Here’s another free to access paper, by Robert Dunn et al, which discusses circumstances under which extinctions can occur,  how extinction of one species leads to others, and how extinction dynamics can be assessed and used to predict similar events in the future, when coextinction rates are predicted to increase.

This is the abstract:

The effects of species declines and extinction on biotic interactions remain poorly understood. The loss of a species is expected to result in the loss of other species that depend on it (coextinction), leading to cascading effects across trophic levels. Such effects are likely to be most severe in mutualistic and parasitic interactions. Indeed, models suggest that coextinction may be the most common form of biodiversity loss. Paradoxically, few historical or contemporary coextinction events have actually been recorded. We review the current knowledge of coextinction by: (i) considering plausible explanations for the discrepancy between predicted and observed coextinction rates; (ii) exploring the potential consequences of coextinctions; (iii) discussing the interactions and synergies between coextinction and other drivers of species loss, particularly climate change; and (iv) suggesting the way forward for understanding the phenomenon of coextinction, which may well be the most insidious threat to global biodiversity.

Reference: The Sixth Mass Coextinction: Are Most Endangered Species Parasites and Mutualists? by Robert R. Dunn, Nyeema C. Harris, Robert K. Colwell, Lian Pin Koh, Navjot S. Sodhi

Published online before print May 27, 2009, doi: 10.1098/rspb.2009.0413 Proc. R. Soc. B 7 September 2009 vol. 276 no. 1670 3037-3045

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