2007 GSA Denver Annual Meeting (28–31 October 2007)

Paper No. 15
Presentation Time: 5:00 PM

SEASONALITY AND THE LATITUDINAL GRADIENT OF DIVERSITY: THE EOCENE INSECT PERSPECTIVE


ARCHIBALD, S. Bruce, Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada, BOSSERT, William H., Department of Organismic and Evolutionary Biology and School of Engineering and Applied Science, Harvard University, Maxwell-Dworkin, Room 135, 33 Oxford St, Cambridge, MA 02138, GREENWOOD, David R., Zoology Dept, Brandon University, 270 18th St, Brandon, MB R7A 6A9, Canada and FARRELL, Brian D., Department of Organismic and Evolutionary Biology, Harvard University, Museum of Comparative Zoology, 26 Oxford St, Cambridge, MA 02138, barchibald@oeb.harvard.edu

We test the hypothesis that the latitudinal gradient of species diversity is more a function of difference in temperature seasonality than mean annual temperature. We compare insect species diversity in cool mean annual temperature, highly seasonal Harvard Forest, Massachusetts, USA; high mean annual temperature, seasonally equable La Selva, Costa Rica; and cool mean annual temperature, seasonally equable Eocene McAbee, British Columbia, Canada. Insect diversity in the Eocene sample is more similar to that of La Selva than Harvard Forest in increased species richness of most groups and in decreased diversity of Ichneumonidae. This implies that latitudinal patterns of species diversity, including high tropical species richness, are associated with differential temperature seasonality rather than mean annual temperature, a climatic regime established after the Eocene.