In ecology the term rarity is used in a different context to how collectors
would normally use it. There are no environments where all species are
equally common. Some are very abundant, others moderately common, and the
rest (this is usually most of the species present) are rare. This is a very
well know pattern in ecology and is found in all taxonomic groups. The
definition of rarity is dependent on the scale at which species are
assessed. There are other factors to consider such as community dynamics,
dispersal rates, temporality, aggregation and life rates and cycles.
There are many ecological models that are used to describe patterns
in species presence/absence and abundance, and relationships to factors such
as environmental parameters, habitat heterogeneity and complexity. We can
see that the subject of rarity is quite complex and of great interest in
community and conservation ecology.
Alex
-----Original Message-----
From: Conchologists List [mailto:[log in to unmask]] On Behalf Of
marlo
Sent: 14 October 2008 01:01
To: [log in to unmask]
Subject: [CONCH-L] rare, uncommon, common, shells
I guess "rare" is a matter of perspective. If you collect by purchasing,
then I guess rare is when you can't find what you want for sale. If you
trade, I guess rare is when no one has what you are seeking. If you collect
in the field, rare is when you're lucky to find a species once in 2-3 years.
I don't think rare relates to presence in nature. Shells living in
difficult to reach locations or protected areas might be plentiful, but just
not available in the market place. As several people have commented here on
Conch-L, some very common shells are rarely offered by dealers. For
collectors who rely upon dealers, that makes them rare.
By "rare," most books mean the species is in a habitat difficult (or
unprofitable) to reach (or unknown) and few come to market. I guess "rare"
would also apply to those endemic species that are over collected to near
extinction or in locations like thermal vents that are virtually
inaccessible.
Marlo
merritt island, fl
Visit my website: Let's Talk Seashells
<http://s14.invisionfree.com/Conchologist_Forum/index.php?s=561483d184897208
19ac86b139d3e075&act=site>
Sent: Monday, October 13, 2008 4:25 PM
Hello
In any shell book, the words rare, common, abundant, etc., should they be
ignored? A rare shell might be rare until a large colony is found or
several colonies are found then it is common, right?
Jordan Star
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