Thursday, May 29, 2008 - 4:00 PM
606

Comparison of historical and contemporary biodiversity of Minnesota caddisflies (insecta: trichoptera)

David C. Houghton, Biology, Hillsdale College, 33 East College Street, Hillsdale, MI 49242

The biological diversity reflected by nearly 300,000 caddisfly specimens collected from 294 localities throughout Minnesota since 1985 was compared with that of the 25,000 specimens recorded prior to 1950.  Biological diversity was analyzed based on the 5 “caddisfly regions” of Minnesota.  In the Lake Superior, Northern, and Southeastern regions, over 90% of species known historically from each region were recovered, and additional species were discovered.  In the Northwestern and Southern regions — the most disturbed regions of Minnesota — species recovery ranged 60–70%.  Historical and contemporary caddisfly assemblages were similar to each other in the former three regions as determined by a UPGMA algorithm, and noticeably different in the latter two regions.  Prior to 1950, all functional groups were abundant in all regions.  A similar pattern still exists in the Lake Superior, Northern, and Southeastern regions, whereas the Northwestern and Southern regions are now dominated by filtering collectors.  Over 65% of all species apparently extirpated from any region were in the long-lived families Limnephilidae and Phryganeidae, and 70% of the same species were in the shredder functional group.  Two conspicuous and common species prior to 1950, Agrypnia glacialis and Anabolia sordida (Phryganeidae), appear to be extirpated from the entire state, and an additional common species, Limnephilus secludens (Limnephilidae), is known only from a single specimen since 1985.  This study suggests that biological diversity of Minnesota caddisflies has been seriously reduced in at least the Northwestern and Southern regions of the state.


Web Page: Trichoptera, Extinction, Minnesota

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