature of the predation risk, and responding to it accurately, is crucial to fitness. Yet, even the most accurate adaptive responses to predation risk usually entail costs, both immediate and lifelong. Rooting in life-history theory, we hypothesize that an animal can perceive the nuances of prey size and age selectivity by the predator and modulate its life history accordingly. We test the prediction that-contrary to the faster or earlier senescence under predation risk that incr ...[more]

PMID: 32257312

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Project description:BackgroundPredator-induced defences are a prominent example of phenotypic plasticity found from single-celled organisms to vertebrates. The water flea Daphnia pulex is a very convenient ecological genomic model for studying predator-induced defences as it exhibits substantial morphological changes under predation risk. Most importantly, however, genetically identical clones can be transcriptionally profiled under both control and predation risk conditions and be compared due to the availability of the sequenced reference genome. Earlier gene expression analyses of candidate genes as well as a tiled genomic microarray expression experiment have provided insights into some genes involved in predator-induced phenotypic plasticity. Here we performed the first RNA-Seq analysis to identify genes that were differentially expressed in defended vs. undefended D. pulex specimens in order to explore the genetic mechanisms underlying predator-induced defences at a qualitatively novel level.ResultsWe report 230 differentially expressed genes (158 up- and 72 down-regulated) identified in at least two of three different assembly approaches. Several of the differentially regulated genes belong to families of paralogous genes. The most prominent classes amongst the up-regulated genes include cuticle genes, zinc-metalloproteinases and vitellogenin genes. Furthermore, several genes from this group code for proteins recruited in chromatin-reorganization or regulation of the cell cycle (cyclins). Down-regulated gene classes include C-type lectins, proteins involved in lipogenesis, and other families, some of which encode proteins with no known molecular function.ConclusionsThe RNA-Seq transcriptome data presented in this study provide important insights into gene regulatory patterns underlying predator-induced defences. In particular, we characterized different effector genes and gene families found to be regulated in Daphnia in response to the presence of an invertebrate predator. These effector genes are mostly in agreement with expectations based on observed phenotypic changes including morphological alterations, i.e., expression of proteins involved in formation of protective structures and in cuticle strengthening, as well as proteins required for resource re-allocation. Our findings identify key genetic pathways associated with anti-predator defences.

Project description:This study measured the differential expression of genes from a single clonal Daphnia pulex isolate obtained from an eutrophic flooded opencast mine near Gräfenhain (Saxony, Germany) and has been kept in the laboratory since 2002. The daphniids (50 adult animals per batch) were raised in 3-L glass beakers under a 16 h:8 h L:D photoperiod. Three-quarter of the culture medium (M4) was renewed once a week, and the animals were equally fed ad libitum with algae (Desmodesmus subspicatus; SAG 53.80, Göttingen, Germany). Long-term-acclimated animals were kept at three different temperatures (i.e., 10 ± 0.5°C, 20 ± 0.3°C, and 24 ± 0.3°C) under normoxia (Po2 ≥ 20 kPa) for at least twelve weeks. Time-resolved experiments (acute heat stress) were carried out with long-term 20°C acclimated animals, which were exposed for three different time intervals (2, 4, and 8 h) to either 30 ± 0.2°C (test conditions) or 20 ± 0.3°C (control conditions). For this, 50 animals each were rapidly transferred with a sieve (mesh size: 1.2 mm) from 20°C-medium to a set of beakers containing 30°C-medium. As control, 50 animals each were transferred from 20°C-medium to another set of beakers with 20°C-medium. Only adult female animals with a body length of 2−2.5 mm (between the base of the apical spine and the anterior part of the head) and carrying parthenogenetic eggs and embryos were used for experiments. Animals were not fed during short-term exposures. During experiments, all animals were in good physical condition. After thermal acclimation or heat exposure, animals were transferred into 1.5-ml microcentrifuge tubes and shock-frozen in liquid nitrogen after removing adhering water with a tissue paper. Samples were short-term stored at -80°C. For all experimental conditions, four independent replicates (50 animals each) were analyzed. This GEO record is for the acute heat stress temperature contrasts between animals conditioned to 20 degrees Celsius (condition 1) versus heat shock to 30 degrees Celsius (condition 2) exposed for 2 hours (treatment 1), 4 hours (treatment 2), and 8 hours (treatment 3).

Project description:This study measured the differential expression of genes from a single clonal Daphnia pulex isolate obtained from an eutrophic flooded opencast mine near Gräfenhain (Saxony, Germany) and has been kept in the laboratory since 2002. The daphniids (50 adult animals per batch) were raised in 3-L glass beakers under a 16 h:8 h L:D photoperiod. Three-quarter of the culture medium (M4) was renewed once a week, and the animals were equally fed ad libitum with algae (Desmodesmus subspicatus; SAG 53.80, Göttingen, Germany). Long-term-acclimated animals were kept at three different temperatures (i.e., 10 ± 0.5°C, 20 ± 0.3°C, and 24 ± 0.3°C) under normoxia (Po2 ≥ 20 kPa) for at least twelve weeks. Time-resolved experiments (acute heat stress) were carried out with long-term 20°C acclimated animals, which were exposed for three different time intervals (2, 4, and 8 h) to either 30 ± 0.2°C (test conditions) or 20 ± 0.3°C (control conditions). For this, 50 animals each were rapidly transferred with a sieve (mesh size: 1.2 mm) from 20°C-medium to a set of beakers containing 30°C-medium. As control, 50 animals each were transferred from 20°C-medium to another set of beakers with 20°C-medium. Only adult female animals with a body length of 2−2.5 mm (between the base of the apical spine and the anterior part of the head) and carrying parthenogenetic eggs and embryos were used for experiments. Animals were not fed during short-term exposures. During experiments, all animals were in good physical condition. After thermal acclimation or heat exposure, animals were transferred into 1.5-ml microcentrifuge tubes and shock-frozen in liquid nitrogen after removing adhering water with a tissue paper. Samples were short-term stored at -80°C. For all experimental conditions, four independent replicates (50 animals each) were analyzed. This GEO record is for the contrasts between animals conditioned to 10 degrees Celsius (condition 1) versus 20 degrees Celsius (condition 2), 10 degrees Celsius (condition 1) versus 24 degrees Celsius (condition 3), and 20 degrees Celsius (condition 2) versus 24 degrees Celsius (condition 3)

Dataset Information

Phenotypic plasticity of senescence in Daphnia under predation impact: no ageing acceleration when the perceived risk decreases with age.

Publications

Phenotypic plasticity of senescence in <i>Daphnia</i> under predation impact: no ageing acceleration when the perceived risk decreases with age.

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