High numbers of African lizard species are found in areas where their ancestors have entered the continent more than 20 million years ago, which suggests strong dispersal limitations. These are the findings of a new study led by Daniel Kissling, Associate Professor at the UvA Institute for Biodiversity and Ecosystem Dynamics (IBED), which have been published in the Nature journal ‘Scientific Reports’.
Daniel Kissling investigated the historical colonization and dispersal of African lizards, in order to understand how this has shaped biodiversity across the continent.
Many lizards occur only in dry and warm habitats. The agamid lizards (family Agamidae) are a diverse and widespread reptile group in Africa inhabiting mostly savannahs. The >70 species have ancestors who colonized Africa from the Arabian peninsula about 23 million years ago. Today, these lizards occur in all parts of Africa except the Sahara and the Congolian rainforest. However, how fast they have colonized the African continent and to what extent current and past environment can explain their distributions had not yet been examined.
The researchers compiled species distribution data and mapped the number of lizard species across the continent. They then simulated potential historical colonization routes from the Arabian peninsula into Africa and tested to what extent dispersal limitation and environmental conditions could explain species numbers across Africa. The researchers found that dispersal was limited over historical time, and that this was of key importance to explain the current distribution of lizards. Furthermore, high numbers of lizards were found in topographically and climatically suitable areas, suggesting that climate and mountains together with dispersal limitation strongly shape current biodiversity.
‘I was really surprised to find that the present-day distribution of lizards across the African continent is still so strongly influenced by how their ancestors entered into the continent more than 20 million years ago,’ says Daniel Kissling. ‘Although we don’t have actual field measurements of lizard dispersal, these results suggest that the natural dispersal and movement rates of these species are probably very low,’ he continues. Knowledge on movement and dispersal is therefore urgently needed to better predict biodiversity responses to global change.
The combination of biodiversity with geosciences is the focus of Kissling’s research team. ‘We are particularly interested to understand the distribution of life on Earth, and how it is shaped by the physical environment,’ says Kissling. ‘We use large datasets of species distributions together with environmental and ecological data to quantify the drivers of biodiversity. This research is not only important for understanding the origin of biodiversity but also for predicting the future of biodiversity in response to climate and land use change.’
Kissling, W.D., Blach-Overgaard, A., Zwaan, R. E. & Wagner, P. (2016): Historical colonization and dispersal limitation supplement climate and topography in shaping species richness of African lizards (Reptilia: Agaminae). Scientific Reports 6: 34014.