Oceanic islands provide valuable models for studying ecology, biogeography, and evolutionary research, including Darwin’s theory of evolution. A team of international researchers led by the University of Göttingen recently studied the flora of Tenerife, one of the Canary Islands. The results were unexpected, as the island’s plant-life displayed a remarkable range of forms, but functionally, they were similar to mainland plants. However, Tenerife’s flora is dominated by slow-growing, woody shrubs with a “low-risk” life strategy. These findings were published in Nature.
The researchers conducted extensive field research and measurements at over 500 sites on Tenerife using the latest methods of functional ecology. These sites covered a range of altitudes, from sea level to mountainous regions above 3,300 meters. They recorded approximately 80% of the island’s native seed plants and examined eight plant characteristics: plant size, specific wood density, leaf thickness, absolute and specific leaf area, leaf dry matter, nitrogen concentration in leaf tissue, and seed weight. The data was then compared to information on more than 2,000 plant species found on the mainland.
Professor Holger Kreft, head of the study and the Biodiversity, Macroecology, and Biogeography research group at Göttingen University, explains, “Our study reveals, for the first time and contrary to expectations, that species groups that evolved on the Canary Islands do not contribute to the expansion of different traits. This means they do not increase functional diversity.” Previous comparisons have shown significant differences between island and mainland species. For example, the Galapagos giant tortoise is much larger than its mainland relatives due to adaptation to the islands’ environmental conditions. The research team anticipated similar distinctions between island and mainland plants, but this was not the case. “Instead, we observe that most species conform to the constraints of the island climate. Thus, medium-sized woody species emerge, which are able to survive with limited resources and face a high risk of extinction. Consequently, they grow slowly. The high functional diversity primarily arises from the species that are widespread on the island and the nearby mainland,” Kreft explains.
“At the start of our research, we assumed that island plants would exhibit fundamental differences and have limited functional diversity due to their geographical isolation,” says Dr. Paola Barajas Barbosa, the first author of the study. These findings are part of her doctoral thesis, which she completed at the University of Göttingen. She now conducts research at the German Centre for Integrative Biodiversity Research in Leipzig (iDiv). “We were particularly surprised to discover that Tenerife’s plants exhibit comparatively high functional diversity.”