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Co-Extinction

Sun, 2006-03-12 17:52 — Vince Smith
Species Co-Extinctions and the Biodiversity Crisis
 
LIAN PIN KOH(1,2*), ROBERT R. DUNN(3)*, NAVJOT S. SODHI(1&), ROBERT K. COLWELL(4), HEATHER C. PROCTOR(5), AND VINCENT S. SMITH(6) 
 
 
1, Dept. of Biological Sciences, National Univ. of Singapore, 14 Science Drive 4, Singapore 117543 2, Present address: Dept. of Ecology and Evolutionary Biology, Princeton Univ., Princeton, NJ 08544-1003, USA 3, Dept. of Ecol. & Evol.Biology, Univ. of Tennessee, 1416 Circle Drive, 569 Dabney Hall, Knoxville, TN 37996-1610, USA 4, Dept. of Ecol. & Evol.Biology, Univ. of Connecticut, Storrs, CT 06269-3043, USA 5, Dept. of Biological Sciences, University of Alberta, Edmonton, Alberta Canada, T6G 2E9 6, Institute of Biomedical and Life Sciences, Univ. of Glasgow, Glasgow, Scotland, G12 8QQ, UK. (Present address: Illinois Natural History Survey, 607 East Peabody Drive, Champaign, IL 61820-6970, USA)
Joint First Authors*: Lian Pin Koh and Robert R. Dunn
Corresponding Author: Navjot S. Sodhi
e-mail: dbsns@nus.edu.sg

Status: Published 10th Sept. 2004 in Science, vol. 305, no. 5690. pp. 1632-1634.

Mini Press Release

Species co-extinction: till death do us part?
Of the 12,200 species of plants and animals currently listed as threatened or endangered, a further 6,300 affiliate species should be classified as “co-endangered”. This is the bleak assessment offered by a new study attempting to quantify the phenomenon of co-extinction – the loss of an “affiliate” species when its host goes extinct.

Many plants and animals have a diverse selection of insects, fungi, and other organisms associated with them that are uniquely adapted to their host. This specialization makes these affiliate species vulnerable to host extinction. Using estimates of host specificity, Lian Pin Koh, Robert R. Dunn and colleagues calculated the expected levels of co-extinction across a diverse selection of host and associate systems. For the groups examined, the authors show that at least 200 affiliate species have historically been lost through co-extinction, and a further 6,300 are co-endangered with their hosts. These processes have been widely overlooked, perhaps because some of the most susceptible organisms are uncharismatic parasites. For example, many herald the success of conservation efforts to save the Californian condor from extinction, but who mourns the condor louse that went extinct as a result of efforts by well-meaning conservation biologists to rid the birds of their parasites? The authors suggest that co-extinction is a largely unexamined and potentially substantial contributor to the present global extinction crisis and that estimates of species extinction should be re-calibrated, taking estimates of co-extinction into account.

Abstract

The co-extinction of species (the loss of a species upon the loss of another) remains a critical process. We present a probabilistic model, scaled with empirical data, to examine the relationship between co-extinction levels (proportion of species extinct) of affiliates and their hosts across a wide range of coevolved interspecific systems: pollinating Ficus-wasps and Ficus, parasites and their hosts, butterflies and their larval hostplants, and ant-butterflies and their host ants. Applying a nomographic method based on mean host specificity (number of host species per affiliate species), we estimate that 6300 affiliate species are “co-endangered” with host species currently listed as endangered. Current extinction estimates need to be re-calibrated by taking species co-extinctions into account.

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Literature Citation
Koh, L.P., Dunn, R.D., Sodhi, N.S., Colwell, R.K., Proctor, H.C., Smith, V.S. 2004. Species Co-Extinctions and the Biodiversity Crisis. Science, vol. 305, no. 5690. pp. 1632-1634.

Media Coverage

Lian Pin Koh has compiled a PDF containing articles written by the 70+ news organizations that the reported this paper between 10-13 Sept. 2004. The complete PDF is available here (note this is a very large file - 6.6MB). Thomas Brooks of Washinton based Conservation International said of this study "The team has done the conservation community a great favour by synthesizing the theory and data on the co-extinction crisis." (11 Sept, 04, New Scientist). Sept '04

Publicity Images*

Promotional Fig. 1 (High Res TIFF File)
The endangered California condor (Gymnogyps californianus) and its now extinct louse (Colpocephalum californici). This louse was only known from the California condor and went extinct as a result of efforts by conservation biologists to rid the bird of its parasites. Condor image used with permission from del Hoyo, J., Elliott, A. & Sargatal, J. eds. (1994). Handbook of the Birds of the World. Vol. 2. New World Vultures to Guineafowl. Lynx Edicions, Barcelona. Copyright information available in the first instance from from Vince Smith.

Promotional Fig. 2 (High Res TIFF File)
A pair of feather mites (Rhytidelasma punctata), from the pale-headed rosella (Platycercus adscitus). Image by David Evans Walter. Copyright information available from Heather Proctor.
Rhytidelasma

Promotional Fig. 3 (High Res TIFF File)
This feather mite is known only from the threatened southern cassowary, Casuarius casuarius, in Australia. Copyright information available from Heather Proctor.

Mite

Promotional Fig. 4 (High Res TIFF File)
The locally extinct butterfly hostplant (Tylophora sp.) and its co-extinct affiliate butterfly species (Parantica aspasia) from Singapore. Copyright information available from Lian Pin Koh.
Tylophora

Promotional Fig. 5 (High Res TIFF File)
Hummingbird flower mites can go extinct if either the hummingbirds they use for transport or flowers on which the mites depend for nectar and pollen go extinct. In the illustration, the mite Tropicoseius uniformis, monophagous on its host plant Psychotria poepegiana, is phoretic on the hummingbird Amazilia tobaci in Trinidad, West Indies. Credits - Amazilia tobaci (hummingbird), Rick and Nora Bowers; Tropicoseius uniformis (mite): Shahid Naeem; Psychotria poepegiana (host plant), R. K. Colwell. Copyright information available from Robert Colwell.
Cover

 

* Note that these figures do not constitute part of the publication and are intended for promotional use of this paper. High resolution images are available in TIFF format from the links above. Copyright permission must be sought from the relevant contact listed by each figure BEFORE use. Requests for use of multiple figures can be directed to Vince Smith in the first instance.

Figures from the Paper

Figure 3 (High Res TIFF File)
Predictions of affiliate extinctions from the nomographic and combinatorial models. (A) Estimated numbers of historically extinct affiliate species based on the number of host species recorded as extinct. (B) Projected numbers of affiliate species extinctions, were all currently endangered hosts to go extinct. The first value in parentheses represents the absolute number and the second value the percentage of species extinct or endangered as predicted by the nomographic model; the second set of values in parentheses represents predictions from the combinatorial model for selected affiliate-host groups where affiliation matrices are available. See ref. 10 within the manuscript for details on datasets. Copyright information available from Lian Pin Koh.

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