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).

Read the rest of this entry »





Know thy threat

9 06 2011

Here’s another great guest post by Megan Evans of UQ – her previous post on resolving the environmentalist’s paradox was a real hit, so I hope you enjoy this one too.

The reasons for the decline of Australia’s unique biodiversity are many, and most are well known. Clearing of vegetation for urban and agricultural land uses, introduced species and changed fire patterns are regularly cited in State of the Environment reports, recovery plans and published studies as major threats to biodiversity. But, while these threats are widely acknowledged, little has been done to quantify them in terms of the proportion of species affected, or their spatial extent at a national, state or local scale. To understand why such information on threats may be useful, consider for instance how resources are allocated in public health care1.

Threat knowledge

Conditions such as cancer, heart disease and mental health are regarded as National Health Priority Areas in Australia, and have been given special attention when prioritising funds since the late 1980s. The burden of disease in these priority areas are quantified according to the incidence or prevalence of disease or condition, and its social and economic costs. Estimates of burden of disease and their geographic distribution (often according to local government areas) can assist in communicating broad trends in disease burden, but also in prioritising efforts to achieve the best outcomes for public health. An approach similar to that used in healthcare could help to identify priorities for biodiversity conservation – using information on the species which are impacted by key threats, the spatial distributions of species and threats, and the costs of implementing specific management actions to address these threats. Read the rest of this entry »