Evolution in a Glaciated Landscape: Contribution of Endemism to Great Lakes Biodiversity
Hamilton, K. G. Andrew .
Phytophagous Insects: Evidence for the Development of Great Lakes Ecosystems.
Cicadas, leafhoppers, planthoppers, spittle bugs and treehoppers (Homoptera Auchenorrhyncha) are phytophagous insects that mostly are not widely dispersing and often show great fidelity to particular host plants (commonly grasses, sedges, shrubs and trees). The high degree of monophagy exhibited by this group can be traced through the evolutionary history of whole genera such as Flexamia, showing that insect-plant associations persist for hundreds of thousands (or perhaps millions) of years. The plant-insect patterns thus reveal a great amount of information on the prehistoric development of ecosystems such as those endemic to the Great Lakes region. Twelve species of Auchenorrhyncha are entirely endemic to the vicinity of the Great Lakes (between the head of Lake Superior and Lake Champlain), and another 64 such bugs represent incipient species or disjunct populations from ecosystems now remote from this part of the continent, mainly prairies. These 76 species amount to approximately 10% of the entire fauna of these bugs in this region. The greatest number of these species is found only on sandy sites (22 species). Alvars have another 16 such species, while six species are found on both alvars and sandy sites. Fifteen other species are found in swales and fens (often in association with alvars) and another four species live on bogs; one other species inhabits both bogs and sandy sites. The presence of flightless leafhoppers on alvar-adapted plants on islands of known age shows that an alvar flora and fauna was established in Lake Huron at least 9000 years ago when the ice front had retreated only about 300 km to the north. The present distribution of Great Lakes endemic insects and their host associations thus verifies the conjecture of a Pleistocene periglacial grassland and gives evidence of its extent and floristic composition.
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1 - Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Centre, 960 Carling Avenue, Ottawa, Ontario, K1A 0C6, Canada
Presentation Type: Symposium or Colloquium Presentation
Location: Boulevard A/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:15 AM