Jonas Jourdan

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Verified

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• Dr. rer. nat
• Group Leader at Goethe University Frankfurt

Long-term observations on riverine benthic invertebrate communities enable assessments of the potential impacts of global change on stream ecosystems. Besides increasing average temperatures, many studies predict greater temperature extremes and intense precipitation events as a consequence of climate change. In this study we examined long-term obs...

Species reintroductions-the translocation of individuals to areas in which a species has been extirpated with the aim of re-establishing a self-sustaining population-have become a widespread practice in conservation biology. Reintroduction projects have tended to focus on terrestrial vertebrates and, to a lesser extent, fishes. Much less effort has...

Crustacean amphipods serve as intermediate hosts for parasites and are at the same time sensitive indicators of environmental pollution in aquatic ecosystems. The extent to which interaction with the parasite influences their persistence in polluted ecosystems is poorly understood. Here, we compared infections of Gammarus roeselii with two species...

Wastewater treatment plants (WWTP) are essential infrastructure in our developing world. However, with the development and release of novel entities and without modern upgrades, they are ineffective at fully removing micropollutants before treated effluents are released back into aquatic environments. Thus, WWTPs may represent additional point sour...

The advent of genetic methods has led to the discovery of an increasing number of species that previously could not be distinguished from each other on basis of morphological characteristics. Even though we observe an exponential growth of publications on cryptic species, cryptic species are rarely considered in ecotoxicology. Thus, particularly th...

Increasing chemical pollution calls for a closer look at ecologically highly relevant host-parasite interactions to understand the persistence of organisms and populations in a polluted environment. The impact of chemical exposure within the host-parasite interactions – particularly the distinctive bioaccumulation behavior of organic micropollutant...

Native and invasive species often occupy similar ecological niches and environments where they face comparable risks from chemical exposure. Sometimes, invasive species are phylogenetically related to native species, e.g. they may come from the same family and have potentially similar sensitivities to environmental stressors due to phylogenetic con...

The spread of non-native species is one of the outcomes of global change, threatening many native communities through predation and competition. Freshwater ecosystems are particularly affected by species turnover with non-native species. One species that has been established in Central Europe for many decades-or even a few centuries-is the amphipod...

The black fly genus Simulium includes medically and ecologically important species, characterized by a wide variation of ecological niches largely determining their distributional patterns. In a rapidly changing environment, species-specific niche characteristics determine whether a species benefits or not. With aquatic egg, larval and pupal stages...

The comprehensive assessment of the long-term impacts of constant exposure to pollutants on wildlife populations remains a relatively unexplored area of ecological risk assessment. Empirical evidence to suggest that multigenerational exposure affects the susceptibility of organisms is scarce, and the underlying mechanisms in the natural environment...

Free download of final paper: https://doi.org/10.1016/j.envpol.2024.124888

Background: The discovery of cryptic species complexes within morphologically established species comes with challenges in the classification and handling of these species. We hardly know to what extent species within a species complex differ ecologically. Such knowledge is essential to assess the vulnerability of individual genetic lineages in the...

Sublethal effects are becoming more relevant in ecotoxicological test methods due to their higher sensitivity compared to lethal endpoints and their preventive nature. Such a promising sublethal endpoint is the movement behavior of invertebrates which is associated with the direct maintenance of various ecosystem processes, hence being of special i...

Full text: rdcu.be/dfKRi Chemical pollution research should be better integrated with other drivers of biodiversity loss and the assessment of human impacts on ecosystems, to more effectively guide management strategies for biodiversity loss mitigation

Oral presentation about the different tolerances to nitrite between 3 different populations of eastern mosquitofish (Gambusia holbrooki) in Florida and those other 3 from North Carolina (USA)

The exploration of biodiversity has predominantly been based on taxonomic measures, whereas functional diversity, a key component of biodiversity, is comparatively understudied. Therefore, studies simultaneously investigating patterns of taxonomic and functional diversity change in biological communities are of increasing interest. We collated high...

Central European riverine networks are subject to widely varying local anthropogenic pressures, forcing species with limited dispersal abilities to adapt or become locally extinct. Previous catchment-wide studies have shown that some invertebrates tend to have pronounced population structuring throughout mountainous river networks, raising the ques...

Oral presentation about the interpopulation different tolerances to nitrite pollution, based on the background nitrogen pollution.

Due to their success as an invasive alien species, eastern mosquitofish (Gambusia holbrooki, Girard 1859) are now almost globally distributed, yet some aspects of their phenotype remain unexplored. Drawing on data from 50 native and invasive mosquitofish populations, we examined the extent of variation in offspring size, offspring fat content and m...

Ecological gradients can drive adaptive phenotypic diversification, but the extent of local adaptation depends on the strength, temporal stability and spatial dimensions of selective forces at play. We examined diversification in morphology and life histories of a live-bearing fish (Poecilia mexicana) that has adapted to two concomitant gradients:...

Invasive alien species (IAS) have become a major threat to ecosystems worldwide. From an evolutionary ecological perspective, they allow teasing apart the relative contributions of plasticity and evolutionary divergence in driving rapid phenotypic diversification. When IAS spread across extensive geographic ranges, climatic variation may represent...

Feral populations of tropical fish species in temperate climates like Central Europe are a rare but repeatedly observed phenomenon. Due to the influence of industrial or geothermal heated water, released tropical fish may be able to survive harsh winter conditions. Here we characterize a newly discovered thermally polluted river, with an establishe...

Size is one of the most outwardly obvious characteristics of animals, determined by multiple phylogenetic and environmental variables. Numerous hypotheses have been suggested to explain the relationship between the body size of animals and their geographic latitude. Bergmann’s Rule, describing a positive relationship between the body size of endoth...

In the past two decades, an increasing body of studies has been published on the intersex phenomenon in separate-sexed crustaceans from marine and freshwater ecosystems. Various causes are being considered that could have an influence on the occurrence of intersex. Besides genetic factors, environmental conditions such as photoperiodicity, temperat...

Aim Formerly introduced for their presumed value in controlling mosquito-borne diseases, the two mosquitofish Gambusia affinis and G. holbrooki (Poeciliidae) are now among the world's most widespread invasive alien species, negatively impacting aquatic ecosystems around the world. These inconspicuous freshwater fish are, once their presence is noti...

The extent of male mate choosiness is driven by a trade-off between various environmental factors associated with the costs of mate acquisition, quality assessment and opportunity costs. Our knowledge about natural variation in male mate choosiness across different populations of the same species, however, remains limited. In the current study, we...

A recent global meta‐analysis reported a decrease in terrestrial but increase in freshwater insect abundance and biomass (van Klink et al., Science 368, p. 417). The authors suggested that water quality has been improving, thereby challenging recent reports documenting drastic global declines in freshwater biodiversity. We raise two major concerns...

Freshwater ecosystems are dynamic, complex systems with a multitude of physical and ecological processes and stressors which drive fluctuations on the community-level. Disentangling the effects of different processes and stressors is challenging due to their interconnected nature. However, as protected areas (i.e. national parks) are less anthropog...

We still have a limited understanding of why animals colonize extreme environments, but one hypothesis (the Pathogen Refuge Hypothesis, PRH) posits that they might represent a safe haven from parasites and other pathogens. We tested this idea by quantifying endoparasite infections in five populations of the neotropical freshwater fish Poecilia mexi...

• Recent advances in molecular methods foster the documentation of small spatial scale biological diversity over large geographical areas. These advances allow to correctly record α‐diversity, but also enable biomonitoring that describes intraspecific molecular diversity, providing valuable insights into the contemporary history of species. Such in...

The ongoing biodiversity crisis becomes evident in the widely observed decline in abundance and diversity of species, profound changes in community structure, and shifts in species’ phenology. Insects are among the most affected groups, with documented decreases in abundance up to 76% in the last 25–30 years in some terrestrial ecosystems. Identify...

Rising global temperatures force many species to shift their distribution ranges. However, whether or not (and how fast) such range shifts occur depends on species' dispersal capacities. In most ecological studies, dispersal‐related traits (such as the wing size or wing loading in insects) are treated as fixed, species‐specific characteristics, ign...

Background: Selective landscapes in rivers are made up by an array of selective forces that vary from source to downstream regions or between seasons, and local/temporal variation in fitness maxima can result in gradual spatio-temporal variation of phenotypic traits. This study aimed at establishing freshwater amphipods as future model organisms t...

Although experiences with ecological restoration continue to accumulate, the effectiveness of restoration for biota remains debated. We complemented a traditional taxonomic analysis approach with information on 56 species traits to uncover the responses of 3 aquatic (fish, macroinvertebrates, macrophytes) and 2 terrestrial (carabid beetles, floodpl...

Within-species diversity is often driven by changing selective regimes along environmental gradients. Here, we pro- vide a direct test of the environmental factors underlying phenotypic diversity across the wide native distribution of eastern mosquitofish (Gambusia holbrooki). We investigated life-history and body-shape divergence (including mul- t...

Invasive species that rapidly spread throughout novel distribution ranges are prime models to investigate climate-driven phenotypic diversification on a contemporary scale. Previous studies on adaptive diversification along latitudinal gradients in fish have mainly considered body size and reported either increased or decreased body size towards hi...

Since its founding in 1993 the International Long-term Ecological Research Network (ILTER) has gone through pronounced development phases. The current network comprises 44 active member LTER networks representing 700 LTER Sites and ~ 80 LTSER Platforms across all continents, active in the fields of ecosystem, critical zone and socio-ecological rese...

Divergent selection between ecologically dissimilar habitats promotes local adaptation, which can lead to reproductive isolation (RI). Populations in the Poecilia mexicana species complex have independently adapted to toxic hydrogen sulfide and show varying degrees of RI. Here, we examined the variation in the mate choice component of prezygotic RI...

Two North American species of mosquitofish, the Western (Gambusia affinis Baird and Girard, 1853) and Eastern mosquitofish (G. holbrooki Girard, 1859), rank amongst the most invasive freshwater fishes worldwide. While the existing literature suggests that G. affinis was introduced to mainland China, empirical evidence supporting this assumption was...

Thermally influenced freshwater systems provide suitable conditions for non-native species of tropical and subtropical origin to survive and form proliferating populations beyond their native ranges. In Germany, non-native convict cichlids (Amatitlania nigrofasciata) and tilapia (Oreochromis sp.) have established populations in the Gillbach, a smal...

The goal of this deliverable is to provide recommendations and strategies for building and sustaining a network of EU BON sites. Thus, a guide is proposed to set up, operate and continuously develop a biodiversity observation network. It is subdivided into three sections. A) Biodiversity observation: sites and schemes: This section addresses differ...

Stream ecosystems show gradual variation of various selection factors, which can result in a zonation of species distributions and gradient evolution of morphological and life-history traits within species. Identifying the selective agents underlying such phenotypic evolution is challenging as different species could show shared and/or unique (spec...

Die Fischfauna Deutschlands im „Homogenozän“: Wie invasive Fische vom Wegfall geographischer Barrieren und dem Klimawandel profitieren Lebensgemeinschaften in aquatischen Ökosystemen haben sich in den letzten Jahrzehnten deutlich verändert, da neu eingeschleppte Fischarten einheimische Arten verdrängen. Hierfür ist meist der Mensch verantwortlich:...

Cavefishes typically evolve sensory adaptations to compensate for the loss of visual orientation and communication in their naturally dark habitats. We compared the response to chemical cues from conspecifics between surface- and cave-dwelling populations of Atlantic mollies (Poecilia mexicana) using dichotomous association preference tests. In one...

Background One aspect of premating isolation between diverging, locally-adapted population pairs is female mate choice for resident over alien male phenotypes. Mating preferences often show considerable individual variation, and whether or not certain individuals are more likely to contribute to population interbreeding remains to be studied. In th...

Background Replicate population pairs that diverge in response to similar selective regimes allow for an investigation of (a) whether phenotypic traits diverge in a similar and predictable fashion, (b) whether there is gradual variation in phenotypic divergence reflecting variation in the strength of natural selection among populations, (c) whether...

Behavioral differences between native and introduced species may contribute to the invasiveness of certain species. This includes differences at the species level, consistent variation among individuals (“personality”) and within-individual variation (e.g., behavioral plasticity). Here, we investigated swimming activity of individuals from four dif...

Phenotypic plasticity is predicted to evolve when subsequent generations are likely to experience alternating selection pressures; e.g., piscine predation on mosquitoes (Culex pipiens) varies strongly depending on habitat type. A prey-choice experiment (exp. 1) detected a predilection of common mosquito predators (sticklebacks, Gasterosteus aculeat...

A growing body of literature focuses on the adverse effects of biological invasions, e.g., on the decline of indigenous biodiversity, while studies on the consequences of invasions on components of ecosystem functioning are comparatively rare. Owing to their leaf shredding activity, amphipods play a fundamental role in determining energy flow dynam...

In the presence of predators, many prey species exhibit immediate behavioral responses like the avoidance of risky areas, which imposes opportunity costs, for instance, in the form of reduced foraging. Thus, prey species should be able to discriminate between different predator types and adjust their response to the imminent predation risk. In our...

Two of the major drivers of recent anthropogenic global change and biodiversity loss are rising temperatures and biological invasions. The strong interrelatedness of these two factors has been acknowledged repeatedly, and investigating synergies between them has been suggested. To date, however, studies addressing these calls have been sparse. We p...

Artificially heated water bodies represent unusual habitats in temperate regions and form a refuge for exceptional fish communities. The Gillbach, a tributary of the river Erft in Germany, receives thermally polluted cooling water from a power plant. Here, we present data on the composition of the fish community in the Gillbach and found a high abu...

The Cueva del Azufre in Tabasco,Mexico, is a nutrient-rich cave and its inhabitants need to cope with high levels of dissolved hydrogen sulfide and extreme hypoxia. One of the successful colonizers of this cave is the poeciliid fish Poecilia mexicana, which has received considerable attention as a model organism to examine evolutionary adaptations...

Social organization is often studied through point estimates of individual association or interaction patterns, which does not account for temporal changes in the course of familiarization processes and the establishment of social dominance. Here, we present new insights on short-term temporal dynamics in social organization of mixed-sex groups tha...

Group-living provides major benefits to the individual group members; e.g., teleost fishes often form shoals to reduce piscine and avian predation risk. A number of studies reported that shoal members can have a calming effect on individual fish, whereby individuals show typical stress responses (like in creased oxygen consumption) in a lone compar...

This study presents the first confirmed record of Dikerogammarus haemobaphes Eichwald 1841, occurring in the River Lahn, a right-armed tributary of the Rhine. We sampled three sites in the Lahn repeatedly between August 2011 and June 2012. Two individuals of D. haemobaphes were collected from one of the sampling sites on April 24, 2012 during regul...