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Last day of November already – I am now convinced that my suspicions are correct: time is not constant and in fact accelerates as you age (in mathematical terms, a unit of time becomes a progressively smaller proportion of the time elapsed since your birth, so this makes sense). But, I digress…
This short post will act mostly as a spruik for my upcoming talk at the International Congress for Conservation Biology next week in Auckland (10.30 in New Zealand Room 2 on Friday, 9 December) entitled: Species Ability to Forestall Extinction (SAFE) index for IUCN Red Listed species. The post also sets a bit of the backdrop to this paper and why I think people might be interested in attending.
As regular readers of CB will know, we published a paper this year in Frontiers in Ecology and the Environment describing a relatively simple metric we called SAFE (Species Ability to Forestall Extinction) that could enhance the information provided by the IUCN Red List of Threatened Species for assessing relative extinction threat. I won’t go into all the detail here (you can read more about it in this previous post), but I do want to point out that it ended up being rather controversial.
The journal ended up delaying final publication because there were 3 groups who opposed the metric rather vehemently, including people who are very much in the conservation decision-making space and/or involved directly with the IUCN Red List. The journal ended up publishing our original paper, the 3 critiques, and our collective response in the same issue (you can read these here if you’re subscribed, or email me for a PDF reprint). Again, I won’t go into an detail here because our arguments are clearly outlined in the response.
What I do want to highlight is that even beyond the normal in-print tête-à-tête the original paper elicited, we were emailed by several people behind the critiques who were apparently unsatisfied with our response. We found this slightly odd, because many of the objections just kept getting re-raised. Of particular note were the accusations that:
- We were somehow promulgating that conservation decisions should be made solely on the back of SAFE (we never said this, nor support such a crazy idea); we merely point out that SAFE provides information that the Red List categories do not.
- The IUCN threshold abundance criteria (mostly inherent in Criteria C & D) are not arbitrary and in fact based in a sound, empirically derived manner:
Well, we had a look at this in the original paper by Georgina Mace and colleagues justifying the abundance thresholds. First, While some values seem to have some logical basis and are in fact EXACTLY in line with our previous work on minimum viable population size supporting the ‘thousands’ (median: 5000) mark (in other words, our detractors have, retro-actively, agreed with us), all other thresholds are based on a theoretical paper published by Russ Lande in 1993 entitled: Risks of population extinction from demographic and environmental stochasticity and random catastrophes (American Naturalist 142: 911–927). Now, Russ is a bit of a theoretical ecology god, and the paper is great; however, the practicality (and biological reality) of the thresholds he derives can be questioned. His theoretical estimates are based on an unstructured, exponential model with a ceiling carrying capacity; while certainly informative, relying on such a relatively simple model that really only describes the effects of demographic stochasticity (kicking in at very small population sizes) should have rung some alarm bells. On the contrary, our analyses examining fully standardised MVP estimates from a wide range of taxa and based on empirical measurements give a more conservatively based estimate of a generalisable extinction-risk threshold. Thus, we come back to our original point – pegging a species’ population size to a generalised target makes intuitive sense and goes well beyond the theoretical (and simplistic) abundance threshold criteria provided in the Red List (but see previous point about not relying solely on SAFE – ours is an added dimension, not a replacement).
- Almost NO species are assessed in the Red List based on Category E alone (population viability analysis); SAFE does this implicitly.
- If our detractors are in fact so against any threshold criteria, then we propose that the power brokers of IUCN Red List should do the right thing and dump categories D and E entirely (as well as components of C). We would advise against this, but the corner in which they appear to be painting themselves argues for this outcome.
Now, I do not want to give readers the impression that my invective is in any way a criticism of our detractors’ research. I am a HUGE fan of many of them (e.g., the legend of Mace, the brilliance of McCarthy, the numerical genius of Akçakaya), I have published with some of them, and I clearly think that much of their research is directly and indirectly responsible for reducing extinctions. However, I am increasingly surprised by the blockade they keep putting up against the elegant simplicity of SAFE and its potential applications.
So, back to the conference in Auckland next week. I will expand on some of these issues and present some more data supporting our case. I imagine a few stone throwers will be in the crowd, so question time should be entertaining ;-).
CJA Bradshaw
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