2009 Portland GSA Annual Meeting (18-21 October 2009)
Paper No. 219-12
Presentation Time: 10:45 AM-11:00 AM


ARCHIBALD, S. Bruce1, MATHEWES, Rolf W.1, and GREENWOOD, David2, (1) Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada, sba48@sfu.ca, (2) Brandon Univ, Brandon, MB R7A 6A9, Canada

Climatic factors and species diversity notably co-vary with latitude in the modern world. However, both mean annual temperature and cold month mean temperature have been shown to have had a much shallower latitudinal gradient in the Eocene, and various paleontological data have also shown much higher Eocene alpha diversity at middle and high latitudes. Here, we examine Eocene beta diversity. Just over four decades ago, Janzen hypothesized a relationship between modern beta diversity, topography, climate, and latitude in the evocatively titled paper: Why mountain passes are higher in the tropics (1967). He proposed that while warm valleys and cool mountain passes in seasonal temperate regions would have a temperature overlap at least part of the year, allowing dispersal of animals adapted to valley climates, the same elevation difference in the equable tropics would share no common temperatures over a year, and would then constitute a physiological dispersal barrier resulting in increased beta diversity. By this model, uplands in the globally less seasonal Eocene should have had high beta diversity even in higher latitudes. We test this with fossil insect beta diversity between localities across a thousand kilometer transect of the Early Eocene Okanagan Highlands of southern British Columbia, Canada and northern Washington, USA, and present our preliminary results.

2009 Portland GSA Annual Meeting (18-21 October 2009)
General Information for this Meeting
Session No. 219
Paleontology: Environment & Evolution
Oregon Convention Center: Portland Ballroom 256
8:00 AM-12:00 PM, Wednesday, 21 October 2009

Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 561

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