Das Projekt "Überprüfung der Hypothese zu Artbildungsprozessen bei der Kirschfruchtfliege und ihren Parasitoiden" wird vom Umweltbundesamt gefördert und von Universität Kiel, Zoologisches Institut durchgeführt. Artentstehung setzt die reproduktive Isolation von Populationen voraus. Die gängige Vorstellung für die Entstehung von Arten ist die allopatrische Speziation, bei der Populationen durch geographische Barrieren getrennt sind. Doch kann diese Vorstellung unseres Erachtens kaum den ungeheuren Artenreichtum erklären und ist besonders problematisch, wenn es gilt, die häufige Sympatrie nächstverwandter Insektenarten zu erklären. Die Theorie der sympatrischen Speziation schlägt vor, dass Wirtswechsel bei phytophagen Insekten mit einem Wechsel des Paarungsortes einhergehen und es so zur reproduktiven Isolation von Populationen kommen kann. Das bekannteste und am besten untersuchte Modellsystem hierfür ist die Artengruppe um die amerikanische Apfelfruchtfliege. Wir wollen anhand der Wirtsrassen der Kirschfruchtfliege auf Kirschen und Heckenkirschen (Lonicera xylosteum) sowie der postglazialen Nord- beziehungsweise Südrasse dieser Art überprüfen, ob bei dieser Fliege sympatrische Speziation oder Wirtskreiserweiterung vorliegt. Darüber hinaus wollen wir überprüfen, ob parallel zu den Fliegen auch bei deren Parasitoiden Speziationsereignisse stattfinden. Zunächst beginnen wir mit einem Vergleich sympatrischer Fliegenpopulationen, die von unserem Kooperationspartner Dr. Boller in der Schweiz bzw. von uns in Deutschland besammelt werden. Eine Isoenzymanalyse, bei der wir in Anlehnung an die Arbeiten unseres Kooperationspartners Prof. McPheron sämtliche Allozyme berücksichtigen, die bei der Apfelfruchtliege von diagnostischem Wert sind (und einige zusätzliche), soll Aufschluss über die lokale Populationsdifferenzierung durch Wirtsrassenbildung erbringen. Ein Vergleich mit der geografischen Isolation von Populationen gibt uns Auskunft über den Isolationseffekt der Wirtsrassenbildung.
Das Projekt "Evolutionary Conflicts and their Impact on Speciation" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Integrative Biologie durchgeführt. Within the general framework of evolutionary theory, I am particularly interested in sexual selection and evolutionary conflicts within and between species (sexual and host-parasite conflicts) as potential drivers of speciation. Reproductive barriers between populations are of crucial importance as they can help explain how new species are formed and what factors encourage or constrain biodiversity. Reproductive traits are known to be susceptible to very rapid evolutionary change yet the exact traits responsible for reproductive isolation generally remain unclear. I aim to identify such traits and understand how they diverge and affect reproductive barriers between populations in Tribolium flour beetles (important pests of stored products and genetically tractable model organisms). I will mainly use a powerful long-term 'experimental evolution' approach to examine whether sexual selection generates greater differences in reproductive traits and accelerates reproductive isolation. To do this, I will be using different populations maintained under different levels of sexual selection (through variation in the intensity of competition between males to produce offspring). In addition to detailed experimental studies of a range of reproductive characters and the impact of endosymbionts on host reproduction, I will run a combined experimental evolution experiment incorporating different levels of sexual selection and status of infection (infected vs. uninfected). This will enable me to judge how both sexual selection and reproductive parasites (such as the bacterial endosymbiont Wolbachia) impact on speciation. Despite strong theoretical support, the importance of sexual selection and evolutionary conflicts as speciation engines remains controversial and hence generates intense debate. This research aims to establish whether these forces can act singly or combined to accelerate speciation (and ultimately generate biodiversity) and their overall and relative importance as engines of speciation. This will be of particular interest to scientists working in the fields of evolutionary biology and behavioural ecology, but also to ecologists, reproductive biologists, and conservation biologists. Because Tribolium beetles are agricultural pests of considerable economic importance, results will also be relevant to more applied researchers. Moreover, as endosymbionts could have potential applications as biocontrol agents for pests or insect vectors of disease, it is critical that detailed knowledge of consequences for the host of infection with the symbiont is available.
Das Projekt "Evolutionary ecology of floral signals and pollinator specificity in plants" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Agrarwissenschaften, Departement Biologie durchgeführt. Plants grow in complex ecological networks, and show finely tuned adaptations to attact mutualists such as pollinators, and deter enemies such as herbivores. To do so, plants use volatile signals (BVOCs biogenic volatile organic compounds) that are emitted from vegetative (e.g. leaves) or flowers. Leaf volatiles are often thought to be involved in defense, whereas floral volatiles are traditionally interpreted as attractants for pollinators. However, recent studies have shown that floral scent may as well be involved in defending reproductive structures against antagonists. This can be achieved by emitting repellent compounds from flowers. The obvious need of plants to attract pollinators to flowers on the one hand, and to defend flowers on the other hand, puts them into a dilemma. Such signaling dilemma or trade-offs suggest optimal fitness outcomes may be a compromise between attraction (pollinators, parasitoids) and deterrence (herbivores); a key factor selecting for differential signaling may thus be the abundance and species identity of these interacting organisms in a given habitat. Signaling conflicts may also differ among pollination systems, e.g. when pollinators are also herbivores (moth pollination), attracting an herbivore is unavoidable for pollination. Under strong herbivore attack, however, plants may even switch pollination system by changing BVOC signaling to escape the herbivore pressure. This particular project will focus on ecological and evolutionary aspects of flower signaling to pollinators and the impact of novel herbivores on this mutualism. Up till now, we know surprisingly little about how herbivore induced changes in floral volatiles (HICFV) and the resulting change in flower attractiveness to pollinators. This IP will investigate HICFV after attack of established and novel herbivores (both on shoots and roots) and its molecular basis and variability. Lastly, natural selection on HICFV will be studied in populations with and without invasive herbivores, to asses their impact on the evolution of this key plant signaling trait and model future evolutionary change.
Das Projekt "Evolutionary Conflicts and their Impact on Speciation (follow-up)" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Integrative Biologie durchgeführt. In addition to recognizing natural selection as a universal mechanism in evolution, Darwin also saw the importance of sexual selection, yet the two have been traditionally treated largely in isolation. Here I propose to apply experimental evolution (exposing experimental populations to controlled specific selective pressures over many generations in the laboratory) to the ideally suited model system Tribolium castaneum to explore how these evolutionary forces interact and impact on the key processes underlying biodiversity. Understanding how these fundamental forces, singly and in conjunction, influence species divergence remains a major challenge in evolutionary biology. Participation of sexual selection in driving speciation is supported by substantial theoretical evidence. Theory further suggests that evolutionary conflicts (such as between the sexes or between host and parasite) might also accelerate extinction. Additional complexity is introduced by including the environmental context, linking back to natural selection. Direct experimental tests of the above concepts are essentially lacking. I will explicitly target this gap by exploiting powerful experimental evolution, incorporating the interplay between sexual selection intensity, host-parasite conflict, and adaptation to increasing temperature. Projects will assess how selection under evolutionary conflict and environmental change affects both adaptation and extinction rates, aiming to elucidate underlying mechanisms. Additionally, building on clear phenotypic divergence in key traits across experimental evolution lines, I will significantly expand on previous work by assessing patterns of divergence in gene expression, concentrating on target genes associated with reproduction, immunity and heat shock. This research will be of particular interest to scientists working in the fields of evolutionary biology and behavioural ecology, but also to ecologists, reproductive biologists, and conservation biologists. As Tribolium beetles are widespread agricultural pests, results will also be relevant to more applied researchers.