Severin Irl is passionate about islands. Since 2018, he has held the professorship for Biogeography and Biodiversity at Goethe University Frankfurt’s Faculty of Geosciences/Geography, where he researches the diversity of life – in his case, plants – across different world regions.
On islands, naturally limited by water, organizing such research is much easier than in deserts, jungles, or oceans: “Here, we have closed systems with very clear boundaries, allowing us to observe and study evolutionary processes in real time,” Irl emphasizes. “At the same time, larger islands like Gran Canaria, Maui, or Madagascar offer many different climate – and therefore also vegetation – zones in a very small area.”
To study and compare flora and fauna on islands, scientists don’t need to travel hundreds of kilometers across entire continents, Irl points out. Instead, they find “evolutionary laboratories”, where they can examine the fundamental processes through which biodiversity emerges in three dimensions: taxonomically (as species diversity), functionally (in the form of varying appearances and, consequently, different traits), and phylogenetically (in terms of diverse evolutionary relationships).
To explore biodiversity in these three dimensions, Irl and his research group map out areas on islands and record which plant species occur there and in what numbers. They measure the plants’ traits to understand the roles they play in their respective habitats. And, through collaborations with colleagues in biology who analyze the plants’ genomes, Irl learns about the evolutionary relationships among the plants he has found – that is, the phylogenetic diversity on each island.
Out in the Field Rather Than in the Lab
“What excites me is that my research contributes to a better understanding of how nature fundamentally works,” Irl says enthusiastically, describing how this passion has grown over the years. Even as a child and teenager, and later as a high school graduate and university student, he preferred being out in the field rather than in the lab and was drawn to a variety of outdoor natural sciences – from volcanology to geoecology, glaciology (glacier research), and soil science. “Over the course of my studies, I eventually found exactly the right fit for me in biodiversity research and biogeography.”
However, Irl also points to human-caused climate change, the destruction of natural habitats through changes in land use, and the spread of invasive animal and plant species, and adds: “My research aims to show how we are treating the foundations of our existence – how we are influencing and even destroying our ecosystems and unique biodiversity. Being able to contribute to this knowledge is something I consider a great privilege.”
One of the ecosystems that fascinates Irl lies in the Canary Islands, where he has studied endemic plant species – that is, species found only in that specific region – in great detail. “One important finding from recent years is that herbivores introduced by humans, such as rabbits, feed much more on endemic species than on plants that also grow elsewhere.” The reason for this, he explains, is that the endemic species evolved on the islands at a time when there were no rabbits – so they never had a chance to develop natural defenses against such herbivores. “These endemic species, which exist only in the Canaries, already face a higher risk of extinction – and the pressure from invasive herbivores introduced by humans makes them even more vulnerable than non-endemic plants that rabbits feed on,” Irl explains.
Eye-Level Engagement
When Irl shares his enthusiasm with students, he’s no longer limited to lecture halls and seminar rooms: in March 2026, he’s planning an excursion to La Palma with twelve students. “The students will work on their own small research projects. I’m really looking forward to meeting them on equal footing – even more so than is usually possible in everyday university life.”
But Irl also explores islands in a metaphorical sense – not surrounded by water: for instance, the quartz islands of the South African Karoo semi-desert. These are round or oval patches, ranging from several hundred square meters to a few square kilometers in size, covered by a thick layer of nearly pure white quartz fragments, each about the size of a golf ball. “These quartz islands offer an incredible variety of unusual life forms that exist nowhere else in the world – a true global biodiversity hotspot,” Irl enthuses. With their unique soil composition, distinct chemical conditions, low nutrient availability, and – in some areas – high salinity, the quartz islands stand in stark contrast to the surrounding terrain. Based on his observations, Irl concludes: “To colonize the habitat of the quartz islands, plants had to adapt to these extreme environments by changing their morphology and biology – leading to the emergence of new, highly specialized species.”
Stefanie Hense
