BILL, et al. . . .
If "empty niche" is an invalid concept (according to Hutchinsonians),
I've always wondered how House Finches, Carpodacus mexicanus--a
western species released on Long Island NY in 1940-41--were able to
spread so rapidly they now breed across the entire eastern U.S. and
the population has met its western conspecifics in western Nebraska.
Eastern House Finches often nest on human-built structures (and in
hanging baskets) and eat inordinate amounts of sunflower seeds we
provide.
House Finches seem not to have displaced native eastern species.
The same question might be asked about the Cattle Egret, Bubulcus
ibis, an African-Asian native that apparently showed up on its own in
Florida in 1953 and now breeds nearly throughout the U.S. and
southern Canada. In North America, Cattle Egrets often hang out in
conjunction with people and their domesticated livestock, feeding on
very large insects stirred up by cattle, sheep, and horses.
Cheers,
BILL
===========
The niche is a flexible concept and I think that trying to come up
with a precise definition is pointless. Hutchinson had a very formal
definition relating environmental conditions to the persistence of a
population, which has been widely adopted even though the
environmental conditions usually represent a transient situation and
persistence is of course long term. Strict Hutchinsonians abhor such
useful concepts as the "empty niche", an attitude which I find to be
an annoyance and a nuisance. Fenchel and Christiansen wrote a nice
book on niche theory with some useful material on niche packing. The
late Rob Peters did his best to make the concept useless by his
attacks on Gauss' Competitive Exclusion Principle.
It is a very useful concept, but efforts to be precise and rigorous
have discouraged its use.
Bill Silvert
----- Original Message ----- From: "malcolm McCallum"
<malcolm.mccal...@herpconbio.org>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Monday, August 10, 2009 3:57 AM
Subject: Re: [ECOLOG-L] Ecology Terms Definition Niche
when I have a niche I scratch it! :)
there are many different niche definitions.
Here is what I use in Ecology:
fundamental niche: the theoretical maximum resources that could be
used by a population.
Realized niche: the actual resources that are used by a population.
there is also a functional niche that comes out of functional ecology.
On Sat, Aug 8, 2009 at 5:51 PM, Wayne Tyson<landr...@cox.net> wrote:
All:
What is your definition of niche?
WT
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