Role of abiotic factors and biotic interactions in biological invasions: a comparison of natural and human-induced invasions in freshwater ecosystems Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften vorgelegt beim Fachbereich Biowissenschaften der Johann Wolfgang Goethe -Universität in Frankfurt am Main von Jonas Jourdan aus Siegen Frankfurt am Main, 2016 (D 30) ii vom Fachbereich Biowissenschaften der Johann Wolfgang Goethe - Universität als Dissertation angenommen. Dekanin: Prof. Dr. Meike Piepenbring Gutachter: Prof. Dr. Martin Plath Prof. Dr. Jörg Oehlmann Datum der Disputation: 13.10.2016 ii iii TABLE OF CONTENTS Summary ...............................................................................................................................................................................iv Zusammenfassung .......................................................................................................................................................... vii Preface ................................................................................................................................................................................ xiii 1. General Overview .......................................................................................................................................................... 1 1.1 Introduction ............................................................................................................................................................. 1 1.1.1 General aspects of human-induced biological invasions .............................................................. 1 1.1.2 Human-induced biological invasions in aquatic ecosystems ...................................................... 3 1.1.3 Natural biological invasions ...................................................................................................................... 5 1.1.4 Ecological and evolutionary consequences of biological invasions ......................................... 7 1.2 Manuscript overview ........................................................................................................................................... 8 1.2.1 Human-induced biological invasions .................................................................................................... 8 1.2.2 Natural biological invasions ................................................................................................................... 16 1.3 Further research prospects ............................................................................................................................ 22 1.4 Concluding remarks ........................................................................................................................................... 25 1.5 References ............................................................................................................................................................. 31 2. Human-induced biological invasions ................................................................................................................. 48 2.1 Invasive species in an artificially heated stream ................................................................................... 49 2.2 Novel predator-prey interactions ................................................................................................................ 0 2.3 The effect of invasive species on ecosystem services .......................................................................... 2.4 Behavioural differences between native and invasive species ........................................................ 3 3. Natural biological invasions................................................................................................................................... 3.1 Distribution and phenotypic trait divergence along environmental gradients .......................... 3.2 The natural invasion of extreme habitats ................................................................................................ 3.3 Evolution of constructive traits in extreme habitats .......................................................................... 3 Eidesstattliche Erklärung ............................................................................................................................................ 3 88 iii iv SUMMARY Invasive non-native species are key components of human-induced global environmen- tal change and lead to a loss of biodiversity, alterations of species interactions and changes of ecosystem services. Freshwater ecosystems in particular are strongly af- fected by biological invasions, since they are spatially restricted environments and often already heavily impacted by anthropogenic activities. Recent human-induced species invasions are often characterized by long-distance dispersal, with many species having extended their native distribution range within a very short time frame. However, a long term view into the past shows that biological invasions are common phenomena in na- ture ─ representing the arrival of a species into a location in which it did not originally evolve ─ as a result of climatic changes, geotectonic activity or other natural events. Once a species arrives in a new habitat, it may experience an array of novel selection pressures resulting from abiotic and biotic environmental factors and simultaneously act as a novel selective agent on the native fauna. Consequences of species invasions are manifold. My thesis, which combines seven studies on different aspects of biological in- vasions, aims to explore the influence of abiotic stressors and biotic interactions during species introductions and range expansions, as well as the consequences of biological invasions on evolutionary and ecosystem processes. The first part of my thesis examines human-induced biological invasions. It starts with the characterization of a thermally altered stream ecosystem in Germany and pro- vides basic ecological characteristics of the community structure that consist of a unique mixture of native and invasive species (in this case teleost fishes). Next, I investigated the impact of introduced fish predators on native prey organisms with complex life cycles, in this case biting mosquitoes (Culex pipiens). The results highlight the impor- tance of a shared (co-evolutionary) history of predator and prey species for the ability of prey to detect and respond to a (novel) predator type. Furthermore, it illustrates the strength of selection on both native and introduced species to adapt quickly to novel predator-prey interactions after biological invasions. While a growing body of literature focuses on the adverse effects of biological invasions, studies on the effects of invasions on components of ecosystem functioning are comparatively rare. Therefore, I also inves- tigated functional consequences of species invasions (amphipods in the Rhine drainage system) on basic ecosystems processes. The results indicated that the replacement of iv v native species likely affects vital ecosystem services. Certain behavioral traits (like con- sistent individual differences in activity) may contribute to the invasiveness of some species. To investigate this possibility, I compared behavioral variation between native and invasive amphipod species and found that traits like activity are not necessarily higher in invasive compared to native species. However, the results indicate highly vari- able and unpredictable patterns of individual activity variation in the invasive species ─ a pattern that might indeed be advantageous when copying with new environmental conditions. The second part of my thesis examined distribution patterns and phenotypic trait divergence in species that historically invaded new geographical areas. I investigated variation of abiotic and biotic selection factors along a stream gradient to study species’ distributions and gradient evolution of morphological and life-history traits within spe- cies while focusing on two species of neotropical mosquitofishes (Gambusia spp.). This study exemplifies that even closely related, congeneric species can respond in unique ways to the same components of a river gradient. In another study, I investigated ecolog- ical and evolutionary consequences of species invasions to extreme habitats focusing on the colonization of two cave ecosystems by a neotropical fish. I found evidence for im- proved olfaction in one of two populations of cave fishes, suggesting independent evolu- tionary trajectories of both cave populations. Finally, I give first insights into a study that considers genetic and phenotypic trait divergence across both, the native (US American) and the invasive (European) distribution range of Eastern mosquitofish (Gambusia hol- brooki). The results highlight the importance of simultaneously considering processes involved in natural invasions and during human-induced invasions to understand the success of invading species. We often lack detailed information on the impacts of historical biological inva- sions. Also, we are currently lacking crucial knowledge about the time scales during which different mechanisms (behavioral flexibility, plastic phenotypic changes, and ge- netic adaptation) play a role during biological invasions and affect species exchange and establishment. Comparative analyses of historical, natural invasion and recent (man- made) invasions can provide insights into the