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Team, greetings from OSU. here's some comments that might relate
to the discussion. I think that the stream diatoms are diverse
because there are many "niches" to fill, ranging from the tolerance
of dessication for years at time (such as the species that are
dominant in Wormherder Creek), to vulnerability to removal by scour,
and to nutrient requirements for N, P and Si. For nutrients
accessible by the mats in the streams, there is actually variability
at the patch scale due to hyporheic upwelling and downwelling and
with time due to flow regime influences on solute concentrations.
Tyler's experiments with the nutrient diffusing substrates in the
streams show significant nutrient effects. <br>
<br>
This more dynamic and chemically variable habitat as a driver for
diversity would be consistent with the 2 fold higher species
richness for diatoms in stream matgs compared to diatoms in the more
stable pond and lake mats. <br>
<br>
Cheers Diane<br>
<br>
<div class="moz-cite-prefix">On 9/16/2015 10:29 AM, Priscu, John
wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Viruses
or fungi would also be my guess. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
lakes are stable on a large scale, but if they were stable
at the niche scale for microorganisms, then we should have
competitive exclusion—given the almost monospecific layering
of phytoplankton in the lakes, perhaps we do—but not sure
how to explain the bacterial diversity; maybe small scale
differences in the flavor of DOC? The MCM system definitely
pushes the limits of typical ecological paradigms that are
used to assess diversity, stability and resilience.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">JP<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
John Barrett [<a class="moz-txt-link-freetext" href="mailto:jebarre@vt.edu">mailto:jebarre@vt.edu</a>] <br>
<b>Sent:</b> Wednesday, September 16, 2015 10:22 AM<br>
<b>To:</b> Priscu, John<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:mcm-pi@lists.lternet.edu">mcm-pi@lists.lternet.edu</a><br>
<b>Subject:</b> Re: [LTER-mcm-pi] 5 min gem for the week<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">Wow, that's uncanny John. I was just
using the paradox of the plankton in discussion with my grad
students. <o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
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<div>
<p class="MsoNormal">My guess would be viruses to explain
diversity in lakes. They are otherwise too stable - unless
we can invoke flood years as a physical disruption that
offsets competative exclusion. Are there data in the cool
years to show decreases in diversity? That would be a test
of whether floods acted to upset equilibrium in species
composition.<o:p></o:p></p>
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<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On Wed, Sep 16, 2015 at 12:15 PM,
Priscu, John <<a moz-do-not-send="true"
href="mailto:jpriscu@montana.edu" target="_blank">jpriscu@montana.edu</a>>
wrote:<o:p></o:p></p>
<div>
<div>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Sorry
that I missed the call yesterday—didn’t get home from
Europe until midnight and was not well organized—in
other words, I forgot about the call.<o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Here
would be my gem for the week: So, where does the MCM
fit into Terborgh’s scheme? We have few predators (I
think we do—at least for the lakes), yet biodiversity
is relatively high. What replaces predators in our
system—Viruses? physical disruption? Maybe physical
disruption occurs faster than competitive exclusion,
maintaining high diversity? This kind of
contemporaneous disequilibrium has been proposed by
Richerson et al. 1970 (attached) [Richerson was the
chair of my grad committee].<o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">JP<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
_______________________________________________<br>
Long Term Ecological Research Network<br>
mcm-pi mailing list<br>
<a moz-do-not-send="true" href="mailto:mcm-pi@lternet.edu">mcm-pi@lternet.edu</a><o:p></o:p></p>
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<p class="MsoNormal"><br>
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<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<p class="MsoNormal">-- <o:p></o:p></p>
<div>
<div>
<p class="MsoNormal">J. E. Barrett, Ph.D.<br>
Associate Professor<br>
2125 Derring Hall<br>
Department of Biological Sciences<br>
Virginia Tech<br>
Blacksburg VA, 24061<o:p></o:p></p>
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<pre class="moz-signature" cols="72">--
Diane McKnight
INSTAAR
1560 30th Street
Boulder, CO 80309
phone: 303 492-4687, fax 303 492-6388, cellphone 857 998-1926
<a class="moz-txt-link-freetext" href="http://huey.Colorado.EDU/~mcknight/CV/index.html">http://huey.Colorado.EDU/~mcknight/CV/index.html</a>
I have two offices and may not log on to email regularly through the day. Please call or use "urgent" header on topics requiring immediate attention.
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