Biology subjects

Stoks, R.

Publications and source records attributed to Stoks, R..

5 recordsLinked to original sources

bioRxiv2026

Global synthesis of aquatic insect heat tolerance reveals oxygen availability as a key driver of climate vulnerability

Accurately predicting species responses to climate change requires an understanding of the drivers of their thermal limits. Despite rapid warming of freshwater ecosystems worldwide, we still lack a global perspective on how upper thermal limits (UTLs) vary among aquatic insects, what constrains these limits, and how they contribute to species vulnerability. Here, we compiled a global dataset encompassing 423 aquatic insect species to test the effects of environmental conditions, organismal traits, acclimation history, and phylogenic relationships on patterns of heat tolerance. Maximum habitat temperatures were positively correlated with UTLs supporting the Climate Extremes Hypothesis, and insects relying exclusively on dissolved oxygen had the lowest UTLs supporting the Oxygen- and Capacity-Limited Thermal Tolerance hypothesis. Functional traits also explained substantial variation in UTLs; those that feed via scraping and shredding exhibited some of the lowest UTLs. Laboratory acclimation methods further influenced UTL estimates. Short-term exposure to higher acclimation temperatures increased UTLs, but longer exposure led to decreased heat tolerance. Finally, warming tolerance, i.e., the difference between UTL and the maximum habitat temperature) varied with breathing mode. Across latitude, warming tolerances were lowest for obligate dissolved oxygen-breathers but increased more rapidly in insects that can access terrestrial air. Collectively, these patterns indicate that oxygen is a key mechanism shaping thermal vulnerability in aquatic insects.

ecology↗

bioRxiv2024

How does co-occurrence of Daphnia species affect their gut microbiome?

Species co-occurrence can lead to competitive interactions that influence fitness. Competition is typically assumed to be modulated by species niche, especially food-acquisition related traits. The influence of interspecific interactions on host microbiome communities has rarely been considered, and yet may provide an alternative mechanism regarding the effect of host species co-occurrence on their fitness. Here, we investigated whether the composition of the gut microbial community differs between two Daphnia species (D. magna and D. pulex), and whether the gut microbiome of one species depends on the presence of the other. We hypothesized the stronger filter-feeder D. magna to have a larger effect on the gut microbiome of the weaker filter-feeder D. pulex than vice versa. To this purpose, three D. magna and three D. pulex genotypes were first made axenic and then grown in monocultures or in cocultures in natural environmental bacterioplankton-enriched water, before assessing the community composition of the gut microbiomes and bacterioplankton. We found that the composition of the gut microbiome of the two Daphnia species did not significantly differ overall. However, subtle differences between mono- and cocultures were found at the Daphnia genotype level. For most genotype combinations (six out of nine), the microbiome of D. pulex changed more when grown in cocultures with D. magna than in monocultures. This provides limited support for our hypothesis that the stronger competitor has a larger effect on the gut microbiome of the weaker one than vice versa, and that this effect is possibly mediated via the bacterioplankton community.

ecology↗

bioRxiv2023

Latitude-specific urbanization effects on life history traits in the damselfly Ischnura elegans

O_LIMany species are currently adapting to cities at different latitudes. Adaptation to urbanization may require eco-evolutionary changes in response to temperature and invasive species that may differ between latitudes. C_LIO_LIHere, we studied single and combined effects of increased temperatures and invasive alien predator presence on the phenotypic response of replicated urban and rural populations of the damselfly Ischnura elegans and contrasted these between central and high latitudes. C_LIO_LILarvae were exposed to temperature treatments (current [20 {o}C], mild warming [24 {o}C], and heat wave [28 {o}C; for high latitude only]) crossed with the presence or absence of chemical cues released by the spiny-cheek crayfish (Faxonius limosus), only present at the central latitude. We measured treatment effects on larval development time, mass, and growth rate. C_LIO_LIUrbanization type affected all life history traits, yet these responses were often dependent on latitude, temperature, and sex. Mild warming decreased mass in rural and increased growth rate in urban populations. The effects of urbanization on mass were latitude-dependent, with central-latitude populations having a greater phenotypic difference. Urbanization effects were sex-specific with urban males being lighter and having a lower growth rate than rural males. At the current temperature and mild warming, the predator cue reduced the growth rate, and this independently of urbanization level and latitude of origin. This pattern was reversed during a heat wave in high-latitude damselflies. C_LIO_LIOur results highlight the context-dependency of evolutionary and plastic responses to urbanisation, and caution for generalizing how populations respond to cities based on populations at a single latitude. C_LI

evolutionary biology↗

bioRxiv2023

Synergistic survival-related effects of larval exposure to an aquatic pollutant and food stress get stronger during and especially after metamorphosis and shape fitness of terrestrial adults

To improve the ecological risk assessment of aquatic pollutants it is needed to study their effects not only in the aquatic larval stage, but also in the terrestrial adult stage of the many animals with a complex life cycle. This remains understudied, especially with regard to interactive effects between aquatic pollutants and natural abiotic stressors. We studied effects of exposure to the pesticide DNP (2,4-Dinitrophenol) and how these were modulated by limited food availability in the aquatic larvae, and the possible delayed effects in the terrestrial adults of the damselfly Lestes viridis. Our results revealed that DNP and low food each had large negative effects on the life history, behaviour and to a lesser extent on the physiology of not only the larvae, but also the adults. Food limitation magnified the negative effects of DNP as seen by a strong decline in larval survival, metamorphosis success and adult lifespan. Notably, the synergism between the aquatic pollutant and food limitation for survival-related traits was stronger in the non-exposed adults than in the exposed larvae, likely because metamorphosis is stressful itself. Our results highlight that identifying effects of aquatic pollutants and synergisms with natural abiotic stressors, not only in the aquatic larval but also in the terrestrial adult stage, is crucial to fully assess the ecological impact of aquatic pollutants and to reveal the impact on the receiving terrestrial ecosystem through a changed aquatic-terrestrial subsidy.

ecology↗

bioRxiv2017

Kin competition as driver of range expansions

With ongoing global change, life is continuously forced to move to novel areas, which leads to dynamically changing species ranges. As dispersal is central to range dynamics, factors promoting fast and distant dispersal are key to understanding and predicting species ranges. During range expansions, genetic variation is depleted at the expanding front. Such conditions should reduce evolutionary potential, while increasing kin competition. Organisms able to recognise relatives may be able to assess increased levels of relatedness at expanding range margins and to increase their dispersal in a plastic manner. Using individual-based simulations and experimental range expansions of a spider mite, we demonstrate that plastic responses to kin structure can be at least as important as evolution in driving range expansion speed. Because recognition of kin or kind is increasingly documented across the tree of life, we anticipate it to be a highly important but neglected driver of range expansions.

ecology↗