Populations Of Threespine Stickleback Research Articles

Accumulation of Deleterious Mutations in Landlocked Threespine Stickleback Populations.

Colonization of new habitats often reduces population sizes and may result in the accumulation of deleterious mutations by genetic drift. Compared with the genomic basis for adaptation to new environments, genome-wide analysis of deleterious mutations in isolated populations remains limited. In the present study, we investigated the accumulation of deleterious mutations in five endangered freshwater populations of threespine stickleback (Gasterosteus aculeatus) in the central part of the mainland of Japan. Using whole-genome resequencing data, we first conducted phylogenomic analysis and confirmed at least two independent freshwater colonization events in the central mainland from ancestral marine ecotypes. Next, analyses of single nucleotide polymorphisms showed a substantial reduction of heterozygosity in freshwater populations compared with marine populations. Reduction in heterozygosity was more apparent at the center of each chromosome than the peripheries and on X chromosomes compared with autosomes. Third, bioinformatic analysis of deleterious mutations showed increased accumulation of putatively deleterious mutations in the landlocked freshwater populations compared with marine populations. For the majority of populations examined, the frequencies of putatively deleterious mutations were higher on X chromosomes than on autosomes. The interpopulation comparison indicated that the majority of putatively deleterious mutations may have accumulated independently. Thus, whole-genome resequencing of endangered populations can help to estimate the accumulation of deleterious mutations and inform us of which populations are the most severely endangered. Furthermore, analysis of variation among chromosomes can give insights into whether any particular chromosomes are likely to accumulate deleterious mutations.

Effects of predation risk on egg steroid profiles across multiple populations of threespine stickleback

Predation often has consistent effects on prey behavior and morphology, but whether the physiological mechanisms underlying these effects show similarly consistent patterns across different populations remains an open question. In vertebrates, predation risk activates the hypothalamic-pituitary-adrenal (HPA) axis, and there is growing evidence that activation of the maternal HPA axis can have intergenerational consequences via, for example, maternally-derived steroids in eggs. Here, we investigated how predation risk affects a suite of maternally-derived steroids in threespine stickleback eggs across nine Alaskan lakes that vary in whether predatory trout are absent, native, or have been stocked within the last 25 years. Using liquid chromatography coupled with mass spectroscopy (LC-MS/MS), we detected 20 steroids within unfertilized eggs. Factor analysis suggests that steroids covary within and across steroid classes (i.e. glucocorticoids, progestogens, sex steroids), emphasizing the modularity and interconnectedness of the endocrine response. Surprisingly, egg steroid profiles were not significantly associated with predator regime, although they were more variable when predators were absent compared to when predators were present, with either native or stocked trout. Despite being the most abundant steroid, cortisol was not consistently associated with predation regime. Thus, while predators can affect steroids in adults, including mothers, the link between maternal stress and embryonic development is more complex than a simple one-to-one relationship between the population-level predation risk experienced by mothers and the steroids mothers transfer to their eggs.

Nearly year-round reproduction among individuals of a Japanese freshwater threespine stickleback population

The freshwater threespine stickleback (Gasterosteus aculeatus) shows tremendous interpopulation variation in a variety of phenotypic traits, including reproductive characteristics. We investigated individual-level reproductive patterns in the freshwater Ono population in Japan, which occurs nearly at the southern global range limit for this species. Although G. aculeatus populations generally only reproduce in spring and/or summer, we directly observed tagged individuals in semi-natural enclosures and found that both males and females reproduced almost the year long. We observed two peaks in reproductive activity, spring to early summer and autumn to early winter, at both the population and individual levels. Thus, we found unique features in the timing and duration of reproduction of this freshwater population, which inhabits spring-fed areas with constant year-round water temperatures.

Microhabitat contributes to microgeographic divergence in threespine stickleback

Since the New Synthesis, most migration-selection balance theory has predicted that there should be negligible differentiation over small spatial scales (relative to dispersal), because gene flow should erode any effect of divergent selection. Nevertheless, there are classic examples of microgeographic divergence, which theory suggests can arise under specific conditions: exceptionally strong selection, phenotypic plasticity in philopatric individuals, or nonrandom dispersal. Here, we present evidence of microgeographic morphological variation within lake and stream populations of threespine stickleback (Gasterosteus aculeatus). It seems reasonable to assume that a given lake or stream population of fish is well-mixed. However, we found this assumption to be untenable. We examined trap-to-trap variation in 34 morphological traits measured on stickleback from 16 lakes and 16 streams. Most traits varied appreciably among traps within populations. Both between-trap distance and microhabitat characteristics such as depth and substrate explained some of the within-population morphological variance. Microhabitat was also associated with genotype at particular loci but there was no genetic isolation by distance, implying that heritable habitat preferences may contribute to microgeographic variation. Our study adds to growing evidence that microgeographic divergence can occur across small spatial scales within individuals' daily dispersal neighborhood where gene flow is expected to be strong.

Population growth correlates with increased fecundity in three-spined stickleback populations in a human-disturbed environment

Human activity is altering the dynamics of populations through effects on fecundity, mortality and migration. An increased abundance of three-spined stickleback (Gasterosteus aculeatus) in the Baltic Sea has been attributed to a human-caused decline of top predators. However, recent research indicates that a top-down effect cannot fully explain the population growth, but the contribution of a bottom-up effect has not been investigated. Yet, anthropogenic eutrophication has increased algae biomass at the spawning sites of the stickleback and, thus, the abundance of benthic prey. We investigated if increased fecundity could have contributed to the population growth of the stickleback by analysing a two decade time series of stickleback abundance, fecundity, and body size at three spawning sites. The results show an increase in the proportion of gravid females in the populations, which correlates with the population growth. In particular, the proportion of gravid females late in the spawning season has increased, which indicates enhanced food intake at the sites during the spawning season. Thus, a bottom-up effect could have contributed to the growth of the populations by increasing the number of egg clutches females produce. These results stress the importance of considering both bottom-up and top-down processes when investigating the mechanisms behind human impact on population dynamics.

Climate-driven habitat change causes evolution in Threespine Stickleback.

Climate change can shape evolution directly by altering abiotic conditions or indirectly by modifying habitats, yet few studies have investigated the effects of climate-driven habitat change on contemporary evolution. We resampled populations of Threespine Stickleback (Gasterosteus aculeatus) along a latitudinal gradient in California bar-built estuaries to examine their evolution in response to changing climate and habitat. We took advantage of the strong association between stickleback lateral plate phenotypes and Ectodysplasin A (Eda) genotypes to infer changes in allele frequencies over time. Our results show that over time the frequency of low-plated alleles has generally increased and heterozygosity has decreased. Latitudinal patterns in stickleback plate phenotypes suggest that evolution at Eda is a response to climate-driven habitat transformation rather than a direct consequence of climate. As climate change has reduced precipitation and increased temperature and drought, bar-built estuaries have transitioned from lotic (flowing-water) to lentic (still-water) habitats, where the low-plated allele is favoured. The low-plated allele has achieved fixation at the driest, hottest southernmost sites, a trend that is progressing northward with climate change. Climate-driven habitat change is therefore causing a reduction in genetic variation that may hinder future adaptation for populations facing multiple threats.

Estimating uncertainty in divergence times among three-spined stickleback clades using the multispecies coalescent

Incomplete lineage sorting (ILS) can lead to biased divergence time estimates. To explore if and how ILS has influenced the results of a recent worldwide phylogeny of three-spined sticklebacks (Gasterosteus aculeatus), we estimated divergence times among major clades by applying both a concatenation approach and the multispecies coalescent (MSC) model to single-nucleotide polymorphisms. To further test the influence of different calibration strategies, we applied different calibrations to the root and to younger nodes in addition to the ones used in the previous study. Both the updated calibrations and the application of the MSC model influenced divergence time estimates, sometimes significantly. The new divergence time estimates were more ancient than in the previous study for older nodes, whereas the estimates of younger nodes were not strongly affected by the re-analyses. However, since the applied MSC method employs a simple substitution model and cannot account for changes in population size, we suggest that different analytical approaches and calibration strategies should be used in order to explore uncertainty in divergence time estimates. This study provides a valuable reference timeline for the ages of worldwide three-spined stickleback populations and emphasizes the need to embrace, rather than obscure, uncertainties around divergence time estimates.

Architecture of Parallel Adaptation in Ten Lacustrine Threespine Stickleback Populations from the White Sea Area.

Adaptation of threespine stickleback to freshwater involves parallel recruitment of freshwater alleles in clusters of closely linked sites, or divergence islands (DIs). However, it remains unclear to what extent the DIs and the alleles that constitute them coincide between populations that underwent adaptation to freshwater independently. We examine threespine sticklebacks from ten freshwater lakes that emerged 500–1500 years ago in the White Sea basin, with the emphasis on repeatability of genomic patterns of adaptation among the lake populations and the role of local recombination rate in the distribution and structure of DIs. The 65 detected DIs are clustered in the genome, forming 12 aggregations, and this clustering cannot be explained by the variation of the recombination rate. Only 21 of the DIs are present in all the freshwater populations, likely being indispensable for successful colonization of freshwater environment by the ancestral marine population. Within most DIs, the same set of single nucleotide polymorphisms (SNPs) distinguish marine and freshwater haplotypes in all the lake populations; however, in some DIs, freshwater alleles differ between populations, suggesting that they could have been established by recruitment of different haplotypes in different populations.

Genetic divergence outpaces phenotypic evolution among threespine stickleback populations in old freshwater habitats.

Species such as threespine stickleback (Gasterosteus aculeatus) that inhabit divergent selective environments and that have diversified on different time scales can be of value for understanding evolutionary processes. Here we synthesize high-resolution genotypic and phenotypic data to explore a largely unstudied distribution of threespine stickleback populations living in oceanic and freshwater habitats along coastal and inland regions of Oregon. Many inland aquatic habitats of Oregon remained unglaciated during the last ice age, meaning that some extant Oregon lake and river stickleback may have descended from freshwater populations established long before more well-studied, post-glacial freshwater populations. To address the degree of congruence between genetic and phenotypic divergence, we directly compared Oregon stickleback to much younger (post-glacial) Alaskan populations. We found phenotypic variation in Oregon stickleback to be primarily partitioned between oceanic and freshwater habitats, as has been documented in other stickleback systems. However, the main axis of genetic divergence was between coastal and inland regions regardless of habitat type. Furthermore, when comparing patterns between Oregon and Alaska we found similar levels of phenotypic divergence, but much greater genetic divergence among Oregon's populations. The Oregon stickleback system therefore appears well suited for future studies linking genotypic and phenotypic change, further extending the utility of this small fish to provide general insights into evolutionary processes.

Modelling BPA effects on three-spined stickleback population dynamics in mesocosms to improve the understanding of population effects.

Bisphenol A (BPA), a well-known endocrine-disrupting chemical, is ubiquitously present in the aquatic environment. Its impacts at the population level on three-spined sticklebacks (Gasterosteus aculeatus) have been studied in artificial streams with low-dose BPA concentrations. The causes explaining the observed effects remained unclear. Here, we used an individual-based model coupled to a Dynamic Energy Budget model to (i) assess the potential of modelling to predict impacts at the population level using individual level laboratory ecotoxicological endpoints and (ii) provide insight on the mechanisms of BPA toxicity in these mesocosms. To do that, both direct and indirect effects of BPA on three-spined sticklebacks were incorporated in the model. Indeed, direct BPA effects on fish have been identified based on literature data whereas indirect effects on sticklebacks have been taken into account using sampling data of their prey from the exposed artificial streams. Results of the modelling showed that direct BPA effects on fish (impacts on gonad formation, growth, male reproductive behavior, eggs and larvae survival) mainly explained the three-spined stickleback population structure in the mesocosms, but indirect effects were not negligible. Hence, this study showed the potential of modelling in risk assessment to predict the impacts on fish population viability from behavioral and physiological effects measured on organisms.

Specificity of resistance and geographic patterns of virulence in a vertebrate host-parasite system

BackgroundHost genotype - parasite genotype co-evolutionary dynamics are influenced by local biotic and abiotic environmental conditions. This results in spatially heterogeneous selection among host populations. How such heterogeneous selection influences host resistance, parasite infectivity and virulence remains largely unknown. We hypothesized that different co-evolutionary trajectories of a vertebrate host-parasite association result in specific virulence patterns when assessed on a large geographic scale. We used two reference host populations of three-spined sticklebacks and nine strains of their specific cestode parasite Schistocephalus solidus from across the Northern Hemisphere for controlled infection experiments. Host and parasite effects on infection phenotypes including host immune gene expression were determined.ResultsS. solidus strains grew generally larger in hosts coming from a population with high parasite diversity and low S. solidus prevalence (DE hosts). Hosts from a population with low parasite diversity and high S. solidus prevalence (NO hosts) were better able to control the parasite’s growth, regardless of the origin of the parasite. Host condition and immunological parameters converged upon infection and parasite growth showed the same geographic pattern in both host types.ConclusionOur results suggest that NO sticklebacks evolved resistance against a variety of S. solidus strains, whereas DE sticklebacks are less resistant against S. solidus. Our data provide evidence that differences in parasite prevalence can cause immunological heterogeneity and that parasite size, a proxy for virulence and resistance, is, on a geographic scale, determined by main effects of the host and the parasite and less by an interaction of both genotypes.

Modelling population dynamics in mesocosms using an individual-based model coupled to a bioenergetics model

Developing population models is of great interest as these models enable to extrapolate toxicity observed at the molecular or individual levels to the population level, and thus improve environmental risk assessment of chemical substances. For this purpose, accounting for natural variations of environmental conditions and prey dynamics along with the chemical stress is needed. In this study, an individual-based model (IBM) coupled to a Dynamic Energy Budget (DEB) model was developed in order to predict three-spined stickleback population dynamics in semi-controlled stream experiments (in mesocosms). Datasets obtained in mesocosms offer the opportunity to develop and evaluate the model predictions. The most sensitive parameters of the DEB-IBM were identified by sensitivity analyses and were calibrated based on data from two independent mesocosm experiments. The predictive capacities of our model were subsequently evaluated using three independent mesocosm datasets under different environmental scenarios. Finally, our model was applied to a theoretical case of toxic effects to show an example of application of the model in a regulatory context. While the most uncertain population processes (in particular, competition for food in mesocosms) in our three-spined stickleback DEB-IBM could be modelled more accurately, our model can already serve to assess the impacts of toxicants at the population level by improving the analyses of mesocosm experiments, in decreasing the uncertainty of the experimental results. Therefore, in a second step, it could be used to predict the consequences on viability of a population exposed to a contaminant under various environmental and exposure scenarios.

Parasite-induced colour alteration of intermediate hosts increases ingestion by suitable final host species

Abstract Parasites with complex life cycles often alter the phenotypic appearance of their intermediate hosts in order to facilitate ingestion by the final host. However, such manipulation can be costly as it might increase ingestion by less suitable or dead-end hosts as well. Species-specific parasitic manipulation is a way to enhance the transmission to suitable final hosts. Here, we experimentally show that the altered body colouration of the intermediate host Gammarus pulex caused by its acanthocephalan parasite Pomphorhynchus laevis differently affects predation by different fish species (barbel, perch, ruffe, brown trout and two populations of three-spined stickleback) depending on their suitability to act as final host. Species that were responsive to colour manipulation in a predation experiment were more susceptible to infection with P. laevis than unresponsive species. Furthermore, three-spined stickleback from different populations responded to parasite manipulation in opposite directions. Such increased ingestion of the intermediate host by preferred and suitable hosts suggests fine-tuned adaptive parasitic manipulation and sheds light on the ongoing evolutionary arms race between hosts and manipulative parasites.

Carry-over effects of early thermal conditions on somatic and germline oxidative damages are mediated by compensatory growth in sticklebacks.

Most studies of climate change impacts focus on the effects of summer temperatures, which can immediately impact fitness of breeders, but winter temperatures are expected to have a greater impact on development and growth of animals with long-lasting consequences. Exposure to warmer temperatures can increase cellular oxidative damage in ectotherms. Yet, it is unknown whether thermal stress during early life has prolonged effects on oxidative status during adulthood. In an experiment using F1 fish originated from a wild three-spined stickleback population at the southern edge of its European distribution, we examined whether experimental thermal conditions experienced in winter had carry-over effects on oxidative status and telomere length, a marker of accumulated stress, in the soma and germline during adulthood. For this, oxidative DNA damage, enzymatic antioxidant activities and telomere length were measured three months after the termination of the temperature manipulation. In addition, we tested whether such delayed effects, if any, were due to individuals' compensatory growth after experiencing unfavourable growth conditions in winter. Warm acclimation during winter induced increased levels of oxidative DNA damage in muscle and sperm and increased enzymatic antioxidant defences in muscle during the breeding season. Telomere length of adult fish was not influenced by thermal conditions experienced during early life. Winter temperature manipulation influenced fish to alter the temporal pattern of growth trajectories across the juvenile and adult stages. Fish reared in warm winter conditions grew at a slower rate than the controls during the period of temperature manipulation then accelerated body mass gain to catch up during the breeding season. Faster somatic growth during the breeding season incurred a higher cost in terms of oxidative damage in the warm-treated individuals. For the first time, we experimentally show the long-lasting detrimental effects of thermal stress on and the positive link between catch-up growth and oxidative DNA damage in the soma and germline. Winter temperature increases due to climate change can reduce fertility and survival of fish by inducing catch-up growth. The detrimental effects of winter climate change may accumulate across generations through the pre-mutagenic DNA damage in the germline.

Evolution of steroid hormones in reproductive females of the threespine stickleback fish

Hormones play a prominent role in animal development, mediating the expression of traits and coordinating phenotypic responses to the environment. Their role as physiological integrators has implications for how populations respond to natural selection and can impact the speed and direction of evolutionary change. However, many emerging and established fish models with the potential to be ecologically or evolutionarily informative are small-bodied, making hormone sampling through traditional methods (whole-body or plasma) lethal or highly disruptive. Sampling methodology has thus restricted study design, often limiting sample sizes, and has prevented the study of at-risk/endangered populations. We utilize water-borne hormone sampling, a minimally invasive method of measuring the rate of steroid hormone release across the gills and further validate this method in a novel, evolutionary context. First, we compare water-borne hormone measures of cortisol with those quantified from plasma and whole-body samples collected from the same individuals to establish the relationship between concentrations quantified via the three methods. We then compare the release of steroid hormones in three populations of threespine stickleback to establish the sensitivity of this tool in measuring within-individual and between-individual variation in biologically relevant contexts (reproductive stages), and in assessing differences among populations with distinct evolutionary histories. We demonstrate a strong positive relationship between cortisol concentrations measured with water-borne, plasma, and whole-body collection techniques. Tracking estradiol and testosterone throughout clutch production in females produced anticipated patterns associated with growing and maturing eggs, with divergence in estradiol production in one population. Additionally, differences among populations in cortisol levels at ovulation paralleled the relative presence of a social stressor, and thus expected energetic needs within each population. We confirm that water-borne hormone sampling is sufficiently sensitive to capture biologically relevant fluctuations in steroid hormones between environmental contexts and demonstrate that among-population differences are detectable. This technique can be applied broadly to small fish to answer important ecological and evolutionary questions. By linking population variation in hormones and the multivariate phenotype, this technique will help elucidate both proximate mechanisms underlying phenotypic development and variation, and the way hormone networks alter evolutionary responses to selection.

Otolith development in wild populations of stickleback: Jones & Hynes method does not apply to most populations.

This paper critiques Jones & Hynes (1950) findings by analysing sequential samples of otoliths from three wild populations of Gasterosteus aculeatus from North Uist, Scotland and Nottingham, England. Contrary to Jones & Hynes (1950), but coincident with the finding of later researchers, our results showed that no true translucent ring formed in the otolith of G. aculeatus during their first summer. The first translucent ring was probably starting to be formed by the end of summer and was completed by the end of their first winter. There was no second opaque ring in the otoliths of G. aculeatus before they passed their first winter. The second opaque ring was just starting to appear by early April of the second year in the southern population i.e. Nottingham, but later, by May, in the northern populations i.e. North Uist. Formation of the opaque ring in G. aculeatus mostly occurs in spring and summer, with younger fish starting earlier. In contrast, the formation of translucent rings is mostly during autumn and winter, but can be more widespread through the year, possibly as a result of reproductive investment.

Opsin expression predicts male nuptial color in threespine stickleback.

Theoretical models of sexual selection suggest that male courtship signals can evolve through the build‐up of genetic correlations between the male signal and female preference. When preference is mediated via increased sensitivity of the signal characteristics, correlations between male signal and perception/sensitivity are expected. When signal expression is limited to males, we would expect to find signal‐sensitivity correlations in males. Here, we document such a correlation within a breeding population of threespine stickleback mediated by differences in opsin expression. Males with redder nuptial coloration express more long‐wavelength‐sensitive (LWS) opsin, making them more sensitive to orange and red. This correlation is not an artifact of shared tuning to the optical microhabitat. Such correlations are an essential feature of many models of sexual selection, and our results highlight the potential importance of opsin expression variation as a substrate for signal‐preference evolution. Finally, these results suggest a potential sensory mechanism that could drive negative frequency‐dependent selection via male–male competition and thus maintain variation in male nuptial color.

Liver Protein Comparisons of Warm‐adapted Versus Cold‐adapted Populations of Threespine Sticklebacks (Gasterosteus aculeatus)

This study investigated the molecular phenotypes of a warm‐adapted population of threespine sticklebacks (Gasterosteus aculeatus). We created a liver protein assay consisting of 1,016 proteins with Skyline (MacCoss Lab) from four populations (N=24) using data dependent acquisition (DDA) shotgun proteomics. This assay will be used to perform targeted proteomics on future comparisons, which will allow for more precise identification and quantification of the targeted proteins. A population of sticklebacks from Baja California, Mexico is surviving and breeding at temperatures near 30 degrees Celsius, which is close to the upper thermal limit for this species. Understanding what this population is doing at the molecular level to function at these high temperatures may give insight into mechanisms that have allowed for their survival, as well as the potential for other populations to adapt to higher temperatures. Livers from sticklebacks of the Baja California population were then compared to three cold‐adapted populations using gel‐free quantitative proteomics by liquid chromatography‐mass spectrometry (LC‐MS/MS). A resident marine population (Bodega Harbor, CA), a freshwater population (Lake Solano, CA), and an anadromous population (Anchorage, Alaska) were used in these comparisons. Six Baja California threespine sticklebacks and six fish from each of the other three groups were compared in four separate sets (N=96). Approximately 20 proteins were significantly more abundant in the Baja California population than the other three populations across all four sets. Our results suggest that certain molecular chaperones and redox/antioxidant proteins may contribute to the survival of the Baja California population. Our study lays the foundation for highly accurate quantification of protein differences in future comparisons using targeted proteomics. This study also highlights proteins that are consistently found at higher abundance in the warm‐adapted population and thus may be important for liver adaptation to warmer temperatures.Support or Funding InformationFunded by NSF Grant IOS‐1355098.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Interactive effects of salinity and temperature acclimation on gill morphology and gene expression in threespine stickleback

Colonization of freshwater habitats from marine environments exposes organisms to novel combinations of temperature and salinity, but little is known about physiological responses to the interactive effects of these stressors. Here, we examined the effects of temperature (14 versus 4 °C) and salinity (11 versus 0.3 ppt) on gill gene expression in marine, anadromous, and freshwater populations of threespine stickleback (Gasterosteus aculeatus). Expression of the epithelial calcium channel was not affected by temperature or salinity, but had significantly higher expression in the freshwater ecotype. The combination of low temperature and low salinity had non-additive effects on the expression of the Na+/H+ exchanger. Fish exposed to the combination of low temperature and low salinity had expression levels similar to fish exposed to either factor in isolation. Expression of Na+,K+-ATPase α-subunit was greater in fish exposed to low temperature and low salinity than in fish exposed to the factors separately, and this effect was the most pronounced in the marine ecotype. We also examined the interactive effects of salinity and temperature on gill morphology in the marine ecotype, and observed non-additive effects. Low temperature increased the size of the interlamellar cell mass in fish held at 11 ppt, but not at 0.3 ppt, and the effect of low salinity was in the opposite direction in fish at high and low temperatures. These data demonstrate interactive effects of temperature and salinity and highlight that overwintering in cold freshwater was likely a physiological challenge for marine stickleback as they colonized freshwater following the last glaciation.

Foraging habits of invasive three-spined sticklebacks (Gasterosteus aculeatus) – impacts on fisheries yield in Upper Lake Constance

A massive increase in the pelagic population of non-endemic three-spined sticklebacks, Gasterosteus aculeatus L. in Lake Constance has coincided with drastic declines in fishery yields. This study assesses the possible direct and indirect impact of the mass occurrence on native fish species in the lake. Laboratory foraging experiments showed that larvae of roach Rutilus rutilus L., perch Perca fluviatilis L. and whitefish Coregonus lavaretus L. are accessible to sticklebacks as food. However, distinct species effects were apparent, with whitefish showing no effective predator avoidance strategy and therefore experiencing drastically increased mortality risk compared to the other predator adapted prey species. Furthermore, in absence of larval prey, sticklebacks were shown to feed predominantly on Daphnia in the field, indicating a strong interspecific food competition with whitefish.The results suggest that sticklebacks, acting as both an invasive species and a predator in the pelagic zone where prior no predator or neozoon existed, create a unique challenge to the unadapted autochthonous fish, and thus threaten the ecological resilience of the lake. Impacts on recruitment, e.g. through larval predation and interspecific competition for zooplankton could explain recent drastic declines in fishing yields.