Linda Carolin Weiss

Ruhr-Universität Bochum | RUB · Evolutionsökologie und Biodiversität der Tiere

Fluoxetine, a common pharmaceutical used as an antidepressant, is already considered potentially hazardous to biota due to its increasing use and detection in European, North American, and Asian rivers. We studied the effects of fluoxetine on Daphnia magna, as we hypothesized that fluoxetine might have harmful effects, short and long-term, at diffe...

The freshwater crustacean Daphnia is well known for its expression of morphological defenses in the presence of predators. Research into this phenomenon has mostly centered on the ecology and evolution of Daphnia defenses; information is limited on the cellular mechanisms that underlie site-specific tissue growth. We aimed to determine these cellul...

Every ecosystem shows multiple levels of species interactions, which are often difficult to isolate and to classify regarding their specific nature. For most of the observed interactions, it comes down to either competition or consumption. The modes of consumption are various and defined by the nature of the consumed organism, e.g., carnivory, herb...

Editorial on the Research Topic Sensory Ecology of Phenotypic Plasticity: From Receptors viaModulators to Effectors

Acquiring environmental information is vital for organisms as it informs about the location of resources, mating partners, and predators. The freshwater crustacean Daphnia detects predator specific chemical cues released by its predators and subsequently develops defensive morphological features that reduce the predation risk. The detection of such...

Inducible defenses are a wide-spread defensive mechanism in Daphnia. For example, D. cucullata is known to form different adaptive morphologies under changing environmental conditions. In this species, predator presence elicits defensive helmets. Defended animals perform better and survive more frequently in predation attempts. Another peculiarity...

Fluoxetine, a common pharmaceutical used as an antidepressant, is already considered poten-tially hazardous to biota due to its increasing use and detection in European, North American, and Asian rivers. We studied the effects of fluoxetine on Daphnia magna, as we hypothesized that fluoxetine might have harmful effects, short and long-term, at diff...

Phenotypic plasticity describes the ability of an organism with a given genotype to respond to changing environmental conditions through the adaptation of the phenotype. Phenotypic plasticity is a widespread means of adaptation, allowing organisms to optimize fitness levels in changing environments. A core prerequisite for adaptive predictive plast...

Citation: Langer, S. M., M. Horstmann, L. C. Weiss, W. Junke, S. Herlitze, and R. Tollrian. 2021. On Daphnia's path: a semi-automatic system to analyze three-dimensional movement patterns. Ecosphere 12(12): Abstract. Analyzing movement is essential for understanding complex behavioral interactions. Up to date, there are different movement analysis...

Water fleas of the family Daphniidae are keystone species in many lentic ecosystems and, as most abundant filter feeders, link the primary production to higher trophic levels. As a response to the high predatory pressures, water fleas have evolved a range of defenses, including inducible defenses against animal predators. Here we show in Ceriodaphn...

Predation is a major selective agent, so that many taxa evolved phenotypically plastic defensive mechanisms. Among them are many species of the microcrustacean genus Daphnia, which respond to an increased predation risk by developing inducible morphological alterations. Some of these features are obvious and easily recognized, e.g., crests in D. lo...

Fossil fuel combustion results in rising atmospheric carbon dioxide (CO2), which is known to impact the global climate and the oceans. Latest insights indicate that rising atmospheric CO2 levels also affect CO2 partial pressure (pCO2) in freshwaters, where pCO2 is controlled by a multitude of parameters. However, up to date there is no standardized...

Predator-induced phenotypic plasticity describes the ability of prey to respond to an increased predation risk by developing adaptive phenotypes. Upon the perception of chemical predator cues, the freshwater crustacean Daphnia longicephala develops defensive crests against its predator Notonecta spec. (Heteroptera). Chemical predator perception ini...

Fossil fuel combustion results in rising atmospheric carbon dioxide (CO2), which is known to impact the global climate and the oceans. Latest insights indicate that rising atmospheric CO2 levels also affect CO2 partial pressure (pCO2) in freshwaters, where pCO2 is controlled by a multitude of parameters. However, up to date there is no standardized...

Dormancy is a lifecycle delay that allows organisms to escape suboptimal environmental conditions. As a genetically programmed type of dormancy, diapause is usually accompanied by metabolic depression and enhanced tolerance toward adverse environmental factors. However, the drivers and regulators that steer an organism’s development into a state of...

Prey species can respond to the presence of predators by inducing phenotypic plastic traits which form morphological, life history or behavioral defenses. These so-called inducible defenses have evolved within a cost-benefit framework. They are only formed when they are needed, and costs associated with defenses are saved when predators are not pre...

Increased carbon dioxide from fossil fuel combustion results in an enrichment of CO2 in the global carbon cycle. Recent evidence indicates that rising atmospheric CO2 impacts the partial pressure of carbon dioxide (pCO2) in freshwaters. This affects freshwater biota by disrupting chemical communication between predator and prey. One such well-descr...

Abstract Diapause is a mechanism necessary for survival in arthropods. Often diapause induction and resurrection is light-dependent and therefore dependent on the photoperiod length and on the number of consecutive short-days. In many organisms, including the microcrustacean Daphnia magna, one functional entity with the capacity to measure seasonal...

Ciliates are unicellular protists of the phylum Ciliophora and found in high abundances in water systemsworld-wide. Today their important ecological role in all aquatic systems is well known. However, morphologicalspecies identification in ciliates is difficult due to sometimes tiny morphological characteristics. We here present asimplified method...

Aquatic acidification is a major consequence of fossil fuel combustion. In marine ecosystems it was shown, that increasing pCO2 levels significantly affect behavioural and sensory capacities in a diversity of species. This can result in altered predator and prey interactions and thereby change community structures. Just recently also CO2 dependent...

The flashlight fish Photoblepharon steinitzi inhabit coral reef caves in the Red Sea. During the night they dwell alone or in pairs near their cave entrance, characteristic of territorial like behavior. A special feature of the flashlight fish is a bioluminescent organ located under their eyes, which emits blue green light. This bioluminescence may...

Synopsis The critically endangered carnivorous waterwheel plant (Aldrovanda vesiculosa, Droseraceae) possesses underwater snap traps for capturing small aquatic animals, but knowledge on the exact prey species is limited. Such information would be essential for continuing ecological research, drawing conclusions regarding trapping efficiency and tr...

Filter feeding zooplankton are a crucial component of limnic food webs. Copepods and cladocerans are important prey organisms for first-level predators like the common and abundant larvae of phantom midges (Chaoborus sp.). The latter possess a complex catching basket built of head appendages specialized to capture small crustaceans. The predator-pr...

Surface mesh (.stl) of the Chaoborus larva head morphology with closed catching basket. (STL)

Surface mesh (.stl) of the Chaoborus larva head morphology with opened catching basket. (STL)

High-speed footage of a Chaoborus larva attacking a defended daphniid. (MP4)

Animation of the opening catching basket of Chaoborus larvae based on micro-CT data and high-speed footage, multiple angles of view. (MOV)

Animation of the opening catching basket of Chaoborus larvae based on micro-CT data and high-speed footage. (AVI)

Behavioral adaptations play an important role in predator–prey interactions as they reduce predation risk. Prey organisms have therefore evolved a tremendous variability in behavioral adaptations. In case of small crustaceans of the genus Daphnia, which are common and important herbivores transferring energy from primary producers to higher trophic...

Ecological communities are organized in trophic levels that share manifold interactions forming complex food webs. Infochemicals can further modify these interactions, e.g., by inducing defenses in prey. The micro-crustacean Daphnia is able to respond to predator-specific chemical cues indicating an increased predation risk. Daphnia shows plastic r...

Background Diapause is a form of dormancy that is genetically predetermined to allow animals to overcome harsh environmental conditions. It is induced by predictive environmental cues bringing cellular activity levels into a state of suspended animation. Entering diapause requires organismal, molecular and cellular adaptation to severely reduced en...

Infochemicals play important roles in aquatic ecosystems. They even modify food web interactions, such as by inducing defenses in prey. In one classic but still not fully understood example, the planktonic freshwater crustacean Daphnia pulex forms specific morphological defenses (neckteeth) induced by chemical cues (kairomones) released from its pr...

Quantitative analysis of shape and form is critical in many biological disciplines, as context-dependent morphotypes reflect changes in gene expression and physiology, e.g., in comparisons of environment-dependent phenotypes, forward/reverse genetic assays or shape development during ontogenesis. 3D-shape rendering methods produce models with arbit...

Confidence ellipsoid analysis of permutated treatments Displayed are the results of the usual confidence ellipsoid analysis, conducted with the natural treatments leading to complete non-overlap of all the confidence ellipsoids (black clouring) (A). Figures (B) to (D) show three random permutations among the samples, each keeping the number of anim...

Light microscopic comparison of undefended (A) and defended (B) D. magna K34Q (A) The undefended morphological state is mainly characterised by a comparatively short tail spine, while (B) the one of defended animals is elongated and inserts on an almost circular body outline. Apart from these alterations, no other differences between the shapes can...

Q-values against their respective p-values Given are p- q-plots for the x- (A), y-(B) and z-dimension (C). Figure S3 (D) gives an exemplary λ–π (λ)-plot for the z-coordinates, calculated with Matlab, to determine π0 and therefore indirectly π1, which is the lower bound on the proportion of test decisions correctly following the alternative hypothes...

Overall displacement, size adjusted By applying a Procrustes-fit with adjustment of size, most alterations, as the ones visualised in Fig. 3C, disappear. Therefore, the true changes of shape become obvious, which are mainly located at the tail spine, which is elongated non-proportionally to body length in defended specimens. Further shape alteratio...

The capacity of an organism with a given genotype to respond to changing environmental conditions by the expression of an alternative phenotype is a fascinating biological phenomenon. Plasticity enables organisms to cope with environmental challenges by altering their morphology, behavior, physiology, and life history. Especially, predation is a ma...

Anthropogenically released CO2 accumulates in the global carbon cycle and is anticipated to imbalance global carbon fluxes [1]. For example, increased atmospheric CO2 induces a net air-to-sea flux where the oceans take up large amounts of atmospheric CO2 (i.e., ocean acidification [2-5]). Research on ocean acidification is ongoing, and studies have...

The freshwater crustacean Daphnia is known for its ability to develop inducible morphological defences that thwart predators. These defences are developed only in the presence of predators and are realized as morphological shape alterations e.g. 'neckteeth' in D. pulex and 'crests' in D. longicephala. Both are discussed to hamper capture, handling...

The micro-crustacean Daphnia pulex is a model species for studying predator-induced defenses. When exposed to chemical cues released by its predator, the phantom midge larvae Chaoborus (Diptera), it develops protective neckteeth that reduce the predator’s success of predation in the juvenile instars. Defensive traits need to be expressed as soon as...

Daphnia (Crustacea, Cladocera) are well known for their ability to form morphological adaptations to defend against predators. In addition to spines and helmets, the carapace itself is a protective structure encapsulating the main body, but not the head. It is formed by a double layer of the integument interconnected by small pillars and hemolympha...

Tag-Seq is a high-throughput approach used for discovering SNPs and characterizing gene expression. In comparison to RNA-Seq, Tag-Seq eases data processing and allows detection of rare mRNA species using only one tag per transcript molecule. However, reduced library complexity raises the issue of PCR duplicates, which distort gene expression levels...

The waterflea Daphnia is a model to investigate the genetic basis of phenoty-pic plasticity resulting from one differentially expressed genome. Daphnia develops adaptive phenotypes (e.g. morphological defences) thwarting predators, based on chemical predator cue perception. To understand the genomic basis of phenotypic plasticity, the description o...

The freshwater crustacean Daphnia adapts to changing predation risks by forming inducible defences. These are only formed when they are advantageous, saving associated costs when the defence is superfluous. However, in order to be effective, the time lag between the onset of predation and the defence formation has to be short. Daphnia longicephala...

Predation is a major factor driving evolution, and organisms have evolved adaptations increasing their survival chances. However, most defenses incur trade-offs between benefits and costs. Many organisms save costs by employing inducible defenses as responses to fluctuating predation risk. The level of defense often increases with predator densitie...

Background Predator-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,...

In recent years, a few colonial marine invertebrates have shown intracolonial genetic variability, a previously unreported phenomenon. Intracolonial genetic variability describes the occurrence of more than a single genotype within an individual colony. This variability can be traced back to two underlying processes: chimerism and mosaicism. Chimer...

The publication of the Daphnia genome has driven research in this ecologically relevant model organism in many directions. However, information on this organism’s physiology and the relevant controlling factors is limited. In this regard, especially neuropeptides are important biochemical regulators that control a variety of cellular processes, whi...

Phenotypic plasticity is defined as the ability of an organism with a given genotype to respond to changing environmental conditions by undergoing a phenotypic adaptation. Predator-induced defences are one form of phenotypic plasticity. Only when needed i.e. in the presence of a predator, organisms build defensive structures (e.g. crests, thorns or...

The freshwater crustacean Daphnia is well known for its phenotypic plasticity, in which environmental cues are perceived by the nervous system and transformed into phenotypic adaptations beneficial under current conditions. Critical knowledge regarding the distribution and localization of neuronal antigens or neurotransmitters and differentially ex...

Many prey species evolved inducible defense strategies that protect effectively against predation threats. Especially the crustacean Daphnia emerged as a model system for studying the ecology and evolution of inducible defenses. Daphnia pulex e.g. shows different phenotypic adaptations against vertebrate and invertebrate predators. In response to t...

Toxicity Testing in Pre-trials. A: Plotted is the mortality rate in dependence of physostigmine. EC 50 (the concentration at which 50% of the animals die) lies at 0.01 µM, which is double of the applied concentration that was used in the physiological induction assay. B: Plotted is the mortality rate in dependence of atropine. EC 50 lies above 10 µ...

During the past century enormous progress has been made in the understanding of how predator– prey interactions are shaping ecosystems. We have obtained a broader knowledge of the effect of pre-dation on cascading trophic interactions in food webs and recently it has become increasingly clear that in aquatic ecosystems such processes are immensely...