Prof. Dr. Catherine H. Graham

Research Priorities: Tropical ecology, macroecology, biogeography, network ecology, ornithology
Catherine Graham is a US ecologist working at the Swiss Federal Research Institute (WSL) in Switzerland, who is primarily interested in the interrelationship between environmental conditions and biodiversity. How does biological diversity develop and how is it maintained? Which factors have played a role in this in the past, which ones currently play a role, and which ones could become important in the future? These are the sort of questions that Catherine Graham addresses in both individual ecosystems and on a global scale. She also investigates how humans interfere in these processes. In this way, she wants to contribute to more effective nature conservation and more sustainable land use.
At local to regional scales Catherine Graham and her team rely primarily on experiments and observations. This helps them better understand how parts of the ecosystem influence each other, and which special adaptations are used to avoid too much competition. They investigate such connections in various ecosystems – from tropical rainforests to the grasslands of the Alps and Carpathian Mountains.
The interrelationship between hummingbirds and flowering plants is a particular focus of their research. Both groups are linked by a very close relationship: The birds feed on the nectar of the plants and in return carry out their pollination. Catherine Graham wants to find out how this mutualism influences the rich biodiversity. It appears that hummingbirds prefer to forage on flowers where there is a morphological match between hummingbird bills and the tube length of flowers. A detailed insight of this kind into the relationship between plants and animals requires the analysis of enormous amounts of data, which the team collects at various altitudes in Costa Rica, Ecuador and Brazil.
Catherine Graham also investigates the unusually high biodiversity of the tropics from a global perspective. Catherine Graham and her working group discovered that the size and distribution of the climate zones strongly influence patterns of biological diversity. For example, the tropical climes comprise huge areas offering sufficient space and different habitats for all kinds of species. They are also spread across various continents that were isolated from each other for a long time. This led to different tropical species being able to develop in South America, Africa, Asia and Australia.
Such insights also have a practical benefit, as the size and distribution of climate zones can be altered by climate change. Being able to estimate the consequences of this development is thus crucial for the future protection of biological diversity. Many other aspects of Catherine Graham’s work are aimed at more effective nature protection. Understanding how the engines of biodiversity work is vital in order to keep them running.