Dokument: Functional floral traits as mechanistic explanation for community structure
| Titel: | Functional floral traits as mechanistic explanation for community structure | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=39563 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20160926-112920-2 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Kuppler, Jonas [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Lunau, Klaus [Gutachter] Prof. Dr. Janssen, Arnold [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 580 Pflanzen (Botanik) | |||||||
| Beschreibung: | Ecological communities are composed of multiple species. These co-occuring organisms are entangled in a complex web of interactions, interdependences and connections, which is the basis of ecological and evolutionary dynamics and processes. Thus, many ecosystem functions such as pollination, seed dispersal and nutrient cycling as well as community structure and stability depend on biotic interactions. Within plant-animal communities, functional plant traits, such as morphology, scent or phenology, mediate interactions and consequently affect community structure. This thesis explores functional floral traits as mechanistic explanation for flower-visitor community structure, with a focus on two topics: Impact of intraspecific floral trait variation in flower-visitor communities and floral traits as mechanism underlying alterations in communities due to changes in the species assemblage and disturbances, e.g. due to invasive species.
Within flower-visitor communities, we begin to understand how intraspecific variation in behavioural characteristics within an animal species is affecting the dynamics and structures of interactions. However, to what extent intraspecific variation in floral traits leads to differences in flower-visitor interactions between plant individuals is poorly understood. In a common garden experiment, we studied differences between plant individuals in their interactions with flower visitors and the correlation of these differences to intraspecific variation in phenotype and reproductive success. Therefore, all interactions between arthropods and flowers of 97 Sinapis arvensis individuals throughout their lifetime were recorded and linked to plant individuals’ phenotypes. We showed that plant individuals significantly differed in their quantitative and qualitative interactions with arthropods on flowers. These intraspecific differences remained stable over the entire season and thus were time-invariant. Variation in interacting arthropod communities was driven by a marked intraspecific variability in the floral phenotype (i.e. phenology, morphology and scent) and resulted in differences in reproductive success. Further, this variation may subsequently affect network statistics that are commonly used to characterize the structure of interaction networks since these statistics classically summarise interactions at species level and neglect intraspecific variation. In a resampling approach using the field data complemented with the recordings from the common garden experiment described above, we evaluated whether and how intraspecific variation in interactions alters commonly used aggregate statistics. Our results show that commonly used network statistics are sensitive towards changes in the interaction patterns of one plant species within a multi-species network, which may affect the ecological interpretation of the stability of communities or other network properties. Our results show that intraspecific variation in functional floral traits and interactions of plant species has pronounced effects in community and network context, potentially with implications for the persistence of communities and populations, and their ability to withstand environmental fluctuations. Further, by challenging the robustness of commonly applied network indices our findings have important methodological implications for theinvestigation of community and network structure and especially emphasize the urge for a sufficient and representative sampling of interactions. The structures and dynamics of a given community can be severely altered by the establishment and spread of introduced species (i.e. invasive species). Driven by the strong competitive abilities of invasive, native and endemic species often suffer from resource depletion, which may even lead to the displacement of these species. We quantified the niche sizes and overlaps of native and introduced flower visitor taxa in Hawaii Volcanoes National Park in order to reveal the ecological mechanisms underlying competition. We developed and used a novel trait-based approach (dynamic range boxes) adopting the concept of n-dimensional hypervolumes. This approach improves the concept of multivariate range boxes by accounting for the distribution of the data within their range, while still no assumptions on the underlying distributions are needed. Each dimension of the hypervolume represents one functional floral trait that affects foraging choices of flower visitor species. We could show that on average introduced flower visitor taxa were more generalized in resource use (larger niches) than native taxa. Small niche sizes of native taxa partly resulted from their specialization on native flowering plant species whereas introduced flower visitors interacted with both native and introduced plant species proportional to their abundance. Additionally, natives shared a larger proportion of their niches with introduced taxa than vice versa, suggesting a higher competitive ability of introduced taxa. Our results showed that the functional composition of plant communities as well as the ecological and evolutionary background of consumers are important factors in explaining the structure of interaction networks, and help to reveal competitive patterns within communities. Predicted range expansion of invasive plant and flower visitor species may further reduce the availability of resource for native flower visitors; at the same time competition for the remaining resources may increase. Thus, introduced species with a strong competition potential can cause severe current and future threats for native species. In summary, this thesis analyses the linkage between intraspecific floral trait variation and interaction patterns as well as floral trait variation as mechanistic explanation for alterations in community structure due to invasive species. This work highlights the importance of intraspecific trait variation for interaction patterns within communities and shows how functional traits can explain and may predict the impact of alterations within communities. All chapters demonstrate that functional traits as an interface of plants and plant-visiting animal species provide a central mechanism explaining community structures. Thus, considering functional plant traits at different hierarchical levels can improve our knowledge of community structure and dynamics and thereby help to generate a general understanding of the fate of communities under global change. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät | |||||||
| Dokument erstellt am: | 26.09.2016 | |||||||
| Dateien geändert am: | 30.09.2016 | |||||||
| Promotionsantrag am: | 11.05.2016 | |||||||
| Datum der Promotion: | 26.07.2016 |
