Extinction vs accuracy

[Patrick Foley]

David and everyone else,
 
In Allee and al 1949. Principles of Animal Ecology, on p. 287 we find the following
 
" Excluding radical changes in the exploitable resources of an environment or some equally radical biotic maladjustment, a natural
population rarely reaches a density so low as to be in danger of extinction."
 
Sewall Wright (1929) published a one page abstract of his new shifting- balance theory of evolution in Anatomical Record, 44:287. He
wrote,
 
"In too small a population, there is nearly complete random fixation, little variation, little effect of selection and thus a static
condition, modified by chance fixation of a new mutation, leading to degeneration and extinction."
 
Pardon me if I continue the traditional use of 'extinction' for all levels of extinction, a use ecologists have cut their teeth on.
 
Patrick Foley
patfoley at csus.edu
 
"But however small may be the selective advantage the new character will spread,
 
David Webster wrote:
 
> Hi John, Patrick and All:            Jan 18, 2001
>     Perhaps some did not understand the basis of my original comment about extinction (Jan 31), so I will spell this out and then
> add a few afterthoughts. Note that this is not intended to be an argument-- just an explanation of a point of view.
> 1) Most literate people cut teeth on accounts of famous extinctions; e.g. great auk, dodo, passenger pigeon.
> 2) Extinct and extinctions are therefore words in the public domain and "extinct" is strongly associated with irreversible loss of
> a species.
> 3) Being in the public domain, "extinct" is not a technical term, and thus can not be redefined for scientific purposes without
> causing confusion.
> 4) This is not an era of contemplation (even National Geographic wrongly had the millennium start one year too soon and refused to
> admit it). It is an era of 5-sec sound clips, 5 word factiods, keyword searches, superficial journalism and hot-button words in
> which nearly everything is heard or seen out of context, sometimes with the intent to misinform.
> 5) It is also an era of proliferating charities, so conservation organizations have to make their causes sound more dire than they
> really are in order to get contributions.
> 6) The entire conservation movement would suffer if even one conservation organization, by accident, inflated species extinction
> statistics by including some population extinctions.
> Afterthoughts--- To take one example, the range of the Ringlet is expanding and recently reached Nova Scotia. If a contraction of a
> range is some kind of extinction, should an expansion be called an unextiction, a disextinction or a creation ? Obviously, none of
> the above, it's an expansion. And if that is correct then I wonder why the loss of a species from an island or an outlier station
> is more than a decrease in range; often only a symptom of underlying causes.
>     Habitat destruction, as Anne says so eloquently, is the loss which counts.
>     Dave Webster, Kentville, Nova Scotia
>
> John Shuey wrote:
>
> > I can only go so long with chiming in on this conversation.  Without looking up anything, here is my take (from the perspective
> > of a conservation practitioner).  Also note that my grammar sucks in general, so that I may have missed some obvious points
> > below.
> >
> > Extinction - a noun, describes a process that works at several levels - levels which therefore should always be specified when
> > using the term.
> >
> > Extinct - an adjective, describes the status of an entity, such as a population, species, or group of species.
> >
> > Extirpated, an adjective, similarly describes the status of an entity.  As I know the term, it is always applied to species in
> > the context of a definable geographic area. I have never seen this term used to describe single population sites.
> >
> > So here's how they relate in my mind:
> >
> >   -    At its most fundamental level, EXTINCTION is a population level process - populations are
> >        always at risk of extinction.  But in a functioning ecological landscape, new populations
> >        are generally founded at the same rate that populations become extinct, so the net effect is
> >        a wash (this would be a stable regional metapopulation).  In today's human dominated
> >        landscape, population level extinction often outpaces the founding of new populations.
> >
> >   -    As localized population extinctions accumulate, a species may become EXTIRPATED
> >        from a defined geographic region.  For example, Mitchell's satyr was known historically
> >        from a single population in Ohio,  The extinction of that that butterfly from Streetsboro Fen
> >        resulted in the extirpation of Mitchell's satyr from Ohio. Karner blues were known
> >        from several populations in Ohio, all of which were extinct by the late 1980's  resulting in the
> >        extirpation of Karner blues from Ohio (note that it has been re-introduced to Ohio,
> >        which doesn't negate the fact of past  population-level extinction nor of past regional
> >        extirpation).
> >
> >    -   As population-level extinctions further accumulate, a species may become EXTINCT - no living
> >        individuals survive.  A single population-level extinction resulted in the extinction of a species,
> >        the Dodo.  Hundreds, of not thousands of populations of the Wabash Riffelshell Mussel
> >        became extinct, ultimately resulting in the extinction of that species.
> >
> >   -    As groups of species become extinct, the term is often applied to even larger taxonomic
> >        groupings.  For example, millions of populations became extinct, resulting in the extinction
> >         of hundreds of species, and now all dinosaurs are extinct (except maybe those pesky birds).
> >
> > If these terms are used properly, (especially relative to the subject of the discussion), they can be very accurate terms with
> > little or no ambiguity.
> >
> >  --
> >
> > John Shuey
> >
> >
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