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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Howard H. Whiteman</dc:contributor>
  <dc:contributor>G. B. Sparks</dc:contributor>
  <dc:contributor>G. L. Rouse</dc:contributor>
  <dc:contributor>W. S. Brown</dc:contributor>
  <dc:creator>Scott A Wissinger</dc:creator>
  <dc:date>1999</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;We conducted a series of field and laboratory experiments to determine the direct and indirect effects of a top predator, the tiger salamander (&lt;/span&gt;&lt;i&gt;Ambystoma tigrinum nebulosum&lt;/i&gt;&lt;span&gt;), on larvae of two species of limnephilid caddisflies (&lt;/span&gt;&lt;i&gt;Limnephilus externus&lt;/i&gt;&lt;span&gt;&amp;nbsp;and&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus nigriculus&lt;/i&gt;&lt;span&gt;) in subalpine wetlands in central Colorado.&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;larvae predominate in temporary wetlands and are aggressive intraguild predators on&amp;nbsp;&lt;/span&gt;&lt;i&gt;Limnephilus&lt;/i&gt;&lt;span&gt;&amp;nbsp;larvae, which only predominate in permanent basins with salamanders. We first conducted a field experiment in mesocosms (cattle tanks) to quantify the predatory effects of different life stages of salamanders on the two caddisfly species. Two life stages of the salamanders (larvae and paedomorphs) preferentially preyed on&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;relative to&amp;nbsp;&lt;/span&gt;&lt;i&gt;Limnephilus.&lt;/i&gt;&lt;span&gt;&amp;nbsp;Subsequent laboratory experiments revealed that high&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;activity rates and relatively ineffective antipredatory behaviors led to higher salamander detection and attack rates compared to&amp;nbsp;&lt;/span&gt;&lt;i&gt;Limnephilus.&lt;/i&gt;&lt;span&gt;&amp;nbsp;In a second field experiment (full factorial for presence and absence of each of the three species), we found that salamander predation on&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;had an indirect positive effect on&amp;nbsp;&lt;/span&gt;&lt;i&gt;Limnephilus&lt;/i&gt;&lt;span&gt;: survival was higher in the presence of salamanders +&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;than with just&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus.&lt;/i&gt;&lt;span&gt;&amp;nbsp;In the laboratory we compared the predatory effects of salamanders with and without their mouths sewn shut and found the observed indirect positive effect on&amp;nbsp;&lt;/span&gt;&lt;i&gt;Limnephilus&lt;/i&gt;&lt;span&gt;&amp;nbsp;survival to be mainly the result of reduced numbers of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;rather than salamander-induced changes in&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;behavior. We argue that indirect effects of predator–predator interactions on shared prey will be mainly density-mediated and not trait-mediated when one of the predators (in this case,&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;) is under strong selection for rapid growth and therefore does not modify foraging behaviors in response to the other predator. The reciprocal dominance of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Limnephilus&lt;/i&gt;&lt;span&gt;&amp;nbsp;and&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;in habitats with and without salamanders probably reflects a trade-off between competitive superiority and vulnerability to predation. The high activity levels and aggressiveness that enable&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;to complete development in temporary habitats result in strong asymmetric competition (via intraguild predation) with&amp;nbsp;&lt;/span&gt;&lt;i&gt;Limnephilus.&lt;/i&gt;&lt;span&gt;&amp;nbsp;In permanent habitats these same behaviors increase&amp;nbsp;&lt;/span&gt;&lt;i&gt;Asynarchus&lt;/i&gt;&lt;span&gt;&amp;nbsp;vulnerability to salamander predation, which indirectly benefits&amp;nbsp;&lt;/span&gt;&lt;i&gt;Limnephilus.&lt;/i&gt;&lt;span&gt;&amp;nbsp;This and previous work implicate salamanders as keystone predators that exert a major influence on the composition of benthic and planktonic assemblages in subalpine wetlands.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1890/0012-9658(1999)080[2102:FTOAAP]2.0.CO;2</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Ecological Society of America</dc:publisher>
  <dc:title>Foraging trade-offs along a predator-permanence gradient in subalpine wetlands</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>