# dots on maps

[Frederick W. Schueler]

Dr. Neil Snow wrote:

> The question of general relevance is: Should a taxonomist,
> biogeographer, ecologist or conservation biologist trust an unvouchered
> report of (for example) a rare beetle from a mega-diverse tropical
> country, where the majority of the local population of humans has never
> seen the beetle, much less has in their collective minds a common or
> scientific name?

* but the thread was about dot distribution maps in general, not solely
about rare tropical Beetles. There's a whole range of probability
associated with non-specimen records (and with the relationship between
specimens and their collection data, for that matter), so one can't be
categorical about whether maps done in one way or another, or based on
one kind of record or another, are useful. I think one of the most
important things is that the text associated with the map discuss the
details of periferal and other unlikely-looking records so that the user
knows that the author has considered their probability, and that symbols
be used to convey such information when it can be reduced to categories
(e.g. spcemen vs non-specimen records).

A distribution map is a hypothesis (Xus yus is securely known from
territory so-and-so with such-and-such a spatial pattern of records), and
the user of a map should be told as much as possible about how
alternatives were falsified (certain herp atlases that don't distinguish
specimen/non-specimen and plausible/implusible records may recognize
themselves here). Environmental replotting of the records, or comparisons
with maps of related or ecologically similar species may help to refine
the hypothesis and make it less purely spatial, but that doesn't change
the fact that even the purely spatial map is an hypothesis... but this
thread has gone on long enough, eh?

fred schueler.
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