Along with Robert K. Colwell (University of Connecticut), Lian Pin Koh (Princeton), and Navjot Sodhi (National University of Singapore) and others, I am examining aspects of extinction and in particular the extinction of insects. We have recently developed a new series of models used to estimate both future and historical co-extinction rates (Koh, Dunn et al. 2004), and are in the process of exploring more evolutionary aspects of the extinction of parasites and mutualists with the extinction of their hosts. Other work has explored why so few insect extinctions have been documented and whether insect extinction rates differ from those of other taxa (Dunn, in press), or the consequences of losses of particular species, such as the Hemlock tree, from forests for community level extinctions (Dunn & Danoff-Burg, in prep.).

Pictures above show exammples of a potential co-extinction (the loss of parasite or mutualist with the loss of its host) and a known example. At left is a hummingbird flower mite which could go extinct either if its host plant goes extinct (on which it feeds or breeds) or if its host bird goes extinct (which carries it from plant to plant). At right is the endangered California condor (Gymnogyps californianus) and its now extinct louse (Colpocephalum californici). This louse was only known from the California condor and was extinguished 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.

Of the 12,200 species of plants and animals currently listed as threatened or endangered, we estimate (Koh, Dunn et al. 2004) at least a further 6,300 affiliate species (parasites and mutualists) should be classified as “co-endangered”. This is the bleak, but conservative, estimate of the potential losses of mutualiss and parasites. While some of these co-endangered species are parasites loved mostly by taxonomists and their diminutive mothers, others are pollinators, such as bees and butterflies, that if they are extinguished will likely result in losses not only of long an interesting evolutoinary histories, but potentially also ecological functions. In the top left panel are a pair of feather mites (Rhytidelasma punctata), from the endangered pale-headed rosella (Platycercus adscitus), and in the bottom pannel a feather mite known only from the threatened southern cassowary, Casuarius casuarius, in Australia.

Dunn, R.R., and T. Romdal. 2005. The effects of local forest conversion on mean geographic range size of Neotropical bird assemblages. Global Ecology and Biogeography. 14 (4): 359-366. PDF

N.S. Sodhi, T.M. Lee*, L.P. Koh* and R.R. Dunn. 2005. A century of avifaunal losses from a small tropical rainforest fragment. Animal Conservation. 8: 217-222.

Koh, L.P., R.R. Dunn (Joint First Author), N.S. Sodhi, R.K. Colwell, H.C. Proctor, & V.S. Smith. 2004. Species co-extinctions and the biodiversity crisis. Science 305: 1632-1634. PDF, PDF of supplement.

Dunn, R.R. 2005. Insect extinctions, the neglected majority. Conservation Biology. 19 (4): 1030-1036.PDF

Dunn, R.R. 2004. Managing the tropical landscape: a comparison of the effects of logging and forest conversion to agriculture on ants, birds, and Lepidoptera. Forest Ecology and Management 191: 215-224. PDF

Dunn, R.R. 2004. Recovery of faunal communities during tropical forest regeneration. Conservation Biology. 18: 302-309.PDF