Precise estimates of modern biodiversity extinction rates PDF Print E-mail

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Project overview


The Earth’s biodiversity has experienced 5 mass extinction events since the Cambrian. Extinction has kept pace with speciation, with >99% of all species that have ever existed now gone. Despite consensus that biodiversity has entered the 6th mass extinction, dubbed the Anthropocene because of human-driven changes, estimated extinction rates above background are highly imprecise. This arises partly because species richness is unknown for many taxa, and most extinctions go unnoticed. Without precise estimates of modern extinction rates, the urgency of the biodiversity crisis is not appreciated by society, and efforts to reduce biodiversity loss are weakened. We propose to collate existing information on the extent of meta-population extinctions of various Australian and global taxa. We will begin with Australian plants, mammals, birds & molluscs as 4 well-studied taxa within a single continent. Extinctions will be inferred from rates of observed meta-population extirpations. Given the good fossil evidence of pre-human extinctions in Australia, our inferred extinction rates will be compared to determine the modern inflation factor. We will also trawl the literature and update rates based on observed disappearances, correcting for unobserved extinctions using zero-inflated models. Using these empirical estimates, we will extend our range to global extinction rates based on state-of-the-art species-area relationships of species loss.


Slash and Burn

Slash-and-burn in the Amazon



Endangered white lemuroid possum from Mt Lewis, NQ


Bulldozer in Indonesia

Bulldozer in Indonesian Borneo


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Workshop 1 Report (4–8 July 2011)

The following is extracted for the ACEAS web site from the formal report for the group, and also from Corey’s blog ‘Conservation Bytes’ which has devoted two articles to the activities of this group. The latter one at the time of writing (August 2011) is titled ‘Life, death and Linnaeus’.

The main aims of the workshop were to:

  • revise species-area relationship (SAR) extinction risks for terrestrial taxa, including mammals and birds;
  • investigate data biases and their effect on species area relationships (SAR) versus endemic-area relationships (EAR);
  • identify trends and omissions across taxa and biomes in relaxation-time studies;
  • investigate the relationship between Extent of Occurrence (EOO) and Area of Occurrence (AOO) and the consequences for species threat status;
  • to apply SAR theory to reefs to examine transferability and reef fish extinction risks; and
  • overall to review the factors which contribute to extinction risks.


The first major achievement was the development of a spatial community simulation to examine various assumptions underlying species-area relationships. Fangliang He developed the code to simulate landscapes populated by many species following various abundance patterns and aggregation coefficients; Barry Brook developed the sampling code to construct SAR and endemic species-area relationships (EAR), incorporating aspects of extinction debt; and Corey Bradshaw developed a spatial habitat-destroying routine that simulates harvest patch distributions from completely random to highly clumped (based on the negative binomial distribution).

Lian Pin Koh, Stephen Gregory, Xingli Giam and Cagan Sekercioglu worked feverishly on constructing biogeographical realm- and ecoregion-scale SAR for birds and mammals at a global scale. Lian Pin and Tien Ming Lee have put together a series of land-use projections (incorporating deforestation trends and climate change expectations) and we will combine these with the global-scale SARs to estimate extinction rates in these taxa.

Nigel Stork focussed on putting together papers and datasets looking at relaxation times (extinction debt) for various taxa. Our goal here is to put together a meta-analytical paper on relaxation times.

Damien Fordham, Stephen Gregory and Corey focussed on constructing SAR for coral reef fish on the Great Barrier Reef using species richness and abundance predictions we published last year (see relevant papers by Camille Mellin and colleagues here and here). They’ll be projecting coral bleaching events using combined global circulation model predictions of sea surface temperatures, and predicting reef fish species loss based on the extent of predicted bleaching. Finally, Fangliang He and Cagan Sekercioglu worked on putting together bird range-loss data to estimate population size reductions based on a model Fangliang developed.

The plans for the second workshop will build on the work done between the meetings, and will focus mainly on writing, and developing plans for regionally-focussed SARs from Australia, with comparisons with Africa and South America.



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Last Updated on Sunday, 08 February 2015 16:11