Volker Hahn, the Head of the Media and Communication team at iDiv, wrote an outreach article for the general public, as part of the online magazine of the University of Leipzig, about our work on Madagascar. It features both me and PhD student Laura Mendez and her adventures in the field, the lab, and behind the computer. The article also describes some of the future ideas and directions of our work. It’s in German.
Along with the article, Gabriele Rada made a short video about the Madagascar work, using our video footage from Madagascar. Watch the video here. And do not forget to also watch our other Madagascar video using megafauna animal animations by TRICKLABOR.
In a recent study, published in the journal Global Ecology and Biogeography, we investigate the evolution of leaf morphologies and climatic niches in the Proteaceae family. Proteaceae is a Southern Hemisphere family famous especially in Australia and South Africa for their impressive flowers and leaves. They are also tasty – the macademia nut belongs to the Proteaceae as well. Species in the Proteaceae family occur in all kinds of habitats, from montane forests to dry heathlands to tropical rainforests. During their evolution over millions of years, they managed to adapt to these variable and extreme habitats and climates, and their leaves may have helped them doing so. In this study we test whether open (e.g. mediterranean) and closed (e.g. tropical rainforest) habitats have selected for divergent leaf designs. We also show that the combination of certain leaf traits (e.g. small, sclerophyllous leaves with many teeth) in interaction with certain climatic niches (e.g. warm, dry, mediterranean) may increase diversification rates. This could explain some of the spectacular radiations within the family, for example in genus Banksia in Australia, or the Protea in Africa. Last, we show that there is more stochastic evolution of traits and niches in open habitats, which may explain some of the extreme forms and ‘misfits’ we find here. This “disparification” maybe even led to the process of reproductive isolation and speciation, via ecological divergence, and the ~1700 species of Proteaceae we find on Earth.
Onstein, R.E., Jordan, G.J., Sauquet, H., Weston, P.H., Bouchenak-Khelladi, Y., Carpenter, R.J., Linder, H.P. (2016). “Evolutionary radiations of Proteaceae are triggered by the interaction between traits and climates in open habitats.” Global Ecology and Biogeography 25 (10):1239–1251. doi: 10.1111/geb.12481
Why do plants in geographically distinct areas sometimes look so similar, even though they are different species, and have had different evolutionary histories? This may be, because they have evolved similar morphological features, or ‘adaptations’, in response to the similar environmental conditions in these areas. This is called ‘convergent evolution’. Convergent evolution may therefore explain why the five Mediterranean-type ecosystems of the world (California, central Chile, the Mediterranean Basin, the Cape and South and Southwestern Australia) have such a similar appearance, dominated by highly branched, woody shrubs with small sclerophyllous leaves. The similar environmental conditions in these regions – the typical ‘Mediterranean’ climate, very dry summers and fire – may have selected for these typical traits, independently in all five Mediterranean areas. However, the five regions show also considerable differences, such as absence of fire in Chile, and very poor soils (low in nutrients) in the Cape and Australia. This may explain why plants in the Cape and Australia are particularly ‘sclerophyllous’ – i.e. these sclerophyllous traits help to conserve their nutrients.
Being well adapted to your environment may decrease your chance to go extinct, and may allow for high rates of diversification, and the accumulation of species over long periods of time. These Mediterranean-type ecosystems indeed are very species-rich, and many species can co-exist in these systems. The evolution of these sclerophyllous traits in the Cape and Australia may therefore also partly explain why these systems are so diverse and species-rich, and became biodiversity ‘hotspots’ of the world.