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Ecological specialization and population size in a biodiversity hotspot: How rare species avoid extinction


Williams, SE and Williams, YM and VanDerWal, J and Isaac, JL and Shoo, LP and Johnson, CN, Ecological specialization and population size in a biodiversity hotspot: How rare species avoid extinction, National Academy of Sciences of The United States of America. Proceedings, 106, (Supplement 2) pp. 19737-19741. ISSN 0027-8424 (2009) [Refereed Article]

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PNAS Copyright 2009 by the National Academy of Sciences

DOI: doi:10.1073/pnas.0901640106


Species with narrow environmental niches typically have small geographic ranges. Small range size is, in turn, often associated with low local abundance. Together, these factors should mean that ecological specialists have very small total populations, put- ting them at high risk of extinction. But some specialized and geographically restricted species are ancient, and some ecological communities have high proportions of rare and specialized endem- ics. We studied niche characteristics and patterns of distribution and abundance of terrestrial vertebrates in the rainforests of the Australian Wet Tropics (AWT) to identify mechanisms by which rare species might resist extinction. We show that species with narrow environmental niches and small geographic ranges tend to have high and uniform local abundances. The compensation of geographic rarity by local abundance is exact, such that total population size in the rainforest vertebrates of the AWT is inde- pendent of environmental specialization. This effect would tend to help equalize extinction risk for specialists and generalists. Phylo- genetic analysis suggests that environmental specialists have been gradually accumulating in this fauna, indicating that small range size/environmental specialization can be a successful trait as long as it is compensated for by demographic commonness. These results provide an explanation of how range-restricted specialists can persist for long periods, so that they now form a major component of high-diversity assemblages such as the AWT.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Community ecology (excl. invasive species ecology)
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Terrestrial biodiversity
UTAS Author:Johnson, CN (Professor Christopher Johnson)
ID Code:72187
Year Published:2009
Web of Science® Times Cited:76
Deposited By:Zoology
Deposited On:2011-08-23
Last Modified:2012-03-06

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