Wed Sep 4 16:12:14 CDT 2002

At 05:03 PM 9/3/02 -0700, you wrote:
>Steven Manning wrote:
>>Also, it seems likely that in some cases, when it is a race against time or
>>competing interests to save an endangered but poorly collected species or
>>ecosystem, the models can be used to predict and thus designate areas most
>>urgently needing protection at least temporarily until field work confirms
>>or refutes the predictions of the models, based on whatever climatic or
>>ecological data are available.  The models could also be used to prioritize
>>locations for fieldwork to be undertaken.
>That's actually the situation with this modeler I mentioned; the
>target species is endangered, and they are proposing to exclude
>certain areas from fieldwork (i.e., surveys) because the model
>predicts they won't be found there - even though some of the
>model-excluded areas contain known, confirmed sightings. The story
>I've heard is that the tolerances on the model "had to be narrowed"
>because if it was designed to include the habitat parameters of ALL
>known observations, the final predicted area would be essentially
>every piece of undeveloped land in the entire region, and that was
>considered unacceptable and unrealistic. No one seems to be objecting
>to this approach, to my knowledge, even though common sense would
>seem to dictate that one simply can't trust a model for this
>particular species, and that only survey work can tell us where it is
>or is not.
>Clearly, every organism has habitat preferences, but these
>preferences can be overridden in many cases. It seems to me that any
>model based solely on preferences is going to miss many marginal
>and/or suboptimal areas where a species could (or does) survive, and
>for endangered species, especially, that's a VERY risky approach to
>What does one do then?

Well, I will try again.  I actually agree with you!  When you said earlier
that with range extensions, eventually the model would predict presence of
an endangered species in every undeveloped land in a certain area, what I
would say is that then, the whole area should be conserved until it can be
investigated further.  I don't see this as a problem with the model, but
rather with the interpretation of it if the interpretation is that the
model's conclusion is "unrealistic" or "needs to be narrowed".  So what to
do about it may be nothing more than political - depending on how important
that particular area or species is for conservation - and random selection
of area for preservation, including "transient" locations among the

Short of that, I suppose one could start being quantitative rather than
qualitative, and assessing probabilities of natural occurrence rather than
predicting simply "yes" or "no" based on the model or asserting "natural
occurrence" or "transient".  If something is considered transient, and the
person making that evaluation is sincere, he or she must have some at least
subjective, hopefully objective basis for it.  If this basis could be made
explicit, ultimately perhaps it could be incorporated into refining the
model for future use although doing too much of this is obviously not a
substitute for field observations, as some have said earlier on this
general topic.  And finally, if field observations show repeated
observations in a particular place, this reduces the transiency in direct
proportion to the length of time spanned by collections/observations of the
species in the locality.  Resurveying may be a worthwhile option.


>Doug Yanega        Dept. of Entomology         Entomology Research Museum
>Univ. of California - Riverside, Riverside, CA 92521
>phone: (909) 787-4315 (standard disclaimer: opinions are mine, not UCR's)
>   "There are some enterprises in which a careful disorderliness
>         is the true method" - Herman Melville, Moby Dick, Chap. 82

More information about the Taxacom mailing list