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Ecological specialization and population size in a biodiversity hotspot: How rare species avoid extinction
journal contribution
posted on 2023-05-17, 07:26 authored by Williams, SE, Williams, YM, VanDerWal, J, Isaac, JL, Shoo, LP, Christopher JohnsonChristopher JohnsonSpecies 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.
History
Publication title
National Academy of Sciences of The United States of America. ProceedingsVolume
106Issue
Supplement 2Pagination
19737-19741ISSN
0027-8424Department/School
School of Natural SciencesPublisher
Natl Acad SciencesPlace of publication
2101 Constitution Ave Nw, Washington, USA, Dc, 204Rights statement
PNAS Copyright © 2009 by the National Academy of SciencesRepository Status
- Restricted