African Biodiversity pp 69-84
Madagascar as a Model Region for the Study of Tempo and Pattern in Adaptive Radiations
- Cite this paper as:
- Vences M. (2005) Madagascar as a Model Region for the Study of Tempo and Pattern in Adaptive Radiations. In: African Biodiversity. Springer, Boston, MA
The comparative study of adaptive radiations is a fruitful field that allows to test hypotheses and predictions of evolutionary theory. Madagascar is ideal for such studies because a large number of such radiations evolved on this island in isolation. In vertebrates, the historical biogeography of many Malagasy groups has recently been elucidated by molecular phylogenetic analyses, and by molecular time estimates. Such molecular clocks are a suitable method to estimate colonization times. However, as reviewed herein, they need to be applied cautiously due to the recent discovery of various potential artefacts and pitfalls. As an example of possible comparative studies across radiations, divergences of the Malagasy vertebrate clades to their closest non-Malagasy relatives in the mitochondrial 16S rRNA gene were found to be correlated to species diversity of the Malagasy clades. This suggests that the more diverged clades are richer in species. Pseudoxyrhophiine snakes and mantellid frogs contain distinctly more species than would be expected by this correlation alone. Further such comparative analyses appear to be promising but require a yet better state of knowledge on phylogeny and divergence times of the Malagasy taxa.
Key wordsAdaptive radiation molecular clock biogeography vertebrate origins Madagascar
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