Pickled niches

2 08 2011

Another fine contribution from Salvador Herrando-Pérez (see previous posts here, here, here and here).

Sometimes evolution fails to shape new species that are able to expand the habitat of their ancestors. This failure does not rein in speciation, but forces it to take place in a habitat that changes little over geological time. Such evolutionary outcomes are important to predict the distribution of groups of phylogenetically related species.

Those who have ever written a novel, a biography, or even a court application, will know that a termite-eaten photo or an old hand-written letter can help rebuild moments of our lives with surgical precision. Likewise, museums of natural sciences store historical biodiversity data of great value for modern research and conservation1.

A notable example is the study of chameleons from Madagascar by Chris Raxworthy and colleagues2. By collating 621 records of 11 species of the tongue-throwing reptiles, these authors subsequently concentrated survey efforts on particular regions where they discovered the impressive figure of seven new species to science, which has continued to expand3 (see figure below). The trick was to characterise the habitat at historical and modern chameleon records on the basis of satellite data describing climate, hydrology, topography, soil and vegetation, then extrapolate over the entire island to predict what land features were most likely to harbour other populations and species. This application of species distribution models4 supports the idea that the phenotypic, morphological and ecological shifts brought about by speciation can take place at slower rates than changes in the habitats where species evolve – the so-called ‘niche conservatism’ (a young concept with already contrasting definitions, e.g.,5-7).

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