I will definately check that out, and I agree that's about all that needs
discussed here. I also found some nice studies in forestry websearching on
Hill's Index (only 2 pages of google!) that may have applicability. My
advisor is helping me review their methods. I'm sure he can help me with
the rarefaction the same, it just hadn't occurred to him or he's not used
it. I'm certainly on a different path than the dead end I was at this
morning.
Dave, I think you're dead on... That's exactly what I'm getting into trouble
with, and it seems all about vernacular. Perhaps if I can iron out among my
lab what is being expressed in a word, I can get somewhere with this.
Probably wouldn't hurt me to draw it on the blackboard too, so I can see it.
This is excellent. Thanks so much for your help.
Okay, back to your regularly schedule NANFA programming....
Todd
----- Original Message -----
From: "Bruce Stallsmith" <fundulus at hotmail.com>
To: <nanfa-l at nanfa.org>
Sent: Thursday, September 29, 2005 1:16 PM
Subject: Re: NANFA-L-- Diversity Indicies
> Since I'm the kinda geek who likes haggling over statistics, allow me to
> suggest that you use rarefaction to compare species composition between
> communities if you have unequal sample sizes. I won't try to descibe it
> here. But look for the original description of this approach in: Hurlbert,
> S. H. (1971) The non-concept of species diversity: A critique and
> alternative parameters. Ecology 52: 577-586. Hurlbert has pissed off lots
of
> people with his bluntness, but since he's pretty much right and can
> demonstrate why, his criticisms are important and useful.
>
> --Bruce Stallsmith
> along the Tennessee
> Huntsville, AL, US of A
>
> >From: "Todd D. Crail" <tcrail at UTNet.UToledo.Edu>
> >Reply-To: nanfa-l at nanfa.org
> >To: <nanfa-l at nanfa.org>
> >Subject: Re: NANFA-L-- Diversity Indicies
> >Date: Thu, 29 Sep 2005 12:44:56 -0400
> >
> >Yeah IBI isn't going to work. I didn't describe my situation very well,
> >sorry about the argument there.
> >
> >So if I'm understanding what I'm reading about Hill's, it will account
for
> >the discrepantcy in the biomass? I'm just looking for a simple way to
> >compare multiple yet similar sites within a watershed, using the fish
> >community sampled as the response variable.
> >
> >The problem I'm running into is something like this:
> >
> >One of my sites consisted of:
> >bluntnose(13)
> >fathead(15)
> >green sunfish(1)
> >least darter(95)
> >johnny(4)
> >orangethroat(24)
> >
> >If I caluculate Simpsons on that site alone, I get 1.15, in part, because
> >least darter are so proportionately more represented than other species
> >when
> >you compare it to another replicate site:
> >
> >bluntnose(4)
> >fathead (1)
> >johnny(3)
> >least(2)
> >
> >...which comes out 1.28.
> >
> >The second site is more "diverse"? It's definately more even, but
c'mmon!
> >And we also loose the fact the least darter is a large proportion of the
> >individuals found at the first site, and more aggrivatingly, is a SSC
fish.
> >The whole diversity issue irons out when all the replicates are taken in
> >consideration, but I'd rather drive my point home with a hammer, rather
> >than
> >some feather-like p value that doesn't make any sense to anyone besides
the
> >0.05% I work with lol.
> >
> >What I'd really like to do is find a way to compare each site against the
> >whole of the sample, where each replicate receives a score against the
> >whole. I would think there'd be some way to compare stream segments
along
> >a
> >gradient (perhaps by stream order?) but I guess everyone has been too
busy
> >counting mayflies and snails they can't speciate to look at something
> >easier
> >to identify, like fish.
> >
> >I dunno. I dunno if this works for on-list traffic either. I guess I
> >rationalize it that if there isn't an easy way to compare parts of
streams
> >by a response variable such as fish community, then the NANFA list is
> >making
> >something useful and doesn't require understanding how greek symbols
relate
> >to each other to figure out if part of a stream fares better than another
> >part of the same system. It sure seems can't voice my opinion here at
> >school... Apparently masters students are to only be seen and not heard.
> >Oh
> >bondage... {obscure x-ray specs reference}
> >
> >Thanks for your help and continued tolerance :)
> >Todd
> >Madness!
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> / visit http://www.nanfa.org Please make sure all posts to nanfa-l are
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/ This is the discussion list of the North American Native Fishes
/ Association (NANFA). Comments made on this list do not necessarily
/ reflect the beliefs or goals of NANFA. For more information about NANFA,
/ visit http://www.nanfa.org Please make sure all posts to nanfa-l are
/ consistent with the guidelines as per
/ http://www.nanfa.org/guidelines.shtml To subscribe, unsubscribe, or get
/ help, visit the NANFA email list home page and archive at
/ http://www.nanfa.org/email.shtml